Document Type thesis Author Name Arakelian, Andrea Katherine URN etd-122208-145717 Title Strength Analysis of Bolted Shear Connections Under Fire Conditions Using the Finite Element Approach Degree ME Department Civil & Environmental Engineering Advisors Leonard D. Albano, Advisor Robert W. Fitzgerald, Co-Advisor Keywords shear connections fire conditions finite element approach Date of Presentation/Defense 2008-12-09 Availability unrestricted
The fire resistance of structural building elements has become an increasing concern after the terrorist attacks on September 11th, 2001. This concern has pushed for changes in the building codes and standards to incorporate a performance-based approach to design. Performance-based design is a process where fire safety solutions are determined using a representation of the actual fire stages that may occur in a structure during a fire event.
The American Institute of Steel Construction (AISC) has added Appendix 4 in the Specification for Structural Steel Buildings to the current edition of the Steel Construction Manual to provide engineers with guidance in designing steel structures and components for fire conditions. The performance-based approach outlined in Appendix 4 is designed to prevent loss of life, structural collapse, and the outbreak of fires through elimination of ignition sources. Adopting this approach, requires structural engineers to have a better understanding of the behavior of steel connections under fire conditions as well as the tools, techniques and judgment for analysis.
The focus of this thesis is to study the strength behavior of steel connections under fire conditions with the assistance of the finite element software, ALGOR. Connections of varying thickness and bolt patterns are constructed using the ALGOR pre-processing software. A time-temperature fire curve is combined with external loads, applied to the models and then analyzed in the program. Stress-strain diagrams are created using the results and yield loads are determined for the various connections at normal and elevated temperatures. These yield loads are compared to values found from a mathematical analysis of the limit state equations in Chapter J of the Specifications. The elevated models are created with temperature-dependent material properties, therefore the yield loads are associated with critical temperatures within the connection models.
It is found that the capacity and governing temperature of the connections is determined by the limit state of bearing at the bolt hole. At elevated temperatures, the finite element analysis produces capacities significantly lower than the analysis at normal temperatures.
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