Capacity Moment capacity Set the cross-section on the left. Drag the slider to apply a larger or smaller moment M, between the hogging (M⁻) and sagging (M⁺) capacity. See how strains and stresses relate and vary through the section.
Cross-section
Material Concrete C12/15 C16/20 C20/25 C25/30 C28/35 C30/37 C32/40 C35/45 C40/50 C45/55 C50/60 Reinforcement B500B B500C B450A
M⁻ (hog)
54.7
kNm/m · under-reinforced
M⁺ (sag)
54.7
kNm/m · under-reinforced
◀ F up (hogging) 0 F down (sagging) ▶
M = 54.7 kNm/m
Beam · simply supported, central load M_sag (span moment) F tension compression crack (M ≥ M_cr) reinforcement Side Strain ε Stress σ Forces (resultants) top mid bot NA longitudinal 5.85‰ -1.45‰ rectangle f_R3 triangle f_R1 tp C_c=435kN T_cf=194kN T_s=239kN T_s=1kN Steel σ–ε -6 -4 -1 1 4 6 -522 -261 0 261 522 ε [‰] σ [MPa] bot top Concrete σ–ε -25 -15 -5 5 15 25 -24 -12 0 12 24 ε [‰] σ [MPa] top mid bot Concrete tension (zoom) -1 2 5 8 11 14 -0 1 2 3 4 ε [‰] σ [MPa] f_ctm f_Ftu fibre (f_R1,f_R3) mid bot Calculation
M = Σ Fᵢ · (h/2 − yᵢ)
C_c : -435·-0.086 = +37.3
T_cf : +194·+0.017 = +3.3
T_s : +239·+0.060 = +14.3
T_s : +1·-0.060 = -0.1
ΣF = -0 kN ≈ 0
M = +54.8 kNm