第四章-水平荷载作用下的框架内力分析

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1、第四章水平荷载作用下的框架内力分析4.1梁的线刚度：在计算梁的线刚度时，考虑楼板对梁刚度有利影响,认为翼缘参加工作,为简化计算，先按矩形截面计算惯性矩，然后乘以一个增大系数。现浇钢筋砼梁：边框架梁=1.5I0中框架梁=2I0柱、梁均采用Ｃ30混凝土，ＥC3.0×107kN/m²I0=1/12×bh3(m4)KB单位：KNm框架梁线刚度计算部位截面（m²）高度（m）截面惯性矩I0(m4)边框架中框架I=1.5I0(m4)KB=EI/l(kn.m)I=1.5I0m4)KB=EI/l(kn.m)边框架0.3×0.77.28.57×10-31

2、2.86×10-3535831.71×10-2712500中框架0.3×0.52.73.13×10-34.69×10-3469000.63×10-263000边框架0.3×0.77.28.57×10-312.86×10-3535831.71×10-2712504.2框架柱侧移刚度计算1.柱线刚度：柱采用C30混凝土，，首层高度4.43m,2-5层3.6m；柱截面：各层600mm×600mm则I0=1/12×bh3=10.8×10-3m4;KC=EI/h2.柱的侧移刚度D：一般层：=D=首层：=D=部位截面(m²)层高(m)惯性矩(m4

3、)Ic=EI/h(104)边框架边柱C1边框架中柱C2Kα1Dc1Kα2Dc25层0.6²3.610.8×10-390.60.23191671.120.36300004层0.6²3.610.8×10-390.60.23191671.120.36300003层0.6²3.610.8×10-390.60.23191671.120.36300002层0.6²3.610.8×10-390.60.23191671.120.36300001层0.6²4.4310.8×10-37.31380.730.45201251.370.5530000部位中框

4、架边柱C1中框架中柱C2各层各柱刚度层间刚度Kα3Dc3Kα4Dc4ΣDc1ΣDc2ΣDc3ΣDc45层0.80.28233331.490.433583319167×430000×423333×1635833×1812149904层0.80.28233331.490.433583319167×430000×523333×1835833×1913274893层0.80.28233331.490.433583319167×430000×523333×1835833×1913274892层0.80.28233331.490.43358331

5、9167×430000×523333×1835833×1913274891层10.49219141.840.612728019167×424597×521914×1827280×191139440层间侧移刚度的验算∑D1/∑D2=1139440/1327489=0.86﹥0.7满足要求4.3.3水平地震作用分析（底部剪力法）本框架结构符合底部剪力法的适用范围，故采用底部剪力法计算水平地震作用。1.框架自振周期计算:用能量法计算。用能量法计算的数据过程及其结果见表表5用能量法计算的数据层次（KN）(KN)（KN/m）(m)56973.3

6、26973.3212149900.0060.110767.184.38410003.2816976.613274890.0130.1041040.3108.20310410.7327387.3313274890.0210.091947.486.21210410.7337798.0613274890.0280.07728.751.01110170.2047968.2611394400.0420.042427.117.941.考虑七度设防：аmax=0.08考虑I组类别Ⅱ类场地土Tg=0.35S因为T1=0.39<1.4Tg=0.49S所

7、以考虑顶部附加水平地震作用底部剪力为：а1=(Tg/T1)0.9×аmax=(0.35/0.39)0.9×0.08=0.073FEk=а1×Geq=0.073×0.85×47968.26=2976.43kN由公式Fi=(GiHi/ΣGjHj)×FEk×(1-δn)横向框架顶点位移计算层数HiGiGiHiGiHi/ΣGjHjFiVi518.86973.3213107.620.25744.1744.1415.210003.28152349.950.29863.21607.3311.610410.73121076.790.23684.622

8、91.928.0310410.7383598.160.17501.02797.914.4310170.2045053.990.08238.13036.0剪力分布图：4.3.4.验算框架层间弹性位移角1.层数层间剪力ＶI(