Jin Qiu

Timber buildings have been preferred in many regions for the sustainable nature of timber material. Although engineered timber products become promising alternates to traditional construction materials, the fire safety of timber buildings remains a key barrier to wider use. Currently, the design of timber structures mostly adopts the Eurocode 5 approach, which estimates the heat transfer or char depth under the premise of standard fire exposure. To investigate the behaviour of timber structural members in the context of realistic fire action in compartments, appropriate models for different stages of numerical simulation are needed. A series of development have now been conducted in the open‐source platform OpenSees, which enables modelling the heat transfer of timber sections in non‐standard fire scenarios and thermo‐mechanical analysis model using either beam elements or shell elements for various timber structural members. Corresponding thermal actions are developed to deal with timber slabs in fire or timber beams subjected to three‐side fire exposure. Tests on cross‐laminated timber beams at ambient temperature and under fire exposure are modelled to validate the developed capabilities, which is followed by modelling a glued laminated timber beam heated by furnace. In the end, a timber‐concrete composite slab is modelled using the fire impact from a Computational Fluid Dynamics model, which demonstrates the current vision of modelling timber structures in fire and OpenSees for fire is committed to providing such an open‐source research platform to support further modelling work.

Purpose: Reinforced concrete slabs in fire have been heavily studied over the last three decades. However, most experimental and numerical work focuses on long-duration uniform exposure to standard fire. Considerably less effort has been put into investigating the response to localised fires that result in planarly non-uniform temperature distribution in the exposed elements.Design/methodology/approach: In this paper, the OpenSees for Fire framework for modelling slabs under non-uniform fire exposure is presented, verified against numerical predictions by Abaqus and then validated against experimental tests. The thermal wrapper developed within OpenSees for Fire is then utilised to apply localised fire exposure to the validated slab models using the parameters of an experimentally observed localised fire. The effect of the smoke layer is also considered in this model and shown to significantly contribute to the thermal and thus thermo-mechanical response of slabs. Finally, the effect of localised fire heat release rate (HRR) and boundary conditions are studied.Findings: The analysis showed that boundary conditions are very important for the response of slabs subject to localised fire, and expansive strains may be accommodated as deflections without severely damaging the slab by considering the lateral restraint.Originality/value: This work demonstrates the capabilities of OpenSees for Fire in modelling structural behaviours subjected to non-uniform fire conditions and investigates the damage pattens of flat slabs exposed to localised fires. It is an advancing step towards understanding structural responses to realistic fires.