Fire behaviour of GFRP-reinforced concrete slab strips. Effect of straight and 90° bent tension lap splices

Abstract

This paper presents results of fire resistance tests on concrete slab strips reinforced with ribbed glass fibre reinforced polymer (GFRP) bars, comprising continuous reinforcement or tension lap splices with different geometries (straight- and 90° bent-ends), overlap lengths and bar types. The type of reinforcement (material and surface finish), the rebar diameter and the concrete cover thickness were also assessed. It was shown that GFRP-reinforced concrete slabs with continuous reinforcement can endure over 180 min of fire exposure with considerably lower concrete covers than those currently recommended in design codes, provided that the rebars remain well-anchored in cool zones of the member. Slabs with straight-end splices failed due to debonding of the overlapped rebars after 19 to 39 min of fire exposure, depending on the type of bar and splice length. With 90° bent-end splices, the fire resistance significantly increased, up to 75 min, as they allowed anchoring the reinforcement in a cooler zone of the slab where bond was less degraded.