Inelastic Cyclic Response of Restrained Imperfect Columns

Abstract

The hysteretic behavior of a prismatic column subjected to cyclic loading is examined herein. An analytical model is described that includes two types of imperfections: (1) An initial out‐of‐straightness of the column and (2) an initial eccentricity of the applied axial loading and also the effect of end restraints. The analysis is based on the plastic‐hinge concept and takes into consideration the theory of plastic flow in the vicinity of plastic hinges. The effect of end connections is modeled by a combination of elastic rotational springs and connection segments of various flexural strength with the fully plastic moment modified due to axial load. A closed‐form solution is obtained using any type of cross‐sectional shape by employing a piecewise linear approximation to the analytical expression of the interaction curve. Results are presented that illustrate the imperfection sensitivity of restrained columns under cyclic inelastic loading. The effect of various initial imperfection sizes and degrees of fixity of the columns are also considered.