| In years precast/prestressed concrete (PPC) double T-beams have gained wide popularity in numerous building applications. Since structural fire safety is a high priority, building codes generally specify fire resistance requirements. The current approach for evaluating fire resistance of structural members, including those of PPC double T-beams, through prescriptive-based methods has numerous drawbacks. The guidelines are limited in scope and restrictive in application, since they were developed based on ASTM E-119 standard fire tests. Furthermore, these guidelines are only valid for a narrow range of beams and do not fully account for realistic fire, loading or restraint scenarios. To overcome these drawbacks, a performance-based methodology is applied to evaluate the fire resistance of PPC beams under realistic fire, loading, and restraint scenarios. SAFIR, a special-purpose finite element program, was used to carry a set of numerical analyses to study the effect of various factors governing the fire resistance of PPC double T-beams. In the analysis, high temperature material properties, various load and restraint levels, and material and geometric nonlinearity were accounted for. A realistic failure criterion was also included to determine failure. Results from the analysis indicate that fire scenario, load level, and failure criterion have significant influence on the fire resistance of PPC double T-beams. The steps involved in undertaking a performance-based fire approach are outlined. |
