Effect of end restraint on the fire-resistance performance of hollow core concrete slabs

Abstract

Hollow core concrete slabs have been widely used in building construction due to key advantages in lighter weight, ease of installation and quality control of the fabrication process. However, the load-bearing capacity of hollow core concrete slabs tends to reduce dramatically in fire under elevated temperatures, leading to a structural collapse, depending on the installation details. A typical end detail for hollow core concrete slabs in practice is the slab-end beam connection in which the slab units are installed on cast-in-place supporting beams with embedded steel rebars to enhance the negative moment capacity at the support and an additional layer of concrete topping along with temperature steel. This installation induces the end restraint of hollow core concrete slabs at high temperature. The current study aims to investigate the effect of end restraint on the behavior of hollow core concrete slabs through a series of fire tests. Thirteen specimens were tested using ISO834 standard fire curve. The effect of three factors including heating duration, slab thickness and load ratio were examined for simply supported specimens. The behavior of hollow core concrete slabs with varying end details were compared in order to examine the effect of end restraint. Based on the test results, the end restraint provided by the slab-end beam connection and concrete topping significantly enhanced the fire-resistance performance of hollow core concrete slabs due to the axial restraint and the rotational restraint at the support.