门式刚架受到质块撞击时弹塑性动态响应的近似分析

本文报道一种求解门式刚架在冲击载荷作用下动态弹塑性大变形响应的简便分析方法。考虑到精确测量接触力的困难知问题的一般性,将冲击物与结构看作一个整体系统。当响应处于弹性时系统比拟一“弹黄-质点”系;当刚架冲击点及二结点处出现全塑性截面时,认为塑性变形起主导作用,而将刚架的变形以一单自由度刚塑性模态的运动表示。最后应用弹性与塑性分离的思想,以即时速率计入应变率效应,获得了刚架跨中受到质块冲击时响应全过程的解析解。本文解答与实测曲线及SEP解答进行了比较,符合很好。

Simplified Analysis on Elasto-plastic Dynamic Response of Portal Frame Impacted by Mass Block

A simplified analytical method for the elasto-plastic dynamic large deflection response of portal frames under impact loading is reported in this paper.In view of the difficulty in accurate measurement of contacting force and the generality of the problem, we consider impacting object and impacted structure a whole system, and the system is compared to a 'string-mass'mechnism when the response is in elastic stage; however, after the impacted position and the two joints of the frame become wholly plastic, the deforming of the frame is represented by a single-freedomdegree rigid-plastic mode,as plastic deformation play a principal part in the response of that s tage.Analytical solution of the entire response for a portal frame impacted at its midspan by a mass block is attained in terms of the concept of the separation of elasticity and plasticity, in which strain rate effect is taken into account by relating it to instant velocity. Comparisions among analitical solutions and experimental results and SEP results show reasonably good agreement.