Fire resistance of concrete-filled steel plate composite (CFSPC) walls

Concrete-filled steel plate composite walls (CFSPC walls) have recently emerged as promising alternatives to conventional reinforcement concrete shear walls due to the benefits of effective space use, less construction time/effort, and higher ductility. While the basic load carrying capacity and seismic performance of CFSPC walls have been receiving great attention, little work has been conducted so far on their fire performance. This paper aims to bridge the knowledge gap by performing 12 fire tests on CFSPC walls, where shear stud spacing, wall height, wall thickness, steel ratio, and fire scenario (uniform or single-sided fire) were considered as the main test parameters. For the uniform fire tests, the specimens exhibited reasonably good fire resistance, where the fire resistance time exceeded 2 h. Three dominating failure modes were observed, namely, local buckling of steel plates (LB), severe cracking ('tearing') of the weld along the corner line of the wall (WC), and global instability (GI). For the specimens subjected to single-sided fire, minor local buckling of the heated steel plate accompanied by tie bar failure in the buckled areas were observed, but no further load bearing failure was induced by the end of the heating process. The fire resistance time, which exceeded 2.5 h for the specimens exposed to single-sided fire, was governed by the 'thermal insulation criterion'. After 2.5 h of heating, some specimens lost their thermal insulation capacity. Based on the test phenomena, preliminary design recommendations are proposed, and future research directions are also outlined.