梁的剪力动力系数的确定

DETERMINATION OF SHEAR DYNAMIC FACTOR IN BEAMS

分别应用振型叠加法和非线性有限元方法,研究了线性和非线性条件下梁的剪力响应,给出了抗爆结构设计计算所需要的剪力动力系数。研究结果表明:(1)在突加三角形荷载作用下,正向剪力动力系数随荷载作用时间与基本周期比(td/T1)的增大而增大,负向剪力动力系数先随td/T1的增大而增大,在保持常值前随td/T1的增大而略有减小;而在升压平台型荷载作用下,正向剪力动力系数随荷载升压时间与基本周期比(tr/T1)的增大而减小。(2)正向和负向剪力动力系数都随厚跨比(h/l)的增大而增大。(3)当梁进入塑性响应阶段后,随着延性比的增大,与弹性响应相比支座剪力逐渐减小;剪力的降低幅度随荷载作用时间(td)或升压时间(tr)的增大而减小。

In this paper, the shear of beams in elastic and elastic-plastic responses is investigated by analytical method and nonlinear finite element method, respectively. A shear dynamic factor, which is one of important parameters in the design of blast-resistant structures, is introduced. It is demonstrated that （1） Under the triangle load with zero rise time, the positive shear dynamic factor increases with the increase the ratio of duration of the load to the first natural period, td/T1. The negative shear dynamic factor increases with the increase of td/T1 first and then decreases slightly. Under the ramp load, the positive shear dynamic factor decreases with the increase of the ratio of load rise time to the first natural period, td/T1. （2） The positive and negative shear dynamic factors increase with the increase of height to length ratio of beams. （3） When entering into the plastic response, the shears at the end of beams decrease comparing with the elastic response. The longer the duration or load rise time, the more decrease of the shears.