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ADE | An innovative indicator for determining the relative improvement upon a Best
Alternative to a Negotiated Alternative (BATNA) solution allows stakeholders to rapidly
assess how well a solution performs across multiple objectives and multiple objective
spaces. In addition, as the joint-Pareto solutions are Pareto optimal... |
ADE | CHAPTER 5
Conclusion
Recently, the application of Water Sensitive Urban Design (WSUD) has demonstrated
an ability to mitigate the impacts of development on urban water supply security and
natural ecosystem health (Askarizadeh, Rippy et al. 2015). An increasingly popular
WSUD technique is urban stormwater harvesting (SW... |
ADE | multiple stakeholder groups with different preferences to encourage the adoption of a final
WSUD solution. In order to address these issues, three optimization frameworks using
multiobjective metaheuristic algorithms were introduced in this thesis, which are able to:
1) handle SWH systems preliminary design incorporati... |
ADE | The specific research contributions to address the objectives stated in the Introduction
are as follows:
1. A generic multiobjective optimization framework to assess trade-offs in spatially
distributed SWH system designs, featuring the Non-Dominated Sorting Genetic
Algorithm (NSGA-II) linked with an integrated stormwat... |
ADE | decision spaces could assist in overcoming institutionally influenced biases to
include particular projects or BMP technologies to demonstrate alternative
similar cost options to decision-makers.
3. A general optimization-visualisation framework that deals with multiple
stakeholders with multiple objectives, and encour... |
ADE | 1. The framework for a SWH preliminary design in Paper 1 considers harvesting and
water quality control functions, but not flood control functions as is the case in
many WSUD systems. The case study was selected to allow the water quality
control volumes in BMPs to be sized separately from any flood control
infrastruct... |
ADE | pollutant load reduction of a WSUD system in MUSIC it is typical practice to
simulate the system several times with a stochastic function for the pollutant wash-
off model in MUSIC switched on, and to then to calculate an average performance
value. This was not possible in the framework in Paper 1 due to limitations on... |
ADE | to prevent simulation of inferior solutions that could reduce run-time further, as
discussed in Maier, Kapelan et al. (2014). This would permit larger WSUD
systems, additional decision options, scenarios including the impact of climate
change on optimal BMP placement, as well as consideration of solution robustness
and... |
ADE | Table B- 1 Detailed costings of stormwater harvesting components used to develop the model for LCCSWH [$] (Eqn. 8) in the case
study application of the optimization framework. Based on values in Inamdar (2014). SWH component cost values were adjusted
from 2012$ to 2016$, at 1% p.a (D. Browne, personal communication, 20... |
ADE | Equation ( D-3 )
where a sum of the cost of BMPs to capture and treat stormwater runoff, LCC [$]
BMP
(Equation (D-2)), and to transfer harvested water to a balancing storage for further
treatment and distribution, LCC [$] (Equation (D-3)) is applied with BMP
SWH i
representing the ith BMP in the candidate portfolio, N ... |
ADE | Equation ( D-5 )
where, [mass year-1] is the mean annual pollutant mass retained by BMPs in
each candifd˘ a‰ t(cid:181) e… k· p˙ o rtfolio, N is the number of BMPs in a portfolio, Resid [mass year-1] is
i
the mean annual mass of pollutant leaving the ith BMP’s contributing catchment area, and
Source [mass year-1] is th... |
ADE | Equation ( D-6 )
where Supply [volume] is the average annual stormwater harvested volume for the ith
i
BMP in a portfolio, and N [integer] is the number of projects in a portfolio.
Experts on stormwater harvesting from each LGA were asked to evaluate the
stormwater harvesting potential of BMPs within their jurisdiction... |
ADE | Abstract
ABSTRACT
Terrorism has become a serious threat in the world, with bomb attacks carried out
both inside and outside buildings. There are already many unreinforced masonry
buildings in existence, and some of them are historical buildings. However, they do
not perform well under blast loading. Aiming on protectin... |
ADE | Chapter 1: Introduction
1. INTRODUCTION
1.1. BACKGOURND
The protection of structures against blast loads is a government research priority for
“Safeguarding Australia” against terrorism. Unreinforced masonry (URM)
construction, which is widely used in public buildings, is extremely vulnerable to
blast loads. An effecti... |
ADE | Chapter 1: Introduction
The analyses of retrofitted masonry member against static, cyclic or seismic loading
have received considerable attention in recent years (Baratta and Corbi 2007;
Bastianini et al. 2005; El-Dakhakhni et al. 2004; ElGawady et al. 2006b; ElGawady et
al. 2007; Hamoush et al. 2002; Hamoush et al. 20... |
ADE | Chapter 1: Introduction
1.2. SCOPE AND OBJECTIVES
The primary aim of this project is to establish numerical models to investigate the
behaviours of retrofitted URM walls under blast loading. To achieve this goal, there
were four milestones during the project:
1) Simulation of URM walls using homogenization technique. T... |
ADE | Chapter 1: Introduction
retrofitted masonry wall subjected to blast loading. Several types of
retrofitting techniques were tested. Parametric studies were conducted to
simulate masonry walls with different retrofitting techniques subjected to
blast loading and effective retrofits are found. A comparison of the
effectiv... |
ADE | Chapter 2: Literature Review
2. LITERATURE REVIEW
2.1. INTRODUCTION
Masonry walls are widely used in Australia, but are not commonly designed with blast
resistance in mind. In recent years, several retrofitting reinforced technologies have
been developed to strengthen reinforced concrete structures, which have been
ext... |
ADE | Chapter 2: Literature Review
durable, and provides effective thermal and sound insulation and excellent fire
resistance (Page 1996). However, it is found that URM construction is extremely
vulnerable to terrorist bomb attacks since the powerful pressure wave at the airblast
front strikes buildings unevenly and may even... |
ADE | Chapter 2: Literature Review
Purcell (2003) tested four unretrofitted URM walls with different standoff distances.
All mortar joints failed, some masonry blocks spalled and breaching occurred under
high explosive detonations. Experiments (Davidson et al. 2005; Muszynski and
Purcell 2003) showed that cracking usually oc... |
ADE | Chapter 2: Literature Review
resistance to corrosion, solvents and chemicals, flexible manufacturing and fast
application (Bastianini et al. 2005). They have been widely used in structural
repairing and seismic resistance, and in recent years some studies for explosion
resistance using FRP have been conducted. A variet... |
ADE | Chapter 2: Literature Review
The key factor in increasing ductility and preventing the intrusion of wall fragments
into occupant areas is the ability to absorb strain energy (Davidson et al. 2004b).
Some recent experiments (Davidson et al. 2004b; Muszynski and Purcell 2003) on EB
retrofitting techniques indicated that ... |
ADE | Chapter 2: Literature Review
retrofitted with EB and NSM plates. Pull tests, in which an FRP strip or plate is
bonded to a masonry prism and loaded in tension, are often used to study the
bond-slip relationship of FRP-to-masonry. In the last decade, considerable research,
including experimental, analytical and numerica... |
ADE | Chapter 2: Literature Review
spayed-on polyurea performed well and succeeded in reducing the hazard level inside.
The previous tests indicated that spray-on polyurea can be an effective technique for
increasing the ductility of masonry walls.
2.3.3. Aluminium Foam
Aluminium foams are new, lightweight materials with exc... |
ADE | Chapter 2: Literature Review
vehicle, which isolated from the ground, the ground shock can be diminished
(Luccioni et al. 2004). Henrych (1979) developed empirical formulae for estimating
the blast pressure history. In 2005, (Alia and Souli 2006; Remennikov and Rose 2005;
Wu and Hao 2005, Shi, 2007 #484) improved Henry... |
ADE | Chapter 2: Literature Review
developed as an application of the code TM-5-855-1 (Headquarters 1986), and has
been incorporated into finite element programs AUTODYN and LS-DYNA
(Randers-Pehrson and Bannister 1997). Given charge weight and stand-off distance,
the blast history can be calculated automatically and applied ... |
ADE | Chapter 2: Literature Review
2.4.2. Finite Element Method
Numerical simulation is a cost-effective method for investigating the behaviour of
masonry structures. Compared with experiments, it gives better understanding of the
detailed process of events. The numerical simulation has become a widely used
method for invest... |
ADE | Chapter 2: Literature Review
following section.
(2) Homogenized model
The homogenization technique has been used in the past to derive the equivalent
material properties and failure characteristics for solid brick masonry. Considerable
research has been conducted in the last decade to investigate the complex mechanical... |
ADE | Chapter 2: Literature Review
to blast loading has been investigated by researchers (Anthoine 1995; Cecchi and Di
Marco 2002; ElGawady et al. 2006a; Luccioni et al. 2004; Milani et al. 2006a; Wu
and Ha 2006; Zucchini and Lourenco 2004) in recent years.
Figure 2.4 Homogenization of Masonry Material (Wu and Ha 2006)
The h... |
ADE | Chapter 2: Literature Review
2.4.3. Design Guideline
According to previous studies, URM walls are weak, brittle, and have low ductility
under blast loading. In order to develop effective retrofitting technologies, major
damage levels should be studied, due to their significant hazard to occupants and
surrounding constr... |
ADE | Chapter 2: Literature Review
strengthen masonry constructions. Still, a suitable solution is required to provide the
better protection against all blast loads. According to published studies, existing
retrofitting technologies are efficient in providing protection to concrete and masonry
structures. Commonly used and n... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
3. NUMERICAL SIMULATION OF URM WALLS USING THE
HOMOGENIZATION TECHNIQUE
3.1. INTRODUCTION
Homogenization techniques have been used to derive the equivalent material
properties of masonry for many years. However, no research has been conducte... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
Masonry is a composite structure constituted by bricks and mortar. Thus, the
homogenization technique can be used to derive the equivalent material properties of
masonry unit.
In this section, a highly detailed finite element model was used ... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
individual components. The average stress and strain (cid:3) and (cid:4) are defined by the
ij ij
integral over the basic cell as
1
(cid:3) (cid:6) (cid:5) (cid:3)dV
ij V V ij Eq. 3-1
1
(cid:4) (cid:6) (cid:5) (cid:4)dV
Eq. 3-2
ij V V ij
whe... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
then,
m(cid:7)1 2(cid:3)
(cid:9)(cid:6) and k (cid:6) c Eq. 3-8
3(m(cid:8)1) 3(m(cid:8)1)
The constants (cid:2) and k can be determined from the yield stresses in uniaxial tension
and compression.
Typical 10-core clay brick unit manufactured... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
strength model were derived, with their values listed in Table 3.1, and material
properties for brick and mortar were coded into a finite element program LS-DYNA
(LSTC 2007). The key parameters for using in simulations of masonry basic cell ... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
a (cid:6) k2
0
a (cid:6) (cid:7)6(cid:9)k Eq. 3-11
1
a (cid:6)9(cid:9)2
2
Considering the limited material properties and the efficiency of simulation, the “Soil
and Foam” model in LS-DYNA was selected to model both brick and mortar in this
... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
simulations of complex models, the equivalent tensile curve shows some ductility.
This is because individual elements did not fail at the same time under tension.
Therefore, there were always some elements that could carry loads until the sp... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
Aiming to simulate the compression test, a 5-layer-brick finite element model was
built as shown in Figure 3.8. The boundary conditions were set the same as the test,
and the results of stress and strain were obtained from the elements with ... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
The masonry basic cell is a finely meshed. 8-node solid element, with 24 degrees of
freedom was used to represent the cell. Because the full integration of the element
may produce element locking problem, which makes the elements hard to def... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
Table 3.4 Average stress and strain of central elements
Model Stress (MPa) Strain (1×10-4) Young’s Modulus (MPa) Difference
3560 -2.03 -5.30 3826 0.15%
5760 -2.03 -5.30 3829 0.25%
6144 -1.97 -5.16 3825 0.13%
10208 -2.01 -5.27 3823 0.07%
2375... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
compressive-shear and tensile-shear stress states were simulated. Over 50 cases were
simulated, and the calculated results are presented in Figure 3.11, Figure 3.12, and
Figure 3.13.
Figure 3.11 shows the typical stress-strain curves of the ... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
strength of the basic cell in the Z direction is much smaller than tensile strength of
mortar (0.6 MPa) as the volume of the cores is counted as part of the total volume of
the basic cell, as well as geometric size influence. The simulated r... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
interlaminar normal direction and a single interlaminar shear direction. For the normal
component, failure can only occur under tensile loading and for the shear component,
the behaviour is symmetric around zero. There are two ways of applyi... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
(2007). The experimental results were used to validate the numerical results. And the
configuration of this experiment is presented in Table 3.6. Bottom edges were
mortar bonded to the floor, and laterally supported by steel members, meaning... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
A uniform out-of-plane pressure was applied on the outside surface of the main wall.
Airbags were used to provide the static loading, and distribute the pressure uniformly.
Only the solid portions of the walls were acted on by airbags, meani... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
3.4.3. Experimental and Numerical Validation
The test data was used to verify the experimental results. The numerical verification
was achieved by comparing the simulation results of the distinct and homogenized
models with test data. Result... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
(a) without pre-compression (b) with pre-compression 0.1 MPa
Figure 3.22 Comparison of results from the short wall with and without
pre-compression test and simulation
By defining an ultimate strain for materials, elements can be removed dur... |
ADE | Chapter 3: Numerical Simulation of URM Walls by Using Homogenization Technique
3.5. CONCLUSIONS
This chapter presented numerical investigation of the ten-core brick URM wall using
the homogenization technique. The equivalent material properties of the masonry unit
such as the elastic moduli and failure characteristics ... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
4. SIMULATION OF FRP REPAIRED URM WALL UNDER
OUT-OF-PLANE LOADING
4.1. INTRODUCTION
The retrofitting of masonry structures with near-surface mounted (NSM) FRP plates
and externally bonded (EB) FRP plates has proven to be an innovative and cost
e... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
In this Chapter, a numerical model will be used to simulate the response of the FRP
repaired URM wall under out-of-plane loads. The FRP-to-masonry interface is
modelled by a layer of interface elements or contact surface of zero thickness. The
i... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
4.2.2. FRP Models
FRP composites, which are adhesively bonded to the masonry, can be modelled
using an elastic-brittle material model. Both CFRP and GFRP plates were used in
pull-tests. The reinforcing strips used in NSM pull-test were carbon fi... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
strain was found to be approximately 11500 microstrain. The experimental values
for Young’s modulus and strength of the GFPR strip are 19.3 MPa and 223 MPa,
respectively.
4.2.3. Bond-Slip Models
Adhesive material is used in practice to produce a... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
(a) Interface element method (b)Contact surface method
Figure 4.1 Interface elements model and contact model
For the interface element model, the interface was modelled as a thin layer of
elements with thickness of 1 mm. The interface element be... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
were used in the near surface mounted specimen. In the testing, the bottoms of the
specimens were fixed, and a tensile load was applied to the top of FRP strips until
debonding occurred. The load and strains along FRP strips were recorded in the... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
4.3.2. Distinct Models
A distinct model for masonry introduced in Chapter 3 was used in the simulation of
the pull tests. Figure 4.7 shows distinct numerical models of NSM and EB pull-tests.
The top surface of the masonry block was fixed in the ... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
EB GFRP model NSM CFRP model
Figure 4.13 Crack patterns
It should be noted that although both the interface element method and contact
surface method gave reliable estimations of local bond-slip relationships and global
load-displacement curves ... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
homogenized models of pull-tests of NSM CFRP plates and EB GFRP strips bonded
to two five-brick high masonry prisms. In order to check the reliability and
computational efficiency of the homogenized model in the numerical simulation, the
same pu... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
that both models gave good results, indicating that the homogenized model derived
from basic cell of masonry in Chapter 3 can also be used to simulate EB GFRP and
NSM CFRP plates to five-brick high masonry prism.
6.00E+06
Test 1.50E+07
Distinct ... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
using the smear crack model and distinct model. As shown, reasonable predictions
were obtained for both FRP strips or plates bonded to masonry prisms in pull tests.
6.00E+06
1.50E+07
Test
Test
Distinct Model
Distinct model
4.00E+06 Smeared crack... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
prediction of results of pull tests with far less time compared with the distinct model,
it may not yield reasonable prediction of debonding failure mechanism of the pull
tests as good as the distinct model because the weak mortar joints may sig... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
five EB 77 mm wide x 2.0 mm thick prefabricated GFRP strips spaced at 500 mm,
with two strips also placed adjacent to the window opening. The details of existing
crack patterns are depicted in Figure 4.21 and the experimental setup of the two FR... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
V1 V2 V3 V4 V5
SG1 SG4 SG11 SG18 SG25
SG5 SG12 SG19 SG26
SG6 SG13 SG20 SG27
SG2 SG7 SG14 SG21 SG28
LVDT 1 LVDT 2 LVDT 3
SG8 SG15 SG22 SG29
SG9 SG16 SG23 SG30
SG3 SG10 SG17 SG24 SG31
1550 500 500 500 500
Strain Gauge LVDT
(a) Crack patterns (b) L... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
5.00E+03
4.00E+03
3.00E+03
2.00E+03 Cyclic test
Static test
Simulation cf=0.7
1.00E+03
Simulation cf=0.9
Simulation cf=1.3
0.00E+00
0 0.01 0.02 0.03 0.04
Displacement (m)
Figure 4.25 Simulation of the last part of load-displacement curve with va... |
ADE | Chapter 4: Simulation of FRP Repaired URM Walls under Out-of-plane Loading
10 Test 10 Test
HCoommpoogseinteiz deadm maoged eml odel Smeared crack model
8 8
6 6
4 4
V1 V2 V3 V4 V5
V1 V2 V3 V4 V5
2 2
0 1550 INSIDEFAC50 E0 500 500 500 0 1550 INSIDEFAC50 E0 500 500 500
0 20 40 60 80 100 120 0 20 40 60 80 100 120
Deflection... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
5. MITIGATION OF BLAST EFFECTS ON RETROFITTED
URM WALLS
5.1. INTRODUCTION
Unreinforced masonry (URM) construction is extremely vulnerable to terrorist bomb
attacks since the powerful pressure wave at the airblast front strikes buildings
unevenly and may ev... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
model described and validated in Chapter 4 was used to model the
“partial-interaction” behaviours between the URM wall and the various retrofit
materials. The aluminium foam was modelled by a nonlinear elastoplastic material
model which was validated by te... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
preventing fragmentation. Compared with stiffer material such as CFRP, it provides a
cost-effective solution, and is easy to apply. The material model
MAT_PLASTIC_KINEMATIC developed for plastic material in LS-DYNA was used
to simulate the spray-on polyure... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
simulations with a validated numerical model was used here to provide an alternative
method for investigating the effectiveness of aluminium foam to mitigate airblast
loads on URM construction.
NOTE:
This figure is included on page 81 of the print copy of
... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
5.3.2. URM Walls
Parametric studies were carried out to estimate the response of the URM walls against
airblast loads with a scaled distance increment of 0.01 m/kg1/3. It was found that the
critical scaled distance to prevent the URM wall from collapse is ... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
the URM wall which was simply supported at its four edges. Blast loading at different
scaled distances was applied on the front surface of the wall. Simulation results are
shown in Figure 5.11. It was found that maximum blast loads for the vertical or
hori... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
Rear side Rear side
Figure 5.11 Debonding failure of NSM CFRP retrofitted URM walls
5.3.4. EB CFRP or GFRP Retrofitted URM Walls
The EB FRP retrofitting technique was selected next. Figure 5.12a shows four
100mm×2mm GFRP plates applied on the rear surface ... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
A comparison of effectiveness of EB GFRP retrofitted URM walls against blast
loading is shown in Figure 5.17. It is observed that GFRP applied on both surfaces
provides the best protection by increasing the capability of blast-resistance to 464%
compared w... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
EB CFRP plate retrofitted wall. However, when a layer of CFRP was added to the
entire front surface (Figure 5.19b), the wall failed at a scaled distance of 3.3 m/kg1/3,
and debonded at scaled distance of 3.7 m/kg1/3, as shown in Figure 5.21. Protection
eff... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
500%
464%
URM wall
400% 382%
EB GFRP (v4)
355%
EB GFRP (v4+h4)
296%
300% EB GFRP (fully, inside) 265%
221% 221% EB GFRP (v4, 2sides)
200% EB GFRP (fully, 2sides)
142% EB CFRP (v4)
100% EB CFRP (fully, inside)
100%
EB CFRP (fully, 2sides)
0%
EB FRP retrofit... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
Local failure of the
spray-on polyurea
Local failure of the
masonry around the
center of the wall
Debonding failure Front side
Figure 5.26 Local failure of the spray-on polyurea and masonry (vertical section)
The results for polyurea sprayed on the both su... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
1000%
858.95%
URM wall
800%
Inside sprayed- on polyurea
retrofitted URM wall
600% Two sides retrofitted spray-on
polyurea URM wall
400% 326.84%
200%
100.00%
0%
URM wall and Retrofitted URM wall
Figure 5.28 Comparison of energy absorption of the spray-on po... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
Furthermore, different types of aluminium foam sheets can have great influence on its
blast energy absorption capacity. Tables 5.3 and Table 5.4 list the material properties
for A356SiC030 and A356SiC020 aluminium foams. Parametric sttudies were
conducted ... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
transferred to the wall by absorbing more of the blast energy. However, the remaining
impulse acted on the masonry wall was still too great for the soft retrofits. Therefore,
a strong rear support was expected to work best with the aluminium foam. Thus, a
... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
diagram, damage levels for aluminium foam protected URM walls should be defined.
For URM wall, the ultimate deflection at instability (cid:8) is predicted by using a one-way
u
vertical bending theory derived by Willis (Willis et al. 2004),
(cid:28) (cid:3)... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
Table 5.5 Material properties of URM wall
(cid:127)(cid:8)(cid:128)(cid:129)<(cid:130)(cid:19)3) g (m/s2) f (Mpa) t (mm) (cid:9)(cid:8)(cid:128)(cid:131)(cid:132)(cid:4)(cid:133) h (mm)
mt
1800 9.8 0.614 110 0 2500
Rear side Rear side Rear side
(a) Before ... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
failure process of aluminium foam protected URM wall. When a foam protected
URM wall is subjected to airblast loads, the foam and the steel sheet will initially
deform together with the URM wall (see Figure 5.44b). However, as the deformation
of the URM wa... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
also start to debond from the foam. The starting debonding point was defined as
Damage Level 1 as shown in Figure 5.45. Further increasing the impulse cause more
and more energy to be absorbed by the foam due to more foam cells rupturing until
the wall rea... |
ADE | Chapter 5: Mitigation of Blast Effects on Retrofitted URM Walls
3000
URM 2Foam -level1
1Foam -level1 EB - GFRP - level1
2500 EB-CFRP- level1 Spray-on Polyurea – level 1
2000
125kg TNT 512kg TNT 1000kg TNT
1500
1000
500
0
0 500 1000 1500 2000 2500
I (KPa.ms)
Figure 5.59 P-I diagrams for retrofitted URM walls at damage l... |
ADE | Chapter 6: Conclusions and Recommendations
6. CONCLUSIONS AND RECOMMENDATIONS
6.1. SUMMARY AND CONCLUSIONS
Masonry buildings exhibit the vulnerability of poor blast-resistant capacity with little
ductility. Aiming to find effective strengthening solutions to enhance masonry walls
against explosion, this project focused... |
ADE | Chapter 6: Conclusions and Recommendations
of retrofitted masonry wall under blast loading. To increase ductility of the wall, a
new technique known as spray-on polyurea was employed in this study. It was found
that the capability of absorbing stain energy was the key factor that influenced
performance. A new energy ab... |
ADE | Chapter 6: Conclusions and Recommendations
have become apparent, namely,
1. Material models for bricks and mortar could be improved to consider
microscopic material failures and the effect of strain rate. This would mean
more accurate results could be obtained, the relationship between retrofits and
masonry would be mo... |
ADE | Notations
NOTATIONS
A = area perpendicular to the principal strain direction
a = shear failure surface constants in Drucker-Prager model
0-2
E =modulus of elasticity
E =compressive modulus of elasticity
c
E =tensile modulus of elasticity
t
E = elastic moduli of aluminium foam
ij
Eu = elastic/shear modulus in uncompress... |
ADE | ~ i ~
Abstract
The recovery of sulphuric refractory gold requires pre-treatment of the material for the
liberation of gold particles from sulphide-bearing minerals (mainly pyrite). This pre-treatment
is expensive and can increase significantly the total processing cost. However, for low-grade
materials stockpiled for a... |
ADE | ~ vii ~
Declaration
I certify that this work contains no material which has been accepted for the award of any
other degree or diploma in my name, in any university or other tertiary institution and, to the
best of my knowledge and belief, contains no material previously published or written by
another person, except w... |
ADE | ~ ix ~
Acknowledgements
I gratefully acknowledge Newcrest Mining Limited for the sponsorship of my PhD stipend. I
would like to acknowledge Minerals Council Australia for awarding a research scholarship.
Undertaking this PhD has been a challenging and life-changing experience for me and I could
not make it this far wit... |
ADE | ~ 2 ~
This section provides a brief description of the research background, a review of the literature
related to the research problem, the research objectives and a summary of the research
conducted to address the problem.
Research background
This project was initiated and funded by Newcrest Mining Limited. The compan... |
ADE | ~ 3 ~
1.2.1 Atmospheric oxidation of pyrite
In the natural environment, pyrite oxidation can occur spontaneously when exposed either
to atmospheric water and oxygen or to aqueous water and dissolved oxygen (DO). In the long
term, atmospheric oxidation of pyrite is a slower process than aqueous oxidation of pyrite.
The ... |
ADE | ~ 4 ~
significantly, approaching the aqueous oxidation rates reported by humidity cell studies. Jerz
and Rimstidt (2004) attributed the slowing of the oxidation rate to the development of a
solution film around the pyrite surface due to hygroscopic oxidation products absorbing water
from the surrounding vapour as this ... |
ADE | ~ 5 ~
sulphite (𝑆𝑂2−) and elemental sulphur (𝑆0) in the aqueous oxidation of pyrite. Hiskey and
3
Shlitt (1982) pointed out that, depending on the exact reaction conditions, intermediates such
as thiosulphate, sulphite, dithionate and dithionite may also be formed in the overall reaction
of pyrite decomposition. On ... |
ADE | ~ 6 ~
Eq.(1-4)). For the indirect pathway, the intermediate ferric ion is subject to loss due to
hydrolysis (Eq.(1-5)) when the pH is greater than about 3. The hydrolysis of ferric ion
corresponds to extra consumption of oxygen in the overall system in addition to pyrite
oxidation.
For the prediction of the level of py... |
ADE | ~ 7 ~
1.2.3 Kinetics and reaction rate formula for pyrite oxidation with oxygen
Empirical reaction rate formulas for pyrite oxidation with dissolved oxygen have been derived
by McKibben and Barnes (1986) and Williamson and Rimstidt (1994). In McKibben and Barnes
(1986), the rate formula was derived for the aqueous oxid... |
ADE | ~ 8 ~
Table 1-1: Theoretical rate equations derived for pyrite oxidation with dissolved oxygen
Reaction mechanism/
Theoretical rate equation
Reference
rate-determining step
Mathews and Robins 𝑑𝐹𝑒𝑆 𝐾 [𝑃 ]0.5 Adsorption isotherm of
2 = 𝐾𝐴 2 𝑂2
(1974) 𝑑𝑡 1+𝐾 [𝑃 ]0.5 oxygen on pyrite surface
2 𝑂2
Bailey and P... |
ADE | ~ 9 ~
oxidation in carbonate-buffered solution, an oxidised layer was formed on the pyrite surface
and oxygen diffusion through the oxidised layer was a part of the reaction process. Both the
surface reaction and the diffusion of O through the oxidised layer can be affected by
2
temperature. The apparent activation ene... |
ADE | ~ 10 ~
Lehner and Savage (2008) conducted mixed flow and batch experiments to measure the
oxidation rate of pyrite synthesized with different impurities at different concentrations. The
results show that, statistically, pyrite with impurities has higher reactivity. However, Lehner
and Savage (2008) suggested that, in e... |
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