Nonlinear dynamic analysis of frames with arbitrary plastic hinges

Abstract

This paper presents a method for nonlinear dynamic analysis of frames subjected to distributed loads, which is based on the semi-rigid technique and moving node strategy. The plastic hinge that accounts for the material nonlinearity is modelled as a pseudo-semi-rigid connection at the element end. The stiffness matrix of a frame member with material and geometric nonlinearities is expressed as the sum of products of the standard stiffness matrix and the geometric stiffness matrix of the member with their corresponding correction matrices. Each beam member is modelled by two elements. The moving node strategy is applied to the intermediate node to track the exact location of any intermediate plastic hinge that may be formed. The method presented is efficient in computation and it needs no additional connection elements. A portal frame and a five-storey frame are used to verify and illustrate the applicability of the method. © 2008 Taylor & Francis Group, London.