Thermo-mechanical behavior of Glulam beam-to-girder assemblies with steel doweled connections before, during and after fire

Abstract

PurposeThe purpose of this paper is to investigate the thermo-mechanical behavior of intermediate-size glued-laminated beam-to-girder assemblies connected with T-shaped slotted-in steel doweled connections at ambient temperature (AT), after and during non-standard fire exposure.Design/methodology/approachAT tests were performed using a universal testing machine (UTM) to evaluate the load-carrying capacity and failure modes of the assembly at room temperature. Post-fire-performance (PFP) tests were conducted to study the impact of 30-min and 60-min partial exposure to a non-standard fire on the residual strength of the assemblies. The assemblies were subject to fire in a custom-designed frame, then cooled and loaded to failure in the UTM. A fire-performance test was conducted to investigate the fire-resistance during non-standard fire exposure by simultaneously applying fire and mechanical load with the custom frame.FindingsAt AT, embedment failure of the dowels followed by brittle splitting failure were found to be the dominant failure modes in the beams. In the PFP tests, embedment failure and plastic bending of the dowels were the only observed failure modes. The residual strength of the assembly was reduced by 23.7% after 30-min and 47.8% after 60-min of fire exposure. Ductile embedment failure of the timber in contact with the dowels was the only failure mode observed during the fire-performance test, with the maximum rate of displacement at 57 min into the fire.Originality/valueData are presented for full-contact (no gap) connections in Glulam assemblies. PFP results are first to be published.