Fire Analysis of Steel Structures Considering The Heating and Cooling Processes
Date Issued
2011
Date
2011
Author(s)
Lee, Yi-Huei
Abstract
The objective of this thesis is to investigate the behavior of steel frames under the heating and cooling processes. In the past decades, steel has been wieldy used in civil engineering. Compared with other commonly used materials, the properties of steel, such as strength, drop rapidly with the increase in temperature. For example, when the temperature reaches 600 degrees Celsius, the ultimate strength of steel structures decreases drastically along with large deformation.
This thesis focuses on the analysis of the steel structural behavior in the heating and cooling stages using the finite element method. To simulate the softening behavior of steel structures in high temperatures, a nonlinear analysis theory incorporating the refined hinge concept and the reduction coefficients for steel defined by Eurocode 3 is presented. The governing equations for the beam element is derived by the updated Lagrangian formulation, in which the thermal stiffness matrix, thermal loads, and reduced member loads due to the temperature rise are derived by the variational method. Using the numerical method presented in this study, the nonlinear behavior of steel structures under the thermal change is studied considering various factors, such as the loading combination, the uniformity of temperature distribution, and the presence of geometrical imperfections. From the numerical results obtained, the effects of all these factors on the critical temperature and residual deformation of the structure undergoing the heating and cooling processes are evaluated.
Subjects
cooling
heating
nonlinear analysis
plastic hinge
steel structures
temperature
Type
thesis
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