טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentRatner Evgeniy
SubjectFire Behavior of Conventional Steel Structures and with
Concrete Cores - Comparative Study
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Rachel Becker


Abstract

During fire, buildings' structural elements warm up. Structural steel components warm up especially fast, due to their large thermal conductivity, small specific heat, small thermal mass, and thin sections. While heating up, mechanical properties of steel decrease. Stress redistribution processes, generated by changes in elasticity modulus, as well as thermal expansion of heated elements, affect structural behavior. Severe damage, up to the total structural failure, may occur due to the combined processes.

This research is dedicated to a comparative fire behavior study of steel structures with and without concrete cores. The research is based on a numerical analysis of a model-building. It addresses behavior of individual structural elements subject to heating, then simple frames, and finally more complex frames, representing the behavior of the entire building under the influence of various heating scenarios. Mechanisms of failure are analyzed and discussed.

Based on the set of results, some generalized conclusions were drawn on the following themes: Dependence of a structural element's fire resistance on the restraints imposed on it by the rest of the structure during the element's thermal expansion; Effect of fire exposure of a certain structural element on the change in internal forces in other elements of the frame; Influence of the fire scenario (the composition and sequence of heated up elements) on structural behavior and on the failure mechanisms for the various model structural schemes; and effect of the presence of rigid structural elements (such as the concrete core) on the fire resistance of the steel structure.