File size: 6,957 Bytes
a8ced59 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 | % Simple RC-SRP Script Calculator (Inline Configuration)
% Author: Rembrant Oyangoren Albeos
% Year: 2026
clear; clc;
%% --- CONFIGURABLE SETTINGS ---
% Modify these variables directly before running the script.
% Concrete and Steel Properties
fc = 4000; % Concrete compressive strength f_c' (psi)
fy = 60000; % Steel yield strength f_y (psi)
% Beam Dimensions
b = 12; % Beam width b (in)
h = 20; % Beam height h (in)
cover = 2.5; % Cover distance to extreme tension layer (in)
% Layer 1 (Bottom) Reinforcement
n_bars1 = 4; % Number of bars in layer 1
a_bar = 0.79; % Area per bar (in^2)
% Layer 2 (Top) Reinforcement
% Set n_bars2 to 0 for a Single Layer computation.
n_bars2 = 0; % Number of bars in layer 2
spacing = 0; % Spacing between layers (in)
% Output Option
show_output = true; % Set to true to display calculation output in Command Window
%% --- CALCULATION LOGIC ---
if show_output
disp(' ');
disp('--- CALCULATION OUTPUT ---');
% Basic constants
fc_ksi = fc / 1000;
fy_ksi = fy / 1000;
Es_ksi = 29000;
E_cu = 0.003;
% Calculate beta1 factor
beta1 = 0.85;
if fc > 4000
beta1 = 0.85 - 0.05 * ((fc - 4000) / 1000);
end
beta1 = max(beta1, 0.65);
% Minimum steel factor
limit_val = 3 * sqrt(fc);
As_min_factor = max(limit_val, 200);
% Determine if it's Single or Double Layer automatically
if n_bars2 == 0
layer_type = 'Single Layer Singly Reinforced';
% --- SINGLE LAYER CALCULATION ---
d = h - cover;
As = n_bars1 * a_bar;
disp(['1. Effective depth (d): ', num2str(d), ' in']);
disp([' Area of steel (A_s): ', num2str(As), ' in^2']);
% Force and depth of compression block
T = As * fy_ksi;
disp(['2. Tension force (T, assuming yield): ', num2str(T), ' kips']);
a = T / (0.85 * fc_ksi * b);
c = a / beta1;
disp(['3. Compression block depth (a): ', num2str(a), ' in']);
disp([' Neutral axis depth (c): ', num2str(c), ' in']);
% Check if steel actually yields
eps_y = fy_ksi / Es_ksi;
eps_s = ((d - c) / c) * E_cu;
disp(['4. Yield strain (eps_y): ', num2str(eps_y)]);
disp([' Steel strain (eps_s): ', num2str(eps_s)]);
if eps_s >= eps_y
disp(' Status: Steel yielded. Assumption OK.');
else
disp(' Status: Steel did NOT yield. Assumption failed.');
end
% Calculate Nominal Moment
Mn = T * (d - a/2) / 12;
disp(['5. Nominal Moment (M_n): ', num2str(Mn), ' kip-ft']);
% Check minimum code requirement for steel
As_min = (As_min_factor / fy) * b * d;
disp(['6. Minimum steel (A_s,min): ', num2str(As_min), ' in^2']);
if As >= As_min
disp(' Status: A_s >= A_s,min. OK.');
else
disp(' Status: A_s < A_s,min. Does not meet minimum requirement.');
end
% Compute reduction factor
eps_t = eps_s;
if eps_t >= 0.005
phi = 0.90;
elseif eps_t <= 0.002
phi = 0.65;
else
phi = 0.65 + (eps_t - 0.002) * (250/3);
end
phi_Mn = phi * Mn;
disp(['7. Reduction factor (phi): ', num2str(phi)]);
disp(['8. Design Moment (phi*M_n): ', num2str(phi_Mn), ' kip-ft']);
else
layer_type = 'Double Layer Singly Reinforced';
% --- DOUBLE LAYER CALCULATION ---
As1 = n_bars1 * a_bar;
As2 = n_bars2 * a_bar;
As = As1 + As2;
dist1 = cover;
dist2 = cover + spacing;
% Calculate centroid of steel
g = (As1 * dist1 + As2 * dist2) / As;
d = h - g;
d_t = h - cover;
disp(['1. Centroid distance (g): ', num2str(g), ' in']);
disp([' Effective depth (d): ', num2str(d), ' in']);
disp([' Area of steel (A_s): ', num2str(As), ' in^2']);
% Force and depth of compression block
T = As * fy_ksi;
a = T / (0.85 * fc_ksi * b);
c = a / beta1;
disp(['2. Tension force (T, assuming yield): ', num2str(T), ' kips']);
disp(['3. Compression block depth (a): ', num2str(a), ' in']);
disp([' Neutral axis depth (c): ', num2str(c), ' in']);
% Check if steel yields
eps_y = fy_ksi / Es_ksi;
eps_s = ((d - c) / c) * E_cu;
disp(['4. Yield strain (eps_y): ', num2str(eps_y)]);
disp([' Steel strain (eps_s): ', num2str(eps_s)]);
if eps_s < eps_y
disp(' Status: Over-reinforced section. Assumption Failed.');
disp(' Solving exact c using quadratic method...');
% Use quadratic for exact answer if not yielded
A_quad = 0.85 * fc_ksi * b * beta1;
B_quad = As * Es_ksi * E_cu;
C_quad = -1 * As * Es_ksi * E_cu * d;
roots_c = roots([A_quad, B_quad, C_quad]);
c = max(roots_c(roots_c > 0));
a = beta1 * c;
disp([' Exact Neutral axis (c): ', num2str(c), ' in']);
disp([' Exact Compression block (a): ', num2str(a), ' in']);
T = As * Es_ksi * ((d - c)/c) * E_cu;
disp([' Exact Tension force (T): ', num2str(T), ' kips']);
else
disp(' Status: Steel yielded. Assumption OK.');
end
% Calculate Nominal Moment
Mn = T * (d - a/2) / 12;
disp(['5. Nominal Moment (M_n): ', num2str(Mn), ' kip-ft']);
% Check minimum code requirement for steel
As_min = (As_min_factor / fy) * b * d;
disp(['6. Minimum steel (A_s,min): ', num2str(As_min), ' in^2']);
if As >= As_min
disp(' Status: A_s >= A_s,min. OK.');
else
disp(' Status: A_s < A_s,min. Does not meet minimum requirement.');
end
% Compute reduction factor using extreme tension layer
eps_t = ((d_t - c) / c) * E_cu;
if eps_t >= 0.005
phi = 0.90;
elseif eps_t <= 0.002
phi = 0.65;
else
phi = 0.65 + (eps_t - 0.002) * (250/3);
end
phi_Mn = phi * Mn;
disp(['7. Extreme tension strain (eps_t): ', num2str(eps_t)]);
disp([' Reduction factor (phi): ', num2str(phi)]);
disp(['8. Design Moment (phi*M_n): ', num2str(phi_Mn), ' kip-ft']);
end
disp(' ');
disp(['CONCLUSION: The calculated section is [', layer_type, '].']);
end
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