Design of concrete-filled stainless steel tubular connections

A numerical study was performed on concrete-filled stainless steel tubular T- and X-joints using finite element analysis. The specimens were fabricated from square and rectangular hollow sections (SHS and RHS) with concrete-filled in the chord members. The geometric and material nonlinearities of stainless steel tubes as well as the concrete infill were carefully incorporated in the finite element models. The nominal compressive concrete strengths were ranged from 30 to 110 MPa. The numerical results showed good agreement with the experimental results for the concrete-filled stainless steel SHS and RHS tubular T- and X-joints. Therefore, an extensive parametric study was performed using the verified finite element models to investigate the strength and behaviour of concrete-filled stainless steel tubular connections. The joint strengths obtained from the parametric study and tests were compared with the current design strengths calculated using the CIDECT design rules for concrete-filled carbon steel tubular joints, which is the only existing design guideline for concrete-filled tubular joints. It should be noted that the current CIDECT design rules ignore the contribution of the steel tubes in the calculation of the joint strengths. In this study, design formulae of concrete-filled stainless steel tubular T- and X-joints are proposed. The proposed design formulae include the contribution of the stainless steel tubes. A reliability analysis was performed to assess the reliability of the current and proposed design rules. It is shown that the design strengths calculated using the proposed equations are generally accurate and reliable.