Influence of H-column stiffness on the anti-collapse performance of composite frame in the minor-axis direction

Abstract

This study is the first attempt to investigate the resistance mechanism in the minor axis of H-columns and aims to provide essential information for improving the reliability of the anti-collapse transmission path of spatial structures. A one-third scale composite frame extending in the minor-axis direction of the H-column, comprising a welded flange and bolted web beam–beam connection, was investigated through monotonic static loading test to clarify the resistance transmission mechanism of structures. Based on the progress in the internal force under different displacements, the minor-axis specimen experienced stages of elasticity, compression arch, and mixed mechanism. The influence of column stiffness on the resistance and internal force development in the minor-axis specimen was comparatively significant with respect to the results of the major-axis specimen. For parametric analysis, a full-scale model was developed, which confirmed the influence of column stiffness and boundary axial restraint stiffness on collapse performance of composite frames in the minor-axis direction, providing an underlying mechanism for anti-collapse design and optimization research. Furthermore, a multispan solid model was developed to reflect the attenuation law of the axial restraint stiffness provided by the external substructure (surroundings) with the appropriate number of spans, which assisted in formulating a simplified modeling process. To avoid or delay the negative impact of potential defects on the structure, local weakening strategies were applied to the minor-axis direction based on the experimental and simulation results, and the collapse resistance mechanism was verified using the developed model.