Post-earthquake fire behaviour of steel-to-concrete joints using post-installed anchorages

Abstract

Post-installed anchors have gained widespread application for connecting new structural steel components to existing concrete structures. However, knowledge about these anchor systems in hazardous conditions such as a post-earthquake fire (PEF) is very limited. An experimental and numerical investigation into steel-to-concrete connections using retrofitted anchorages subjected to a PEF was thus carried out. To explore the influence of different seismic damage levels, two cyclic loading protocols were adopted in pre-damage tests. Numerical analysis indicated there was a sharp reduction in residual strength after the bonded-in part of the anchor yielded. A damage-index-dependent prediction method of residual strength was developed based on the simulation results. In the subsequent fire test, three specimens were heated for 2 h in a furnace and then cooled to room temperature. The maximum temperature of the bonded-in anchor was 172°C while the peak furnace temperature was 588°C. The simulation results of thermal analysis exhibited a clear temperature gradient along the length of the anchor. Finally, a monotonic test with increasing load up to failure after fire exposure was carried out. The results showed that ductile steel failure of the anchor system could be achieved even under a PEF scenario.