Development of a reinforced concrete plastic hinge model

Abstract

To develop rational rules for seismic design, it is important that the inelastic behaviour of structures can be predicted with a sufficient degree of accuracy. Today, most structures situated in seismically active areas are designed to ensure a beam sway mechanism will develop in a severe seismic event. In New Zealand the most commonly used seismic design procedure is termed the Capacity Design Method. As the inelastic response of capacity designed structures is directly related to the behaviour of the plastic hinges that develop, a comprehensive understanding of these regions is essential. This thesis describes the development of a finite element sub-structure which simulates the observed behaviour of reinforced concrete beam plastic hinges. The physical behaviour of the materials and the mechanics which underlie the response of plastic hinges are investigated in detail. A sub-structure model which recognises the continuously varying stiffnesses and modes of deformation of beam plastic hinges is developed. The model is implemented into a nonlinear dynamic computer program which enables a variety of analysis types to be carried out on a diverse range of structures. When developing the model, emphasis was placed on minimising computational time and maintaining end user simplicity. Its performance was assessed by comparing the predicted and measured response of a number of reinforced concrete assemblages. The model is one of the most accurate, versatile analytical methods available for predicting the inelastic cyclic behaviour of reinforced concrete beam plastic hinges.