Structural behaviour of Q355 and Q460 press-braked rectangular hollow section stub columns

As inspired by the concept of modular integrated construction, component-assembly-structure, it leads to a great opportunity to reassess the basic structural elements made by an uncommon manufacturing process. Rectangular hollow sections (RHS) can be fabricated by tip-to-tip welding two press-braked channels together to form an integrated cross-section. This unique technique gains more flexibilities and economic efficiencies regarding the setup of production equipment as compared to the mainstream manufacturing process. In this paper, a comprehensive investigation into press-braked RHSs comprising material tests, residual stress measurements, stub column tests, and numerical studies is presented. A total of 40 tensile coupons, 108 sectioned residual stress strips, 10 stub columns, and 290 numerical models were combined to investigate various characteristics of press-braked RHSs. Of the results observed, the strength enhancement of corner materials due to the cold-working can be conservatively captured by the predictive model from AISI S100-16. A simplified predictive residual stress pattern is proposed to represent residual stress distributions of press-braked RHSs. The applicability of Eurocode 3, ANSI/AISC 360-16, and the direct strength method (DSM) for the design of press-braked RHS stub columns under compression was evaluated based on the experimental and numerical results. And modified design approaches were also proposed and shown to have a more accurate, consistent, and safe prediction of compressive resistance for press-braked RHSs.