aoy = Min{Sb - 0.5bc, Ho} = Min{100,340} = 100mm
2 * βox * (bc + aoy) * βhp * ft * ho
= 2*1.417*(800+100)*1*1.43*340
= 1242972N ≥ Fl = 924750N,满足要求。
(2)、角桩对承台的冲切验算:
扣除承台和其上填土自重后的角桩桩顶相应于荷载效应基本组合时的竖向力设计值:
Nl = Nmax = 462375N
承台受角桩冲切的承载力可由基础规范 8.5.17-1 式推导出按下列公式:
Nl ≤ β1x * (bp + a1y) * βhp * ft * ho
X 方向上自桩内边缘到最近柱边的水平距离:
a1x = 750 - 0.5hc - 0.5bp = 750-800/2-433/2 = 133mm
λ1x = a1x / ho = 133/(450-110) = 0.393
X 方向上冲切系数 β1x = 0.84 / (λ1x + 0.2) (基础规范 8.5.17-3)
β1x = 0.84/(0.393+0.2) = 1.417
a1y = Min{Sb - 0.5bp, ho} = Min{283,340} = 283mm
β1x * (bp + a1y) * βhp * ft * ho
= 1.417*(433+283)*1*1.43*340
= 494776N ≥ Nl = 462375N,满足要求。
3、承台斜截面受剪承载力计算:
(1)、Y方向斜截面受剪承载力计算:
扣除承台及其上填土自重后 Y 方向斜截面的最大剪力设计值:
Vy = Max{N1, N2} = 462375N
承台斜截面受剪承载力按下列公式计算:
Vy ≤ βhs * βx * ft * byo * ho (基础规范 8.5.18-1)
Y 方向上自桩内边缘到最近柱边的水平距离:
ax = 750 - 0.5hc - 0.5bp = 750-800/2-433/2 = 133mm
λx = ax / ho = 133/(450-110) = 0.393
βx = 1.75 / (λx + 1.0) = 1.75/(0.393+1.0) = 1.257
βhs * βx * ft * byo * ho = 1*1.257*1.43*1000*340 = 612202N
≥ Vy = 462375N,满足要求。
4、柱下局部受压承载力计算:
局部荷载设计值 F = 924750N
混凝土局部受压面积 Al = bc * hc = 640000mm2
承台在柱下局部受压时的计算底面积按下列公式计算:
Ab = (bx + 2 * c) * (by + 2 * c)
c = Min{Cx, Cy, bx, by} = Min{850,100,800,800} = 100mm
Ab = (800+2*100)*(800+2*100) = 1000000mm2
βl = Sqr(Ab / Al) = Sqr(1000000/640000) = 1.25
ω * βl * fcc * Al = 1.0*1.25*0.85*14.33*640000 = 9745371N
≥ F = 924750N,满足要求。
5、桩局部受压承载力计算:
局部荷载设计值 F = Nmax + γg * Qgk = 462.4+1.35*31.9 = 505.5kN
混凝土局部受压面积 Al = π * d ^ 2 / 4 = 196350mm2
承台在角桩局部受压时的计算底面积按下列公式计算: 五层现浇钢筋混凝土框架结构商业中心建筑与结构设计和CAD图纸(75):http://www.youerw.com/gongcheng/lunwen_1016.html