Mechanical properties of π-shaped joints of flat concrete-filled steel tubular column

Abstract

A flat concrete-filled steel tubular column (FCFST) is a concrete-filled steel tubular column (CFST) with a section length-width ratio greater than or equal to two. In this study, the vertical stiffener joint was appropriately modified, and a new type of rigid joint suitable for the width-side direction (weak axis direction) of the FCFST and H-beam was proposed. Four specimens were designed for pseudo-static experiments, and Abaqus was used to establish finite element models (FEM) to provide a supplementary calculation. The results showed that the π-shaped joints had a clear load path, sufficient energy consumption, and good seismic performance. When the beams were eccentrically arranged, the stiffness and ultimate strength of the joints were improved, whereas the ductility was reduced. Subsequently, a parameterized analysis was performed for the π-shaped joint of the FCFST. It was determined that the thickness of the π-shaped part, length of the corbel, thickness of the steel tube, and width of the FCFST have prominent influences on the stiffness and ultimate strength of the joint. Finally, a calculation formula was derived for the joint based on the yield-line theory. The calculation results of the formula were compared with the experimental results. These errors were found to be acceptable, confirming that this approach can be used in actual projects.