1.1 基本资料
1.1.1 工程名称:工程一
1.1.2
混凝土强度等级:C25 fc = 11.94N/mm ft = 1.27N/mm
1.1.3 钢筋强度设计值 fy = 360N/mm Es = 200000N/mm
1.1.4 由
弯矩设计值 M 求配筋面积 As,弯矩 M = 150kN·m
1.1.5 截面尺寸 b×h = 250*650mm ho = h - as = 650-35 = 615mm
1.2 计算结果:
1.2.1 相对界限受压区高度 ξb
ξb = β1 / [1 + fy / (Es * εcu)] = 0.8/[1+360/(200000*0.0033)] = 0.518
1.2.2 受压区高度 x = ho - [ho ^ 2 - 2 * M / (α1 * fc * b)] ^ 0.5
= 615-[615^2-2*150000000/(1*11.94*250)]^0.5 = 88mm
1.2.3 相对受压区高度 ξ = x / ho = 88/615 = 0.143 ≤ ξb = 0.518
1.2.4 纵向受拉钢筋 As = α1 * fc * b * x / fy = 1*11.94*250*88/360 = 730mm
1.2.5 配筋率 ρ = As / (b * ho) = 730/(250*615) = 0.47%
最小配筋率 ρmin = Max{0.20%, 0.45ft/fy} = Max{0.20%, 0.16%} = 0.20%
纵向受拉钢筋 As = 730mm,实配取3根18=763.4mm
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