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Title: Study of steel structural systems subjected to fire
Authors: Zhou, Mian
Advisors: Cardoso, R
Keywords: thermo-mechanical analysis;combined iso-kinematic hardening model;plasticity model;stainless structures in fire;structures in travelling fire
Issue Date: 2019
Publisher: Brunel university London
Abstract: Performance-based engineering design aims to improve codified, rule-based practice by allowing a more flexible, and performance focused approach. In structural fire design, it enables more complex fire loading scenarios to be considered, ranging from fire following earthquakes to a localised fire travelling through a large compartment space, or a combination of both. However, the tools used for performancebased structural fire design rely on accurate material models to capture the structural response to complicated fire loading. One critical limitation in the current generation of performance-based tools is that thermo-mechanical analysis with fire has been frequently performed using material models which do not take strain reversals into account. The assumption of “no strain reversals” in the building materials at elevated temperatures was established because the fire loading is traditionally simplified to a temperature time curve only considering heating stage, and the structural components are usually considered subjected to uniform heating. However this assumption is no longer valid when complex fire loading is applied. A new rate-independent combined isotropic-kinematic hardening plasticity model was developed in this research for the thermo-mechanical analysis of steel materials in fire. This model is capable of modelling: strain reversals, the Bauschinger effect with its associated transient hardening behaviour and material non-linearity at elevated temperatures. Its accuracy is demonstrated through five validation studies of the proposed material model against experimental data. The engineering value of the proposed material model is demonstrated in this work through three case studies. The new material model was adopted for: (1) evaluating the remaining structural fire resistance after a moderate earthquake, (2) investigating stainless steel structural systems in fire, and (3) studying the fire performance of a single steel beam subjected to travelling fires. These studies demonstrated that the new material model produces a more accurate analysis of the structural fire resistance than can be achieved using existing methods. This research proposes an improved computational tool for evaluating structural fire resistance of complex steel structures. It therefore represents a contribution to the improvement and adoption of performance-based engineering for structural fire design, and can be used for various engineering applications.
Description: This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London
Appears in Collections:Civil Engineering
Dept of Mechanical Aerospace and Civil Engineering Theses

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