Fire is a significant threat to the structural integrity of buildings. Depending on the architecture of the structure and the intensity and duration of the fire event, structural members may lose strength and stiffness eventually leading to collapse whether by flexural buckling or crushing. The focus of this research is on the behavior and fire performance of reinforced-concrete columns under fire conditions. In order to effectively study column performance with differing loading, aggregate and dimensional characteristics under varying time-temperature curves and fire exposures, a numerical model was constructed in Microsoft Excel. The spreadsheet model allowed for complete transparency of the calculations and provided a means to visualize the data in flexible ways. ANSYS and several published column furnace tests were used to benchmark the heat transfer and structural analysis portions of the model. One, three and four-sided fire exposures along with the ASTM E119 fire curve and a natural fire curve were used to study latent heating effects, increasing and decreasing eccentricities, moment magnification, and failure modes. Assessments of column structural capacity were performed in accordance with the provisions of ACI 318. The completed model served as an effective tool for the thesis and is available to help aid students and engineers investigate the design of reinforced concrete columns under fire conditions through integration the heat transfer analyses and the structural evaluations.

"As jurisdictions throughout the world progress toward performance based building codes, it is important that the proper tools be made available to the engineering profession in order that they may take full advantage of these new codes. There is currently a large body of work written on the subject of performance based or engineered structural fire safety. Unfortunately, most of this information is scattered throughout technical journals from different countries and organizations, and not easily accessible to the practicing engineer. Under the current prescriptive code regime there is generally no requirement to undertake an engineering approach to structural fire safety, since the required fire resistance ratings are prescribed and the fire resistance ratings of materials/assemblies are determined through standard tests. However, these methods have been shown to be both unnecessary and expensive in some cases. A method will be developed that can be used to determine required fire resistance ratings for fire exposed structural steel based on a realistic engineering approach. A procedure is summarized for calculating time-temperature curves from a real fire in a typical compartment. With this time-temperature relationship a realistic time to failure for structural steel members can be determined. The method is summarized. Comments regarding important considerations and a worked example are provided to demonstrate the utility of the method."

"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. "