Reinforced concrete shear wall to SIA 262

Checks a reinforced concrete wall loaded in its plane, to SIA 262:2025: bending with axial force and shear, detailing, buckling of a strip out of the plane and, for earthquake, capacity design and the detailing of the plastic zone. Every step shows its formula and the clause it comes from.

What it checks

• Design strengths: f_cd = η_fc · η_t · f_ck/γ_c, clause 2.4.2.3, equation (2), with η_fc from 4.2.1.2, equation (26), and f_yd = f_yk/γ_s, equation (4).
• Axial force and bending in the plane, checks 1 and 2: N_d ≤ N_Rd,c, the whole section at ε_c2d, and M_d ≤ [M_Rd], with the compression zone x found from N(x) = N_d (4.2.1.5).
• Shear of the web, checks 3 and 4: V_d ≤ V_Rd,s = A_sw/s · z · f_yd · cot α, 4.3.3.4.3, equation (45), and V_d ≤ V_Rd,c = b_w0 · z · k_c · f_cd · sin α · cos α, 4.3.3.4.6, equation (47), with z = 0.9 · d (4.3.3.4.2) and α between α_min and 45° (4.3.3.3.2, equation (42)).
• Tension chord, check 5: M_d/z − N_d/2 + F_tVd/2 ≤ A_s,E · f_yd (4.3.3.4.10), with F_tVd = V_d · cot α, 4.3.3.4.11, equation (51).
• Detailing: b_w0 ≥ 150 mm cast in place (5.5.4.1, Table 22); 0.6 % ≤ ρ_v,tot ≤ 8 % (5.5.4.3, 5.5.4.5); s_v ≤ min(2 · b_w0 ; 300 mm); ρ_h ≥ 25 % of ρ_v (5.5.4.11); cross-ties with s_t ≤ min(15 · Ø_min ; b_w0 ; 300 mm), 5.5.4.7, equation (117), and Ø_t ≥ Ø_max/3 (5.5.4.9).
• Out of the plane, on a strip of 1 m: n_d ≤ n_Rd,c, then e_0d from α_i (4.1.3.2.3, equation (17)) and d/30 (4.3.7.5, equation (75)), e_1d = m_1d/n_d, equation (76), e_2d = χ_d · l_cr²/c, equation (77), with χ_d from equation (78), and m_d = n_d · e_d ≤ [m_Rd] (4.3.7.3).
• Earthquake, ductile behaviour (4.3.9.3): q from Table 15, the concrete between C20/25 and C50/60 (4.3.9.3.2), the checks in the plane under the seismic actions, and the shear by capacity design, V+_d = ε · κ · V_d, 4.3.9.4.4, equations (95) to (97), with M+_Rd from f_y,m (4.3.9.3.3), against a web with α_min = 40° and k_c = 0.4.
• Plastic zone (5.7.1): h_pl, ν_d ≤ 0.4, the ratios of the boundary elements and the web between 0.3 % and 3 %, the bar spacings, the web and boundary element dimensions (5.7.1.2, 5.7.1.3), and the confinement ω_wd, 5.7.1.4, equations (118) and (119), for μ_φ = 2 · q − 1.

What you enter and what you get

For the wall, you enter l_w, b_w0, constant thickness or thickened ends, and cast in place or precast. Then the cover c_v, the n_E end bars Ø_E in pairs at s_E, the web bars Ø_v at most s_v apart, the horizontal bars Ø_h at s_h, the materials, the resistance factors and η_t. In the plane: N_d, M_d and V_d, the condition of the web, and α chosen or entered. Then the cross-ties Ø_t at s_t. Out of the plane: n_d, m_1d, l_cr and l. For earthquake: the behaviour, the ductility class of the steel, the seismic actions, h_w, h_s, the number of storeys n, the ends of the wall, l_c, the hoops Ø_w at s_cx with s₀ and n_t, and T₁ and T_C.

You get the bar layout used, every resistance and check with its utilisation and clause, and the warnings on detailing. With the Basic plan, it prints as an A4 calculation note.

Assumptions and limits

• The wall is checked at the section you enter the actions for, usually the base. A wall in tension is outside this module.
• Wall and bars are symmetric: both ends alike, and the sign of M_d does not matter.
• The web bars are spread evenly between the end bars, at s_v or a little less; the spacing used is reported.
• Out of the plane, the most loaded metre is checked with the estimated curvature, creep and shrinkage included.
• In capacity design the concrete is kept at f_cd: 4.3.9.3.3 names the steel only. The hoops are taken outside the vertical bars, and ω_wd leaves out the anchorage lengths.
• Not checked: the crack requirements of 4.4.2 for the horizontal bars, and the elastic zones above the plastic zone (4.3.9.4.3).

Worked example

A wall 5,000 mm long and 250 mm thick in f_ck = 30 N/mm², with eight Ø20 end bars at each end, Ø10 web bars at 200 mm, Ø12 horizontal bars at 150 mm and Ø8 cross-ties at 125 mm, under N_d = 2,500 kN, M_d = 6,000 kNm and V_d = 900 kN, with n_d = 500 kN/m and m_1d = 5 kNm/m over l_cr = 2.8 m, and designed for ductile behaviour as a six-storey wall 18 m high under N_d = 2,000 kN, M_d = 5,000 kNm and V_d = 600 kN, with 700 mm boundary elements. These are the module's own results for its worked example, computed when this page was built.

How this module is verified

Verified clause by clause against SIA 262:2025 and against independent calculations used on real projects, before release.

Questions

Why is the seismic shear of the wall raised so much?

Capacity design protects the wall against a shear failure once the plastic zone forms. In the worked example ε = 2.86 and κ = 1.5 raise V_d = 600 kN to V+_d = 2,575 kN.

When does the wall need no plastic zone detailing?

With non-ductile behaviour (4.3.9.2), the wall is designed for the seismic actions with a small q (Table 14) and needs nothing more. The rules of 4.3.9.4 and 5.7.1 apply where h_w/l_w exceeds 2. Boundary elements are not needed where both ends are tied into sufficiently reinforced transverse walls (5.7.1.2).

Which plan includes this module?

The Basic plan, with its calculation note.

Related

• Concrete wall: strut-and-tie model
• Reinforced concrete column
• Concrete walls: all modules
• SIA 262: modules and clauses

Norm: SIA 262:2025 · Page updated: 5 November 2026