An experimental and numerical investigation of concrete pry-out failure after fire exposure: Group effects and failure mechanism

Abstract

In the present study, the load-bearing capacity for concrete pry-out failure of the single stud anchor and multi-stud anchor groups after fire exposure is investigated experimentally and numerically. The main topic of the investigation is the influence of fire duration on the resistance and failure mode and the group effect on the load-bearing behaviour. The standard ISO 834 fire curve was employed. The numerical simulations were conducted using the thermo-mechanical model based on the microplane constitutive model for concrete, which was implemented into a 3D finite element (FE) code. The numerical model was first verified based on the performed experimental tests. Subsequently, the parametric study was performed in order to analyse the failure mechanism and the load distribution over the studs of the anchor group. It was shown that the employed numerical modelling technique can successfully predict the pry-out failure mode and the load-bearing behaviour of anchor groups after fire exposure. The results show that the group effect on the shear stiffness of anchors is strong at ambient temperature, but moderated after fire exposure. The group effect on the pry-out failure load of anchors, both before and after fire exposure, is significant. The evaluation of the load distribution at the interfaces between anchor and concrete contributes to a better understanding of the concrete pry-out failure mechanism before and after fire exposure.