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1585848076Standard_Methods_of_Detailing_Structural_Concrete_2nd_Edition.pdf
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Analyze this page with diagrams, tables, formulas, calculations, and explanations.
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[OCR TEXT]
5.2.11.2 General recommendations for bar curtailments in slabs (clause 3.12.9.1+)
Face of support
—M support
Ta min
Top bars shown
42 LapTO SUIT staggered.
Bottom bars shown
alternate.
END SPAN INTERNAL SPAN
Key Ta= Tension Anchorage Length E = Effective End Anchorage required
N = Nominal 12g or d (effective depth) if simple support
whichever is the greater & = Bar nominal size
5.2.11.3 End anchorage alternatives based on BS 8110: general recommendations (3.12.9.4+)
Simply supported ends
(a) straight bars in bottom (b) bent bars in bottom
39 for R bars
W3 or 30mm, whichever greater 4@ forT bars up to T20
either (i) providing shear stress at face 56 for T bars over T20
i i lue.
or (ii) 126 is less than ¥2 appropriate value (i) standard bend past ¢
or (iii) 126+ Yo or (ii) std. bend +42
Restrained ends
(a) U-bars in top (b) U-bars extended (c) ‘trombone’ bars (d) L-bars in top
!
Ta F 1a F 1 F Ta F
lap
1
Consider non - std.
_ . . . radius if vertical
Key F = Face of vertical bar in restraining member leg >8
Ta= Tension Anchorage Length
5.2.11.4 Tie provision (internal and/or peripheral)
(3.12.3+)
Ensure that any reinforcement specified for stability ties is
effectively continuous by lapping and/or anchoring as
necessary.
38 TStructE Detailing Manual
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Table 15 Minimum tension reinforcement in slabs
Spacing of minimum tension reinforcement
(3.12.5.2.)+ Table 3.27
=a
F, = 460N/mm? b = 1000 F, = 250N/mm? b = 1000
0.13% bh rt 0.24% bh 0.18% flLh
(both directions) jr + (both directions) pn 9 (across flanged beams)
bar nominal size, mm bar nominal size, mm bar nominal size, mm
8 10 12 16 ath 8 10 12 16 ab, 8 10 12 16
pitch, mm {mm pitch, mm mm pitch, mm
a 200 100 200 200 100 200 200
300 300 125 150 250 300 125 275 300
250 375 375 150 125 200 300 375 150 225 350
+
200 300 450 175 100 175 250 450 175 175 300 400
175 300 400 200 150 225 400 200 150 250 350
150 250 350 225 125 200 350 225 150 225 300
150 200 300 250 125 175 300 250 125 200 300
125 200 250 500 300 100 150 250 300 100 175 250 400
100 150 | 250 400 350 125 225 350 150 | 200 350
150 200 375 400 100 200 400 125 175 300
100 175 300 500 150 500 100 150 250
Note: The above chart is not applicable to water-retaining structures.
Table 16 Maximum spacing of tension bars in slabs (3.12.11.2.7+)
(a) In all cases, maximum spacing not to exceed the lesser of 3d or 750mm
Normal cracking controlled using following rules:
(b) Fy = 250, maximum slab depth = 250mm
(c) Fy = 460, maximum slab depth = 200mm
(d) Ag < 0.3% bd
(e) When A, = 0.3 > 1.0% bd limit bar spacing to value from Table below
% reinforcement
(f) When A, > 1% bh use appropriate spacing (mm) from Table below
Spacing of bars according to % redistribution
Ymoment to or from section considered
fy —30 | —25 —20 15 —10 0 +10 +15 +20 +25 +30
250 210 225 240 255 270 300 300 300 300 300 300 Jc o
460 | 115 120 130 135 145 160 180 | 185 195 | 200 210 oof
Note: If % moment redistribution unknown assume (—15) at supports. (0) for span (3.12.11.2.8)
5.2.20 Detailing
5.2.21 Methods of detailing slabs
There are several techniques possible for detailing slabs —
choice perhaps depending on the size of the project, its
complexity and the degree of panel repetition. Normally
the concrete profile dimensions are abstracted from the
relevant general-arrangement drawings. These together
with the calculations should be at their final stage before
commencing the detailing stage.
5.2.21.1 Combined top and bottom reinforcement
(a) Multipanels
Prepare concrete profiles from the general-
arrangement drawing to a suitable scale, usually 1:50.
Identify similar panel types, and detail bottom then top
reinforcement for each different panel type. Large
floors may spread over several drawings linked by key
plans.
IStructE Detailing Manual
(b) Unit panels
Similar to clause 5.2.21.1a, but different panel types
are identified and drawn as single panels linked by key
plan. Method particularly flexible when panel types
repeat throughout a job. Adjacent panel reinforce-
ment should be carefully coordinated.
5.2.21.2 Separate top and bottom reinforcement
Useful when detailing fabric or when the reinforcement is
very complicated. Top and bottom reinforcement is sepa-
rated for clarity and drawn onto two identical outlines,
preferably on the same drawing. Suitable instructions
should ensure that these separate layers are constructed
together.
59
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5.2.21.3 Tabular method
Combinations of informa-
tion such as bar mark, bar
type and size, bar pitch, etc.
can be scheduled alongside
the detail. This will tend to
reduce congestion on the drawing and improve checking
procedures, computer methods and the work of the
quantity surveyor Each typical bar should be identified on
the drawing by its bar mark and bar layer (see clauses
5.2.22.1 and 5.2.34 example.)
etc.
5.2.21.4 Computer methods
Where drawings are produced fully or partly by computer
graphics the method of preparation and presentation
should follow standard principles wherever possible.
5.2.22 Bar detailing on slabs
5.2.22.1 On plan
(a) Locating layers of reinforcement
Reinforcement is fixed in layers starting from the
bottom of the slab upwards and bar marks should
preferably follow a similar sequence of numbering.
Notation is as follows:
(i) abbreviation for T2 T) 12
top outer layer Tl
(ii) abbreviation for 7 Cd
top second layer Teg ers
(iii) abbreviation for
bottom second layer B2 BI 82 31
(iv) abbreviation for bottom outer layer Bl
Note: Repeat this sketch on cach relevant drawing for clarity and presentation.
(b) Typical bar and indicator line
Generally each bar mark is represented on plan by a
typical bar drawn to scale, using a thick line. The bar is
positioned approximately midway along its indicator
line, the junction highlighted by a large dot. The first
and last bars in a zone of several bars are represented
by short thick lines, their extent indicated by arrow-
heads.
Bends or hooks, when they occur at either end of the
typical bar are represented by a medium dot or similar
(i) one bar only 1T10-63-T1
2T10-63-150TI
(ii) two bars
(iii) a zone of three or more bars
20T 10-63-150T 1
hes
(iv) multiple zones, showing
similar marks in each zone, (2) (8)
with quantities indicated in
brackets
20T10-63-150T1t
63 64
(v) multiple zones,
showing 12T10-63-150T!
dissimilar marks in each
zone 8T20-64-200T1
Generally the “calling up’ of bars is located at the
periphery of the detail on an extension of the indicator
line, as shown above.
(vi) when space is restricted
‘calling up’ can be writ-
ten within the zone of the
indicator line, or in ex-
treme cases:
20T10-63
20710-63] 1s0T1
Stg.
63
1$0T1
(vii) written along the bar it-
self
(viii) instructions to stagger
bars of same mark
(ix) instructions to alternate
bars of different mark
(c) Bars detailed ‘elsewhere’ are shown as
a thick dashed line
(d) Bars set out from a radius in a ‘fan’
zone
The indicator line can be located on a
datum radius for measuring the pitch
of the bars. Locate end of bars to
datum.
wor
x
(e) Bars of varying length in a zone
Each bar in the zone is
iven the same bar mark
ut a different suffix, be-
ginning with ‘a’. The bar
schedule will allocate
different bar lengths to
each suffix as appropriate.
207 10-63 (a to v)-150}T1
(f) Bars in long panels
To simplify the ‘calling
up’ of strings of bars in
very long panels, e.g.
distribution bars in one-
way slabs, identical
bars of a convenient
length can be lapped
from end to end of the
panel. State minimum
lap. The use of random
length bars is not re-
commended.
3x8T10 -63-
(g) Cranked and bent bars
These are sometimes, for 63
convenience, drawn on
plan as though laid flat. 64 TAlt
However, confusion on
site can result if some of
these bars are required to be fixed flat and some
upright. Sections and notes should be provided to
clarify this method if used.
(h) Fixing dimensions
Dimensions (mm) are res- |
tricted to those required by
the steel-fixer to locate bars
not already controlled by end
covers. Dimension lines are
thin lines terminated by short |
obliques.
1750
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5.2.22.2 In section — drawn where required to clarify
the fixing
(a) Bars in elevation are repre-
sented by thick line with mark
indicator. 64
First and last bars in a zone are 63
indicated by a dot in section with
appropriate mark.
(c) Curtailed bars are identified by
short 30° obliques with 2 3
appropriate mark. If congested 2
clarify ends with pointers.
(b
Zz
5.2.23 Other requirements for slabs
5.2.23.1 Special notes for slabs
In addition to standard notes for reinforcement drawings
(see subsection 2.8) the following note should appear on all
slab drawings:
(a) Cover to outer reinforcement: B1...T1...end...
(b) Bar layer notation: top outer layer Tl
top second layer T2
bottom second layer B2
bottom outer Bl
5.2.23.2 Chairs and spacers
Chairs support the top reinforcement. Where specified,
traditional bent chairs of shape code 83 should be
scheduled using the following guidelines:
(a) bar size for slab less than 200mm thick — 10mm
(b) bar size for slab greater than 200mm thick — 12mm
minimum.
(c) location within panel — along periphery of 0.1 span
(d) additional location for flat slab — along interior
supports
(e) spacing of chairs (and spacers) — 1000mm.
The bottomlayer is generally supported from the deck by
plastic or concrete-block spacers selected to provide the
appropriate concrete cover. For more comprehensive
information concerning chairs and spacers, see Section 6.
5.2.23.3 Trimming of holes in slabs
(a) Where holes, or groups of holes are considered to be of
structural significance (i.e. in flat slabs, etc.), the
design data should indicate any special reinforcement.
(b) Where holes, or groups of holes are considered to be
Structurally insignificant, then the following rules
apply:
(i) minimum Ww)
unsupported
edge distance =
width of hole w,
(ii) maximum width
of isolated
opening
measured at
tight-angles to
span = 1000
(ili) maximum length
of isolated
opening
measured
parallel to span =
0.25 span (x
(iv) maximum total width (w,;+w2+ws) of multiple
holes measured at right-angles to the span /, =
0.25 span /,
(v) small isolated holes with sides 150mm or less can
generally be ignored structurally. Significant
holes should be drawn to scale and shown on the
reinforcement drawing.
IStructE Detailing Manual
(vi) larger isolated holes with sides 500mm or less
either:
displace affected bars
equally either side of hole,
provided that resultant
spacing does not exceed
the values shown in
Tables 15 and 16.
or:
cut or slide back affected
bars to face of hole. Com-
pensating bars of equal
area should be provided
to trim all sides.
Trimmers should extend a
minimum 45@ (nominal
anchorage length) beyond
the hole.
(vii) large isolated holes
with sides (500-
1000)mm
Treat as (vi) above,
but in addition trim
top of holes with
similar bars. If depth
of slab exceeds
250mm, provide di-
agonal reinforce-
ment of similar area
in top and bottom,
but
consideration should be given to the congestion
of multiple layers.
(viii) groups of
holes within
boundary of
500mm or
less
Trim as
single hole
using
methods
described in
(vi) above.
Bars should
pass
alongside holes where possible.
(ix) groups of holes within boundary of (500-
1000)mm or less
Trim as single hole using methods described in
(vi) and (vii) above.
61
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5.2.24 Shear reinforcement in slabs (where minimum 5.2.26 Fabric reinforcement in slabs
depth = 200mm) (3.5.5.3+) Table 3.177
Generally provided by vertical links which also serve as
chairs.
5.2.24.1 Flat slabs (3.7.6+)
(a) Column shear heads
G.7.7.54)
(i) A minimum of 2
shear perimeters 8
are spaced at 0.75d
from face of column
(ii) Vertical shear legs &
are shape code 81 °
(2 legs) or shape
code 85 (1 leg)
spaced at a
maximum of 1.5d
around each
perimeter
(iii) Links can be threaded onto say T12 lacer bars to
form convenient ‘ladders’ which are fixed along
side the B2 then T2 layers of slab reinforcement.
This detail also ensures that adequate cover to
links is achieved.
(b) Column drops
(i) Main slab
reinforcement
carries through
(ii) Nominal mat:
T12 at 300
each way
Design data to specify
other
Alternatively, consider the use of fabric in these regions
(see subsection 2.6)
§.2.25 Torsion reinforcement in restrained slabs
(3.5.3.5f)
5.2.25.1 At corners (2 discontinuous edges, both
simple supports)
(a) Torsion
reinforcement
required top
and bottom.
Gross area
required = 0.75 x
maximum A, span
bottom each way
in both top and
bottom.
(c) Extent of torsion bars = 0.2 X shorter span.
(b)
62
(a) General
Two-directional reinforcement can be factory welded
and fabricated into sheets to help speed fixing and
achieve economy in construction costs. BS 4466:1981
defines three types of fabric:
(i) Designated (standard mesh) fabric — see Tables,
Section 3.
Stock sheet sizes are 4.8 X 2.4m; these can be
reduced by cutting to suit. Wire sizes range up to
12mm with standard 100/200mm meshes.
Peripheral wires are welded at 2 pitch from the
edge of the sheet.
(ii) Scheduled (non-standard) fabric
Wire sizes (maximum 12mm) and sheet sizes can
be varied. Wire pitches must remain constant but
may be non-standard. Wire projections at edges
may vary.
(iii) Detailed (purpose-made) fabric
These sheets can be specified using standard
reinforcing bars. These bars can be set at varying
pitches and edge projections. Sheet sizes can vary
with due consideration given to handling and
transportation.
All fabrics can be bent to most BS shapes. However, ensure
that redundant cross-wires do not inhibit fixing. These
wires can be eliminated by specifying purpose-made fabric.
For further guidance consult the manufacturers of fabric.
(b) Suspended solid floor construction
For clarity on plan it is recommended that the top
sheets of fabric be drawn separately from the bottom
sheets, preferably on the same drawing. Fabric is
identified by a chain double-dashed line.
(i) Fabric detailing on plan. Each
individual sheet is given a mark
number and related on plan to the
concrete outline.
Indicate the \ |
direction of the &
main reinforcement 1 oN t
and its layer notation. n\\|
Wherever multiple sheets LT.
of identical marks occur
they can be combined as
shown.
Areas of reinforcement
can be increased TI
by double ‘layering’.
13
Also consider the main
possible advantages of
‘nesting’ the two sheets B2
to maximize the lever arm.
main
Similarly ‘nesting’ when
main steel is required Ti
in two directions, T2
crossing at 90°.
Structural mesh type ‘B’ is often specified for
suspended slabs, possibly with the addition of
loose bars. With reasonable production runs, con-
sideration should be given to specifying ‘purpose-
made’ fabric. For each fabric mark indicate its
reinforcement in a table alongside the plan. Mini-
mum reinforcement requirements are shown in
Table 15.
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(c)
(d)
(ii) Laps in fabric
The need for laps
should be kept to a
minimum and, where
required, should be
located away from
regions of high tensile t
force. Allow sufficient
clearance to a
accommodate any ~
‘multi-layering’ of
sheets at laps,
reducing these 3 sheets lap.
occurrences
where possible by 2 sheets lap
‘staggering’ sheets.
Show lap dimensions on plan and/or indicate
minimum lap requirements in a note on the
drawing. Minimum laps are required to prevent
cracks caused by secondary stresses. Explanatory
notes and Tables of lap lengths for welded fabric
are given in Appendix 3B.
Voided-slab construction
A nominal designated fabric is normally placed within
the topping of trough and waffle-type floors. The
extent of the fabric is shown by a diagonal on the plan
of the reinforcement drawing and the fabric type
scheduled as gross area in m? by adding a suitable per-
centage to the net area of the floor to allow for laps. For
ordering purposes, the contractor should translate this
gross area into the quantity of sheets required to suit
his method of working. Where more comprehensive
detailing of fabric sheets is required refer to clause
5.2.26a.
Ground-slab construction
The presence of fabric reinforcement can be indicated
by a sketch and a prominent note on the drawing. This
can be the general-arrangement drawing (in straight-
forward cases.) The note should include type of fabric,
location within the depth of slab and mini-
mum lap requirements. A typical section to
clarify this construction should be included.
The fabric type is scheduled as a gross area by
adding a suitable percentage to the net area
of slab to allow for laps. For ordering pur-
poses, the contractor should translate this
gross area into the quantity of sheets required to suit
his method of working. Where more comprehensive
detailing of fabric sheet is required, refer to subclause
5.2.26(a).
IStructE Detailing Manual
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5.2.30 Examples of detailing
5.2.31 Typical one-way spanning slab
8T10-7-200 T1
37716-6-200T) 447 20-8-125 T) stg
20T 10-4-200 T2 stg .
10 T10-S-200 T2
-
Al 150
20T10-3-200 B2
supports
sls 19T20-1] 200 Bi
drg $7 18T20-2} alt
PLAN Cover T1=20
(@) B1= 20
End= 40
6 8 stg : Staggered
alt: Alternate
IStructE Detailing Manual 65
[FORMULAS]
End= 40
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5.2.32 Typical ribbed-slab panel
17R Baal 300
178-13) FANS 17 8-14-30 links
10T16-6-T2 10T10-7-T2 10T25-8-T2 stg
2 per rib 2 per rib 2 per rib.
See
drg B11
© oH - - Zt
PL tL | + al ||
~
I é | 3T25-9-T1 stg.
Mel ft Tt per
8T 25-10-125 T1 stg.
1550
1325
PL
iT | [tty oy NT TE 4
2000
Pa
PC
sit | [s|
n T V
6112-11250 ely S —
tea ote
iT _| ao ,—_____
A | - fa
61 20-1-125 BI stg 1 L
3T25-2-B1 stg. 27 25-3-B) stg.
1 per rib |
z 1
!
rey
z
w
L_4
be CC CO
¢ cols.
| |
4
3 [7
wo
See ¢ $T20-4] B2 alt
drgS8 oeée12 8120-5) 2pertib.
(m) PLAN (N) Cover T1235
Bi=25
End=40
n stg : Staggered
b 6 fabric 8 alt : Alternate
6 IStructE Detailing Manual
[FORMULAS]
End=40
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5.2.33 Typical flat-slab panel
16112 -9-250T2
12T 20- 7-200
12725-10-200
12 |r stg
18T12 -8- 200 15716 -11-250
®
8T16-13-250
Tis
12725-12-175
2000
9T12-14-250 T1
tt |
* ela dll M
ars th ie Jere (4+5) (3+3)
111 25- 21 on @175
cols.
ll
See 6125-3
an siol BT 25-4 1200 B2alt.
10T 20-5 Cover T1=30
175 B2alt.
PLAN 107 20-64 B1= 25
End= 40
stg: Staggered
8 " 99
alt : Alternate
iB)
IStructE Detailing Manual 67
[FORMULAS]
End= 40
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5.2.34 Typical flat-slab panel (tabular method)
PLAN
Fixing information
Layer- Pitch (mm)
¢ cols
M« | Type/size | No.bars |] Layer-Pitch(mm) | M< | Type/size | No.bars
BI m5 |---| 725 7 || t2 200 |-9-| T12
250 |-2-] 125 9 250 |-10-| T12
ws | -3-] 125 6 200 |-n-| 12s
4-| 125 343 250 | -12-| 116
B2 200
rts -| 125 343 aa] 750 |-13-| 725
-| 4 -14-
"5 ts 20 10 250 1% T16
7-1 720 10 175 |-18-] 125
T2 200 |-8-| 120 6+6 250 |-16-| 112
Cover T1=30
Bi = 25
End=40
stg : Staggered
alt : Alternate
IStructE Detailing Manual
[FORMULAS]
Bi = 25; End=40
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[OCR TEXT]
5.2.35 Typical flat-slab panel showing fabric reinforcement
ut fabric to
uit hole.
PART PLAN-
BOTTOM FABRIC
+BARS
IStructE Detailing Manual
PART PLAN-
TOP FABRIC
PT type [Main [Secondary
712 e 100
T8 @ 200
T12e@ 150
T16e@ 150
Cover: T1 = 20
Bi = 15
End = 40
Min lap = 250
69
[FORMULAS]
T1 = 20; Bi = 15; End = 40
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[OCR TEXT]
5.3 COLUMNS
5.3.10 Design information
These data are output from the approved calculations for
each column type and should indicate:
(a) General
(i) concrete grade to determine laps, durability,
ete.
(ii) cover requirements to vertical bars or links
Wy type of reinforcement and any size restrictions
iv) required area and distribution of main vertical
bars A,.(mm7) or preferred actual type/size, and
location
(v) kicker height, otherwise assumed as 75mm
(vi) state lap length requirements at column splices
and whether tension or compression
(vii) state link type/size and pitch otherwise assumed
to be as code requirements, see below, also Table
17
(viii) any special requirements.
Type'A’
Summary of column calculations
For convenience and simplicity it is often pos-
sible to rationalize similar reinforcement areas/
type, size and location:
For example, these can be summarized at the
end of the calculations as columns - reinforce-
ment types A, B, etc. Mark their location on
Asc
3000mm?
OR
copy of the relevant general-arrangement
drawings.
nN Type B' Ni 47 16
€ —
£ E x nN
Oo oO
BO 5
T16@300 4716
5.3.11 Design code requirements
(a) Main vertical reinforcement
(i) Minimum area
(3.12.5.3+) Table 3.27*
Gi) Minimum size ot bars — 12mm
(iii) Minimum number of bars — no. in rectangular
columns
(iv) Minimum number of bars — 6 no. in circular
columns
(v) Maximum area if vertically cast — 6% of cross-
section (3.12.6.27)
(vi) Maximum area if horizontally precast — 8% of
cross-section (3.12.6.2+)
(vii) Maximum area at laps — 10% of cross-section
(3.12.6.27)
(viii) Minimum overall jog-
gle offset = 2D + 10%
tolerance
(ix) Minimum joggle length
= 10 X centre-line
ofset or 300mm mini-
mum
(x) Allow 75 clearance
above lower bar to
start of joggle for toler-
ance
0.4% of cross section
IStructE Detailing Manual
(b) Horizontal links
(i) Minimum size — % size of
largest vertical bar (3.12.7.1*)
(ii) maximum pitch — 12 x size of
smallest compression bar (see
Table 17).
(iii) all vertical corner bars or groups
to be tied by links at minimum
135°. (3.12.7.2+)
(iv) alternate outer vertical bars or
groups should be tied by links
3.12.7.2%)
(v) however, outer vertical bars or
groups, should be tied if spacing
between them exceeds 150mm.
(3.12.7.24)
(vi) circular links or spiral reinforce-
ment provides adequate restraint
in circular columns. (3.12.7.37)
EJ
h<4b
(c) In section, the length of the longer |
side should not exceed 4 x length of
the shorter side. (3.8.17) b
Table 17 Column link data
nominal size
of vertical minimum size of links maximum pitch
bars of links
mm mm mm
12 6 (8 preferred) 125
16 6 (8 preferred) 175
20 6 (8 preferred) 225
25 8 300
32 8 * 375) often
40 10 475 } reduced
50 16 600 J to 300
* Reduce pitch of links to 200 at laps when cover is less than 1‘ x largest vertical bar
size (3.12.8.12+)
5.3.20 Detailing
5.3.21 Methods of detailing columns
Most columns with straightforward profiles are prepared in
tabular form, especially for the larger jobs. Alternatively,
columns can be shown in full elevation. Normally the
concrete profile dimensions are abstracted from the re-
levant general-arrangement drawings. These, together
with the calculations, should be at their final stage before
commencing the detailing stage.
5.3.21.1 Column schedules
The elevation is prepared in economical tabular form, the
concrete profile appearing only in the section.
71
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[OCR TEXT]
Each column type is sche-
duled, indicating storey
height, floor levels, kicker
heights and depth of hori-
zontal member. The verti-
cal reinforcement and links
are added to the schedule
and bar mark location iden-
tified from a mid-storey
height section. Additional
sections may be added for
special features. Column
Levels [Reinforcement |Sect.
kicker.
starter bars cast with and projecting from other members,
e.g. bases, should be detailed with those members.
5.3.21.2 Column eleva-
tions
SFL
SZ
(d)
Where large bending
moments occur at ends, it is
sometimes necessary to pro-
vide separate bars fixed with SFL
the column to carry these >.
moments from the framing §
beam. They often require a
large radius bend (see
Appendix A) and are difficult
to place accurately. These
bars should be detailed with
the column, not with the
beam, and referenced ex-
tremely carefully to avoid
clashes with other beam reinforcement. If structurally
feasible a U-bar placed and detailed with the beam is a
preferred detail.
50 Cover
5.3.22 Bar detailing on columns
5.3.22.1 On elevation
Concrete profiles are ele- > a (a) Vertical bars
vated from at least one side 2 Generally each bar mark is illustrated by a typical bar
depending on their com- erticat drawn as a thick line in elevation. Bars detailed
plexity and preferably bars
‘elsewhere’ are shown as a thick dashed line.
drawn looking from a con- (i) In the tabular form jog- Ture gions
sistent direction. Main ver- ri
tical and link reinforcement SEL gles and bends are drawn /
a in their correct relative
is added, with sections to i
clarify the fixing.
5.3.21.3 Column/beam intersections
Often the most critical details on a job will be the
column—beam junctions. Careful thought should be given
at an early stage to the arrangement of bars. Preferably one
detail solution should be consistently followed throughout
the job.
(a) The simplest solution is to
SFL
position. ‘Calling-up’ of
bars can be written along
the bar. Loose bars
should be located from a
floor datum. Note any
special orientation of
bends required.
In the elevated form bars
are related to the con-
(ii)
allow the column bars to crete profiles. Bars are 4125-4
run through the beam at generally ‘called-up’ on
constant cover. The trans- indicator lines. SFL
verse beam reinforcement
is detailed to avoid these
bars. The lower end of the
vertical bar is joggled to
accommodate the splice with the lower member.
(b) Alternatively, the top end
of the vertical bar is jog-
gled to avoid beam bars
and/or to accommodate
the splice above. Howev-
er, this reduces the mo-
SFL
ment capacity of the col- a . 8
umn_at the kicker. This (i) single links =} 4 wi
detail is also useful when } we wr
the column above de- — sFt % zu OBSn
umn aaa ° Z6 KZs
creases in size by up to 2
75mm, say.
(c) When there are large
reductions in size of the
column above, the step
between faces can be-
come excessive for a
bar to joggle. Usually
the vertical bar is ter-
minated within the
beam and a separate
Starter bar provided.
These starter bars are
offset
| ‘splice
links for
starters
(b)
Links II
Generally the spread of links is indicated by an
indicator line terminated by arrowheads. The links are
provided to restrain the vertical bars from buckling.
Generally the top link terminates at the soffit of the
slab for peripheral columns, or at the soffit of the
shallowest beam for internal columns. Mild steel links
with their standard 2d internal bend radius allow
vertical corner bars to fit more closely into corners.
(ii) multiple links
5.3.22.2 On section
Generally sections are drawn at mid-
storey height looking down. Sections are
preferably drawn to a suitable scale to
clarify the fixing of the links and to locate
the vertical bars. Reinforcement in nibs
and projections should also be indicated.
Bars cut in section appear as black dots
with appropriate mark. Any starter bars
beyond appear as open circles. Links are
drawn with a thick line...
provided with links tied into the lower column bars to
align them to lap with bars in the offset column above.
For bars with top bend, allow top clearance for beam
reinforcement (say, 100mm cover).
72 IStructE Detailing Manual
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5.3.23 Other requirements for columns
5.3.23.1 Special notes for columns
In addition to standard notes for reinforcement drawings
(see subsection 2.8) the following note should appear on all
column drawings:
Nominal cover to links.....mm, unless noted.
5.3.23.2 Column heads
Column head shear reinforcement is a special requirement
specified by the designer. This can be incorporated with the
column reinforcement or referenced and detailed as a
separate item or with the slab.
IStructE Detailing Manual
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[OCR TEXT]
5.3.30 Examples of detailing
COLUMN SCHEDULE
Column tas
Type'C-27No | 3B8,4B-27 No
COLUMN ELEVATIONS
©
Roof SFL
0
_t
2716-9
14R8-10-200
°
a
14R8-10- 200
ist SFL
| 13R8-2-240
T-— SS
|L see drg.....
COLUMNS 3B,4B (2 No)
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[OCR TEXT]
5.4 BEAMS
5.4.10 Design information
These data are output from the calculations for each span
and the designer should indicate:
(a) For beams designed and detailed in accordance with BS
8110 simplified rules (for bar curtailment rules etc. see
subclause 5.4.11.1)
(i) concrete grade to determine laps, durability,
t
etc.
(ii) type of support assumed, i.e. simple restrained,
cantilever, etc.
(iii) nominal cover requirements to links/longitudin-
al bars with proper regard for durability and fire
resistance (see clause 3.3.9). Clearance should
be allowed for the layering of slab reinforcement
(see clause 5.2.22.1) and for beam bars at the
beam/column intersection (see clause 5.4.21)
(iv) type of reinforcement and any size restrictions
(v) area of.main longitudinal tension bars (required)
A,(mm*) or, preferred type/size, with sketch
(actual)
(vi) location of shear zones with dimensions from
centre-line of supports
(vii) area of shear reinforcement in each shear zone
(required) _A,(mm‘) or, preferred type/size
and pitch of link legs both in elevation and
section, with sketch (actual)
(viii) any special requirements, e.g. location of com-
pression bars, torsion bars, bent-up shear bars,
trim for slots and holes, tie bars, laps and critical
stresses, radius of bend, etc.
(b) For other beams, e.g. those with point loads, in
addition to above:
(ix) location of bar curtailments, if non-standard (for
BS 8110 general bar curtailment rules see clause
5.4,11.2). Provide bending moment diagrams if
available.
(c,
~
Summary of beam calculations
When large areas of simple floor beams occur it is
possible to rationalize main reinforcement areas/type,
size including shear links. For example, these can be
summarized and presented to the detailer by marking
up two copies of the relevant general arrangement
drawing — one copy for east/west beams, the second
copy for north/south beams. Top from bottom data can
be differentiated by using coloured pencils, or the
abbreviations B and T.
i.e. locate A, bottom midspan thus:
1000 mm? al o 2725 at
locate A, top support 1600mm?T 2732T
mm or
£ LC
locate Ay, links and extent
500mm?/m or , R8@175
peodemm im or | RO@I7S
Previous page
TStructE Detailing Manual is blank
Additional data required can be sketched or noted
on the print etc.
(d) Minimum reinforcement
(i) For minimum link reinforce-
ment see Table 19.
(ii) For min tension reinforce-
ment under various condi-
tions see Tables 21 and 22.
Beams whose depth exceeds
750mm should be provided with | b
side lacers (3.12.11.2.6+)
maximum pitch 250mm
\ /5p Xb .
minimum bar size = an mm. (3.12.5.4+)
where s,, is the bar spacing
b is the breadth of section at the point consi-
dered (or 500mm if less).
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[OCR TEXT]
5.4.11 Code requirements for beams
5.4.11.1 Curtailment and areas of bars based on BS 8110 simplified rules (Fig 3.24, 3.12.10+)
Assumptions:
(a) Continuous spans are approximately equal (within 15% of longest)
(b) Beams support dominantly uniformly distributed loads
(c) Characteristic imposed loads do not exceed characteristic dead loads
(d) Tie force requirements should also be considered.
Use General Method shown in 5.4.11.2
min 0-25!" or 1-25k*™
min0151* or 0-75k™
minimum lap
curtail 50% As Top max
Nominal link hanger bar As Top
end anchorage
(see 5.4.11. 3
a or b) 50°% As min 30% As min
k
vO cantilever
Ceffective support G effective support
!
{i) simply supported end (ii) cantilever end
x or 45 g, whichever is greater
0:25 ix* 0-25 1x*
link hangers
20°%. As Top min.
Check tie force
requirements
curtail
50% As Top max
As Top
Unless specified
50°. As min
tension
anchorage
(see 5.4.11. 3
cord) _
30%. As min 30°. As min
ly la
* >
lx = greater of adjacent spans lyorl2
€ effective support effective support
1 '
{iii) restrained end (iv) continuous interior
78 IStructE Detailing Manual
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[OCR TEXT]
5.4.11.2 Bar curtailments for beams based on BS 8110: general recommendations (3.12.9+)
Ta = Tension Anchorage Length or effective depth d whichever is the greater
N = Nominal 129 or beam effective depth d whichever is the greater
Face of support
(See 5.4.11.3
esi PAL _
Tha
As Top
3 bars shown F
depth
3 As min
3 bars shown
end cover
|
effective ld
-M
B.M envelope
‘3 As min
2 bars shown
¢ effective support
I
Restrained end support
¢ effective support
'
Continuous interior support
5.4.11.3 Anchorage alternatives based on BS 8110: general recommendations
Simply supported ends (3.12.9.4+)
(a) Straight bars in bottom
d End support
either (i)
20+$ min
Restrained ends
(c) L-bars in top
If bar extended | |
below beam | :
soffit then consider non- std. radius
detail with if vertical leg beyond
column. the bend is greater than 4g
(U-bar preferred) nd cover
IStructE Detailing Manual
face of support
or (b) Bent bars in bottom
¢ End support
# = bar size
either (i) Standard bend
or (ii Std. bend + $
for Type R = 3¢ min
Type T=4¢ min
d=effective depth (T=59 when
#=25mm or greater)
(d) U-bars in top
Ta = Tension Anchorage
Length Ta
F = Face of restraining
vertical bar
end cover
leg can be extended
to lap with span
bars (see 5.4.21.1)
79
consider non-std. radius
if bearing stress
is exceeded
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Table 18 Areas of reinforcement for various link combinations
nominal | no. off areas, mm?
bar link pitch of links (maximum 0).75d), mm (3.4.5.5.7)
size legs 75 100 125 150 175 200 225 250 300 400
2 754 | 566 452 378 324 284 255 226 189 142
4 1508 1132 904 756 648 568 510 452 378 284
6 6 2262 1698 1356 1134 972 852 765 678 567 426
8 3016 2264 1808 1512 1296 1136 1020 904 756 568
|
10 3770 2830 2260 1890 1620 1420 1275 1130 943 710
1342 1006 804 670 S74 504 453 402 336 252
4 2684 2012 1608 1340 1148 1008 906 804 672 S04
8 6 4026 3018 2412 2010 1722 1512 1359 1206 1008 756
8 5368 4024 3216 2680 2296 2016 1812 1608 1344 1008
10 | 6710 5030 4020 [ 3350 2870 2520 2265 2010 1680 1260
2100 1570 1256 1046 898 786 707 628 524 393
4200 3140 2512 2092 1796 1572 1414 1256 1048 786
10 6 6300 4710 3768 3138 2694 2358 2121 1884 1572 1179
8400 6280 5024 4184 3592 3144 2828 2512 2906 1572
10 10500 7850 6280 $230 4490) 3930 3535 3140 2620 1965
2 3020 2260 1810 1508 1292 1132 1018 904 754 366
4 6040 4520 3620 3016 2584 2264 2036 1808 1508 1132
12 6 9060 6780 5430 4524 3876 3396 3054 2712 2262 1698
8 12080 9040 7240 6032 5168 4528 4072 3616 3016 2264
15100. 11300 9050 7540 6460 5660 5090 4520 3770 2830
2020 1340 1010
2680 2020
16 5412 4824 4020 3030
8 _ 16080 12880 10720 9200 8080 7216 6432 5360 4040
10 _ 20100 16100 13400 11500 10100 9020 8040 6700 5050
8380 6280 5020 4180 3600 3140 2830 | 2520 2100 1570
_ 12560 10040 8360 7200 6280 5660 5040 4200 3140
20 6 _ 18840 15060 12540 10800 9420 8490 7560) 6300 4710
— 25120 20080 16720 14400 12560 11320 10080 8400 6280
10 _ 31400 25100 20900 18000 15700 14150 12600 10500 7850
Check that clear distance between groups of multiple links is 60mm minimum.
Maximum pitch of link legs at 90° to span = 1.0 effective depth. d (3.4.5.5.+)
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Table 19 Minimum areas of shear reinforcement
minimum area links (A,,) at any section
v= 0.4 bySy pitch of links along beam(s,), maximum 0.75d
0.87 fy mm
mm? 100 1S0 200 250 300 350 400
ys N/mm? 250 460 250 460 250 460 250 460 250 460 250 460 250 460
y
150 28 15 42 23 56 30 69 38 83 45 97 53 111 60
200 37 20 56 30 74 40 92 50 1 60 129 70 148 80
225 42 23 63 34 83 45 104 57 125 68 145 79 166 90
250 46 25 69 38 92 50 115 63 138 75 161 88 184 100
breadth 275 Sl 28 76 42 102 55 127 69 152 83 178 97 203 110
of 300 56 30 83 45 111 60 138 75 166 90 194 105 221 120
beam 325 60 33 90 49 120 65 150 82 180 98 | 210 114 240 130
db, 350 65 35 97 53 129 70 ) 161 88 194 105 226 123 258 140
mm 375 69 38 104 57 138 75 | 173 94 | 207 113 242 132 | 276 150
400 74 40 111 60 148 80 184 100 | 221 120 | 258 140 | 295 160
450 83 45 125 68 166 90 | 207 113; 249 135; 290 158 | 332 180
500 92 50 138 75 184 100 | 230 125 | 276 150 | 322 175 368 | 200
; 600 111 60 166 90 | 221 120 | 276 150 332 180 | 387 210 442 240
750 138 75 | 207 113 | 276 150 | 345 188 | 414 | 225 | 483 | 263 | 552 | 300
| 1000 184 100 | 276 150 | 368 | 200 | 460 | 250 | 552 | 300 | 644 | 350 | 736 | 400
Note: Maximum pitch of link legs in section = 1.0d (3.4.5.5.+)
examples: 1. fy = 460, by = 400, s, = 300... Ay = 120 — Use 2 legs T10 (157) @ 300
2. fy = 250, by = 500, s. = 200. .-. Ay = 184 — Use 4 legs R8 (201) @ 200
Table 20 Maximum distance between tension bars Table 3.307 (3.12.11.2.37) (3.12.11.2.57)
% Redistribution of moments
A = 460 —30 —25 —20 -15 —10 0 +10 | +15 +20) +25 +30
N/mm |
mm 115 120 130 135 145 160, 180 185 195 200 | 210
ee 57 60) 65 68 72 80 90 93 97 100 | 105
Note: For minimum distance between bars see subsection 4.7.
TStructE Detailing Manual 81
[FORMULAS]
by = 400; by = 500
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Table 21. Minimum areas of reinforcement, mm? Table 3.2.27+ (3.12.5.3+)
Flanged beams
web in tension due to flexure
breadth of web, mm
fy = 460 N/mm-* 250 300 350, 400 450 500 600
web/flange <0.4 | 204] <0.4 | 20.4 | <0.4 | 204 | <0.4 | 204 | <0.4 | 20.4 | <0.4 | 204) <04 S04
minimum % 0.18 | 0.13 | O18 | O13 | OAK | O43 | OB | OF | O18} O13 | O18 | 0.13 7 O18 | 0.13
250 113 82 135 98 158 114 180 130 | 203 147 | 225 163 | 270 195
275 124 90, 149 108 174 126 | 198 143 | 223 161 248 179 297 | 245
300 135 98 162 117 189 137 | 216 156 | 243 176 | 270 195 324 | 234
325 147 106 176 127 | 205 148 | 234 169 | 264 | 191 293 | 212 351 254
350 158 114 189 137 182} 284 | 205 | 315 228 | 378 | 273
depth 375 169 122 | 203 147 | 237 220 | 338 | 244 | 405 293
of 400 180 130 | 216 156 | 252 182 | 288 | 208 | 324 | 234 | 360 | 260 | 432 312
beam 425 192 139 | 230 166 | 268 194 | 306 | 221 345 249 | 383 | 277 | 459 332
mm 450 203 147 | 243 176 | 284 | 205 | 324 | 234 | 365 | 264 | 405 | 293 486 | 351
475 214 155 257 186 | 300 | 217 | 342 | 247 | 385 | 278 | 428 | 309 | 513 371
500 225 260 | 405 | 293 | 450 | 325 540 | 390
$25 237 273 | 426 | 308 | 473 567 | 410
550 248 286 | 446 | 322 | 495 594 | 429
575 259 299 | 466 | 337 | S18 | 374 | 621 HY
600 270 312 | 486 | 351 S40 | 390 | 648 | 468
750 338 390 | 608 | 439 | 675 | 488 810 585
Note: Rectangular section subjected to flexure: minimum “ reinforcement = 0.13
(use 20.4 table above)
Maximum tension/compression reinforcement = 4% gross cross-section concrete (3.12.6.1*)
82
IStructE Detailing Manual
[FORMULAS]
reinforcement = 0
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Table 22 Minimum areas of reinforcement, mm? Table 3.277 (3.12.5.3+)
Flanged beams
flange in tension due to flexure over a continuous support
breadth of web, mm
fy = 460 N/mm? 250 300 350, 400 450 300 600
flange type T L T L T L T L T L T L T L
minimum % 0.26 | 0.20 | 0.26 {| 0.20 | 0.26 | 0.20 | 0.26 | 0.20 } 0.26 | 0.20 | 0.26 | 0.20 | 0.26 | 0.20
250 163 125 195 150 | 228 175 260 | 200 | 293 225 325 250 | 390 300
275 179 138 215 165 251 193 286 | 220 | 322 248 358 | 275 429 330
300 195 150 234 180 | 273 210 312 240 | 351 270 390) 300 | 468 360
325 212 163 254 195 296 228 338 260 | 381 293 423 325 507 390
350 228 175 273 210 | 319 245 364 | 280 | 410 315 455 350 | 546 | 420
depth 375 244 188 293 225 342 [ 263 390 | 300 | 439 338 | 483 375 585 450)
of 400 260 200 | 312 240 | 364 280 | 416 | 320 | 468 360 520 400 | 624 | 480
beam | 425 277 213 332 255 387 298 | 442 | 340 | 498 383 553 425 663 S10
mm 450 293 225 351 270 | 410 | 315 468 | 360 | $27 405 585 450 | 702 | 540
475 309 238 371 285 433 333 494 | 380 | 556 428 613 475 741 S70)
500 325 250 390 300 455 350 | 520 | 400 | 585 450 | 650 500 780 | 600
525 342 263 410 315 478 | 368 546 | 420 | 615 473 683 525 819 | 630
350 358 275 429 330 S01 385 572 | 440 | 644 495 717 550 858 | 660
575 374 288 449 345 524 | 403 598 | 460 673 S18 748 575 897 | 690
600 390 | 300 468 360 | 546 | 420 624 | 480 | 702 540 780 | 600 936 720
750 488 375 585 450 | 683 525 780 | 600 | 878 675 975 750 | 1170 | 900
Note: For (i) Flanged beam with web in compression
or (ii) Rectangular beam in compression
Minimum % reinforcement for either if required for ULS = 0.20% (use L-column in table)
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[OCR TEXT]
5.4.20 Detailing
5.4.21 Methods of detailing beams
Careful consideration should be given to the relationship of
the beam with its column junction, including the construc-
tion technique to be adopted. General-arrangement draw-
ings and design calculations should be at their final stage.
5.4.21.1 Splice-bar method
This simple method uses many straight bars and is ideal for
prefabrication.
links
end support to link top internal
splice bars hangers support
Lor U bars splice
suitable bars
span bars
end span
Span and link hanger bars stop usually 50mm inside the
face of the support. These bars together with the links form
the span cage. which during construction can be lifted then
lowered between supports. For continuity the separate
splice bars are threaded through the vertical bars at the
support and lap alongside the span bars in the cage. The
cover to the splice is independent of the span, allowing
greater freedom to deal with the various clearances re-
quired to avoid other bars, including those from intersect-
ing beams and columns. Normally it can be arranged that
column bars simply run through (see clause 5.3.21.3a).
Each beam can conveniently be detailed separately as a
unit span and can be allocated a ‘reinforcement-type’
reference number — similar beams sharing the same
reference. For location these reinforcement-type refer-
ences can be added to the general-arrangement drawing
alongside the unique beam reference number (see subsec-
tion 2.20), or perhaps added to a separate key plan or
separate schedule.
5.4,21.2 Alternative method
With this method bottom-span bars are normally lapped at
the centre-line of internal supports, although at wide
supports butted bars may be more suitable. Link hangers
lap with the ends of top support bars. Obstructions are
avoided either by stopping or by joggling bars, resulting in
fewer straight bars. Adjacent spans are often detailed
together in beam ‘runs’.
links top internal
support bars
bottom bars '
end span internal
spans
Critical detailing often occurs at intersections as follows:
(a) Beams same breadth as column
(i) If column bars (see
Columns 5.3.21.3a)
are run through the
junction, then ob-
structed beam bars
are stopped.
(ii) Column bars (see
clause 5.3.21.3b)
can be joggled to
allow the outer
beam bars to pass, +
particularly when
members are
narrow. SECT.
(b) Beams of different breadth to column
Column bars are nor-
mally allowed to run
through the junction
and the beam bars are
usually unaffected but
this should be checked.
Wide beams will re-
quire extra links along-
side the column.
—col.
SECT. or
ee
ELEVATION
(c) Secondary beams same depth as
main beam
Generally the cover to the top beam
steel is increased to allow clearance
for the main beam and slab rein-
forcement. Bottom bars can be jog-
gled over at the support.
Narrow members
Care should be taken to avoid
congestion, particularly at laps in
bottom bars at column supports. If
butted bars are unsuitable, i.e. a
lap is required for compression or
for tie force purposes, consider
either:
(d)
ELEVATION
(i) extending joggle to lap
outside column >
or (ii) using splice bar method
ELEVATION
(see clause 5.4.21.1)
5.4.22 Bar detailing on beams
5.4.22.1 On elevation
(a) Longitudinal bars
Generally each bar mark is illustrated by a typical bar
drawn as a thick line and related to its supports and the
formwork. Bends and joggles are shown to scale where
possible. The ‘calling up’ of bars is indicated approx-
imately midway along the bar — maintaining design
‘groups’ where possible, to assist checking. Ends of
curtailed bars are identified by short obliques drawn at
30° and tagged with the appropriate bar mark.
1500
(b) Shear links
Usually the spread of links is indicated above the
elevation with an indicator line terminated by arrow-
heads.
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(i) Single zone, single links For wider beams use shape code 73 73
End links should be a maximum of 0.5 pitch inside | — which has no hooks, but anchor ends
the edge of support with minimum 8d straight beyond the
bend. These links can also be employed nominally rein-
forced side beams, with one leg extended into slab
300 20 R10-6-300
iS \ If cage is to be lifted provide nominal link top closers
! {UL shape code 35 — for stiffness
_— ] I~ Combinations of these links can be f 35 )
employed on wider beams to suit.
(ii) Single zone, multiple links 5.4.23 Other requirements for beams
5.4.23.1 Special notes for beams
In addition to the standard notes for reinforcement draw-
300 20RI0-6 ings (see Section 2) the following note should appear on all
Ix20R8-7 $2300 ' beam drawings:
IL nominal cover to links, mm
| | 1 TOP viceeeceeeeeeeeeeeees
| 7 | rc Bottom i unless noted
i Sides. bees
Ends.............0.0006+
(iii) Multiple zones
Dimension all but one of the ‘gaps’ between link
zones — usually adjacent to the nominal zone — —5.4.23.2 Bent-up shear bars (3.4.5.6.7)
to allow some tolerance for fixing. Gaps should — These are occasionally used in conjunction with shear links
not exceed the adjacent pitch.The first link is to resist up to 50% shear force.
usually located 75mm inside the edge of support. . .
(a) Setting-out of a single 45° system
single shear
Ensure that all corners of links contain a longitu-
dinal bar, especially near the supports where bars
curtail,
5.4.22.2 On section
Typical sections are
selected to clarify the fixing
of the- longitudinal bars
within the link cage, includ-
ing any nibs, upstands, etc.
Sections are drawn looking
left at the elevation. Bars
cut in section appear as
black dots, with appropriate
mark. Those bars beyond, if
required, appear as open
circles. If not evenly spaced,
bars should be located from one side face. Links are drawn
in a thick line with a mark indicator.
Each horizontal leg should extend at least a tension
5.4.22.3 Links on section anchorage length Check radius of bend for bearing stresses
eae . . on the concrete. This radius is likely to be at least 6 x bar
When selecting links consider the following: necessitating a shape 99 bar (3.4.5.77)
Normally provide closed link shape code 60
For torsion-link shape code 74 is used
Open link shape code 72 allows easier access
but check that hooks do not foul other bars 2
[mJ
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5.4.30 Examples of detailing
5.4.31 Splice-bar method A B
1500
CLOSERS 19R8-9-300
LINKS RI0-8 | 2x8@150, £225 11@300
19R8-17-300
TYPICAL SECONDARY BEAM
SPACERS 2725-10
3 3
{i 22 7 eunates
A-A B-B c-c D-D
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5.4.32 Alternative method A *
1500 {
CLOSERS 13 R8-9-300
11@300
LINKS R10-6 | 2x8@150, 5-225
25] (in pairs)
2716-12
TYPICAL SECONDARY BEAM
SPACERS 2725-10
9
5 S S$ 15
8 17
3 3 1121211
221 Bundied
A-A B-B c-c
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5.5 FOUNDATIONS
This subsection deals with the following types of founda-
tions: \
‘T) O
pads
pilecaps
tie beams for pilecaps x
strip A
ground beams
continuous footings
anchor or strap beams type | Fabric Reinforcement
rafts. BS reference
The methods of detailing these items, in particular tie
beams and rafts, are similar to those employed in detailing Coo
c
slabs and beams (see subsections 5.2 and 5.4.), but there A 8
are certain additional considerations to take into account,
and described in this subsection.
Ground floor slabs are dealt with in clause 5.2.26d.
Retaining walls are dealt with in subsection 5.6. Pilecaps
Caissons, cofferdams, basements, shafts, piles and dia-
phragm walls are not illustrated specifically, but can be
detailed using the principles and details in this section. . : lacer ;
type|reinforcement /,|reinforcement /,| bars | starters | _links
5.5.10 Design information A 10720 1oT20 [aie] 4132 | 712-200
These data are output from the approved foundation
K\NY
ENS,
Cc C283 T& B
design calculations and should indicate: B 10T16 10T16 aTi6 | 4T25_|T12-200
(a) (i) concrete grade to determine laps, durability, _C 10T20 15T16 4716 | 6T25_|T12-200
ete. 5
(ii) dimensions of each foundation Dp LTI6 RTI6 | 4T16 | 4125 _{T12-200
E 1ST16 20T16 aT16 | 5T25 1 T12-200
a level to top of each foundation
iv) type of reinforcement and any size restrictions
(v) required area and distribution of all reinforce-
ment
(vi) lap, anchorage and splice lengths
(vii) curtailment of reinforcement
(viii) link type, size and pitch
(ix) position of reinforcement to avoid cut-off tops of
piles
(x) cover requirements, bottom, sides, top (ii) For solid rafts, grillage rafts, combined or con-
(xi) position, number, size of starter bars tinuous footings, tie beams and strap or anchor
(xii) type and thickness of blinding beams, the reinforcement can be presented or
(xiii) position, number and size of holding down bolts, summarized for the detailer by the methods out-
if any lined for slabs (see clauses 5.2.10c and 10d) or
(xiv) any other special requirements beams (see clauses 5.4.10c and 10d).
(xv) type of backfill between the top of the bases and
the underside of the ground floor slab.
(b) Summary of calculations 5.5.11 Design code requirements
For convenience and simplicity it is often possible to 5.5.77. General
rationalize reinforcement: (a) BS 8004
(i) For pad footings, simple strip footings, pilecaps — BS 8004: 1984: Code of practice for foundations deals
by tabulating the reinforcement for the foundation with the overall design of all types of foundations for all
pad, lacer bars, column starters bars and starter types of buildings and various types of soils. It does not
bar links, and cross referencing to preliminary deal with the detailing of individual elements of RC
general arrangements for orientation of columns. foundations.
(b) BS 8110
BS 8110: 1985: The structural use of concrete contains
Pad footings guidelines for detailing individual elements of RC
foundations.
type | reinforcement /, | reinforcement i. | starters links (c) Cover
< Covers recommended by BS 8110 are set out in
2 2- . ) : " :
A 10T16 10T16 4T25__| T12-200 subsection 3.9. Where concrete is cast directly against
B 10T20 20T16 4725 | T12-200 earth faces, the nominal cover should be a minimum of
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(d)
(e)
()
(g)
75mm. Where concrete is cast against blinding con-
crete, the nominal cover should be a minimum of
40mm (excluding blinding).
Minimum area of reinforcement (3.12.5.3t)
Refer to subsections 5.2 and 5.4.
Maximum area of reinforcement (3.12.67)
Refer to subsection 5.4.
Spacing of reinforcement (3.12.117)
Refer to subsections 5.2 and 5.4.
Anchorage and lapping of bars (3.12.8+)
Refer to Appendix 3B.
5.5.11.2 Pad footings
(a)
(b)
(c) Distribution of reinforcement in pad footings
In certain conditions, i.e.
when loads are small or
when the allowable
ground pressures are high,
reinforcement may not be
required, In this event the
depth should be such that
a line at 45° from the edge
of the supported column —
or base intersects the ver-
tical face of the base.
.
In reinforced bases the arrangement of the reinforce-
ment must be specified by the designer.
The total area of rein-
forcement should generally
be evenly spread across the
section considered. Howev-
er, if the breadth of the
section is greater than 1.5
(c+3d) where c is the
breadth of the column mea-
sured parallel to the section
breadth and d is the effec-
tive depth of the base, at
least two-thirds of the area
of reinforcement should be
concentrated in a band
width of (c + 3d) centred on
the column (see also exam-
ples below).
Example EG1
(a)
(b)
Example EG2
(a)
(b)
90
If ly>1.5 (cy + 3d):
two-thirds of reinforcement
spanning in /, direction to be
banded within a width of (c,
+ 3d), where dis the effective
depth of the base.
if 1,.>1.5 (c, + 3d):
two-thirds of reinforcement
spanning in /, direction to be
banded within a width of
(c, + 3d).
Reinforcement span-
ning in /, direction:
4, and 1,5 should be
considered separately.
Reinforcement span-
ning in /, direction:
Band width to be consi-
dered as lesser of (c,, +
3d) and (c,2 + 3d).
L>1-5 (C+3d)
Example EG3
(a) Reinforcement spanning
in /, direction:
as example EG2a above
Reinforcement spanning
in /, direction:
(i) bottom reinforcement
under columns:
as example EG2b
above
(ii) Top reinforcement (if
any) between col-
umns:
all reinforcement
should lie within /,>.
Tf Ly2>1.5 (ex2 + 3d), two-
thirds of this reinforce-
ment should lie within cen-
tral (cy. + 3d).
5.5.11.3 Pilecaps
The distribution of reinforcement for pilecaps should be as
for pad footings, except that the arrangement of the
reinforcement should be specified by the designer where
the pile centres are greater than 3 times the pile diameter.
(b)
5.5.20 Layout of foundations
5.5.21 Foundation plan
Refer to subsection 5.1 for more information on the
preparation of general arrangements drawings.
The position of each foundation will be given relative to
the grid lines. The width, length and depth will be given and
the level of the bottom of the foundation will be given
relative to a given datum.
This information is often given in tabular form. Each
foundation is given a distinguishing letter that will serve as a
cross-reference for the foundation details. detailed else-
where.
The minimum allowable safe ground bearing pressure
should be shown in note form on the drawing. The bearing
thickness and type of blinding should be noted.
It is usual to have a separate general arrangement or
piling plan, when piling is employed. This takes the form of
a plan showing the position of piles relative to grid lines and
will contain a schedule and notes including the following
relevant items depending upon the project:
pile reference number
diameter
safe working load of pile
imposed moment
imposed horizontal force
cut-off level
minimum toe level
main reinforcement
hoop reinforcement
angle of rake
pile positional tolerances.
It is normally stated in the piling specification what the
horizontal dimensional permissible deviation should be.
but it should also be repeated on the piling plan.
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5.5.30 Detailing
5.5.31 Pad footings
5.5.31.1 Introduction
These can be detailed in two ways:
(i) traditional method
(ii) tabular method
5.5.31.2 Tradition method
This method in normally used when the project is small or
when there is little repetition. Individual pad footings are
detailed usually in the form of a plan and a section. Grid
lines are shown on each detail. The detail will give
reinforcement information in the base, in the stub column if
there is one, starter bars where the foundation is supporting
an RC column or holding-down bolts in the case of steel
columns.
Where kickers are specified care should be taken that the
length of the starter bar is an appropriate lap length (for the
stress in the bar) from the top of the kicker and that the
starter bars do not clash with the column bars. It may be
more economical in some cases to use the bottom length of
the column reinforcement as starters. Minimum cover
should be indicated. End anchorages should be avoided
where possible, but their use or otherwise should be
confirmed by the designer.
105-000
50 Blinding
600)
8T20-2-150
5.5.31.3 Tabular method
Where there are large numbers of bases and/or extensive
repetition the details can be drawn schematically and the
information for the individual bases given in tabular form.
This can save time and drawings, but care must be taken
that clarity is not sacrificed by producing tables that are too
complicated. It is usual to draw a plan, section and enlarged
stub column or column starter details, all not to scale,
cross-referenced to a table.
[(aI5F, -2
c Cc
5.5.32 Piled foundations
These can also be detailed by traditional or tabular
methods.
5.5.32.1 Traditional method
The notes on pad footings apply
to pilecaps with the following
additions:
The pile cut-off is usually car-
ried out with pneumatic tools,
leaving a very rough surface to
the piles. Bottom steel should
therefore be detailed, such that
the bottom of the bars is a mini-
mum 75mm above the theoretical
cut-off level. The cut-off level
should be 75mm above the bot-
tom of the base.
105000
60 Cover
24 AT
If moment has to be transmit-
ted from column to pile via the
pilecap, then sufficient reinforcement from the pile should
be left projecting into the pilecap to transfer that moment.
Care should be taken that the reinforcement does not clash
with reinforcement in the base or with starter bars in the
column. It should be remembered that piles are not always
accurately placed and the pilecap details should allow for
such inaccuracies.
It is usual for pilecaps to have horizontal loop steel
around the perimeter of the pilecap. These should be at
200-300mm centres and a minimum of 12mm in size.
The designer should be consulted to check if large-radius
bends are required on the bent-up bars.
27 2
Cc
column no. level base reinforcement section links starters
reference off A B D Cc
Al, A2, A3 3 105.000 | 10T20-1-150 | LOT20-1-150 1-1 3T8-2 4725-3
B3, B4 2 108.000 8T20-4-150 | 10T16-5-150 1-1 3718-2 4725-3
Cl, C2 2 104.500 | 8T20-6-150 | 12T16-7-150 2-2 6T8-8 6125-9
Di, D2 2 104.500 10720-10-150 | 12T16-11-150 1 2-2 GTS-8 6725-9
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5.5.32.2 Tabular method
This can be successfully employed when large numbers of
pilecaps and/or repetitious details are required. The table
should contain all the relevant information as for pad
footings plus pile-cut off levels and hoop-steel details.
‘X’ relates to lettered grids
‘Y’ relates to lettered grids
level
SECT 1-1 SECT 2-2 SECT 3-3 SECT 4-4
column base | no. base cut-off base reinforcement section links starters
reference | type | off level level A B | Cc D E
Al, AS A | 2 | 105.000 105.150 | 10T20-1-150 | 10T20-1-750 | 3T12-2-200 2-2 3T8-3 4725-4
a2a3.A4|B | 3 | 105.000 | 105.150 | 8120-5-150 | 8120-6150 | 31127200 | 33 | otaa | psa
B4, BS A | 2 | 105.000 105.150 | 12T20-9-175 | 12T20-9-175 | 3T12-10-200 2-2 3T8-11 4T25-4
B2, B3, B4 Cc | 3 105.000 105.150 | 12T20-9-150 | 8T20-12-150 | 3T12-13-200 44 9T8-14 8T25-4
Cl, C5 A | 2 104.500 105.150 | 10T20-1-150 | 10T20-1-150 | 3T12-2-200 3-3 6T8-8 6T25-4
C2, C3, C4 B | 3 104,500 105.150 | 10T25-15-200 10725-16-150 | 3T12-17-200 3-3 i 6T8-18 6T25-4
5.5.33 Tie beams for pilecaps
When piles are used singly or tA. A Steps in strip footings, necessary
in pairs it is necessary to tie
the pilecaps together using tie
beams. Piles cannot be driven
accurately, and it is usual to |
specify a horizontal permissi- \
ble deviation in position,
usually 75mm, both in the
specification and on the
drawings. The moment
caused thereby should be T
added to any other imposed
moments and should be a
minimum design case even if
neither moment nor horizon-
tal forces exist at the bottom
of columns.
4
SECT A-A
'
The detailing of these beams will not differ significantly
from other beams except that the amount of cover should
be carefully checked for the particular ground conditions.
It is, however, usual to have equal top and bottom
reinforcement, since inaccuracies can occur on any axis.
Tie beams are not normaily required where piles are
placed on groups of three or more.
Eccentricity
5.5.34 Strip footings
These are foundations that are con-
tinuous and where the loads are
applied continuously, as in the case
of brick or blockwork or reinforced-
concrete walls. The amount of rein-
forcement required in simple strip
footings varies with the type of
ground on which they are placed. In
domestic building, footings are often
unreinforced, providing the depth is
adjusted such that a line at 45° from
the edge of the brickwork intersects
the vertical face of the footing.
Z
of 2Tor2D
92
when the ground is sloping, should
be in brick dimensional increments.
The foundation should be lapped for
at least twice the thickness of the
foundation or twice the depth of the
step, whichever is the greater.
In bad ground, top and bottom
reinforcement may be necessary, in
which case it is better to use cages of
bar reinforcement since it is difficult
to maintain fabric in position in the
top of the slab during concreting.
Longitudinal bar reinforcement should be a minimum of
12mm with 8mm links in order that cages are sufficiently
rigid. Reinforcement should be adequately lapped in
stepped foundations in sloping ground.
Care should be taken that the cover is adequate for the
type of ground in which the concrete is to be placed. Cover
should be generous since the sides and bottom of the
excavations will be rough.
For larger strip footings, where loading is heavier or for
foundations for RC walls, the strip footings should be
detailed as beams and the rules in subsection 5.4 should be
applied.
5.5.35 Ground beams
When the upper layer of
ground has such a low bear-
ing pressure that it is incap-
able of sustaining the loads
imposed on a ground floor
slab, the floor slab is sus-
pended and supported on
beams, cast in the ground.
The beams are in turn supported at column positions on
pad or piled foundations.
Care must be taken that adequate cover is allowed for.
depending on the ground conditions, acidity, etc.
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5.5.36 Continuous footings
These are footings that
sustain two or more col-
umns, often in ground of
low bearing capacity and
where the centres of the \
columns are so close that independent pad footings would
be so large and so close together that they become
uneconomic. '
Care must be taken that adequate
cover is allowed for, depending on
ground conditions, acidity, etc.
In some cases depending on ground
conditions, they may be more economi-
cally designed, and therefore detailed,
as inverted T-beams.
5.5.37 Anchor, strap or
cantilever footings
These foundations are similar
to combined footings, but the
term is applied when one or
more of the loads is positioned
on the edge of the foundation,
usually because of the proxim-
ity of other buildings, founda-
tions, etc. An internal column is used as a counterweight,
and consequently, main reinforcement is required in the
top of the beam.
Again, the normal rules for detailing beams (see
subsection 5.4) will apply, and attention should be paid to
cover.
The detail at the junction of 7
the column on the edge of the
foundation needs particular
attention. Since the top steel
in the foundation is often
highly stressed at this point,
large-radius bends _—(see
section 3) may be needed, and
care should be taken that the
column reinforcement does not clash with beam
reinforcement. It is advisable to provide horizontal U-bars
around the starter bar cage.
U-Storters
U-Bars or hairpins
COLUMN/ BASE JUNCTION
5.5.38 Rafts
There are several different
types of raft foundations:
piled
stiff
flexible
light rafts
cellular
PILED RAFT
The design varies with each type, but
the common purpose of all rafts is to
spread a whole system of loads over a +
large area generally to give alow linear-— #cTon-sFF arr
ly-1 mposed load on to the ground be-
low. The exception to this is the flexible
raft, which results in a variable, yet
tolerable, imposed ground pressure.
SECTION-FLEXIBLE RAFT
' t t
SECTION - CELLULAR RAFTS SECTION- LIGHT RAFT
a} With bottom siab b) Without bottom stab
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5.5.40 Examples of general arrangement drawing for foundations
1250-00N_
©)
500/500
4000
@)
500/500
4500
4500
Q)
500/500
00
3 PILE LAYOUT
3 € Pile
CUTOFF L.| MIN TOE L. | REMARKS
1-8
RAKE 1:15
94 TStructE Detailing Manual
Luvsige of pilecap
29-31
28,4084)
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5.6 WALLS
5.6.10 Design information
These data are output from the approved calculations for
each wall type, which should indicate:
(a) concrete grade, to determine laps, durability, etc.
(b) design type assumed, i.e. plain or reinforced vertical
loadbearing wall, propped or full cantilever retaining
wall, etc.
(c) cover to outer bars each face
(d) orientation of outer bars, i.e. whether horizontal or
vertical
(e) type of reinforcement, and any size restrictions
(f) area of main/secondary reinforcement required A, or
A,e(mm*/m)
or, preferred type/size and pitch (actual)
(g) wall faces with minimum reinforcement requirements
(see tables)
(h) any special requirements, i.e. data for links, tie bars,
trimming for holes, etc.
Provide sketches where appropriate, e.g.
1200 mm?/m
2500mm2/m
T20 a 150
2
Detail with base 2000 mm*/m
2000 mm? /m
Propped-cantilever retaining wall
T20 @ 150
1000.
000
a
T25 @ 150
3000mm?/m
Cantilever retaining wall
Provide minimum reinforcement, unless shown.
IStructE Detailing Manual
5.6.11 Design code requirements
5.6.11.1 A vertical loadbearing =
member is defined as a wall when its
length exceeds four times its thick-
ness t>4h
(1.2.4.1.7)
5.6,11.2 Walls may be either plain or reinforced:
(a)
(b)
(1.2.4.74)
Plain walls
Plain walls contain either zero reinforcement or less
than the minimum requirements for reinforced walls.
Any reinforcement that is provided however is ignored
in design when considering the strength of the wall. To
counteract possible flexural, thermal and hydration
shrinkage cracks, particularly in external walls and at
the junction of internal members, minimum reinforce-
ment is required. This should be provided as a mat of
small bars at relatively close spacings, with reinforce-
ment areas expressed as a percentage of the gross
concrete cross-sectional area. The horizontal bars
should be placed in the outer layer.
grade grade
250 460
Minimum reinforcement lface, or 0.3% 0.25%
in both horizontal and Y% each
vertical directions face 0.15% 0.125%
Reinforced walls
Reinforced walls are considered to contain at least the
minimum area of reinforcement expressed as a percen-
tage of the gross concrete cross-sectional area
(5 Vertical reinforcement
Minimum A,, not less than 0.4% (0.2% each face)
(3.12.5.3t) Table 3.27+
Maximum A,, not to exceed 4% (3.12.6.31)
Maximum bar spacing, when A,. exceeds 2%,
should not exceed 16 X vertical bar size
(3.12.7.5t)
(ii) Horizontal reinforcement
This reinforcement should be evenly spaced in the
outer layers to minimize crack widths and contain
the vertical compression bars.
Where vertical bars are in tension, particularly in
retaining walls, these are sometimes placed in the
outer layer to facilitate fixing and to maximize the
lever arm.
grade grade
250 = 460
, Of
Minimum horizontal jface, or 0.3% 0.25%
reinforcement 2 each
face 0.15% 0.125%
The minimum size of bar should not be less
than one quarter the size of the vertical bar and
preferably not less than 8mm diameter,
(3.12.7.4t)
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Link pitch
max
% 06 6mm min
Additional hori-
zontal restraining
links should be pro-
vided through the
thickness of the
wall when the area Vert. bars 6 (2-4 *%e}
of vertical com-
pression reinforcement exceeds 2%. Link spacing
should not exceed twice the wall thickness in any
direction, Any unrestrained vertical bars should
be within 200mm of a linked bar. (3.12.7.5+)
5.6.11.3 Plain and reinforced walls in tension
(3.9.3.67)
Bars should be arranged in two layers and the max-
imum spacing of tension bars should generally not
exceed 150mm where F, = 460 N/mm” or 300mm where
F, = 250 N/mm? (3.12.11+)
96
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Table 23 Optimum bar spacing for varying % reinforcement and different wall thicknesses
minimum
bar nominal size
mm
reinforcement 8 | 10 | 12 16
wall thickness, mm
% 100 | 150 | 200 | 250 | 300 | 100 | 150 | 200 250 | 300 100 | 150 fe 250 | 300 | 150 | 200 | 250 300 | 350
0.125 — | 250 | 200} 150} 125; — | — | 300 | 250] 200 |
0.15 300 | 200} 150 | 125 | 100 | — | 300 | 250 | 200 | 150) — | — | — } 300} 250} — | — | — | — } 300
0.2 250 | 150} 125 | 100} — | — | 250] 175 | 150} 125 _ | 275 225 | 175} — | — | — | 300] 250
0.25 200 | 125 | 100| — | — | 300] 200] 150] 125 | 100 300 | 225 175 |150 | — | — | 300| 250 | 200
0.3 150} 100} — | — | — 150 | 125 100 | _— 250 | 175 | 150} 125 | — | — | 250} 200| 175
0.4 125;— | —|; —|— 100 175 | 125 | 100} — | — | 250| 200 | 150| 125
0.45 100} —} —}|—|— _ 150 | 125 | 100 | — | 275 | 200} 175 | 150 | 125
0.8 — 100 —|-
maximum
Bar nominal size
mm
reinforcement 20 25 | 32 40
Wall thickness, mm
%o 100 150 | 200 | 250 | 300 100 | 150 | 200 | 250 | 300} 100} 150 | 200 | 250} 300 100 150 | 200 250 | 300
2.0 150 100 | _ | _ | — | 240} 160} 120] 90} 80} 400 | 260 | 200 | 160 | 130] 610 | 420 | 310 | 250 | 210
4.0 —|—| —]—J] =} 120] 80] — | —] — [200] 130] 100] 80} — [310 f 210 f 150 | 120] 100
Note: These tables can be used for plain and reinforced walls, etc. (see clause 5.6.11)
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5.6.20 Detailing
5.6.21 Method of detailing walls
Most walls are detailed on elevation supplemented by
sections drawn to clarify the fixing, especially at member
junctions, openings, etc. The concrete profile dimensions
are abstracted from the relevant general-arrangement
drawings, which together with the design calculations,
should be at their final stage.
5.6.21.1 Wall layout
When elevating walls for
detailing, the direction of
view should be consistent,
i.e. normally viewing from
the bottom/right edges of
the drawing. Walls cast
against an inaccessible face
should be viewed from the
‘open’ side. A key plan is
useful particularly when the plan is complex. e.g. lift shafts,
more especially if the above convention is unable to be
followed, e.g. walls ‘A’ & ‘D’.
~~
WALL A
WALLD S\7
Key plan
Qpenotes direction of view
5.6.22 Bar detailing on walls
5.6.22.1 On elevation
(a) Notation for layers of reinforcement
Reinforcement is fixed in two layers at right-angles to
form a mat, normally one mat at each wall face
(iii) Abbreviation for far face, |
outer layer Fl
(iv) Abbreviation for far face, NI
second layer F2 F2
(b) Typical bar and indicator line
The convention for illustrating and ‘calling up’ bars on
walls follows closely that of slab (see subsection 5.2)
e.g.:
{i) A zone of similar bars in one
face 20T10-63-150N1
(ii) A zone of similar bars in two
faces 40T10-63-150
(20N 1-20F2)
(i) Abbreviation for near face,
outer layer N1
(ii) Abbreviation for near face,
second layer N2
(iii) A zone of dissimilar bars in
two faces 20T10-63-150N1
20T 10-64-150F2
Note that identical bars appearing on different faces are
itemized separately.
To avoid congestion in thin walls less than 150mm thick,
a single mat of reinforcement may be provided, if design
requirements permit.
5.6.22.2 On section
(a) Intermediate storeys
Walls are normally cast in
storey-height lifts, with stan-
dard 75mm high kickers at
each floor level. Kickers help
to align the formwork above.
The vertical reinforcement
should not be less than 12mm
and is lapped above the kick-
er to provide structural con-
tinuity.
|
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Roof
level
Vert
bars’
(b) Top storeys
A variety of details
are possible depend-
ing on design and
construction re-
quirements. Allow
sufficient top cover
for clearance of
intersecting
reinforcement.
(c) Offset walls above Starter.
Normally offsets of up to 15 Ma,
75mm can be achieved by x
joggling the relevant ver- Slope 1:10
tical bars. Otherwise, the min length |
lower bar is terminated be- vee 3
low the floor and a sepa- bars
rate splice-bar starter pro-
vided.
External wallislab junction
In the case where a significant
bending movement is transmit-
ted into the wall from the slab, it
may be necessary to use a L-
shaped bar to provide full
anchorage. If the L-bar is to be
cast with the wall it should be
scheduled with the wall reinforcement, but this is a
non-preferred detail (see subsection 5.2).
Half-landings :
A 20mm deep rebate is
preformed in the sup-
porting wall to provide
bearing for the slab
poured later. The junc-
tion is provided with up
to 12mm, preferably
mild steel, U-bars
which are temporarily
folded back behind the
formwork and later re-
bent into their correct
position for the slab.
(f) Corner details
(i) Closing corners
For corners that are
closing, two simple
alternatives are
shown. Bars should
be provided with
adequate anchor-
age and appropri-
ate laps to suit.
(ii) Opening corners
For corners that ar
Opening, the method
of detailing is far more
important, especially
if the bending moment
is significant. Tests
have shown that the
maximum opening
bending moment that
can be transmitted by
the details shown
above for closing cor-
ners can be less than 25% of the flexural strength of
the corresponding wall section. A looped bar is
more efficient structurally, although difficult to
bend and fix. The recommended detail shown is
more practical and has a high structural efficiency.
In all cases, the structural efficiency will be improved
considerably if it is practicable to provide a splay corner
reinforced with diagonal bars.
(d)
heck for
non - standard
radius
Anchorage
(e)
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5.6.23 Other requirements
5.6.23.1 Special notes
In addition to the standard notes for reinforcement draw-
ings (see subsection 2.8), the following notes should appear
on all wall drawings.
(a) cover to outer reinforcement NI....F1....End....
(b) bar-layer notation: Near face outer bar N1
Near face second bar N2
Far face outer bar Fl
Far face second bar F2
5.6.23.2 Wall reinforcement
spacers
Where links are not required to
restrain vertical compression bars, Ties
reinforcement spacers can be used to
stabilize the two faces during con- Tie to
struction. Adopt say R10 @ 1000, NF2 +
shape code 38. Cover to the outer
bars is normally achieved by using FF2
plastic spacers
5.6.23.3 Trimming of
holes in walls
To prevent cracks springing
from corners, provide
nominal bars placed diago-
nally as shown. Additional
trim requirements should
be indicated in the calcula-
tions.
5.6.23.4 Miscellaneous items
When detailing reinforcement. ensure that adequate clear-
ance is allowed for items such as fixings, pipes, water bars,
weep holes, etc.
5.6.23.5 Fabric reinforcement in walls
Conventional wall layouts lend themselves to the advan-
tages of fabrication as described in clause 5.2.26. Purpose-
made wall sheets can be ordered to deal effectively with
lapping and intersection details. For guidance, consult the
manufacturers of fabric.
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[OCR TEXT]
5.6.30 Examples of detailing
5.6.31 Typical internal wall panel
3-200 NI
17T10-
17710 > ]3-200 Fi
17710 -2- 200
17T10-2 -
2712-1
WALL 'B’ ®
A-A Cover: N1 = 20
F1= 20
End = 20
IStructE Detailing Manual 101
[FORMULAS]
N1 = 20; F1= 20; End = 20
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[OCR TEXT]
5.7 STAIRS
5.7.10 Design information
Requirements for stairs are similar to those indicated for
slabs (see subsection 5.2).
Flight
9 Equal treads
Architectural
finishes shown
°
Tread or going
Storey height
20 Equal risers
Riser
PR Bag Fite tine
Pitch SAA)
nana FEL
th
Soo
TYPICAL STAIR NOTATION
Structural
tread or going
Fillet
Struct. waist
~ VERTICAL RISERS SLOPING RISERS
WITH FILLETS
Finished risers equal Struct. risers vary to suit
thickness of finish
inishes to treads of
each flight line through
Finishes to soitite junction
line through
Previous page
is blank
IStructE Detailing Manual
Notes on setting-out
The stair structural-layout or general-arrangement drawing
should indicate all the dimensions required to set out the
concrete profile.
The architect will normally locate the stair between
floors using the top of the finishes as his vertical datum. The
height of risers will be equal but the thickness of finish may
vary, particularly at floors and landings. It follows that
structural risers may vary in height. Treads may require
sloping risers to provide a nosing, and fillets may be needed
to maintain a constant waist thickness.
It is often arranged that the finishes to nosings of
adjacent flights will line through across the stair. Some-
times the junctions of all soffits are made to line through.
5.7.11 Design code requirements
Bar curtailment rules for stairs follow the simplified or
general rules recommended for slabs (see clause 5.2.11).
End span t
0-314" min
Optional taps to
‘suit construction
9
Span!
Floor or landing
Optional taps to
‘support
suit construction
= 456 min
T = Tension
Ix = Greater of adjacent spans | or |y
y= Lor lz
TYPICAL STAIR FLIGHTS SHOWING REINFORCEMENT :
(Bar curtaitments based on 8S8110 simplified rules (3.12.10.3) fig 3.25
103
[FORMULAS]
T = Tension
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5.7.20 Detailing
5.7.21 Methods of detailing stairs
In all cases concrete profiles are extracted from the relevant
general-arrangement drawings. Each different flight is
drawn in section to a suitable scale, and the appropriate
reinforcement is carefully related to the profile.
5.7.21.1 Simple flights
These can be detailed on section alone, probably with the
aid of a key plan to identify various flights and sections
taken. Separate sections may be necessary across landings.
5.7.21.2 Stair complexes
Reinforcement is shown on the plan of flights and landings
where they differ for each storey height. Sections taken
should clarify the positioning of the bars.
5.7.21.3 Surrounding structures
Starter bars for landings etc. may be required to project
from supporting members for the stair construction to
proceed at a later date. These bars may be folded back from
behind the formwork (see clause 5.6.22.2) and should be
detailed with the support.
5.7.22 Bar detailing on stairs
This follows the conventions used for detailing slabs (see
clause 5.2.22).
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5.7.30 Examples of detailing
7712 -4-150 B1
7712-3-150 Bl
ee
SF 4leb DULL el
PSS SHEEC TT) Ti
|| eH
4710-2-300 T2
10T 10-2-300B2
4110-6-300B2 3-475
4710-6-300T2
|
|
| SFL
LT | lao RS gT10-2-30072
15T10-5-150 | | eH
U-Bars
| | |_|
10T10-2-300B2
7712-8-150B1 7712-13-150T1
7712-12-150B1
7712-9-150T)
7710-10-300T2
TYPICAL STAIRS
Shows flights “A’,"B" and landing detailed on plan
‘tog eI
7 58h
J
15 710-5-150
See drg no...
4T10-6-300
7712-3-150
7712-1-150
TYPICAL STAIR FLIGHT
Shows flight "A’ and part-landing detailed on section
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6.1 Concrete inserts
6.1.1 Types
Concrete inserts may be of the following types:
cast-in
bonded with resins
bonded with cementitious grout
expanding
shot-fired.
Fixings are usually characterized by their shape. or the
way in which anchorage to the concrete is achieved and
sometimes by the purpose for which they are used. A wide
variety of studs, eyes, rods, hangers, loops. bolts. channels,
sockets, blocks and nails may be installed, but in all cases
the manufacturer's advice and installation instructions
must be strictly adhered to.
6.1.2 Problems and solutions
Problems are usually brought about by a lack of technical
knowledge of the fixing, a failure in communications
between supplier and installer or a misunderstanding of the
principles of the fixing. Problems may also be induced by
the location of the reinforcement, the formwork system
employed or the compactive effort used in placing the
concrete.
Always consult the supplier of a fixing before it is
detailed and ensure that the installation is specified on the
detail drawings and contract documents. Particular atten-
tion should be paid to the following:
edge distances and spacings of fixings. particularly when
used in groups
concrete strength and aggregate size
hole diameter and depth
proximity of reinforcement and any special reinforce-
ment to hold the fixing in place
fixings to be used with lightweight aggregate concrete
specification of components to be set in concrete using
jigs to prevent displacement
setting-out of fixings on drawings using reference lines
and running dimensions
cover requirements for fixing and reinforcement
recommendations regarding compatibility of materials.
6.1.3 Durability
This covers three aspects:
corrosion (normally applies only to ferrous fixings,
although the normal rules of galvanic action must still
be observed)
fire resistance (if the fixing is not protected with the
requisite amount of fireproof material a fire test
should be carried out)
long-term performance.
In all these, guidance must be sought from the manufac-
turer before the installation is specified.
6.2 Corbels, half-joints and nibs
The detailing of these elements must relate to the design
assumptions, and the designer should in all circumstances
ensure that the detailed design is clearly specified.
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Specific details
6.2.1 Concrete corbels
In details (a) and (c) (see Fig. 27) the edge of the bearing
and the inside of the welded transverse bar or the inside of
the main reinforcement in the form of horizontal loops
should not be less than the bar diameter. For detail (b) the
bend should not commence before a bar size beyond the
edge of the bearing plate. In all cases these distances
should be increased to the cover to the bar where this is
greater than the bar diameter. It can be seen that the total
projection of the corbel will be much greater in detail (b)
than in the other two details because a larger radius bend
than the standard radius may be required to limit the
bearing stress of the concrete inside the bend. Because of
this, details (a) and (c) may be preferable; it is suggested
that detail (a) be used when using bars of size 20mm or
greater (see also Fig. 28) and detail (c) for bars of 16mm
and smaller (see also Fig. 29).
Main steel welded toa
transverse bar otf equal size
Horizontal shear steel (Asv)
as stirrups over upper
two-thirds of d
(a)
Outside edge of bearing to be
kept clear of bend in main
reinforcement (minimum
clearance =1bar size)
(b)
Main reintorcement in the form
of horizontal loops
Z
i! ha
il %
i| Bars provided to anchor
horizontal stirrups
Detailing rules
thy ¢ 05h
2.0-4<100 Ast /bd<13
3.0:6<100(Agt +Agy)bd<2:0
4. Other details as per diagrams
Fig. 27
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Two column links should be This detail is suitable when using 20mm bars
Placed close to corbel top or greater for the main tensile reinforcement
Distance between edge of bearing
and inside of bar to be a minimum
of the bar size or cover
whichever is greater
|
Main tensile bars welded
to across bar of equal
diameter and to the
oI vertical compression bars
Large radius of
bend required
Horizontal links. Total area
should not be less than 0-5 of
area of the main tensile
reinforcement
N.
Tension lap |
— UB
Compression anchorage
Sectional plan on A-A
Fig. 28
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Two column links should be This detail is suitable when using 16mm size bars
placed close to corbel top or smaller for main tensile reinforcement
4
Distance between edge of bearing
and inside of bar to be a minimum
of the bar size or cover
whichever is greater
Ll ty
= 7 HT
t
Tension lap ————_ |
Main tensile reinforcement.
Large radius of bend
is required
Secondary horizontal
reinforcement. Total area of this
should not be less than 0-5
times area of main tensile
reintorcement
Outer compression bars angled
to pass inside links
Compression anchorage 1
3,4,5
Sectional plan on A-A
Fig. 29
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Horizontal forces
When corbels are designed to resist horizontal forces then
additional reinforcement should be provided to transmit
this force in its entirety. This reinforcement should be
welded to the bearing plate.
6.2.2 Concrete nibs
Nibs are not usually greater than about 300mm deep. For
detailing requirements, the tension reinforcement that will
be near the top surface of the nib can be in the form of
U-bars in the vertical or horizontal plane or straight bars
welded to a transverse bar.
Effective depth
|
Fig. 30 Vertical loops
(a) Vertical loops (see Fig. 30)
(i) size of links or U-bars to be not greater than
12mm
(ii) depth of nib not less than 8 plus two covers for
high-yield bars or 6¢ plus two covers for mild-steel
bars
(iii) dimension a to be a tension anchorage length if
U-bars are used and the width of beam is sufficient
to allow this. If the width is not sufficient then a
closed link can be used with an additional longitu-
dinal bar introduced as indicated
(iv) if the nib is supporting a reinforced concrete
member then there should be a minimum horizon-
tal overlap of reinforcement in the nib and rein-
forcement in the supported member of 60mm
(v) horizontal spacing of the links or U-bars to be not
greater than 3 times the effective depth.
t
Effective depth
Fig. 31 Horizontal loops
110
(b) Horizontal loops (see Fig. 31)
(i) size of bar to be not greater than 16mm
(ii) depth of the nib to be sufficient to provide
adequate top cover to reinforcement in nib
(iii) nib reinforcement to be placed on and wired to the
main reinforcement in the beam. If main rein-
forcement is too low, then additional bars should
be provided (see below)
(iv) dimension a should be a tension anchorage length
and wired to at least two main longitudinal bars
(v) lacer bar in the nib to be the same diameter as the
horizontal U-bar
(vi) Horizontal spacing of the legs of the U-bar or
between the legs of the U-bars to be not greater
than 3 times the effective depth.
(c) Welded bars (see Fig. 32)
Requirements will be the same as for horizontal loops.
«— Full strength
weld
Fig. 32 Welded bars
6.2.3 Halved-joints
The preferred arrangement shown (see Fig. 34) does not
include inclined links or bars as these are often difficult to
fix properly. However. inclined links or bars can be used
especially when large size bars are required and a welded
solution is adopted.
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Effective
depth
Tied to at least two Horizontal ‘U’ bars.
main longitudinal bars Size to be not more
than 16
Lacer bars to be same
diameter as ‘U' bars
Pitch of ‘U'bars to be not more
than 3x effective depth
Sectional plan on A-A
Fig. 33
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[OCR TEXT]
Check that any fixings required do
not interfere with reintorcement
j<—a B B
1
| |
AT toRer!-
Nominal hanser links
‘U' bar 2
Distance between edge of
bearing and inside of bar to
be a minimum of the bar size
or cover whichever is
the greater
‘u’ bar same size
as main bottom
Tension
anchorage hh Full length links sufficient to resist
t total reaction, equally spaced
1 1
2
3
4
Fig. 34 Halved joint.
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7.1 Introduction
Design and detailing of prestressed concrete are to a large
extent inseparable and this section is therefore addressed to
the designer/detailer. Only those structural members that
are commonly used are reviewed, although the principles
are applicable to other prestressed concrete members.
7.2 Drawings
In addition to the drawings showing the general arrange-
ment of the prestressed concrete structure and reinforce-
ment details, a separate set of drawings should be prepared
detailing the prestress to be applied. This set of drawings
should include the following information for each pre-
stressed concrete member:
layout and arrangement of tendons
setting-out data for each tendon profile and tolerances
tendon and duct types and sizes
anchorage recess dimensions (if any)
the prestressing system that is detailed (if any)
force to be applied to each tendon and tensioning
sequence
location of grouting points and vents
for pretensioned members any tendons to be debonded
should be marked on sections and elevations and the
method and length of debonding specified as illus-
trated in Fig. 35
L, Debonded |
1 length
-$- Strands fully bonded
-4- Strands debonded for 1700 from each end of beam
-- Strands debonded for 4500 from each end of beam
Fig. 35 Debonded tendons
tendons to be deflected should be clearly indicated and
dimensioned both horizontally and vertically see (Fig.
36) (radius of curvature to comply with the recom-
mendations of the manufacturer of wire or strand)
concrete grade and minimum strength required at trans-
fer of prestress
relevant design parameters assumed:
relaxation of prestressing steel
friction characteristics
anchorage draw-in
modulus of elasticity of steel and expected tendon
extensions
movements of permanent structure at stressing
variations in camber
IStructE Detailing Manual
Prestressed concrete
rr
Elevation
60
Section A-A Section B-B
-- Straight strands
-#- Deflected strands
Fig. 36 + Strand positions not used
for precast members: test arrangements, handling and
stocking requirements.
It should be clearly stated that the choice of prestressing
system is left to the contractor where no system is shown on
the drawings or where an alternative system to that detailed
is permitted.
It should also be stated on the drawings that any
alternative proposed by the contractor should be checked
by the original detailer/designer, particularly any reinforce-
ment modifications that may be required.
7.3 Components
7.3.1 Pretensioned units
Pretensioned units must be suitable for precasting. Bearing
plates or similar components should not project below the
element in to the soffit form to allow elastic shortening to
the member to take place.
Tendons
Tendons should be in vertical rows with spacing and edge
cover compatible with the maximum size of aggregate to
allow placing and compaction of the concrete. For symmet-
rical concrete sections, the centroid of the tendons should
lie on the vertical centroidal axis (see Fig. 37).
7.3.2 Post-tensioned units
Tendons and anchorages
(a) Tendons may consist of wires, strands or bars, pro-
duced in accordance with BS 5896 or BS 4486. Several
diameters and types of wire and strand are in common
use, but it is recommended that only one particular
type should be employed on a specific project to
obviate errors during installation. Prestressing bars are
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Tendon
locations
Dimensions to suit >
aggregate size and 4 {
concrete compaction _.|
Pretensioned section
Fig. 37 Symmetrical tendon locations
also available in several diameters (see Tables 24, 25
and 26).
(b) Post-tensioning anchorages should be of proprietary
manufacture and meet the requirements of BS 4447.
They may be either live (stressing), dead-end or
passive anchorages or anchorage couplings. Each
manufacturer produces a range of suitable anchorages.
Tendon ducts
(a) A tendon duct should be identified by its internal
diameter, which should be that recommended by the
prestressing equipment supplier for each size and type
of tendon.
(b) Ducts may be formed in several ways, most commonly
by using semi-rigid corrugated steel sheathing, which
may be bent to suit the tendon profile. Rigid steel
sheathing is occasionally used on special projects,
sometimes pre-bent to radius.
(c) External diameters of sheathing vary, depending on
the type and depth of corrugations, for which due
allowance should be made when considering spacing,
clearances and reinforcement details.
(d) The detailing should enable the sheathing or duct
formers to be adequately fixed or supported to prevent
displacement.
Duct spacing and cover
The minimum spacing and cover to ducts are specified in
Codes of Practice and Standards, taking account of the
grouping of tendons, the exposure conditions of the
structure and the maximum size of aggregate. Tolerances
relating to the position of ducts should be stated in
accordance with the relevant Codes of Practice.
Multiple layer tendons
Multiple layer tendons should be arranged in vertical rows
with sufficient space between the rows to facilitate proper
placing and compaction of the concrete without damage to
the sheathing (see Fig. 38).
Curved tendons
Where tendon profiles are curved, vertically and/or hori-
zontally, sufficient concrete must be provided to give full
support to the duct to prevent the radial force from pulling
the tendon through the wall of the duct. The spacing of
ducts may need to be adjusted to comply with Codes of
Practice. The radial stresses on the insides of curves of
small radius are considerable. Increased duct spacing and
tensile reinforcement will normally be required (see also
subsection 7.4).
Recommendations on the minimum radius of curvature
of tendons may be obtained from the prestressing equip-
ment supplier who will take into account the bending,
without damage, of the sheathing and the installation of the
114
Tendon
Dimensions to suit
aggregate size and _
concrete compaction } ' 2
Post - tensioned section
Fig. 38 Symmetrical tendon locations (multiple-layer
tendons)
tendon. Very small radii may require the use of specially
made preformed rigid sheathing. In some circumstances,
larger diameter sheathing may be required locally.
Minimum straight length of tendon
In order to ensure that the elements forming the tendon
bear an equal proportion of the prestressing force at the
anchorage, it is necessary for the duct to be straight where it
connects to the anchorage. The recommended length of
straight tendon may usually be obtained from the anchor-
age manufacturer (see Fig. 39).
Straight length from
anchorage manufacturer
Anchorage
Fig. 39 Minimum straight length of tendon
Grouting points and vents
Grouting points (see Fig. 40) are associated with anchor-
ages and should have facilities for connection to high-
pressure grouting equipment. Vents are required at all high
points to prevent air-locks. For long tendons, intermediate
vents may be advisable at low points, and in an emergency,
these can be used as intermediate grouting points.
Grout vents may be combined with sheathing couplers in
which a short steel tube is riveted to the coupler. Alterna-
tively, a plastic saddle vent is placed in the desired position
against a compressible gasket to prevent leakage and wired
to the sheathing.
A hole is punched in the sheathing through the vent pipe,
using a soft steel punch so as not to damage the tendon. A
plastic pipe is connected to the vent pipe and placed
vertically to protrude above the surface of the concrete; an
internal diameter of not less than 20mm is recommended.
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Table 24 Dimensions and properties of cold-drawn wire from Table 4 of BS 5896: 1980
nominal diameter | nominal tensile strength | nominal cross-section | nominal mass | specified characteristic breaking load
mm N/mm? mm? e/m | kN
7 1570 38.5 302 60.4
7 1670 64.3
6 1670 28.3 222 47.3
6 1770 50.1
5 1670 19.6 154 32.7
5 1770 34.7
4.5 1620 15.9 125 25.8
4 1670 12.6 98.9 21.0
4 1770 22.3
Table 25 Dimensions and properties of strands from Table 6 of BS 5896: 1980
specified characteristic
type of strand nominal diameter |nominal tensile Strength rominal steel area | nominal mass breaking load
mm N/mm? m? g/m kN
7-wire standard 15.2 1670 1090 232
12.5 1770 730 164
11.0 1770 557 125
9.3 1770 408 92
7-wire super 15.7 1770 150 1180 265
12.9 1860 100 785 186
11.3 1860 75, 590 139
9.6 1860 55 432 102
8.0 1860 38 298 70
7-wire drawn 18.0 1700 223 1750 380
15.2 1820 165 1295 300
12.7 1860 112 890 209
Table 26 Dimensions and properties of hot-rolled and hot-rolled-and-processed high-tensile alloy steel bars from Table 1 of
BS 4486: 1980
nominal nominal cross-sectional area nominal mass
type of | nominal tensile smooth ribbed smooth ribbed characteristic
bar size Strength surface bar bar bar bar breaking load
mm N/mm? mm? mm? kg/m kg/m kN
hot rolled 20 smooth 314 349 2.47 2.74 325
25 1030 or 491 538 4.04 4.22 505
32 ribbed 804 874 6.31 6.86 830
40 1257 1348 9.86 10.58 1300
hot rolled 20 smooth 314 349 2.47 2.74 385
and 25 1230 or 491 538 4.04 4.22 600
processed 32 ribbed 804 874 6.31 6.86 990
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Plastic vent pipes should be adequately supported —
possibly by the insertion of a loose-fitting reinforcing bar or
length of prestressing strand.
The grouping of grouting and vent pipes at a single point
should be avoided.
Grout
pipes
A Vent pipes
a
‘ > 2
99}
a----—
cc
oT
Qo1
oe
Fig. 40 Grouting points and vents
Duct profile
The duct profile should preferably be given in tabular form,
the horizontal and vertical dimensions being based on a
datum that is easy to identify on site. The profiles for each
vertical row of ducts should be tabulated separately, with
X-, y- and z-coordinates (see Fig. 41).
Dimensions should be to the centre of the duct or ducts
and should be sufficiently frequent to define adequately the
profile, taking account of its radius of curvature.
Distance atong
member (intervals
ato or 20 of span)}
Ordinate above
soffit,y mm
Tendon @ 1340 = 1203 1061 938 833
Tendon @ 888 771 679
Distance along
member.
Distance from
outside face,z mm
Tendon @
Tendon @
560
1020
300 150 105
770 600 570
Note : All dimensions to duct centre lines
Fig. 41 Duct profiles
Anchorages
If the structure is detailed for a particular prestressing
system, an outline of the anchorage should be shown; it
should be axially in line with the last straight length of
tendon. The spacing and edge distance should not be less
than those recommended by the manufacturer.
If the structure is not detailed for a particular system then
a general outline should be drawn that would generally
encompass approved systems.
Anchorage recesses (see Fig. 42) should be dimensioned
to provide adequate working clearance to the stressing
IStructE Detailing Manual
*
*
co
Part plan
>
*
**
*Key dimensions required
lL
Section End elevation
Fig. 42 Anchorage recesses in end block
equipment and sufficient depth to ensure that they can be
subsequently filled with mortar or concrete to provide
corrosion protection. Reinforcement may be required to
retain the concrete or mortar filling; a convenient method is
to screw small diameter bars into sockets provided in the
faces of the recess.
Working clearances
Space should be provided in front of the anchorages to
enable the stressing jack to be lowered into position with its
oil pipes, to be extended in line with the tendon and to be
removed after stressing (see Fig. 43). There must be
A Total clearance recommended to allow removal of
equipment after completion of stressing
B Overall length of stressing equipment including extension
C Overall length of equipment before stressing
Fig. 43 Jack clearances
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sufficient space for the operators to stand alongside the (c) Tensile stresses occurring on the faces of end
jack.
Where the permanent works cause a temporary obstruc-
tion to the stressing operations, they should be detailed to
allow for the completion of construction after stressing,
e.g. wing and facing walls.
7.4 Reinforcement detailing
It is necessary to identify the areas in the structure that are
subject to tensile forces, and the clauses in this subsection
relate to the detailing of reinforcement in these areas. As
a =
pon
po
+—,——4
Fig. 44 Overall equilibrium of end block
for reinforced concrete, all the reinforcement in any one
part of a concrete member should be detailed on one
drawing.
7.4.1 End blocks in post-tensioned members (see
reference 10.4.1)
An ‘end block’ is that zone of a prestressed concrete
member in which the prestressing force is dispersed from
the tendon anchorages to an approximately linear distribu-
tion across the section.
Reinforcement in end blocks should be detailed to
ensure satisfactory behaviour of the end block under the
following effects:
(a) Overall internal equilibrium of the end block
Both vertical and horizontal equilibrium should be
considered and reinforcement provided to resist the
tensile forces induced (see Fig. 44).
Tensile bursting forces behind the anchorage
These forces act normally to the line of the prestressing
force in all lateral planes. The reinforcement to resist
these forces is normally provided as closed hoops or
spirals. Because the tensile forces act in all lateral
planes the reinforcement will be stressed throughout
its length, and it is essential that any hoops or links are
detailed with full tensile laps (e.g. BS 4466, shape code
74, but with large radius bends to avoid crushing the
concrete).
To restrain the bursting forces effectively the rein-
forcement should be positioned as near as possible to
the outer edge of the largest prism whose cross-section
is similar to and concentric with that of the anchor plate
having regard to the direction in which the load is
spreading, and at least 50mm outside the edge of the
anchor plate (see Fig. 45).
Reinforcement links for adjacent anchorages should
be overlapped and longitudinal bars positioned in the
corners. Where spirals are provided with some prop-
rietary anchorages as part of the anchorage system,
additional reinforcement may be required to resist the
bursting forces.
(5)
118
Force
distribution
blocks adjacent to the anchorages
To resist these stresses and prevent concrete spalling,
reinforcement should be placed in two directions at
right-angles as close to the end face as cover considera-
tions permit.
_ End blocks distribute high forces requiring large quan-
tities of reinforcement in relatively small spaces. This has
two consequences:
Resultant of
distributed
B Cc force
\ wd |
—_ Le
* Shear
Tension
Compression
*Forces required to maintain
equilibrium of block ABCD
Theoretical prism
associated with
horizontal bursting
Prism associated with
vertical bursting
Horizontal bursting
reinforcement
(extends to depth b)
Anchorage. Vertical bursting reinforcement
(extends to depth t)
End elevation
Zone for positioning vertical
bursting reinforcement
bP
Zone tor positioning horizontal
bursting reinforcement
t=Least dimension
Side elevation
of member
Fig. 45 Location of bursting reinforcement
(i) The forces in the reinforcement build up quickly over
relatively short lengths, and great care should be taken
to ensure that the bars are anchored effectively. At all
corners, the bars should have large radius bends to
avoid crushing the concrete or should pass round a
longitudinal bar or tendon of at least the same dia-
meter.
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(ii) As well as the tensile forces described above there are
significant compressive forces in end blocks, particu-
larly immediately behind the anchorages, which must
be resisted by the concrete. The reinforcement should
be detailed to allow the concrete to be properly placed
and compacted.
7.4.2 Secondary reinforcement
While prestress is normally introduced into a member to
enable it to resist bending moments and axial loads, it may
also contribute to the shear and torsion capacity. However,
secondary reinforcement may be required to enhance shear
and torsion resistance, for crack control and for fire
resistance.
Shear reinforcement in post-tensioned beams should
consist of open links or pairs of lapping U-bars so that the
tendons can be easily positioned (see Fig. 46).
Position of
ducts vary
Fig. 46 Shear reinforcement
The detailer should be aware that Codes of Practice may
require that:
@ minimum areas of reinforcement be provided to control
cracking in end blocks or shear requirements for
e reinforcement be provided longitudinally to resist tensile
forces caused by restraints to early thermal movement
(e.g. by the falsework) before the member is stressed.
7.4.3 Additional reinforcement around holes
When holes occur in prestressed concrete members, the
compressive stresses in the direction parallel to the line of
action of the prestress may be significantly increased (see
“Fig. 47). Tensile stresses of the same order as the longitu-
dinal stresses are also induced normal to the line of action
of the prestress. Reinforcement may be required to resist
the tensile forces and the enhanced compressive stresses.
The reinforcement should be fully anchored into the
surrounding concrete.
Local reductions in cross-sectional area also occur at
coupler positions and at ducts for transverse, vertical or
diagonal tendons. These reductions may lead to substan-
tially increased stresses that require additional reinforce-
ment.
> _
_ : —-_
Compression
—_ anchorage _—
length
_ _—
—_ Compression +a
_ = a
p =
_ +s
> +s
£
— +d
3
- . ~_os
Tension §
> anchorage +5
— length _
—_ =
—_ =_
Fig. 47 Stress distribution and additional reinforcement
around circular hole
TStructE Detailing Manual
7.4.4. Reinforcement to resist the normal component
of the prestress
Angular deviation of the tendon line causes forces normal
to the tendon. Although these lateral forces are in equilib-
rium when the member is considered as a whole, local shear
forces and moments are induced, and these should be
resisted by reinforcement,
As an example consider an anchorage blister on the
flange of a box girder (see Fig. 48). The radial component
of the prestress force (PR) is applied to the concrete along
the curved length of the tendon and is balanced by the
forces at the end of the tendon (PV1, PH1 and PH2).
Reinforcement should be provided to resist the forces and
moments induced.
Possible crack
Additional reinforcement
Additional reinforcement
for local bending
Fig. 48 Forces acting at anchorage blisters
Where the radial prestress component PR is applied near
the face of the concrete it may cause spalling. Reinforce-
ment links should be provided to transfer this force into the
concrete flange. They should be distributed along the
curved part of the tendon. Additional links should be
provided beyond the tangent points to allow for any
misalignment of the tendon.
nA
A
Plan
beteaae
throttt
A-A
Forces actingon
cross section Moments around box
Fig. 49 Forces in box girder curved in plan
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When tendons are located in the webs of beams that are
curved in plan (see Fig. 49), the lateral force from the
tendon is balanced by the combined lateral forces from the
compressions in the web and flanges. The distribution of
forces induces bending in the web that should be resisted by
reinforcement.
The radial component of the prestress force increases
with decreasing radius of curvature. In looped anchorages
the radial force is large, and local reinforcement similar to
that in end blocks is required (see Fig. 50).
7.4.5 Reinforcement against grouting pressure
It is usually specified that tendon ducts should be grouted to
a pressure of 0.7N/mm/? (7 bars). In some circumstances,
higher pressure may be used in order to force grout through
the duct. Sheathing, anchorages and couplers are not
designed to resist grouting pressure, which is consequently
transmitted to the concrete where it can induce tensile
stresses.
Fig. 51 shows areas where tensile stresses are induced
when the ducts are grouted. It may be necessary to provide
reinforcement links around the ducts.
Plan
Tensile bursting forces
Radial forces
Elevation
Ducts in thin members
Local reduction in concrete section
at couplers
oa
Local bending at rectangular ducts
Fig. 51 Tensile forces due to grouting pressure
120
7.4.6 Intermediate anchorages
Fig. 52 shows an anchorage within the body of a concrete
member. Under the localized action of the prestress force,
an imaginary line AA will tend to deform to A’‘A‘ creating
tensile forces parallel to the tendon. These tensile forces
may occur even when there is an overall compression in the
member from, for example, other prestressing tendons.
Large radius
bend
AN’
Alternatively :-
Large radius bend
Fig. 52 Tensile forces and additional reinforcement at
intermediate anchorages
Reinforcement fully anchored into the surrounding con-
crete should be provided each side of the anchorage
parallel to the prestressing tendon.
Local tensile forces can also occur at anchorage coup-
lings (see Fig. 53). When the coupled tendon is stressed the
force between the previously stressed concrete and the
anchorage decreases, and the local deformation of this
concrete is reduced. Increased compressive forces are
induced adjacent to the anchorage and balancing tensile
forces between adjacent anchorages. Cracking in the
tensile zones should be controlled by distributing tendons
around the cross-section, by providing fully anchored
reinforcement to resist the tensile forces or by providing
some ayroupled tendons across the joint (reference
10.3.1.4).
7.4.7 Pretensioned members
In pretensioned members the axial prestress force is
transferred from the tendons to the concrete over a finite
length. When the tendons are released from the casting bed
the stress within the transmission length is reduced leading
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to an increase in the diameter of the tendon because of the
Poisson effect.
This transmits a radial compressive force into the
concrete that is balanced by circumferential tensile forces.
Adequately anchored reinforcement should be provided
over the whole transmission length to resist these forces. If .
the tendons are distributed both vertically and laterally in
conformity with the linear prestress distribution remote
from the transmission zone effects, then the transmission
zone will be in internal equilibrium without the need for
any additional reinforcement. If the tendons are concen-
trated in groups the overall internal equilibrium of the
transmission zone should be considered and reinforcement
provided (see Fig. 54).
It is recommended that the end zone of a beam is
designed and detailed as a reinforced concrete member
with longitudinal and shear reinforcement as necessary (see
reference 10.3.3.13).
It is normal practice to provide sets of standard stirrups at
a closer spacing (e.g. 75 mm) in transmission zones that not
only occur at the end of members but also where tendons
are debonded. This reinforcement is usually sufficient to
resist the Poisson effect and equilibrium forces, as well as
providing adequate shear capacity (see Fig. 55).
Note:
Re identical
Force
distribution
Fig. 54 End zones in pretensioned members
7.4.8 Construction joints
Detailing reinforcement should allow for possible locations
of vertical and horizontal construction joints, which should
avoid cast-in components such as anchorages and couplers.
Where construction joints intersect the planes of tendon
ducts, they should be positioned to avoid areas with
restricted access for vibration equipment and scabbling
tools.
7.5 Other effects of prestressing
Information of the aspects below should be provided on the
drawings.
7.5.1 Movements of the permanent structure
During application of the prestressing forces to the perma-
nent structure, horizontal movements arising from elastic
shortening of the concrete members and vertical move-
IStructE Detailing Manual
End zone
——
—
—.
—
—
—
—.
—.
—
—
—.
—> _
—. _
— ~_—_
—+ —
—+. <<
——. <_—
—. __
— __
— _—
—» _
Stage 2
Fig. 53 Tensile forces at anchorage coupling
Stress trajectories
“Balanced”
No reinforcement
Change in force distribution over length of end zone
Stress trajectories
Additional reinforcement
required
Force
distribution
Length of debonding
(see schedule)
Debonded tendon
Bonded tendon
Transmission zone
of bonded tendon
Transmission zone
of debonded tendon
Fig. 55 Transmission zones in pretensioned members
ments due to the induced prestress will take place. The
movements will be transmitted to supporting falsework,
which in turn will tend to move in sympathy. Clear
indications of the expected movements and the method of
articulation should be given to avoid overstressing both
permanent and temporary structures. In particular, tem-
porary restraints to movements should be identified, e.g.
anchored sliding bearings.
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Where prestressed concrete structures are formed on
long-span falsework that has greater flexibility than that of
the permanent structure, consideration should be given to
the effect of any residual deflection of the falsework
imposing additional upward forces on the permanent
structure on completion of the stressing operations (see
Fig. 56).
Stage 1 Concrete
structure
Long span
falsework
Initial falsework deflection = Ay
Stage 2
Tendons stressed
42 4
r
Deflection reduces to Az < Ay
Stage 3
42 4 FATT
/
7
Residual reactions on structure from
falsework left in position
Fig. 56 Effect of leaving falsework in position — case A
Stage 1
Concrete
structure
Previously
stressed
Long span
falsework
Initial falsework deflection = Ay
Stage 2
oat (SSS
Deflection reduces toAg<Ay
7 i
Residual concentrated reactions on structure
from falsework left in position
Corresponding concentration of forces on falsework
Tendons
stressed
Stage 3
Fig. 57 Effect of leaving falsework in position — case B
122
To ensure that these temporary upward forces do not
overload the permanent structure it may be necessary to
release falsework in phase with the application of the
prestress. Any tendency during stressing for the permanent
works to impose additional vertical downward forces on
falsework should be clearly stated on the drawings (see Fig.
57).
7.5.2 Variations in camber
In defining the dimensional tolerances of prestressed
concrete members, variations in the modulus of elasticity
and elastic shortening of the concrete should be con-
sidered. The effects of variations in camber are of great
signifiance at the detailing stage. As an example, variations
in camber will occur between the adjacent units of a floor,
which in turn will influence the average thickness of
subsequent floor screeds.
7.6 Typical details
Figs. 58 to 66 illustrate typical details in prestressed
concrete members and incorporate the recommendations
made in this manual.
Transverse reinforcement in post-tensioned box girder
Fig. 58 shows the variation in reinforcement along a beam
to accommodate the changes in level of the tendons.
Post-tensioned end block, reinforcement
Figs. 59 to 62 illustrate reinforcement in an end block. Each
figure highlights reinforcement that is provided for a
specific function as described in this manual.
Anchorage details for prestressed silo wall
Fig. 63 illustrates typical anchorage reinforcement, which
extends over the full height of the silo. The tendon should
extend from the tangent point to the anchorage ina straight
line, the buttress being dimensioned such that the mini-
mum concrete cover is maintained to the tendons at the
junction of the silo wall with the buttress and that adequate
jack clearance is provided.
Flat-slab prestressing with unbonded strand
Figs. 64, 65 and 66 show the typical three-drawing method
of detailing by which the tendon layout, the tendon support
bars and the additional bonded reinforcement are shown
separately. A typical example of the legend by which
groups of tendons and anchorage types and the tendon
placing sequence are indicated is shown in Fig. 64, while
Fig. 65 shows a typical support bar layout. The actual
layout may be modified by the contractor depending on the
support system adopted so that the specified tendon
profiles are attained and adequate support provided. Fig.
66 shows the reinforcement that is always required in the
top of the slab at columns, the end-block reinforcement and
the reinforcement needed in the bottom of the slab at
mid-span in some design applications (see references
10.4.4, 10.4.5 and 10.4.6).
In addition to the flat plate shown, other types of flat-slab
are used — with drops, coffered or ribbed. The principles
of detailing are however applicable to all.
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Pe Pere Pere
be bo be baba
Elevation of tendon profiles.
Fig. 58 Transverse reinforcement in post-tensioned box girder
Fig. 59 Post-tensioned end block — bursting reinforcement
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OC
LE ISS]
Note:
Some of this reinforcement
resists shear forces
Fig. 61 Post-tensioned end block — vertical equilibrium reinforcement
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=e
oS
Note:
Some of this reinforcement
resists diaphragm bending
moments
Fig. 62 Post-tensioned end block — horizontal equilibrium reinforcement
25
\ Note:
t Detail repeats over full
Anchorage height of silo
1000 1000
25
=|
|
Circumferential ¢ Buttress
strand tendons point
Plan
2 No. per
anchorage
2 No. straight
per anchorage Silo wall
reinforcement
Fig. 63 Anchorage detail for prestressed silo wall
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126
*
So
So190\1o
OlEm~! ao °
LI LE
a
J
SS
14500. O
15500 5
16500 ,
2
So
wo
QD
q——o
13500
q
“a
i
White 43000 ait
20n0.
JEOLOROROLOTOROTORORORORE
6 bs
Blue "9000 TTT
OO ®
{i—
a
iT
PT
Se IT
tte
a
Tendon layout
A-A '
Tendon quantity, length,color-code, elongation
Placing sequence (when required )
wn Dimensions from reference line
N to centreline of tendon group
nu
0. 20 One strand
€lS Two strands
xls
wsl5 Three strands
” Four strands
Fi t
1x10 67 (added) oe Strands
Red 4=75 Add strands
3x24 50 (thru)
Blue a=165 Will be marked with
one of the above
symbols
Edge of slab
Note:
When more than one symbol appears on a tendon
group, the number of strands equal the sum of
the symbol designations.
Fig. 64 Flat slab — tendon layout
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A
—~-—Tendor
4
40 i
ns tied tomesh —
a
1. Height given is from soffit of sab to underside of tendon
2. Diameter of support bar is 10mm
Fig. 65 Flat slab - tendon profile and typical support bar layout
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IStructE Detailing Manual
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Detailing of precast concrete work requires special disci-
plines that do not occur with in situ concrete. The reason for
these are:
The precast unit is, by definition, transported after it is
made before it can be incorporated in the works.
The unit is often incorporated into a ready built or part
built structure. In these cases, consideration of toler-
ances is important.
The unit is often made by a third party who may not
have visited the site and will not have all the drawings.
Clarity of instruction to the precaster and preliminary
discussions are therefore vital.
Precast concrete structures usually require special con-
sideration of joints. Sound detailing of these areas leads
to attractive, serviceable and safe structures.
Precast units are often cast in a different orientation from
that of their final use. The decision of how to cast is often
best left with the precaster or should at least be discussed
and agreed with him. At the detailing stage the designer
should make his intention clear on surface finish and on
tolerance. Areas where tolerances different from the
specification are required for particular reasons should be
clearly noted. Remember that unnecessarily rigid specifica-
tions may not be economic in the long run.
It is particularly difficult to form re-entrant or protruding
corners without having breakage or an unsightly finish.
Acute re-entrant corners are to be avoided as it is difficult
to remove the formwork without damage. Acute protrud-
ing corners are often broken in handling and are often
discoloured because the large aggregate cannot get into the
corner. Fig. 67 shows how a notched skew-ended beam
should be detailed to overcome these problems. Also
shown is a recommendation on the dimensioning of
skew-ended beams.
The need to transport a precast concrete element
requires that consideration should be given not only to its
physical size and weight so that transportation is possible
but also to the specification of permissible lifting positions
and angles of lifting.
These basic rules are not exhaustive but give a guide for
the detailer in proportioning elements:
length 27.4m no restriction if also < 32 tonne
gross and < 3m wide
27.4m special dispensation required from
Department of Transport
4.0m total load no restriction
4.0m special routing necessary
2.9m no restriction
2.9 up to 4.3m possible with notification to
police
4.3 up to 6.1m special dispensation re-
quired from the Department of Trans-
port
<
>
height <
>
width
!StructE Detailing Manual
Precast concrete
weight < 20tonne norestriction on normal 32 tonne
truck . .
< 38 tonne no restriction on special 38 tonne
truck
20 < weight < 60 tonne on low loader or
steerable bogie
60 < weight < 160 tonne police escort
required, possible special routing, use
of air-cushioned vehicle or hydraulic
bogies possible.
The most frequently used loads are with a 20 tonne
payload on a 32 tonne gross truck. In these cases, with
multiple numbers of units on a load, significant savings can
be made if weight of whole number of units approaches but
does not exceed 30 tonne, i.e. 2 no. 9.8 tonne per load as
against 1 no. 10.2 tonne units.
Permissible support points and packing materials should
also be noted.
Lifting strengths for the concrete should be stated on the
drawing, remembering that the maximum mould use on a
repetitive job will bring all its economies only if the very
minimum lifting strength is specified.
The weight of the unit for craneage and for the estima-
tion of transportation should be clearly stated on the
drawing.
According to BS 4449, ordinary reinforcement is not
suitable for use as lifting hooks. Some precast manufac-
turers do use reinforcement for lifting purposes, but it is
presumed that they do so with proper care and attention
to details and lifting practices and on the basis of practical
tests and the risks involved.
A range of proprietary inserts are marketed, both for
fixing and lifting. It is-important that these are used to the
manufacturer’s instructions with adequate factors of safety.
It is also important that secondary load effects or structural
movements do not put forces on inserts for which they have
not been tested or designed. In these cases, means should
be sought to isolate the fixings so that only the correct
forces may be applied.
Where a drawing not only shows a part of a unit that is
cast on to another precast unit, the drawings of each should
clearly state where the weights are noted that the weights
are only for part units.
Units of complex shapes should be discussed with a
precaster before their details are finalized. Units with a
requirement for a high quality of finish may be required to
be cast in one piece moulds. In these cases, a drawing for
demoulding is necessary, and the unit and its surrounding
. Structure should be detailed accordingly.
The design of joints and the requirements for the
detailing of reinforcement and concrete (binding links,
chamfers, etc.) are covered in the Institution of Structural
Engineer’s report Structural joints in precast concrete,
1978 (reference 10.3.3.12).
For precasting, the detailer needs to be fully aware of the
method of moulding and the assembly and handling of the
reinforcement cage, but such expert knowledge is normally
available only in the office of the specialist precaster.
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Grid line Grid line
4215 1500 1500
Special cast in sockets for
lifting device
50 Dia hole
50 Dia hole
Structural
floor level
Cast in sockets for
leveling bolts, see detail
'
i — A
Typical elevation panel type Section A-A
P103 22No.requiredthus 1:25 1:25
Grid line
Flatnes to be half the
specified value in BS 8110 a A
m Typical location plan showing
Section B-B 1:25 layout of units 1:100
Notes:
Unless otherwise specified all concrete units to be
manufactured in accordance with BS 8110
1. Cube strengths: 15 N/mm? before demoulding
40N/mm? at 28 days
. Cover: 25mm nominal
. Finishes : Type C except as noted on drawing
. Cement type: R.H.P.C.
. Aggregate type: 20mm max
Weight of unit: 3-44 tonnes
. Units to be lifted using special cast-in sockets
in top. Lift to be vertical where possible or angle
of lift from vertical
not to exceed 45°
angle
State skew | \
H
NOuUhwWH
Dimension
M™—— to centre line
Plan of skew ended
8. Tolerances: To BS 8110 except as noted on drawing
Fig. 67
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9 Water-retaining structures
9.1 General
Water-retaining structures will in general be detailed in
accordance with the recommendations for normal rein-
forced concrete structures except that the provision of
reinforcement, spacing of reinforcement, cover and dura-
bility requirements are generally more onerous. BS 8007
deals with the design of reinforced concrete service
reservoirs and tanks used for the storage of water and
other aqueous liquids. In normal structures the most
critical aspect of design is generally the ultimate limit state
(strength), whereas for structures designed to retain
liquids not only is strength to be considered but it is
essential to restrict the width of cracks in the concrete.
The provision and spacing of reinforcement to satisfy the
limit state of cracking may therefore control the design
and in many cases exceed that required for strength.
Water-retaining structures designed to BS 8007 require
reinforcement to resist tensile forces caused by:
(a) structural actions due to applied loads and
(b) restraint to thermal contraction and drying shrinkage
The reinforcement to be provided in all slabs and walls in
a particular direction is the larger of the amounts required
separately for (a) and (b).
Unlike normal structures where the construction joints
are not normally shown on the detailed drawings but are
described in the specification, the positions of all construc-
tion joints and movement joints must be shown on the
drawings (see Fig. 68).
It is the responsibility of the designer and not the
contractor to position all joints as the amount of reinforce-
ment to resist the tensile forces arising from thermal
contraction and drying shrinkage is dependent on the
frequency and spacing of all types of joints.
9.2 Cover
Durability is considered to depend on the concrete grade,
cement content, crack width and cover. For reinforced
concrete the maximum design surface crack widths for
direct tension and flexure or restrained temperature and
moisture effects are:
(1) severe or very severe exposure: 0.2 mm
(2) critical aesthetic appearance: 0.1 mm
The nominal cover to any reinforcement given in BS 8007
should not be less than 40 mm. This is satisfactory for
severe exposure. For very severe exposure the cover and
mix should empty with BS 8110; Part 1. A greater cover
may be necessary at a face in contact with aggressive soils
or subject to erosion or abrasion.
9.3 Spacing of reinforcement
For tensile reinforcement the bar spacing should not
exceed 300 mm.
9.4 Bar anchorage lengths
Table 27 gives anchorage lengths in terms of bar size,
according to the allowable steel stress in service conditions
for horizontal bars in members in direct tension (e.g. hoop
tension).
IStructE Detailing Manual
Table 27 Tension anchorage lengths for structural re-
quirements (a)
member in direct tension
deformed
bar type plain (type 2)
concrete] design crack 0.1mm 0.2mm 0.1mm 0.2 mm
grade width
allowable 85 115 100 130
stress, fi, N/mm?
35/40 | anchorage
length, mm 30D 40 20D 26m
45 ancorage
length, mm 26 35 18 23
Notes:
1. If Asproy exceeds Ayjeq multiply by Asce.
sprov
2. If in flexure, multiply anchorage length by 0.7
Table 28 gives anchorage lengths in terms of bar size
for members in flexure in which the steel area provided is
no more than the steel area required for the ultimate limit
state.
Table 28 Tension anchorage lengths for structural
requirements (a)
member in flexure ~ ultimate limit state
bar type deformed
concrete steel strength, f, plain (type 2)
grade N/mm? 250 460
35/40 anchorage length, mm 330 34o
45 anchorage length, mm 29 30
Note:
If Agproy exceeds A,q multiply by Asse
Table 29 gives anchorage lengths in terms of bar size
for slabs and walls in which the steel ratio provided is no
more than the critical steel ratio.
Table 29 Tension anchorage lengths for thermal and
shrinkage requirements (5)
bar type deformed
concrete steel strength, fy plain (type 2)
grade N/mm 250 460
35/40 Perit 0.0064 0.0035
lap length, mm 39 48
45 Perit 0.007 0.0038
lap length, mm 36g 44
Notes:
1. Perit is the critical steel ratio, i.e. the minimum ratio of steel area to the gross
area of the whole concrete section required to distribute cracking.
2. If Asprov exceeds Agr multiply by Ascrit
sprov
where Agcrit = Peri X gross area of whole concrete section.
General note
Tables 28, 29 and 30 give tension anchorage lengths: The lap length = a factor x
anchorage length. The factor may be 1.0, 1.4 or 2.0, and the value to use will
depend on cover, position and spacing of bars (BS 8110, clause 3.12.8.13).
However in many situations the value will be 1.0 or 1.4. The minimum lap length
for bar reinforcement should not be less than 15 times the bar size or 300 mm,
whichever is greater.
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Fig. 68 Examples of movement joints
Non -absorbent
joint filler
Sealing compound on
one or both faces
Wall
No steel
continuity
Centre bulb
waterstop
Initial gap for
expansion
(a) Expansion joints
Sealing compound on
one or both faces
No concrete continuity
and no initial gap
Wall
No steel
continuity
Formed
Waterstop
Sealing compound on
one or both faces Induced crack
No steel
continuity
Induced
Central crack
inducing waterstop
(b) Complete contraction joints
Sealing compound on
one or both faces
No concrete continuity
and no initial gap
Wall
Steel
Waterstop
Sealing compound on
one or both faces ‘\
Steel
Induced
Central crack
inducing waterstop
(c) Partial contraction joints
IStructE Detailing Manual
continuity 50%
Formed
continuity 50%.
Non-absorbent
joint filler
Sealing compound \
Floor
No steel
continuity
Initial gap for
expansion
Expansion type
waterstop
Joint sealing
compound
No concrete continuity
and no initial gap
Floor
No steel
continuity
Waterstop
Wet- formed or sawn
Induced crack slot seated later
Waterstop with
crack inducing upstand
Joint sealing
compound oo,
No concrete continuity
and no initial gap
Floor
Steel
continuity 50%
Waterstop
Joint sealing
compound
a Sa
Bo To
Induced crack
Steel
continuity 50%.
Waterstop _/
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10
10.1 Essential references for detailers
10.1.1 BS 4466 Specification for bending dimensions
and scheduling of reinforcement for concrete
10.1.2 BS 1192 Construction drawing practice
Part i: Recommendations for general prin-
ciples
Part 2: Recommendations for architectural
and engineering drawings
Part 3: Recommendations for symbols and
other graphic conventions
Part 4: Recommendations for landscape
drawings
10.2 Important reference documents
10.2.1 BS 8110 Structural use of concrete
Part 1: Code of practice for design and
construction
10.2.2. BS 8007 Code of practice for the design of
concrete structures for retaining aqueous
liquids
10.2.3. BS 5400 Steel, concrete and composite bridges
10.2.4 Concrete Society Standard reinforced concrete
details, Technical report no. 6, ref. 51.066
10.3 Other useful references
10.3.1 Standards and Codes
10.3.1.1 BS 6100 Glossary of building and civil en-
gineer ing terms
Section 6.2: Concrete
Section 6.3: Aggregates
10.3.1.2 BS 8004 Code of practice for foundations
10.3.1.3. BS 4210 Specification for 35mm microcopying
of technical drawings
10.3.1.4 BS 4449 Specifications for hot rolled steel bars
LY the reinforcement of concrete
10.3.1.5 BS 4482 Specification for cold reduced steel wire
for the reinforcement of concrete
10.3.1.6 BS 4483 Specification for steel fabric for the
reinforcementof concrete
10.2.1.7 BS 5395 Stairs, ladders and walkways
10.3.9 ISO 128 Technical drawings: general principles
of presentation
10.3.1.10 ISO 1046 Architectural and building drawings:
vocabulary
10.3.1.11 ISO 1047 Architectural and building drawings:
presentation of drawings, scales
10.3.1.12 ISO 3098-1 Technical drawings:
Part 1: Currently used characters
10.3.1.13 ISO 5455 Technical drawings: scales
Lettering,
10.3.2 Cement & Concrete Association publica-
tions
10.3.2.1 Balint, P. S., & Taylor, H. P. J. Reinforcement
detailing of frame corner joints with particular
reference to opening corners, 1972, No.
42,462
10.3.2.2. Higgins, J. B., & Rogers, B. R. Designed and
detailed, 1986, no. 43.501
IStructE Detailing Manual
References
10.3.2.3. Green, J. Keith. Detailing for standard pre-
stressed concrete bridge beams, 1973, no. 46.018
10.3.2.4 McKelvey, K. K. Drawings for the structural
concrete engineer, 1974, no. 14.008
10.3.3. Other standards and manuals
10.3.3.1 American Concrete Institute Manual of stan-
dard practice fer. getailing reinforced concrete,
1988, ACI 315
10.3.3.2 Concrete Renforna Steel Institute, Illinois
Manual of standard practice, 1988, MSP-1-80
(3rd ed.)
10.3.3.3. British Reinforcement Manufacturers Associa-
tion Reinforced concrete ground slabs, 1973
10.3.3.4 Canada National Standard of Canada, CAN3-
B78.3-M77
10.3.3.5 New Zealand New Zealand Standard, NZs 5902
Part 2: 1976
10.3.3.6 Concrete Institute of Australia Code of practice
for reinforced concrete detailing manual, 1975
10.3.3.7 South African Bureau of Standards Detailing of
steel reinforcement for concrete, 0144-1978
10.3.3.8 Whittle, R. Reinforcement detailing manual,
Viewpoint Publications, 1981
10.3.3.9 Daltry, C. D., & Crawshaw, D. T., Building
Research Establishment Work drawings in
use, CP18/73, 1973
10,3.3.10 Institution of Structural Engineers/Concrete
Society joint report Design and detailing of
concrete structures for fire resistance, 1978
10.3.3.11 Building Research Establishment Work draw-
ings and their use on building sites, CP60/76,
10.3.3.12 Institution of Structural Engineers report Struc-
tural joints in precast concrete, 1978
10.3.3.13 Construction Industry Research & Information
Association Design of deep beams in rein-
forced concrete, Guide no. 2
10.3.3.14 Comite European du Beton/Federation Inter-
nationale de la Precontrainte Model code for
concrete structures, 1978
10.3.3.15 Leonhardt, F., Federation Internationale de la
Precontrainte 9th Congress ‘Prevention of
damage in bridges’, Proc., 1, 1982
10.3.3.16 Birt, J. C. Large concrete pours: a survey of
current practice, CIRIA report no. 49, 1974
10.3.3.17 Paterson, W. S. & Ravenshill, K. R. Reinforce-
ment connector and anchorages, CIRA report
no. 92, 1981
10.4
10.4.1
Prestressed concrete
Construction Industry Research & Information
Association A guide to the design of anchor
blocks for post-tensioned prestressed concrete
members, Guide no. 1, 1975
Federation Internationale de la Precontrainte
Guide to good practice: practical construc-
tion, 1975
Federation Internationale de la Precontrainte
Guide to good practice: basic reinforced and
prestressed concrete construction, 1978
10.4.2
10.4.3
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CIS 5}274 HMSO 1989813120 MM 8886148 DP 4d?
PART IV
Special procedural provisions for certain orders
18. Preliminary
19. Special provisions for consolidation orders
20. Minor orders
21. Special provisions for experimental traffic orders
22. Special provisions for orders giving permanent effect to experimental orders
23. Orders under section 30 of the 1984 Act (playgrounds in London)
24. Special provisions for loading area orders
25. | Making of orders in part
26. Revocation or revocation and re-enactment where due to exceptional circum-
stances notices of the making of orders are not published
27. Re-enactment of orders which in exceptional circumstances have been revoked
before publication
PART V
Procedures and objections under paragraph 7 of Schedule 5 to the Local
Government Act 1985
28. Preliminary
29. Procedures and objections
PART VI
30. Transitional provisions
SCHEDULES
1. Particulars to be included in press notices
2. Requirements as to notices to be displayed in a road or other place
3. Requirements as to the availability of documents for inspection
4. Documents to accompany the application for the Secretary of State’s consent
5. Minor orders
The Secretary of State for Transport and the Secretary of State for Wales, in exercise of
their powers under sections 30(6) and 124 of and Part III of Schedule 9 to the Road
Traffic Regulation Act 1984(a) (“the 1984 Act”), section 8 of and Schedule 5, paragraph
7 to the Local Government Act 1985(b) and of all other enabling powers, after
consultation with representative organisations in accordance with section 134(2) of the
1984 Act, and after consultation in accordance with paragraph 23 of Schedule 9 to the
1984 Act, hereby make the following Regulations:-
(a) 1984 c,27; section 30 and Schedule 9 were amended by the Local Government Act 1985 (c.51),
Schedule 5, paragraph 4(39).
(b) 1985 ¢.51.
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[NATIVE TEXT]
IStructE/Concrete Society Standard Method of Detailing Structural Concrete
iii
CONTRIBUTORS
Constitution of Steering Group
J K Kenward BEng(Tech) CEng FIStructE MICE MIHT (Hyder Consulting Ltd) Chairman
R Bailey* CEng MIStructE (Milbank Floors)
R Bloomer** BSc CEng MICE (BRC)
B Bowsher (UK CARES)
P S Chana BSc(Eng) PhD CEng FIStructE MICE (British Cement Association)
S M Doran BSc(Eng) AKC PhD CEng MICE ACIS (Institution of Structural Engineers)
C H Goodchild BSc CEng MIStructE MCIOB (The Concrete Centre)
J Kelly (G.D.C. Partnership)
D Keogh (Laing O’Rourke)
S Mahmood BSc CEng MIStructE (Sir Robert McAlpine Ltd)
P Matthew*** (Matthew Consultants)
R P Wolstenholme**** BSc CEng MICE (Atkins)
Corresponding members
R Chu CEng FIStructE FICE FHKIE (Meinhardt (C&S) Ltd Hong Kong)
R Gordon (Mace)
R Lancaster BSc(Eng) CEng FICE FCIArb FACI (Consultant)
G Nice (BRC Special Products)
D Pike BSc(Eng) PhD CEng MICE (Building Design Partnership)
C B Shaw CEng MIStructE FICE MCMI FIIExE (Consultant - Chairman BS 7973)
Consultants to the Steering Group
R Whittle MA(Cantab) CEng MICE (Arup Research and Development)
A E K Jones BEng(Hons) PhD MICE (Arup Research and Development)
Secretary to the Steering Group
J L Clarke MA PhD CEng MIStructE MICE (The Concrete Society)
Editor
B H G Cresswell Riol BEng (The Institution of Structural Engineers)
*
representing the British Precast Concrete Federation
**
representing the Steel Reinforcement Association
*** representing CONSTRUCT
**** representing the DTI
Published by The Institution of Structural Engineers
11 Upper Belgrave Street, London SW1X 8BH, United Kingdom
ISBN 0 901297 41 0
978 0 901297 41 9
© 2006 The Institution of Structural Engineers
The Institution of Structural Engineers and the members who served on the Task Group that produced this report have endeavoured to
ensure the accuracy of its contents. However, the guidance and recommendations given should always be reviewed by those using the
report in the light of the facts of their particular case and any specialist advice. No liability for negligence or otherwise in relation to
this report and its contents is accepted by the Institution, the members of the Task Group, its servants or agents.
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means without prior
permission of the Institution of Structural Engineers, who may be contacted at 11 Upper Belgrave Street, London, SW1X 8BH.
[TABLES]
[[{"0": "Constitution of Steering Group", "1": ""}, {"0": "J K Kenward BEng(Tech) CEng FIStructE MICE MIHT (Hyder Consulting Ltd) Chairman", "1": ""}, {"0": "R Bailey* CEng MIStructE (Milbank Floors)", "1": ""}, {"0": "R Bloomer** BSc CEng MICE (BRC)", "1": ""}, {"0": "B Bowsher (UK CARES)", "1": ""}, {"0": "P S Chana BSc(Eng) PhD CEng FIStructE MICE (British Cement Association)", "1": ""}, {"0": "S M Doran BSc(Eng) AKC PhD CEng MICE ACIS (Institution of Structural Engineers)", "1": ""}, {"0": "C H Goodchild BSc CEng MIStructE MCIOB (The Concrete Centre)", "1": ""}, {"0": "J Kelly (G.D.C. Partnership)", "1": ""}, {"0": "D Keogh (Laing O’Rourke)", "1": ""}, {"0": "S Mahmood BSc CEng MIStructE (Sir Robert McAlpine Ltd)", "1": ""}, {"0": "P Matthew*** (Matthew Consultants)", "1": ""}, {"0": "R P Wolstenholme**** BSc CEng MICE (Atkins)", "1": ""}, {"0": "Corresponding members", "1": ""}, {"0": "R Chu CEng FIStructE FICE FHKIE (Meinhardt (C&S) Ltd Hong Kong)", "1": ""}, {"0": "R Gordon (Mace)", "1": ""}, {"0": "R Lancaster BSc(Eng) CEng FICE FCIArb FACI (Consultant)", "1": ""}, {"0": "G Nice (BRC Special Products)", "1": ""}, {"0": "D Pike BSc(Eng) PhD CEng MICE (Building Design Partnership)", "1": ""}, {"0": "C B Shaw CEng MIStructE FICE MCMI FIIExE (Consultant - Chairman BS 7973)", "1": ""}, {"0": "Consultants to the Steering Group", "1": ""}, {"0": "R Whittle MA(Cantab) CEng MICE (Arup Research and Development)", "1": ""}, {"0": "A E K Jones BEng(Hons) PhD MICE (Arup Research and Development)", "1": ""}, {"0": "Secretary to the Steering Group", "1": ""}, {"0": "J L Clarke MA PhD CEng MIStructE MICE (The Concrete Society)", "1": ""}, {"0": "Editor", "1": ""}, {"0": "B H G Cresswell Riol BEng (The Institution of Structural Engineers)", "1": ""}, {"0": "*", "1": "representing the British Precast Concrete Federation"}, {"0": "**", "1": "representing the Steel Reinforcement Association"}, {"0": "***", "1": "representing CONSTRUCT"}, {"0": "****", "1": "representing the DTI"}, {"0": "Published by The Institution of Structural Engineers", "1": ""}, {"0": "11 Upper Belgrave Street, London SW1X 8BH, United Kingdom", "1": ""}, {"0": "ISBN 0 901297 41 0", "1": ""}, {"0": "", "1": "978 0 901297 41 9"}, {"0": "© 2006 The Institution of Structural Engineers", "1": ""}, {"0": "", "1": "The Institution of Structural Engineers and the members who served on the Task Group that produced this report have endeavoured to"}, {"0": "", "1": "ensure the accuracy of its contents. However, the guidance and recommendations given should always be reviewed by those using the"}, {"0": "", "1": "report in the light of the facts of their particular case and any specialist advice. No liability for negligence or otherwise in relation to"}, {"0": "this report and its contents is accepted by the Institution, the members of the Task Group, its servants or agents.", "1": ""}, {"0": "", "1": "No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means without prior"}, {"0": "permission of the Institution of Structural Engineers, who may be contacted at 11 Upper Belgrave Street, London, SW1X 8BH.", "1": ""}], []]
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3.Standard Method of Detailing Structural Concrete.pdf
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[NATIVE TEXT]
IStructE/Concrete Society Standard Method of Detailing Structural Concrete
[TABLES]
[[{"0": "IStructE/Concrete Society Standard Method of Detailing Structural Concrete"}], []]
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[NATIVE TEXT]
CONTENTS
1
Introduction and scope
1
2
Communication of information
3
2.1
General
3
2.2
The reinforcement process
3
2.3
Designer detailing
6
2.4
Contractor detailing
6
2.5
Electronic data interchange (EDI)
6
2.6
Examples of typical methods of providing the required information for detailing
7
3
Drawings
12
3.1
General
12
3.2
Types of drawings
12
3.2.1
Structural drawings
12
3.2.2
Reinforcement drawings
12
3.2.3
Standard details
12
3.2.4
Diagrams
13
3.2.5
Record drawings
13
3.3
Photocopying and reduction
13
3.4
Abbreviations
13
3.5
Dimensions of drawing sheets
13
3.6
Borders
14
3.7
Title and information panels
14
3.8
Key
14
3.9
Orientation
14
3.9.1
Site plans
14
3.9.2
All other drawings
14
3.10
Thickness of lines
14
3.11
Lettering
14
3.12
Spelling
14
3.13
Dimensions
14
3.14
Levels
15
3.14.1
Datum
15
3.14.2
Levels on plan
15
3.14.3
Levels on section and elevation
15
3.15
Scales
15
3.16
Plans
15
3.17
Elevations
15
3.18
Sections
16
3.19
Grid lines and a recommended reference system
16
3.20
Layout of slabs
16
3.20.1
Methods of preparing general arrangement drawings for concrete structures 16
3.20.2
Information shown on general arrangement drawings for concrete structures 17
3.20.3
Fixing in concrete
21
3.20.4
Example of general arrangement drawing for concrete structures
22
3.21
Layout of foundations
23
3.22
Layout of stairs
23
IStructE/Concrete Society Standard Method of Detailing Structural Concrete
[TABLES]
[[{"0": "", "1": "ContEntS", "2": ""}, {"0": "\u0018", "1": "IntroduCtIon and SCopE", "2": "\u0018"}, {"0": "2", "1": "CommunICatIon of InformatIon", "2": "3"}, {"0": "", "1": "2.1 General", "2": "3"}, {"0": "", "1": "2.2 The reinforcement process", "2": "3"}, {"0": "", "1": "2.3 Designer detailing", "2": "6"}, {"0": "", "1": "2.4 Contractor detailing", "2": "6"}, {"0": "", "1": "2.5 Electronic data interchange (EDI)", "2": "6"}, {"0": "", "1": "2.6 Examples of typical methods of providing the required information for detailing", "2": "7"}, {"0": "3", "1": "drawInGS", "2": "\u00182"}, {"0": "", "1": "3.1 General", "2": "12"}, {"0": "", "1": "3.2 Types of drawings", "2": "12"}, {"0": "", "1": "3.2.1 Structural drawings", "2": "12"}, {"0": "", "1": "3.2.2 Reinforcement drawings", "2": "12"}, {"0": "", "1": "3.2.3 Standard details", "2": "12"}, {"0": "", "1": "3.2.4 Diagrams", "2": "13"}, {"0": "", "1": "3.2.5 Record drawings", "2": "13"}, {"0": "", "1": "3.3 Photocopying and reduction", "2": "13"}, {"0": "", "1": "3.4 Abbreviations", "2": "13"}, {"0": "", "1": "3.5 Dimensions of drawing sheets", "2": "13"}, {"0": "", "1": "3.6 Borders", "2": "14"}, {"0": "", "1": "3.7 Title and information panels", "2": "14"}, {"0": "", "1": "3.8 Key", "2": "14"}, {"0": "", "1": "3.9 Orientation", "2": "14"}, {"0": "", "1": "3.9.1 Site plans", "2": "14"}, {"0": "", "1": "3.9.2 All other drawings", "2": "14"}, {"0": "", "1": "3.10 Thickness of lines", "2": "14"}, {"0": "", "1": "3.11 Lettering", "2": "14"}, {"0": "", "1": "3.12 Spelling", "2": "14"}, {"0": "", "1": "3.13 Dimensions", "2": "14"}, {"0": "", "1": "3.14 Levels", "2": "15"}, {"0": "", "1": "3.14.1 Datum", "2": "15"}, {"0": "", "1": "3.14.2 Levels on plan", "2": "15"}, {"0": "", "1": "3.14.3 Levels on section and elevation", "2": "15"}, {"0": "", "1": "3.15 Scales", "2": "15"}, {"0": "", "1": "3.16 Plans", "2": "15"}, {"0": "", "1": "3.17 Elevations", "2": "15"}, {"0": "", "1": "3.18 Sections", "2": "16"}, {"0": "", "1": "3.19 Grid lines and a recommended reference system", "2": "16"}, {"0": "", "1": "3.20 Layout of slabs", "2": "16"}, {"0": "", "1": "3.20.1", "2": "Methods of preparing general arrangement drawings for concrete structures 16"}, {"0": "", "1": "3.20.2", "2": "Information shown on general arrangement drawings for concrete structures 17"}, {"0": "", "1": "3.20.3 Fixing in concrete", "2": "21"}, {"0": "", "1": "3.20.4 Example of general arrangement drawing for concrete structures", "2": "22"}, {"0": "", "1": "3.21 Layout of foundations", "2": "23"}, {"0": "", "1": "3.22 Layout of stairs", "2": "23"}]]
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IStructE/Concrete Society Standard Method of Detailing Structural Concrete
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IStructE/Concrete Society Standard Method of Detailing Structural Concrete
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[OCR TEXT]
a, is for the effect of the shape of the bars assuming
adequate cover
@)_ is for the effect of concrete minimum cover (see
Figure 5.3)
a3 is for the effect of confinement by transverse
reinforcement
a4 is for the influence of one or more welded
transverse bars (0, > 0.60) along the design
anchorage length /,q
as is for the effect of the pressure transverse to the
plane of splitting along the design anchorage
length
(Gy G3 Os) 2 0.7
Iy.rqd is equal to (9/4) (Ogg /fyg)
where O,q is the design stress of the bar at the
position from where the anchorage is
measured
fod = 2:25 Ny Ny 0.14 fo?)
(for fy, < 50 MPa)
nN, = 1.0 for ‘good’ bond conditions
(see Figure 5.2)
n, = 9.7 for ‘poor’ bond conditions
N2 = 1.0 foro < 32mm
Np = (132 — @)/100 for o > 32mm
is the minimum anchorage length if no other
limitation is applied:
* for anchorages in tension:
Jymin > MAx{0.3/p pga 100; 100mm}
* for anchorages in compression:
!y,min > Max {0.6l, pqqs 100; 100mm}
4 b,min
For direct supports /,q may be taken less than /, min
provided that there is at least one transverse wire
welded within the support. This should be at least
15mm from the face of the support.
5.4.3. Laps in reinforcement
Laps between bars should normally be staggered and
not located in areas of high moments/forces (e.g.
plastic hinges). They should normally be arranged
symmetrically in any section.
The arrangement of lapped bars should comply
with Figure 5.5:
* The clear distance between lapped bars should
not be greater than 4@ or 50mm, otherwise
the lap length should be increased by a length
equal to the clear space where it exceeds 40 or
50mm.
IStructE/Concrete Society Star
Dee |
a) Straight bars
c, = min (a/2, c,, c)
b) Bent or c) Looped bars
hooked bars c,=c
c, = min (a/2, c,)
Figure 5.3 Values of Cy for beams and slabs
As Ast As 2, Ast As Act
lk é ' » : pt
K=0.05 K=0
Figure 5.4 Values of K for beams and slabs
< 50mm
<
4* 40 fg
20.3 lo
s
'o
iS
28
—_— o
F. a 220
-——_ 2 20mm 5
a
fs
~ ———t
5
=
L
Figure 5.5 Adjacent laps
* The longitudinal distance between two adjacent
laps should not be less than 0.3 times the lap
length, /p.
* In case of adjacent laps, the clear distance
between adjacent bars should not be less than 26
or 20mm.
When the provisions comply with the above, the
permissible percentage of lapped bars in tension may
be 100% where the bars are all in one layer. Where
the bars are in several layers the percentage should be
reduced to 50%.
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