Feasibility of dimensionally reduced heat transfer analysis for structural members subjected to localised fire

Abstract

Considerable attention has been placed on the localised fire action in the structural fire safety engineering community. Localised fire action can be represented by a linear or exponential correlation between incident heat flux and radial distance. Society of Fire Protection Engineers proposes an exponential curve suitable for low fire load. Eurocode 1 suggests a combination of linear and exponential curves, which is suitable for high fire loads. This article discusses the feasibility of dimensional reduction for heat transfer analysis in structures subjected to realistic fires. The work has been presented to accurately estimate the error introduced by dimensional reduction under highly varying localised heat flux representative of the most non-uniform fire conditions in a building compartment. It is shown that beams and slabs can be adequately modelled with lower dimensional heat transfer analysis for most of the localised fire action.

Modelling concrete slabs subjected to localised fire action with OpenSees

“…For concrete slabs under the most common standard uniform heating scenarios, one-dimensional heat transfer analysis is often sufficient to produce an accurate temperature history for thermo-mechanical analysis. For localised heating regimens, a series of one-dimensional heat transfer analyses would likely produce a sufficiently detailed temperature history map for structural analysis, as was shown in Jiang et al. (2018).…”

Integrated nonlinear structural simulation of composite buildings in fire

“…Substituting a series of 2D HT analyses for 3D HT analyses to map gas phase temperatures from FDS to solid phase temperatures in the structural elements reduces the computational load considerably while maintaining a good level of accuracy [36]. In large or complex models, the number of required thermocouples and corresponding HT analyses can number in the thousands which then once again increases the computational cost.…”

“…Similar to thermomechanical analysis within OpenSees, the HT module takes in a script that defines the problem and outputs the results as text files. Since the initial work on the HT module presented in [15] and in [36], several new material definitions were added to the HT module particularly for thermal insulation.…”

The Collapse of World Trade Center 7: Revisited

“…OpenSees has been extensively developed and validated as a powerful open-source tool for modelling structures in fire [31][32][33][34][35][36][37][38][39]. It has also been used as the heat transfer and structural analysis solution engine of the Integrated Simulation Environment (ISE).…”

“…The temperature-dependent mechanical and thermal properties are based on the provisions of the Eurocodes such as the EN1993 and EN1992 [50,51]. Details of the implementation of the mechanical models are presented in depth in [33,36,40] while the details of the thermal material models are discussed in [35,52]. The details of the heat transfer analysis undertaken within the ISE are the same as that presented in [40].…”