Title:
Concurrent fire dynamic models and thermomechanical analysis of steel and concrete structures

dc.contributor.advisor Haj-Ali, Rami M.
dc.contributor.author Choi, Joonho en_US
dc.contributor.department Civil and Environmental Engineering en_US
dc.date.accessioned 2009-01-22T15:56:20Z
dc.date.available 2009-01-22T15:56:20Z
dc.date.issued 2008-10-21 en_US
dc.description.abstract The objective of this study is to formulate a general 3D material-structural analysis framework for the thermomechanical behavior of steel-concrete structures in a fire environment. The proposed analysis framework consists of three modeling parts: fire dynamics simulation, heat transfer analysis, and a thermomechanical stress analysis of the structure. The first modeling part consists of applying the NIST (National Institute of Standards and Technology) fire dynamics simulator (FDS) where coupled Computational Fluid Dynamics (CFD) with thermodynamics are combined to model the fire progression within the steel-concrete structure. The goal is to generate the spatial-temporal (ST) solution variables (temperature, heat flux) on the surfaces of the structure. The FDS-ST solutions are generated in a discrete numerical form. Continuous FDS-ST approximations are then developed to represent the temperature or heat-flux at any given time or point within the structure. An extensive numerical study is carried out to examine the best ST approximation functions that strike a balance between accuracy and simplicity. The second modeling part consists of a finite-element (FE) transient heat analysis of the structure using the continuous FDS-ST surface variables as prescribed thermal boundary conditions. The third modeling part is a thermomechanical FE structural analysis using both nonlinear material and geometry. The temperature history from the second modeling part is used at all nodal points. The ABAQUS FE code is used with newly developed external user subroutines for the second and third simulation parts. The main objective is to describe the nonlinear temperature-dependency of the specific heat of concrete materials, especially high-strength concretes, that drastically affects their transient thermal solution. New algorithms are also developed to apply the continuous FDS-ST surface nodal boundary conditions in the transient heat FE analysis. The proposed modeling framework is applied to predict the temperature and deflection of the well-documented Cardington fire tests and to predict the time-to-collapse of the recent Oakland bridge fire caused by a fuel-truck accident. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/26679
dc.publisher Georgia Institute of Technology en_US
dc.subject Fire dynamic simulation en_US
dc.subject High temperature en_US
dc.subject Finite element analysis en_US
dc.subject.lcsh Fires Mathematical models
dc.subject.lcsh Enclosure fires
dc.subject.lcsh Flame spread
dc.subject.lcsh Steel, Structural
dc.subject.lcsh Reinforced concrete construction
dc.title Concurrent fire dynamic models and thermomechanical analysis of steel and concrete structures en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename School of Civil and Environmental Engineering
local.contributor.corporatename College of Engineering
relation.isOrgUnitOfPublication 88639fad-d3ae-4867-9e7a-7c9e6d2ecc7c
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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