抄録
One dimensional combined geometrically and materially nonlinear finite element method (PERT) has recently been refined to be FERT-P utilizing the incremental perturbation method (Refs. 5, 6). In this study, a general methodology and an associated computer system are developed for the dynamic analysis of nonlinear plane frames. A dynamic version of incremental perturbation method is developed to give a powerful tool for the solution of dynamic equations. It is observed that the proposed method for solving dynamic equations based on the incremental perturbation method has following advantages : (1) This method enables to assign the proper time increment automatically so that the calculation errors in each incremental step would fall within prescribed tolerance limits. (2) The elastic-plastic hysteresis path of each element can exactly be traced by this method, while it is inherently not possible by any other usual method. (3) The most significant part of computer operations is the product of inverse mass matrix and perturbation coefficient vector. It should be noted that the mass matrix is usually regular and constant so that the inverse operation need not be repeated. The above mentioned tool for dynamic analysis is implemented to FERT-P with slight modification to develop an accurate and effective dynamical analysis system FERT-PD. Through earthquake response analyses of portal frames, the computer system FERT-PD is verified against FERT-D which is the dynamic version of the FERT. The numerical integration method used in the FERT-D is the incremental averaged acceleration method. It can be concluded that the FERT-PD represents a reliable, highly accurate and efficient computer system for the dynamic analysis of combined nonlinear framed structures.
