计算书 6 配筋计算

第六章截面设计-55-第六章截面设计6.1框架梁以第一层AB框架梁的计算为例，说明计算方法和步骤。6.1.1梁的最不利内力组合根据第五章的计算，梁的最不利内力如下：跨间：Mmax=54.80KN•m支座A：Mmax=-234.6KN•m支座B：Mmax=-184.56KN•mV=96.83KN（调整后）6.1.2梁的正截面受弯承载力计算抗震设计中，对于楼面现浇的框架结构，梁支座负弯矩按矩形截面计算纵筋数量，跨中正弯矩按T形截面计算纵筋数量。跨中截面的计算弯矩，应取该跨的跨间最大弯矩或支座弯矩与1/2简支梁弯矩之中的较大者，依据上述理论，得：（1）考虑跨间最大弯矩处按T形截面设计，翼缘计算宽度'fb按跨度考虑，'fb=l/3=2000mm；按翼缘厚度考虑时，'fb=b=300mm。所以'fb可取2000mm。'fh=100mm。办公楼属一类环境，梁保护层厚度c=20mm，h0=600-20-10-220=560mm。)2('0''1fffchhhbf=1.0×14.3×2000×1000×（560-50）×10-6=1573KN•mmaxM=54.80KN•m可按第一类T形截面进行计算。第六章截面设计-56-201shbfMfc=2656020003.140.11080.54=0.006=1-s21=0.006)211(5.0ss=0.5×（1+0.994）=0.99726017.327560300997.01080.54mmhfMAyss实配钢筋216，sA=402mm2。600300402=0.22％＞min=0.45yff/t=0.45×1.43/300=0.215％，且%23003.14576.00.11ycbff，满足要求。梁端截面受压区相对高度：01yhbfaAffcs5602003.140.1402300=0.075＜b=0.576满足抗震设计要求。(2)考虑两支座处A支座负弯矩比较大，可将下部跨间截面的216钢筋伸入支座，作为支座负弯矩作用下的受压钢筋，'sA=402mm2，再计算相应的受拉钢筋sA，B支座负弯矩较小，可不必伸入。1）支座A上部：2010s)(hbfaahAfMfcssy=265603003.14140560402300106.234）（=0.127=sa21-1=0.136)211(5.0ss=0.93226031.1498560300932.0106.234mmhfMAyss第六章截面设计-57-实配钢筋：422，sA=1520mm2。6003001520=0.84％＞min=0.45yff/t=0.45×1.43/300=0.215％，且%23003.14576.00.11ycbff，满足要求。2）支座B上部：201shbfaMfc=265603003.1411056.184=0.139=sa21-1=0.150)211(5.0ss=0.92526039.1200560300925.01054.186mmhfMAyss实配钢筋：420，sA=1256mm2。6003001256=0.70％＞min=0.45yff/t=0.45×1.43/300=0.215％，且%23003.14576.00.11ycbff，满足要求。其他各梁正截面受弯承载力计算见表6-1。6.1.3梁的斜截面受剪承载力计算（1）验算截面尺寸0whh=560mmbhw/=560/300=1.87＜4025.0bhfcc=0.25×1.0×14.3×300×560=600.6kN＞96.83kN可知，截面符合条件。（2）验算是否需要计算配置箍筋箍筋选用HPB300钢筋，yvf270N/mm2。第六章截面设计-58-07.0bhft0.7×1.43×300×560=168.17kN＞96.83kN故可按构造要求配置箍筋：加密区配置28@100，非加密区配置28@200。加密区长度取1.5h=900mm。（3）梁斜截面受剪承载力计算bsnAsvsv1=2×50.3/（300×200）=0.17％＞min=yvtff24.0=0.24×1.43/270=0.13％满足构造要求。其他各梁斜截面受弯承载力计算见表6-2。表6-2中1层BC跨需按计算配筋（只配箍筋），计算过程如下：00cvsvhfbhfVsAyvt=mmmm/116.036027036020043.10.7-1033.8323svA取101mm即配置双肢8的箍筋，间距可取100mm。其他各层框架梁配筋见表6-1和表6-2。第六章截面设计-59-表6-1框架梁纵筋配筋表楼层截面M(kN·m)2'f0'f'fc1hhhbf20fc1shbfMs211)mm('2sA)mm(2sA实配钢筋(mm2)配筋率（%）5A支座-57.200.0430.043348.010.22AB跨间64.331515.80M0.0070.007384.290.22B支座左-49.890.0370.038302.710.22B支座右-22.570.0610.063215.720.28BC跨间-10.46377.52M0.0070.00797.200.394A支座-123.650.0920.097773.330.42AB跨间90.861515.80M0.0100.010543.600.34B支座左-111.590.0830.087694.290.42B支座右-47.090.1270.136467.890.64BC跨间-12.87377.52M0.0090.009119.650.283A支座-143.010.1060.113902.030.51AB跨间45.211573.00M0.0050.005269.790.22B支座左-123.020.0910.096769.190.42B支座右-57.060.1540.168576.790.75第六章截面设计-60-BC跨间-8.18400.40M0.0060.00675.910.282A支座-179.480.1330.1441151.080.63AB跨间45.031573.00M0.0050.005268.720.22B支座左-150.920.1120.119955.280.52B支座右-69.880.1890.211723.270.95BC跨间-5.09400.40M0.0030.00347.210.281A支座-234.610.1280.1371500.540.84AB跨间54.801573.00M0.0060.006327.210.22B支座左-186.540.1390.1501200.350.70B支座右-88.850.2400.278955.761.18BC跨间-6.45400.400M0.0040.00459.830.50第六章截面设计-61-表6-2框架梁箍筋计算表楼层梁跨最不利剪力V/γREV(kN)0cc25.0bhf(kN)0tcvbhf是否按计算配筋选用箍筋)kN(csVcsVV加密区实配钢筋非加密区实配钢筋5AB71.31600.6满足168.168按构造320.88满足BC19.96600.6满足72.072按构造170.244满足4AB117.62600.6满足168.168按构造320.88满足BC41.27600.6满足72.072按构造170.244满足3AB69.33600.6满足168.168按构造320.88满足BC53.31600.6满足72.072按构造170.244满足2AB79.94600.6满足168.168按构造320.88满足BC66.82600.6满足72.072按构造170.244满足1AB95.94600.6满足168.168按构造320.88满足BC84.33600.6满足72.072按计算170.244满足第六章截面设计-62-6.2框架柱6.2.1柱截面尺寸验算根据《抗震规范》，对于三级抗震等级，剪跨比宜大于2，轴压比小于0.85，表6-3给出了框架柱各层剪跨比和轴压比计算结果。注意：表中的Mc、Vc和N都不应考虑抗震调整系数，由表可见，各柱的剪跨比和轴压比均满足规范要求。表6-3边柱的剪跨比和轴压比验算柱号楼层B(mm)h0(mm)Fc(N/mm2)Mc(kN·m)Vc(kN)N(kN)cA柱550047014.393.2710.04437.0119.760.12450047014.392.1430.07924.656.520.26350047014.3117.1648.491357.965.140.38250047014.3138.2454.921792.335.350.50150047014.3223.7967.982225.047.000.62B柱550047014.394.0121.36454.699.370.13450047014.3131.8850.401041.185.570.29350047014.3135.5475.641575.293.810.44250047014.3160.7486.042108.483.970.59150047014.3246.06102.682641.305.100.746.2.2柱正截面承载力计算以底层柱子为例说明，根据A柱内力组合表，近似取支座中心处弯矩，并与柱端组合弯矩比较后，选出最不利内力进行配筋。（1）最不利组合一(调整后)：maxM=-232.75kN·m，N=1328.19kNM1=186.85kN·m1)考虑二阶效应的偏心距设sa='sa=40mm，0h=h-sa=450-40=410mm。附加偏心距ae取20mm和偏心方向截面尺寸的1/30两者中的较大值，第六章截面设计-63-即：450/30=15mm，故取20mm轴向力对截面重心的偏心距0e=M/N=232.75×106/（1328.19×103）=175.24mm初始偏心距：ie=0e+ae=175.24+20=195.24mm。柱的计算长度，根据《规范》，对于现浇楼盖的底层柱cl=H=4.75m，其它层取cl=1.25H=1.25×3.2=4mc=0.5Afc/N=0.5×14.3×4502/（1328.19×103）=1.09＞1.0，取c=1.0ns=1+c2c013001hlhei=1+(4750/450)2×1.0/（1300×195.24/410）=1.18213.07.0MMCm=0.7+0.3×186.85/232.75=0.942MCMnsm0.94×1.18×232.75=258.3kN·mN/M0e258.3×106/（1328.19×103）=194.48mmie=0e+ae=194.48+20=214.48mm2）配筋计算轴向力作用点至受拉钢筋sA合力点之间的距离：e=ie+h/2-sa=214.48+450/2-40=399.48mm，可取400mm。若按对称配筋考虑，应有sA=sA，yf='yfb=0b1bhfc=1.0×14.3×0.55×450×4102=1451.09kN=1328kN满足对称配筋大偏心受压的条件。bfNxc11328190/(1.0×14.3×450)=206mm2'sa=80mmsA=sA)()5.0('0'01sycahfxhbxfe=)40410(300)2/206410(2064503.140.10041019.1328320'min2mm369410450%2.0mm94.1191bh（2）最不利组合二：maxN=2225.04kN，M=6.58kN·m