2023C0808某预制钢筋混凝土柱与杯口基础连接，已知柱抗震等级四级、截面尺寸0.5m×0.5m、混凝土强度等级 C40，柱内采用HRB400钢筋、主筋直径28mm、保护层厚度40mm， 按照《建筑地基基础设计规范》GB 50007-2011，计算杯口基础的总高度最小值最接近下列哪个选项？ （不考虑吊装时的稳定性要求，柱钢筋受拉且强度充分发挥，钢筋锚固长度修正系数ξ\xiξ取1.10) (A) 710mm (B) 750mm (C) 810mm (D) 850mm 解答据《建筑地基基础设计规范》第 8.2.2条, 8.2.4条h=500mm⇒h1=h=500mm,α1≥200,H≥500+200+50=750mm lab=αfyftd=0.14×3601.71×28=825mm,la=ξalab=1.10×825=908mm 20×d=20×28=560mm,560+40=600mm>500mm Hmin=600+200+50=850mmh = 500mm \Rarr h_1 = h = 500mm, \alpha_1 \geq 200, H \geq 500 + 200 + 50 = 750mm \\~\\ l_{ab} = \alpha \cfrac{f_y}{f_t} d = 0.14 × \cfrac{360}{1.71} × 28 = 825mm, l_a = \xi a l_{ab} = 1.10 × 825 = 908mm \\~\\ 20 × d = 20 × 28 = 560mm, 560 + 40 = 600mm > 500mm \\~\\ H_{min} = 600 + 200 + 50 = 850mmh=500mm⇒h1=h=500mm,α1≥200,H≥500+200+50=750mm lab=αftfyd=0.14×1.71360×28=825mm,la=ξalab=1.10×825=908mm 20×d=20×28=560mm,560+40=600mm>500mm Hmin=600+200+50=850mm