水平地震作用下框筒结构的剪力滞后效应

Shear Lag Effect of Framed Tube Structure under Horizontal Seismic Action

将框筒结构等效为实腹筒,假定筒体翼缘和腹板的纵向翘曲位移函数,利用能量变分原理推导出结构在水平地震作用下的振动微分控制方程,以及静力作用下的微分控制方程,并结合边界条件对其进行求解。通过对振动方程的退化求解,定义了框筒的动剪力滞后系数。随后通过算例分析得出了如下结论:算例结果验证了翘曲位移函数及计算方法的准确性;水平地震作用下,即使地震动幅值不大,框筒结构也会出现明显的剪力滞后效应,且剪力滞后效应随高度的变化规律与静力作用下相同;当地震动频率接近共振频率时,结构剪力滞后效应加重,且角柱轴力幅值很大;框筒高宽比增大可以改善结构的动剪力滞后程度,但也会增大结构的内力,故控制合适的高宽比对结构具有重要意义。

The framed tube structure is equivalent to the solid cylinder, and the longitudinal warping displacement function of the flange and the web is assumed. The governing vibrational differential equations of the structure under the action of horizontal seismic action are deduced by energy variation princip＇- ; the ,,o- -：ning differential equations under the static action are deduced, and the boundary conditions are solved. Through the solution of the vibration e- quation, the dynamic shear lag coefficient of the framed tube is defined. Then the following conclusions are obtained through an example ： the results of the example verify the accuracy of the warping displacement function and the cal- culation method ; under the action of horizontal seismic action, even if the amplitude of ground motion is not large, the shear lag effect will appear obviously in the framed tube structure, and the shear lag effect will be the same as the static effect; when the local vibration frequency is close to the resonant frequency, the structural shear lag effect is aggravated, and the angular force of the corner column is large ; the increase of the aspect ratio of the framed tube can improve the dynamic shear lag of the structure, but also increase the internal force of the structure, therefore, it is important to control the proper aspect ratio to the structure.