10.2.3 自振圆频率与自振周期
列出特征值方程:?K???2?M??0;由此式利用MATLAB内置计算函数“eig” 计算得到结构自振圆频率为:?1?5.76rad/s;?2?17.33rad/s;?3?28.89rad/s;
?4?40.31rad/s;?5?51.35rad/s;?6?61.85rad/s;?7?71.58rad/s;?8?80.32rad/s;?9?88.04rad/s;?10?94.52rad/s;?11?99.63rad/s;?12?103.39rad/s;?13?105.68rad/s;?14?255.85rad/s;
由自振周期与自振频率的关系T?2??,可得结构的各阶自振周期分别为:
T1?1.090s;T2?0.363s;T3?0.217s;T4?0.156s;T5?0.122s;T6?0.102s;T7?0.088s;T8?0.078s;T9?0.071s;T10?0.066s;T11?0.063s;T12?0.061s;T13?0.059s;T14?0.025s;
10.2.4 振型
一般情况下,可取结构前2
3阶振型反应进行组合,由于结构基本周期
T1?1.090s<1.5s,可不必增加振型反应组合数,取结构前三振型分析。故将?1?5.76rad/s;
?2?17.33rad/s;?3?28.89rad/s带入式??K???i2?M????i???0?得前三阶振型为:
?0.107???0.29?8?0.439??0.214???0.59?3?0.866????????0.319???0.82?5?1.038???????0.420?0.9700.904???????0.516???1.01?2?0.502???????0.605?0.946?0.046??????????0.688????0.78??0??0.582???1??????; ; ?????; 230.763?0.531?0.946???????0.829???0.22?6??1.031???????3?0.884??0.10???0.811??0.930??0.42???0.354?1??????5?0.965??0.69??0.207??0.988??0.89??0.708?5??????????1???1???1????????结构前三阶振型图如下所示: 10.3 地震信息
结构处于7度地震设防区,地震加速度为0.1g,场地类别为Ⅱ类,设防地震分组为第一组,结构阻尼比为0.05,查“抗规2010”表5.1.4-1得水平地震影响系数最大值
?max?0.08,查表5.1.4-2得结构特征周期Tg?0.35s;
图10-2 地震影响系数曲线
由于结构阻尼比为0.05,故曲线阻尼调整系数?2?1.0,则地震影响系数?可由下式求得:
?Tg??0.35?由于T1?1.09s??Tg,5Tg?,故?1????max????0.08?0.0288;
T1.09???1??Tg??0.35?由于T2?0.363s??Tg,5Tg?,故?2????max????0.08?0.0793;
?0.363??T2??0.9?0.9由于T3?0.217s??0.1,Tg?,故?3??max?0.08; 10.4 振型参与系数
第j阶振型参与系数?j由式?j???M??1??m????????M?????m?TjiTi?1njjii?1nji算得,则有:
2ji?1???0.214?0.214?0.319?0.420?0.516?0.605?0.688?0.763?0.829??11000702?0.3192?0.4202?0.5162?0.6052?0.6882?0.7632?0.8292??11000700.1072?977374?0.8842?1092872??0.9302?0.9652?0.9882??1100568?12?10872700.107?977374?0.884?1092872??0.930?0.965?0.988??1100568?1?1087270?1.268;
?2??
?0.5932??0.593?0.825?0.970?1.012?0.946?0.780?0.531?0.226??11000702?0.8252?0.9702?1.0122?0.9462?0.7802?0.5312?0.2262??1100070222220.298?977374?0.103?1092872??0.421?0.695?0.895??1100568?1?1087270?0.298?977374?0.103?1092872??0.421?0.695?0.895??1100568?1?1087270
??0.412;?3???0.866?0.866?1.038?0.904?0.502?0.046?0.582?0.946?1.031??11000702?1.0382?0.9042?0.5022?0.0462?0.5822?0.9462?1.0312??11000700.4392?977374?0.8112?1092872??0.3542?0.2072?0.7082??1100568?12?10872700.439?977374?0.811?1092872???0.354?0.207?0.708??1100568?1?1087270
?0.240;10.5 各阶振型下各质点水平地震作用
由式Fji?Gi?j?j?ji得第j阶振型各质点水平地震作用; 10.5.1 第一阶振型各质点水平地震作用
F11?9773.74?0.0288?1.268?0.107?38.191kN; F12?11000.7?0.0288?1.268?0.214?85.969kN; F13?11000.7?0.0288?1.268?0.319?128.151kN; F14?11000.7?0.0288?1.268?0.420?168.725kN; F15?11000.7?0.0288?1.268?0.516?207.291kN; F16?11000.7?0.0288?1.268?0.605?243.045kN; F17?11000.7?0.0288?1.268?0.688?276.388kN; F18?11000.7?0.0288?1.268?0.763?306.518kN; F19?11000.7?0.0288?1.268?0.829?333.032kN; F110?10928.7?0.0288?1.268?0.884?352.803kN; F111?11005.68?0.0288?1.268?0.930?373.776kN; F112?11005.68?0.0288?1.268?0.965?387.842kN; F113?11005.68?0.0288?1.268?0.988?397.086kN; F114?10872.7?0.0288?1.268?1?397.054kN;
10.5.2 第二阶振型各质点水平地震作用
F21?9773.74?0.0793???0.412????0.298??95.158kN; F22?11000.7?0.0793???0.412????0.593??213.130kN;
F23?11000.7?0.0793???0.412????0.825??296.514kN; F24?11000.7?0.0793???0.412????0.970??348.628kN;
F25?11000.7?0.0793???0.412????1.012??363.723kN; F26?11000.7?0.0793???0.412????0.946??340.002kN; F27?11000.7?0.0793???0.412????0.780??280.340kN; F28?11000.7?0.0793???0.412????0.531??190.846kN; F29?11000.7?0.0793???0.412????0.226??81.226kN; F210?10928.7?0.0793???0.412??0.103??36.777kN; F211?11005.68?0.0793???0.412??0.421??151.380kN; F212?11005.68?0.0793???0.412??0.695??249.903kN; F213?11005.68?0.0793???0.412??0.895??321.818kN; F214?10872.7?0.0793???0.412??1??355.228kN;
10.5.3 第三阶振型各质点水平地震作用 F31?9773.74?0.08?0.24?0.439?82.381kN; F32?11000.7?0.08?0.24?0.866?182.911kN; F33?11000.7?0.08?0.24?1.038?219.239kN; F34?11000.7?0.08?0.24?0.904?190.936kN; F35?11000.7?0.08?0.24?0.502?106.029kN; F36?11000.7?0.08?0.24???0.046???9.715kN; F37?11000.7?0.08?0.24???0.582???122.926kN; F38?11000.7?0.08?0.24???0.946???199.808kN; F39?11000.7?0.08?0.24???1.031???217.761kN; F310?10928.7?0.08?0.24???0.811???170.172kN; F311?11005.68?0.08?0.24???0.354???74.803kN; F312?11005.68?0.08?0.24?0.207?43.741kN; F313?11005.68?0.08?0.24?0.708?149.606kN; F314?10872.7?0.08?0.24?1?208.755kN;
10.6 各阶振型水平地震作用产生的各质点水平剪力
由于结构各振型最大反应不在同一时刻发生,因此直接由各振型最大反应叠加估计体系最大反应,结果会偏大。通过随机振动理论分析,得出采用平方和开方的方法(SRSS
法)估计体系最大反应可获得较好的结果,即Vi??Vji2,计算过程详见下表:
表10-7 各阶振型水平地震作用产生的各质点水平剪力 水平地震作用Fji/kN 层号 第一阶 振型 14 13 12 11 10 9 8 7 6 5 4 3 2 1 397.054 397.086 387.842 373.776 352.803 333.032 306.518 276.388 243.045 207.291 168.725 128.151 85.969 38.191 第二阶 振型 -355.28 -321.818 -249.903 -151.380 -36.777 81.226 190.846 280.340 340.002 363.723 348.628 296.514 213.130 95.158 第三阶 振型 208.755 149.606 43.741 -74.803 -170.172 -217.761 -199.808 -122.926 -9.715 106.029 190.936 219.239 182.911 82.381 水平剪力Vji/kN 第一阶 振型 397.054 794.140 1181.982 1555.758 1908.561 2241.593 2548.111 2824.499 3067.544 3274.835 3443.560 3571.711 3657.680 3695.871 第二阶 振型 -355.28 -677.098 -927.001 -1078.381 -1115.158 -1033.932 -843.086 -562.746 -222.744 140.979 489.607 786.121 999.251 1094.409 第三阶 振型 208.755 358.361 402.102 327.299 157.127 -60.634 -260.442 -383.368 -393.083 -287.054 -96.118 123.121 306.032 388.413 振型组合后各层最大剪力Vi/kN 572.2363212 1103.42315 1555.023576 1921.044812 2216.048589 2469.297682 2696.570731 2905.417128 3100.63789 3290.41325 3479.519961 3659.271031 3804.047992 3874.023511
第11章 竖向荷载
高层建筑的竖向荷载主要是结构自重(恒载)和使用荷载(活载)。在计算竖向荷载下产生的内力时,由于高层民用建筑楼面活载不大,一般可以不考虑活载的不利布置,可以按满布考虑。在活载较大时,把满载计算的梁跨中乘以1.1-1.2的放大系数。
取13轴线的一榀框架作为计算单元。
高层教学办公楼设计土木工程框架剪力墙毕业设计



