Dynamic behavior of CHS-SHS tubular T-joints subjected to low-velocity impact loading

摘要

Welded steel tubular structures are easily exposed to impact loading which may cause devastated damage firstly to their connecting joints. The critical joints determine the dynamic mechanical performance of the structures in those unexpected catastrophes. This paper describes an experimental and numerical impact investigation on dynamic behavior of CHS-SHS tubular T-joints, made up of a circular hollow section (CHS) brace and a square hollow section (SHS) chord. Seven CHS-SHS tubular T-joint specimens with different geometric and loading properties were tested on an in-house dropped hammer testing machine. The deformation mode of the joint specimens was identified as outward buckling of the chord side walls and indentation of the chord top surface. The experimental results indicated that increasing the geometric parameter beta (the width ratio of the brace to chord) enhanced the impact resistance, increasing the impact velocity significantly affected the dynamic response, and changing the boundary condition had little effect on the dynamic performance of the joints. Six finite element (FE) models of the tested joint specimens were developed to simulate the dynamic behavior of the joints. The comparison of the impact force, displacement development, and deformation mode showed that the FE analysis was in good agreement with the experimental results. A parametric study was subsequently conducted to quantify the effects of the impact velocity, impact mass, and impact energy on the dynamic performance of the joints. The numerical results showed that the impact force, displacement, and energy dissipation were linearly dependent on the impact energy of the dropped hammer, and the impact duration of the impact process was directly correlated to the impact momentum.