Monotonic and cyclic loading models for panel zones in steel moment frames

Abstract

This paper presents the development of analytical models to predict the elastic and inelastic response of the panel zone portion of columns in steel moment resisting frames. In many practical cases, the panel zone can dominate the inelastic response of a moment frame, and accurate panel zone models are needed to realistically predict overall frame performance. Similar to previous models, the newly proposed models are based on the concept of representing the panel zone as a nonlinear rotational spring. These new models build on previously developed models, and introduce a number of features and refinements that show better correlation with available experimental data. The model for monotonic loading is based on quadri-linear panel zone moment–deformation relations. In this model, both bending and shear deformation modes are considered. The model proposed for cyclic loading is based on Dafalias' bounding surface theory combined with Cofie's rules for movement of the bound line. Additional modifications are suggested to the cyclic loading model to account for the influence of a composite floor slab on panel zone response. Extensive comparisons with experimental data are presented.