Structural behavior of FRP connector enabled precast geopolymer concrete sandwich panels subjected to one-side fire exposure

Precast concrete sandwich panel (PCSPs), consisting of two reinforced concrete (RC) wythes (i.e., interior and exterior), a core insulation layer and connectors, can help to improve the building energy efficiency. This study is concerned with the fire and post-fire residual performance of an innovative PCSP system, in which fiber-reinforced polymer (FRP) reinforced geopolymer concrete is used as the two wythes and FRP tubes are used as the connectors. Six PCSP specimens were fabricated and five of them were tested under one-side fire exposure. The experimental parameters included the concrete type (geopolymer and conventional concrete), the reinforcement type (basalt FRP reinforcement and steel reinforcement), the connector type (plate-type and hexagonal tubular type), and the RC wythe thickness. After the fire exposure, all the specimens were tested under concentric loading to evaluate their residual axial load capacity. In addition, numerical analysis was conducted to facilitate a better understanding on the experienced temperature field of the PCSPs. It was found that the PCSPs with geopolymer concrete exhibited a decrease of the axial load capacity by 88.5% after 4 h one-side fire exposure while they performed better than that with conventional concrete. Besides, the reinforcement type, RC wythe thickness and the connector type are key factors influencing the post-fire structural performance of the PCSPs.