Fire resistance of reinforced SHS T-joints considering gradient temperature effect under post-earthquake fire

Abstract

The earthquake usually causes serious damage on the T-joints in structure, which may reduce its fire resistance. Moreover the gradient temperature distribution for reinforced SHS T-joints appears under a fire. Therefore it is very necessary to evaluate the fire resistance of reinforced SHS T-joint considering gradient temperature effect under post-earthquake fire (PEF). The objective of this paper is to investigate the fire resistance of earthquake-damaged doubler-plate reinforced SHS T-joints considering gradient temperature effect. A computation model was established and validated using the existing experimental results. The gradient-temperature field distribution against reinforced SHS T- joints was conducted by transient-response analysis method, then a parametric study was carried out using 30 established computation models involving following dimensionless parameters such as the width ratio of brace to chord (δ), diameter to thickness ratio of chord (ζ), wall thickness ratio of doubler-plate to chord (α), wall thickness ratio of brace to chord (ε), length ratio of doubler-plate to chord (ξ), ratio of chord length to chord width (φ), welding effect, damage variable (D~) and fire retardant coating thickness. The results demonstrated that damage variable and fire retardant coating thickness had a great influence on the fire resistance of doubler-plate reinforced SHS T-joints, the parameters δ, ζ and α had a major influence on reinforced SHS T-joints. The findings can provide data support and theoretical reference for the design, maintenance and reinforcement of such joints.