Inelastic Buckling of Reinforcing Bars

Abstract

Predicting behavior of concrete members subjected to large inelastic deformations caused by extreme loads, such as earthquakes, plays an important role in assessing stable deformation capacities of concrete structures. An objective of the research is to contribute to the development of a constitutive relationship that predicts the behavior of reinforcing bars under compression given the geometric and material properties. By developing a constitutive relationship for the reinforcing bars under compression, conventional sectional analyses can be extended to incorporate the buckling of longitudinal reinforcement. This will enable an engineer to evaluate the pre- and postbuckling behavior of reinforcing bars under compression given the material properties and geometric nature of the problem, and hence evaluate the impact of the rebar buckling on the deformation capacity of reinforced concrete members at plastic hinges. This paper presents results from an experimental program for bar buckling in which a total of 162 reinforcing bar specimens were tested under monotonic compression loads. In addition, a simple analytical model that can be incorporated in the conventional section analysis is presented.