RC beam shear and torsion: validation

Every formula and clause of RC beam shear and torsion was compared by hand with CSA A23.3-24, and every row matched, on 2026-10-01. The rows below are read from the calculation itself at its declared values, so they are the formulas the page runs today.

Formulas

NameSymbolicClauseAgainstDate
lamb\(\displaystyle 1\)CSA A23.3-24 Cl. 8.6.5 a)-c)2026-10-01
phi_c\(\displaystyle 0.65\)CSA A23.3-24 Cl. 8.4.22026-10-01
phi_s\(\displaystyle 0.85\)CSA A23.3-24 Cl. 8.4.3 a)2026-10-01
d_s\(\displaystyle 11.3\ \mathrm{mm}\)CSA metric bar sizes, nominal diameter and area2026-10-01
d_b\(\displaystyle 25.2\ \mathrm{mm}\)CSA metric bar sizes, nominal diameter and area2026-10-01
A_sb\(\displaystyle 100\ \mathrm{mm}^{2}\)CSA metric bar sizes, nominal diameter and area2026-10-01
theta\(\displaystyle \operatorname{radians}\left(35\right)\)A23.3 Cl. 11.3.6.3, simplified methodCSA A23.3-24 Cl. 11.3.6.3, theta = 35 deg2026-10-01
d\(\displaystyle h - c_{c} - d_{s} - \frac{d_{b}}{2}\)Geometry: h - c_c - d_s - d_b/2, one bar layer inside the stirrup2026-10-01
d_v\(\displaystyle \max\left(0.9 \cdot d, 0.72 \cdot h\right)\)A23.3 Cl. 3.2, effective shear depthCSA A23.3-24 Cl. 3.2, definition of d_v2026-10-01
x_0\(\displaystyle b - 2 \cdot c_{c} - d_{s}\)Geometry: stirrup centreline at c_c + d_s/2 from each face2026-10-01
y_0\(\displaystyle h - 2 \cdot c_{c} - d_{s}\)Geometry: stirrup centreline at c_c + d_s/2 from each face2026-10-01
P_h\(\displaystyle 2 \cdot \left(x_{0} + y_{0}\right)\)A23.3 Cl. 3.2, p_hCSA A23.3-24 Cl. 3.2, p_h on the stirrup centreline2026-10-01
A_0h\(\displaystyle x_{0} \cdot y_{0}\)A23.3 Cl. 3.2, A_ohCSA A23.3-24 Cl. 3.2, A_oh on the stirrup centreline2026-10-01
cot_theta\(\displaystyle \frac{1}{\tan\left(\theta\right)}\)CSA A23.3-24 Cl. 11.3.6.3, cot of theta2026-10-01
A_v_min_per_s\(\displaystyle \frac{0.06 \cdot \sqrt{f_{c} \cdot 1\ \mathrm{MPa}} \cdot b}{f_{y} \cdot 1\ \mathrm{mm}}\)A23.3 Cl. 11.2.8.2, Eq. 11.1CSA A23.3-24 Cl. 11.2.8.2, Eq. 11.1 per unit s2026-10-01
total_stir_provided\(\displaystyle \frac{n \cdot A_{\mathrm{sb}}}{s \cdot 1\ \mathrm{mm}}\)All n legs per s, no clause2026-10-01
b_w\(\displaystyle 1 \cdot b\)A23.3 Cl. 11.2.10.1, minimum web width within dCSA A23.3-24 Cl. 11.2.10.1 for a rectangle, Cl. 11.2.10.5 spalled to the stirrup centreline past 11 A_v,min2026-10-01
beta\(\displaystyle 0.18\)CSA A23.3-24 Cl. 11.3.6.3 a) and b), Eqs. 11.9a/b; Eq. 11.9 also used below the minimum stirrups, which is conservative2026-10-01
V_c\(\displaystyle \phi_{c} \cdot \lambda \cdot \beta \cdot \sqrt{f_{c} \cdot 1\ \mathrm{MPa}} \cdot b_{w} \cdot d_{v}\)A23.3 Cl. 11.3.4, Eq. 11.6CSA A23.3-24 Cl. 11.3.4, Eq. 11.6 on b_w2026-10-01
A_v\(\displaystyle n \cdot A_{\mathrm{sb}}\)All n legs, no clause2026-10-01
V_s\(\displaystyle \frac{\phi_{s} \cdot A_{v} \cdot f_{y} \cdot d_{v} \cdot \mathrm{cot}_{\theta}}{s}\)A23.3 Cl. 11.3.5.1, Eq. 11.7CSA A23.3-24 Cl. 11.3.5.1, Eq. 11.7, A_v = n A_sb2026-10-01
V_rmax\(\displaystyle 0.25 \cdot \phi_{c} \cdot f_{c} \cdot b_{w} \cdot d_{v}\)A23.3 Cl. 11.3.3, Eq. 11.5CSA A23.3-24 Cl. 11.3.3, Eq. 11.5 on b_w, V_p = 02026-10-01
V_r\(\displaystyle \min\left(V_{c} + V_{s}, V_{\mathrm{rmax}}\right)\)A23.3 Cl. 11.3.3, Eqs. 11.4 and 11.5CSA A23.3-24 Cl. 11.3.3, Eqs. 11.4 and 11.5 with V_p = 02026-10-01
shear_utilization\(\displaystyle \frac{V_{f}}{V_{r}}\)Ratio of V_f to V_r, no clause2026-10-01
A_c\(\displaystyle b \cdot h\)A23.3 Cl. 3.2, A_cCSA A23.3-24 Cl. 3.2, definition of A_c2026-10-01
P_c\(\displaystyle 2 \cdot \left(b + h\right)\)A23.3 Cl. 3.2, p_cCSA A23.3-24 Cl. 3.2, definition of p_c2026-10-01
T_cr\(\displaystyle \frac{0.38 \cdot A_{c}^{2} \cdot \lambda \cdot \phi_{c} \cdot \sqrt{f_{c} \cdot 1\ \mathrm{MPa}}}{P_{c}}\)A23.3 Cl. 11.2.9.1, Eq. 11.2CSA A23.3-24 Cl. 11.2.9.1, Eq. 11.2 with f_cp = 02026-10-01
A_v_per_s\(\displaystyle \max\left(\frac{V_{f} - V_{c}}{\phi_{s} \cdot f_{y} \cdot d_{v} \cdot \mathrm{cot}_{\theta} \cdot 1\ \mathrm{mm}}, 0\right)\)A23.3 Cl. 11.3.3 and 11.3.5.1, Eqs. 11.4 and 11.7CSA A23.3-24 Eqs. 11.4 and 11.7 for A_v/s, floored at 0; Eq. 11.1 minimum checked separately2026-10-01
A_0\(\displaystyle 0.85 \cdot A_{0h}\)A23.3 Cl. 11.3.10.3CSA A23.3-24 Cl. 11.3.10.3, A_o = 0.85 A_oh2026-10-01
A_t_per_s\(\displaystyle \frac{T_{0f}}{2 \cdot A_{0} \cdot \phi_{s} \cdot f_{y} \cdot \mathrm{cot}_{\theta} \cdot 1\ \mathrm{mm}}\)A23.3 Cl. 11.3.10.3, Eq. 11.17CSA A23.3-24 Cl. 11.3.10.3, Eq. 11.17 solved for A_t/s, A_o = 0.85 A_oh2026-10-01
torsion_stir_provided\(\displaystyle \frac{A_{\mathrm{sb}}}{s \cdot 1\ \mathrm{mm}}\)One outside leg per s, no clause2026-10-01
torsion_stir_utilization\(\displaystyle \frac{A_{t,\mathrm{per},s}}{\mathrm{torsion}_{\mathrm{stir},\mathrm{provided}}}\)Ratio of A_t/s to one leg provided, no clause2026-10-01
total_stir_required\(\displaystyle A_{v,\mathrm{per},s} + 2 \cdot A_{t,\mathrm{per},s}\)A23.3 Cl. 11.3.10.1CSA A23.3-24 Cl. 11.3.10.1, shear plus torsion, A_t on two legs2026-10-01
total_stir_utilization\(\displaystyle \frac{\mathrm{total}_{\mathrm{stir},\mathrm{required}}}{\mathrm{total}_{\mathrm{stir},\mathrm{provided}}}\)Ratio of required to provided, no clause2026-10-01
shear_stress\(\displaystyle \frac{V_{f}}{b_{w} \cdot d_{v}}\)V_f over b_w d_v, no clause2026-10-01
threshold\(\displaystyle 0.125 \cdot \phi_{c} \cdot \lambda \cdot f_{c}\)A23.3 Cl. 11.3.8.3, as a stress on b_w d_vCSA A23.3-24 Cl. 11.3.8.3, 0.125 lambda phi_c f'c over b_w d_v2026-10-01
S_max\(\displaystyle \min\left(300\ \mathrm{mm}, 0.35 \cdot d_{v}\right)\)A23.3 Cl. 11.3.8.3, half of Cl. 11.3.8.1CSA A23.3-24 Cl. 11.3.8.1 halved by Cl. 11.3.8.3 on shear or torsion2026-10-01
s_w\(\displaystyle \frac{x_{0}}{n - 1}\)Geometry: n legs evenly spaced over the stirrup centreline width2026-10-01
s_w_max\(\displaystyle \min\left(d_{v}, 600\ \mathrm{mm}\right)\)A23.3 Cl. 11.3.8.4CSA A23.3-24 Cl. 11.3.8.4, lesser of d_v and 600 mm2026-10-01
alpha_T\(\displaystyle 1 - \frac{0.005 \cdot f_{c}}{1\ \mathrm{MPa}}\)A23.3 Cl. 11.3.10.4CSA A23.3-24 Cl. 11.3.10.4, alpha_T = 1.0 - 0.005 f'c2026-10-01
torsion_stress\(\displaystyle \frac{T_{0f} \cdot P_{c}}{0.85 \cdot \alpha_{T} \cdot A_{c}^{2}}\)A23.3 Cl. 11.3.10.4 b), torsion termCSA A23.3-24 Cl. 11.3.10.4 b), torsion term2026-10-01
combined_stress\(\displaystyle \sqrt{\mathrm{shear}_{\mathrm{stress}}^{2} + \mathrm{torsion}_{\mathrm{stress}}^{2}}\)A23.3 Cl. 11.3.10.4 b)CSA A23.3-24 Cl. 11.3.10.4 b), non-box section, V_p = 02026-10-01
stress_limit\(\displaystyle 0.25 \cdot \phi_{c} \cdot f_{c}\)A23.3 Cl. 11.3.10.4 b)CSA A23.3-24 Cl. 11.3.10.4, right-hand side of Eq. 11.182026-10-01
torsion_section_utilization\(\displaystyle \frac{\mathrm{combined}_{\mathrm{stress}}}{\mathrm{stress}_{\mathrm{limit}}}\)Ratio of combined stress to its limit, no clause2026-10-01
A_vs_per_s\(\displaystyle \max\left(\mathrm{total}_{\mathrm{stir},\mathrm{provided}} - 2 \cdot A_{t,\mathrm{per},s}, 0\right)\)A23.3 Cl. 11.3.10.1, shear shareCSA A23.3-24 Cl. 11.3.10.1, provided less 2 A_t/s, the share left for shear2026-10-01
V_s_shear\(\displaystyle \phi_{s} \cdot A_{\mathrm{vs},\mathrm{per},s} \cdot 1\ \mathrm{mm} \cdot f_{y} \cdot d_{v} \cdot \mathrm{cot}_{\theta}\)A23.3 Cl. 11.3.5.1, Eq. 11.7CSA A23.3-24 Cl. 11.3.5.1, Eq. 11.7 on the shear share2026-10-01
V_s_lt\(\displaystyle \min\left(V_{s,\mathrm{shear}}, V_{f}\right)\)A23.3 Cl. 11.3.9.2, V_s not over V_fCSA A23.3-24 Cl. 11.3.9.2, V_s not over V_f - V_p2026-10-01
shear_term\(\displaystyle V_{f} - 0.5 \cdot V_{s,\mathrm{lt}}\)A23.3 Cl. 11.3.10.6, V_p = 0CSA A23.3-24 Cl. 11.3.10.6, V_p = 02026-10-01
torsion_term\(\displaystyle \frac{0.45 \cdot P_{h} \cdot T_{0f}}{2 \cdot A_{0}}\)A23.3 Cl. 11.3.10.6CSA A23.3-24 Cl. 11.3.10.6, torsion term with V_p = 02026-10-01
F_lt\(\displaystyle \sqrt{\mathrm{shear}_{\mathrm{term}}^{2} + \mathrm{torsion}_{\mathrm{term}}^{2}} \cdot \mathrm{cot}_{\theta}\)A23.3 Eq. 11.14 with Cl. 11.3.10.6CSA A23.3-24 Eq. 11.14 with Cl. 11.3.10.6, M_f = N_f = V_p = 02026-10-01

Clauses

ClauseStepsAgainstDate
A23.3 Cl. 11.3.6.3, simplified methodthetaCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 3.2, effective shear depthd_vCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 3.2, p_hP_hCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 3.2, A_ohA_0hCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.2.8.2, Eq. 11.1A_v_min_per_sCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.2.10.1, minimum web width within db_wCSA A23.3-24 Section 11, as cited2026-10-01
A23.3 Cl. 11.3.4, Eq. 11.6V_cCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.5.1, Eq. 11.7V_s, V_s_shearCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.3, Eq. 11.5V_rmaxCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.3, Eqs. 11.4 and 11.5V_rCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 3.2, A_cA_cCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 3.2, p_cP_cCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.2.9.1, Eq. 11.2T_crCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.3 and 11.3.5.1, Eqs. 11.4 and 11.7A_v_per_sCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.10.3A_0CSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.10.3, Eq. 11.17A_t_per_sCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.10.1total_stir_requiredCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.8.3, as a stress on b_w d_vthresholdCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.8.3, half of Cl. 11.3.8.1S_maxCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.8.4s_w_maxCSA A23.3-24 Section 11, as cited2026-10-01
A23.3 Cl. 11.3.10.4alpha_TCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.10.4 b), torsion termtorsion_stressCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.10.4 b)combined_stress, stress_limitCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.10.1, shear shareA_vs_per_sCSA A23.3-24 Section 11, as cited2026-10-01
A23.3 Cl. 11.3.9.2, V_s not over V_fV_s_ltCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.10.6, V_p = 0shear_termCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Cl. 11.3.10.6torsion_termCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01
A23.3 Eq. 11.14 with Cl. 11.3.10.6F_ltCSA A23.3-24 Section 11 and Cl. 3.2, as cited2026-10-01