Non-linear structural analysis in performance based fire - integration of design programs
Lehtimäki, Eki Matias
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Epälineaarinen rakenneanalyysi toiminnallisessa palossa - suunnitteluohjelmien yhteensovittaminen
The design of structures in fire has traditionally been based on ISO standard curves. For more accurate design, methods that simulate the real fires possible for the building in case should be preferred. Natural fire design concept is a collection of this kind of methods presented in literature and used in real construction projects. Natural Fire Design environment (NFD-environment) is a "software toolbox" aimed to integrate computer programs needed for performance-based structural fire safety engineering into one design environment easily accessible for structural engineer using natural fire design methods in real projects. NFD-environment has been developed in co-operation of Ruukki and Tampere University of Technology. Purpose of this master's thesis project was to extend non-linear structural finite element analysis capabilities of the environment by integrating structural analysis software Vulcan into it. Analysing structure with linear finite element method and then reducing the resistance of members and joints according to the temperature reached in fire is a sufficient method, when structure is statically determined. For statically undetermined structures, non-linear finite element analysis is needed. Vulcan, being a special software to analyse structures in fire, is suitable for this kind of analysis. It could be integrated in the design environment by programming data transfer links with the building information modelling software and fire dynamics simulation software used in the NFD-environment. Additional development was made also by creating algorithms to linearise and group temperature curves in order to speed up calculation time. The key result of this thesis is a more advanced planning environment for structures in natural fire. Non-linear finite element analysis makes calculation of statically undetermined structures accurate, and temperature curve processing reduces the calculation time cost of non-linear analysis.