Experimental and numerical investigation on axial compressive behavior of HP-FSST columns

Abstract

To promote sustainable utilization of phosphogypsum (PG) solid waste, this study proposes a novel high-strength PG-filled circular stainless steel tubular column (HP-FSST). A comprehensive experimental and numerical investigation was conducted, including axial compression tests performed on three hollow circular stainless steel (CHS) tubes and nine HP-FSST specimens with varying levels of PG compressive strength (f_c) and steel tube wall thicknesses (t). Corresponding finite element (FE) models were developed and validated using ABAQUS, enabling parametric analysis of size effects.The results indicate that HP-FSST columns exhibit favorable composite action, with the PG infill effectively restraining local buckling of the steel tube. Failure modes closely resemble those of traditional concrete-filled steel tube (CFST) columns, primarily characterized by bulging and diagonal shear. The strength index (SI) ranged from 1.45 to 1.70, and the PG contribution ratio (PCR) from 2.09 to 7.61. However, the ductility was lower than that of CFST columns, with residual-to-peak load ratio (RR) between 0.6 and 0.9.The FE analysis demonstrated notable size effects on peak axial stress, while peak strain and the composite elastic modulus were less sensitive. Based on GB 50936–2014 and EN 1994-1-1, modified design equations incorporating size-effect correction factors were proposed, achieving high prediction accuracy (mean values of 1.00 and 0.99; standard deviations of 0.033 and 0.028). This study presents a promising approach for PG waste utilization and provides a theoretical basis for the engineering design of HP-FSST columns.