Shear Wall Required and Design Strength

Notation

A_g = gross area of concrete section, in²
A_v = area of shear reinforcement within spacing s, in.²
D = dead load
E = earthquake load
f_c^' = specified compressive strength of concrete, psi
f_yt = specified yield strength of transverse reinforcement, psi
L = live load
L_r = roof live load
M_n = nominal flexural strength at section, in.-lb
M_u = factored moment at section, in.-lb
P_n = nominal axial compressive strength of member, lb
P_u = factored axial force; to be taken as positive for compression and negative for tension, lb
R = rain load
S = snow load
U = strength of a member or cross section required to resist factored loads or related internal moments and forces in such combinations as stipulated in ACI 318-19
V_n = nominal shear strength, lb
V_u = factored shear force at section, lb
W = wind load
ϕ = strength reduction factor

Required Strength

Required strength is calculated in accordance with the factored load combinations in Load Factors and Combinations title.

Reinforced concrete walls with rectangular, I, T, L, U or C crossection are modeled with finite elements (shells) containing degrees of freedom for both in-plane and out-of-plane displacements. The resultant of the finite element joint forces are obtained as equivalent internal force (M_u, P_u) at the cross-section gravity center, based on shear wall required strength and design strenth calculations.

The wall shear design is applied leg by leg for each of the design load combination. The factored shear force, V_u of the leg is determined and compared with design shear strength ϕV_n.

Design Strength

Design strength at all sections should be satisfy all conditions given below;

• ϕP_n ≥ P_u

• ϕM_n ≥ M_u

• ϕV_n ≥ V_u

Strength reduction factors ϕ is determined according to using ACI Table 21.2.2. Interaction between load effects is considered.

P_n and M_n is calculated in accordance with Axial strength or Combined Flexural and Axial Strength title.