Experimental investigation on fire resistance of sandwich composite walls with truss connectors

Abstract

The sandwich composite wall with truss connectors is a new type of double-steel-plate composite wall, which consists of two external steel plates, square steel tubes at both ends, and in-fill concrete. The external steel plates are constrained by the steel trusses, thereby possessing superior mechanical performance. In order to study the fire resistance of the sandwich composite wall, 4 full-scaled walls were tested under one-side ISO-834 standard fire, aiming to investigate the effects of axial compression ratio, truss spacing to thickness ratio, and steel plate thickness on the fire resistance of the walls. The temperature, axial displacement and transverse displacement of key parts of the walls were measured. Experimental results indicate that, the walls could maintain sufficient load-bearing capacity as specified by the Class I fire resistance rating of Chinese Code. The fire endurance of the wall was controlled by its thermal insulation. The deformation pattern of the walls under the fire was overall deflection toward the unexposed surface, and the steel plate exposed to the fire experienced obvious local buckling. The axial compression ratio and the truss spacing to thickness ratio had great effects on the deformation behavior of the walls. When the axial compression ratio was reduced from 0.5 to 0.3, the axial deformation of the wall was changed from compression-predominant to expansion-predominant deformation. A larger truss spacing to thickness ratio led to more obvious buckling of the steel plate exposed to the fire. It is recommended to restrict the truss spacing to thickness ratio of the wall in engineering design.