Experimental investigation on flexural performance of T-joint concrete-filled steel tube with PBL

T-joint concrete filled-steel tube (CFST) members are widely used in many modern structures. The performance of T-joint CFST is studied as the brace is under axial compressive load and chord bends in this paper. A total of eight specimens were designed and manufactured, and FE models were built by ANSYS. The effect of different parameters, including the brace-chord width ratio, the brace-chord thickness ratio, the influence of the PBL, the thickness of the stiffener, the opening diameter and opening space of the PBL, the material strength, and the number and welding position of stiffeners, on the performance of T-joint CFST were investigated through experimental and numerical studies. A criterion for determining when the T-joint CFST with PBL reaches the ultimate bearing capacity is presented. The calculation method in this paper for ultimate moment capacity is derived based on the limit balance theory. The method considering the reinforcement of the brace on the upper flange of the chord, the confinement effect of the steel tube on concrete, and the plastic stress distribution of the steel tube is in better agreement with the test and FE analysis. The results show that the proposed method can well predict the ultimate moment capacity of T-joint CFST, while the method in DBJ is more conservative.

Automated summary

This paper investigates the performance of T-joint concrete filled-steel tube (CFST) members under axial compressive load and chord bends. Experimental and numerical studies were conducted to analyze the influence of various parameters on the performance of T-joint CFST. A criterion for determining the ultimate bearing capacity of T-joint CFST with PBL is presented. The proposed calculation method for ultimate moment capacity considers the reinforcement of the brace, the confinement effect of the steel tube on concrete, and the plastic stress distribution of the steel tube, showing better agreement with tests and FE analysis compared to the method in DBJ.