Flexural capacity by strain compatibility with the rectangular stress block — rectangular or T-section, optional compression steel, variable φ per 5.5.4.2 — plus the required steel for a target moment, the 5.6.3.3 minimum-reinforcement check, and simplified-method shear (β = 2, θ = 45°) with stirrup spacing limits.
Flexural capacity by strain compatibility with the rectangular stress block — rectangular or T-section, optional compression steel, variable φ per 5.5.4.2 — plus the required steel for a target moment, the 5.6.3.3 minimum-reinforcement check, and simplified-method shear (β = 2, θ = 45°) with stirrup spacing limits.
d = h − bar-centroid offset. For a T-section, take be from the effective flange width rules of 4.6.2.6 — it is an input here, not a computed value.
Bars are placed automatically: side/bottom clear cover + stirrup + half-bar, clear spacing ≥ max(1.5db, 38 mm) per 5.10.3.1.1. When a row fills up, the next bars stack into a second layer with ≥ max(25 mm, db) clear between layers — and d is recomputed from the real bar centroid, layer by layer.
Two habits keep this check honest. First, watch εt, not just the pass/fail: a section that only clears demand in the transition zone (φ sliding below 0.9) is telling you it wants more depth or compression steel — tension-controlled behaviour is a ductility statement, not a formality. Second, the simplified shear method (β = 2, θ = 45°) is deliberately conservative for members with decent longitudinal steel; if shear is the thing failing by a whisker, the general MCFT procedure of 5.7.3.4.2 often finds another 10–20% legitimately. The T-section flange width is an input here because 4.6.2.6 owns that decision — centre-to-centre spacing usually governs on multi-girder decks. What this screen leaves out on purpose: torsion, interface shear at composite joints, crack-control spacing under Service I, and deflections — the last two frequently size the member before strength does on shallow bridge caps.
With Eurocode selected the same section is checked to EN 1992-1-1 using the EN 1992-2 recommended values. Design strengths replace the φ factors: fcd = 0.85 fck/1.5 (αcc 0.85 is a Nationally Determined Parameter, check your National Annex) and fyd = fyk/1.15. Flexure uses the rectangular block ηfcd over 0.8x with a 3.5‰ concrete strain, so MRd carries no separate φ; ductility is read from x/d against the 0.45 guide of 5.6.3. Minimum steel follows 9.2.1.1. Shear uses the variable strut-angle truss of 6.2.3: the page picks the cotθ between 1 and 2.5 that gives the largest stirrup resistance not exceeding the web crushing limit VRd,max, and VRd,c of 6.2.2 applies when no design links are needed.
With KDS selected the check follows KDS 24 14 21 (limit state design for concrete bridges). Material factors φc = 0.65 and φs = 0.90 give fcd = 0.65·0.85 fck and fyd = 0.90 fy. The code gives a parabola-rectangle stress law rather than a rectangular block, so the page integrates it across the compression zone with a 3.3‰ strain limit (less above 40 MPa) to find Md, and limits the neutral axis to cmax = 0.4d at 40 MPa or below. Minimum tension steel is the larger of 0.25√fck/fy and 1.4/fy times bwd. Shear uses the same truss idea as Eurocode with Vsd and Vd,max, where the crushing limit uses φcfck; Vcd applies when links are not needed.