Reliability-Based Design Analysis of Square Recycled Aggregate Concrete-Filled Steel Tubular Stub Columns under Axial Compression

Recycled aggregate concrete-filled steel tubular (RACFST) columns can effectively improve the inferior mechanical properties of recycled aggregate concrete (RAC), which is a promising and efficient structural member. To ensure structural safety, it is crucial to examine the reliability of RACFST columns. In this study, a reliability-based design analysis for square RACFST stub columns under axial compression was performed. First, the accuracy and applicability of existing design specification models were evaluated using a comprehensive experimental database with 107 square RACFST stub columns. Then, the uncertainties in calculation models, material properties, geometric parameters, and loads were identified, and a design space of 1,872 square RACFST stub columns covering a wide range of design cases was constructed by considering various stochastic factors. Subsequently, the reliability was analyzed based on the Monte Carlo simulation method. It was revealed that the reliability indices of the square RACFST stub columns designed using the existing design factors were not consistent with the target reliability indices, indicating an unbalanced design between structural safety and economic efficiency. To this end, a combined partial factor (γcs) was further proposed and calibrated for the design of axially loaded square RACFST stub columns. This work offers a theoretical basis for the safe and reasonable design of RACFST structures.