Realization of Strong Column-Weak Beam Failure Mode for Concrete-Filled Square Steel Tubular Frame Structure

Abstract

Strong column-weak beam failure mode is considered to be a preferable mode for its large capability to absorb earthquake energy and prevent collapse. However, for composite frames composed of steel-concrete composite beams and concrete-filled steel tubular (CFST) columns, strong column-weak beam design methods are not given in Chinese codes. The column-to-beam strength ratio is one of the most important factors that influence the failure mode of frame structures. Moreover, large axial compression ratio of columns may cut down the actual bending capacity of columns, and thus has an adverse effect upon the realization of strong column-weak beam failure mode. In order to investigate the influence of column-to-beam strength ratio and axial compression ratio on the failure mode of concrete-filled square steel tubular frame structures, pushover analysis of a five-story three-bay composite frames with various column-to-beam strength ratios and axial compression ratios are carried out. Based on the analysis results, suggestions about the reasonable value of column-to-beam strength ratio with different axial compression ratios of columns are given to ensure the realization of strong column-weak beam failure mode for concrete-filled square steel tubular frame structures.