Study on post-fire resistance of ceramsite foamed concrete sandwich composite slabs

Abstract

The ceramsite foamed concrete sandwich composite slab has the characteristics of light weight and good heat insulation performance. At present, there are few research on the fire resistance of ceramsite foamed concrete sandwich composite slab at home and abroad, and the damage mechanism of ceramsite foamed concrete sandwich composite slab under fire is not clear. To fill this gap, constant load-temperature rise fire test and static loading test on five slab specimens are conducted by varying the parameters such as sandwich layer thickness, reinforcement pattern, shear span ratio and construction method. Based on the test, the results are studied, including the temperature distribution and deformation characteristics under fire, load–displacement curves, crack pattern and damage mode, residual bearing capacity of the slab after fire. The results show that ceramsite foamed concrete sandwich composite slab has good thermal insulation performance, the overall working performance, flexural bearing capacity and deformation ability of the slab is mainly affected by the slip at the composite surface. The integrity of the slab and the residual bearing capacity and ductility after fire could be significantly improved by the configuration of truss rebar. It is suggested to decrease the time difference of concrete placement at the composite surface or set shear keys and truss rebar to improve the cooperative working ability between the surface layer and the sandwich layer. Moreover, Finite Element analysis is carried out by ABAQUS software and the results show good agreement with experiment results. A new compositeness degree analysis (CDA) method for calculating the residual bearing capacity of ceramsite foamed concrete sandwich composite slab after fire considering different compositeness degree is proposed, which could be used for the practical engineering design.