Plain-English paraphrases of the clauses you cite most. 18 entries across 10 codes.
Engineers look up the same handful of code clauses every day: IS 456 Cl. 26.2.1 (development length), Cl. 31.6.3 (punching shear), ACI 318 §22.5 (one-way shear), Eurocode 2 §9.2 (minimum reinforcement). The official code text is authoritative but rarely the fastest way to recall what a clause actually says. Each entry below is a plain-English summary plus the formula it owns, with a one-click link to the design module that applies it. Use this as your mental quick-reference; for binding interpretation, always consult the published code.
Reinforcement must extend on either side of any section by a length sufficient to develop the bar's design strength through bond. The length depends on bar diameter, design stress, and the bond strength of the surrounding concrete (modified for bar surface and concrete grade).
L_d = (φ × σ_s) / (4 × τ_bd)τ_bd = 1.2 N/mm² (deformed bars × 1.6)Punching shear is checked at a critical perimeter offset d/2 from the column face. Permissible shear stress is k_s × τ_c, where k_s depends on the column aspect ratio.
τ_v = V_u / (b_o × d)k_s × τ_c = (0.5 + β_c) × 0.25 × √f_ck (≤ 0.25√f_ck)Nominal shear stress is computed at the support. Compared against permissible τ_c (varies with %p_t and grade) — concrete alone, then stirrups designed for the excess.
τ_v = V_u / (b × d)τ_c = look-up Table 19 from p_t and f_ckTension reinforcement in any beam shall not be less than the value given by 0.85/fy × b × d for the rectangular tension zone — equivalent to ≈ 0.205% for Fe 415 and 0.17% for Fe 500.
p_t,min = 0.85 / f_y (× 100 %)Maximum cross-sectional area of longitudinal reinforcement in a column = 6% of gross sectional area (4% if lapped). Beyond this, concrete placement is impractical.
Apply in Section DesignFootings must be designed for: bearing pressure under service loads, bending moments, one-way and two-way shear at appropriate critical sections, and development length of reinforcement past the critical bending section.
Apply in Foundation DesignDesign bending moment of a laterally unsupported beam is taken as M_d = β_b × Z_p × f_bd, where f_bd is the design bending compressive stress accounting for buckling.
M_d = β_b × Z_p × f_bdλ_LT = √( β_b × Z_p × f_y / M_cr )Member subject to combined axial force and bending must satisfy the interaction equation including second-order effects (P-δ amplifier on the bending term).
P/P_d + (C_my × M_y)/(M_dy × (1 - P/P_dy)) + (C_mz × M_z)/(M_dz × (1 - P/P_dz)) ≤ 1.0Sections are classified by the b/t ratio of their plate elements. Plastic sections develop full plastic moment with rotation capacity; slender sections fail by local buckling before yield.
b/t ≤ 9.4 εb/t ≤ 15.7 εε = √(250 / f_y)Permissible crack width is 0.2 mm for severe exposure (e.g. liquid retaining face) and 0.1 mm where the surface is in direct contact with potable water.
Apply in Basement DesignNet ultimate bearing capacity is computed via the Terzaghi-style equation with shape, depth, and inclination factors. Safe bearing capacity is q_u / FoS (typical FoS = 2.5 to 3.0).
q_n,u = c·N_c·s_c·d_c + (D_f·γ)·(N_q − 1)·s_q·d_q + 0.5·B·γ·N_γ·s_γ·d_γq_s = q_n,u / FoSSites with saturated cohesionless soils within 20 m of GL must be screened for liquefaction. Cyclic stress ratio (CSR) compared with cyclic resistance ratio (CRR) — FoS_liq < 1.0 indicates liquefiable.
CSR = 0.65 × (a_max / g) × (σ_v / σ'_v) × r_dTarget mean strength = characteristic compressive strength + 1.65 × standard deviation. Standard deviation depends on grade (Table 1) for trial design; use site values once available.
f'_ck = f_ck + 1.65 × sConcrete punching shear strength v_c is the smaller of three expressions, accounting for column aspect ratio (β) and column type (interior/edge/corner — α_s factor).
v_c = min{ 0.33λ√f'_c , 0.17(1 + 2/β)λ√f'_c , 0.083(α_s d/b_o + 2)λ√f'_c }Minimum reinforcement greater of 3√f'_c × b_w × d / f_y or 200 × b_w × d / f_y, in psi units. Prevents brittle failure at first cracking.
Apply in Section DesignNominal flexural strength accounts for the moment gradient via C_b. Equation depends on whether the unbraced length L_b falls below L_p (plastic), between L_p and L_r (inelastic LTB), or above L_r (elastic LTB).
C_b = 12.5 M_max / (2.5 M_max + 3 M_A + 4 M_B + 3 M_C)Crack width w_k = s_r,max × (ε_sm − ε_cm). Limit values depend on exposure class and structure type (Table 7.1N).
Apply in Section DesignDesign buckling resistance moment M_b,Rd = χ_LT × W_y × f_y / γ_M1, where χ_LT depends on slenderness λ̄_LT and an imperfection factor.
Apply in Steel Section DesignEditorial paraphrases for educational reference — the official code text is always authoritative.