钻孔灌注桩结构设计及配筋计算

MAUNSELLCONCULTANTSASIALTD.11.3钻孔灌注桩设计8.2钻孔灌注桩计算1.设计规范2.基本假定1.3.结构内力分析结果结构重要性系数go=弯矩轴力剪力弯矩轴力剪力MNVM'N'V'kN.mkNkNkN.mkNkN121402.50720.71402.50720.7正截面受弯ULS4.材料参数1.混凝土混凝土强度等级=C35混凝土轴心抗压强度设计值fc=16.7N/mm2混凝土轴心抗拉强度设计值ft=1.57N/mm22.普通钢筋纵向钢筋强度等级=HRB400纵向钢筋强度设计值fy'=fy=360N/mm2钢筋弹性模量Es=210000N/mm23.箍筋箍筋强度等级=HRB400箍筋强度设计值fyv=360N/mm25.假定截面参数截面半径r=m保护层厚度=mm纵向钢筋中心所在圆周半径rs=m纵向钢筋根数n=根纵向钢筋直径φz=mm箍筋直径φg=mm箍筋间距s=mm采用普通箍筋6.配筋计算全部纵向钢筋截面面积As'=npfz2/4=30xπx28^2/4=18473mm2构件截面面积1.119280991极限状态结构分析值结构设计值7030280.416根据中国人民共和国国家标准GB50010-2010(混凝土结构设计规范)桩身为沿周边均匀配筋的圆形截面。1402.50720.70.5正截面受弯ULS内力工况受力状态12100C35HRB400HRB40011.3钻孔灌注桩设计第1页共6页钻孔灌注桩设计MAUNSELLCONCULTANTSASIALTD.11.3钻孔灌注桩设计A=pr2=πx0.5^2=0.79m2纵向钢筋配筋率ρs'=As'/A=18472.56/(0.79x10^6)=2.34%3%OK全部纵向钢筋截面面积As=npfz2/4=30xπx28^2/4=18473mm2A)正截面受弯配筋验算弯距M=1928KNm系数α1=1.00解方程αα1fcA(1-sin2πα/2πα)+(α-αt)fyAs=0E.0.4-1令aα1fcA(1-sin2πa/2πa)+(a-αt)fyAs=αx1x16.7x0.79x10^6(1-sin2πxα/2πxα)+(α-αt)360x18472.56=求得对应于受压区混凝土截面面积的圆心角(rad)于2π的比值α=受拉纵向钢筋截面面积于全部纵向钢筋截面面积的比值αt=内力复核[M]=2/3a1fcArsin3pa/p+fyAsrs(sinpa+sinpat)/pE.0.4-2=2/3x1x16.7x0.79x10^6x0.5x10^3xsin(0.28π)^3/π+360x18472.56x0.416x1000x(sin0.28π+sin0.7π)/π=Nmm=KNmM'=1928KNOKB)受弯构件斜截面承载力计算弯矩M=1928.00KNm剪力V=991.00KN截面宽度b=1.76r=1.76x0.5x1000=880.00mm截面有效高度h0=1.6r=1.6x0.5x1000=800.00mm步骤一：截面尺寸判断混凝土强度影响系数βc=1.00截面腹板高度hw=h0=800.00mm截面受剪承载力[V]=0.25bcfcbh0当hw/b≤4=2939.20kN6.3.1-1=0.2bcfcbh0当hw/b≥6=2351.36kN6.3.1-2=线性内插当4hw/b6∵hw/b=800/880=∴[V]=0.25bcfcbh0=KNV'=991.00KNOK步骤二：是否仅需按构造配筋判断0.7ftbh0=0.7x1.57x880x800/10006.3.3-1=KNV'=KNNOTOK0.280.702020.802939.200.91-1189584.372.02E+09773.70991.0011.3钻孔灌注桩设计第2页共6页钻孔灌注桩设计MAUNSELLCONCULTANTSASIALTD.11.3钻孔灌注桩设计步骤三：仅配置箍筋时斜截面受剪承载力计算预加力提高的受剪承载力Vp=KN同一截面内箍筋的截面面积Asv=2pf2g/4=2xπx12^2/4=226.19mm2斜截面上混凝土和箍筋的受剪承载力Vcs=0.7ftbh0+fyvAsv/sh06.3.4-2=(0.7x1.57x880x800+360x226.19/100x800)/1000=1425.14KN截面受剪承载力[V]=Vp+Vcs=0+1425.146.3.4-1=1425.14KNV'=991.00KNOK步骤四：是否需进行斜截面受弯承载力计算判断截面高度h=2r=2x0.5x1000=1000mm6.3.15箍筋最大间距smax=150当150h≤300且V0.7ftbh0表9.2.9200300h≤500250500h≤800300h800200150h≤300且V≤0.7ftbh0300300h≤500350500h≤800400h800=mms=mmOK箍筋配筋率ρsv=Asv/(bs)=226.19/(880x100)=0.26%0.24ft/fyv=0.24x1.57/360=0.10%9.2.9∵0.7ftbh0V'，箍筋配筋率ρsv0.24ft/fyv配有按计算需要的纵向受压钢筋时，箍筋的最大间距9.2.9[S]=min(15φz,400)=mms=100mmOK结论=步骤五：斜截面受弯承载力计算斜截面的水平投影长度c的确定根据公式V=∑fyAsbsinαs+∑fpyApbsinαp+∑fyvAsv6.3.9-2非预应力弯起钢筋面积Asb=0.00mm2预应力弯起钢筋面积Apb=0.00mm2斜截面的水平投影长度c=V*s/(fyv*Asv)=1216.99mm受拉钢筋截面积Asl=Asat=0.7x18472.56=12844.43mm2纵向普通受拉钢筋合力至受压区合力点的距离z=0.9h0=0.9x800=720.00mm斜截面上箍筋的合力至斜截面受压区合力点的距离zsv=c/2=1216.99/2=608.50mm斜截面受弯承载能力[M]=(fyAsl+fpyAp)z+∑fyAsbzsb+∑fpyApbzpb+∑fyvAsvzsv6.3.9-1=((360x12844.43+0)720+0+0+360x226.19x608x1216.99/100)/10^6=3932.30KNmM'=1928.00KNOK不需进行斜截面受弯承载力计算100300不需要满足4000.0011.3钻孔灌注桩设计第3页共6页钻孔灌注桩设计MAUNSELLCONCULTANTSASIALTD.11.3钻孔灌注桩设计C)最大裂缝宽度计算最大裂缝宽度限值wlim=0.3mm表3.4.5构件受力特征系数acr=1.9表7.1.2-1有效受拉混凝土截面面积Ate=0.5bh7.1.2=0.5x880x800=352000mm2按有效受拉混凝土截面面积计算的纵向受拉钢筋配筋率7.1.2-4rte=(As+Ap)/Ate=(atAs'+Ap)/Ate=(0.7x18472.56+0)/352000=0.0367受拉钢筋应力值ssq=Mq/(0.87Asho)7.1.4-3=1402.5x10^6/[0.87x0.7x18472.56x(800-0.416)]=156.97MPa裂缝间纵向受拉钢筋应变不均匀系数f=1.1-0.65ftk/rtessq7.1.2-2=1.1-0.65x1.57/0.0367/156.97=0.92300.2∴=1.0000&1.0最大裂缝宽度wmax=acrxfxsskx(1.9xc+0.08xdeq/rte)/Es7.1.2-1=1.9x0.923x156.97x(1.9x70+0.08x28/0.037)/210000=mm0.3mm满足裂缝宽度要求0.2811.3钻孔灌注桩设计第4页共6页钻孔灌注桩设计r=0.5rs=0.4160.57735n=300.866025圆心00圆00.5阴影圆上点-0.433010.25钢筋00.416标注000.0868240890.492404-0.383020.3213940.0864910.4069090.433013-0.250.1710100720.469846-0.321390.3830220.1692020.3800350.433013-0.250.250.433013-0.250.4330130.2445190.3365510.404145-0.20.3213938050.383022-0.171010.4698460.3091480.2783580.433013-0.250.3830222220.321394-0.086820.4924040.3602670.2080.375278-0.250.4330127020.250.250.4330130.395640.1285510.469846310.1710100.50.4137210.043484000.4924038770.0868240.0868240.4924040.413721-0.0434800.4160.53.06E-170.171010.4698460.39564-0.1285500.4160.492403877-0.086820.250.4330130.360267-0.2080.0240180.37440.46984631-0.171010.3213940.3830220.309148-0.2783600.4160.433012702-0.250.3830220.3213940.244519-0.33655-0.024020.37440.383022222-0.321390.4330130.250.169202-0.380030.321393805-0.383020.086491-0.406910.25-0.433015.1E-17-0.416000.171010072-0.46985-0.08649-0.40691-0.433010.250.086824089-0.4924-0.1692-0.380036.12574E-17-0.5-0.24452-0.3365500-0.086824089-0.4924线上点-0.433010.25-0.30915-0.278360.4330130.25-0.171010072-0.46985-0.454420.25-0.36027-0.208-0.25-0.43301-0.454420.25-0.39564-0.12855-0.321393805-0.38302-0.433010.25-0.41372-0.0434800.15-0.383022222-0.32139-0.390860.25-0.413720.0434840.0130730.149429-0.433012702-0.25-0.329230.25-0.395640.1285510.0260470.147721-0.46984631-0.171010.0669870.25-0.360270.2080.0388230.144889-0.492403877-0.08682-0.250.25-0.309150.2783580.0513030.140954-0.5-9.2E-17-0.155580.250.0633930.135946-0.4924038770.086824-0.048840.250.0750.129904-0.469846310.171010.0669870.250.0860360.122873-0.4330127020.250.1883720.250.0964180.114907-0.3830222220.3213940.3116280.250.1060660.106066-0.3213938050.3830220.4330130.250.1149070.096418-0.250.4330130.250.250.1228730.086036-0.1710