Evaluating Shear Response of UHPC Bridge Girders Exposed to Fire

The use of advanced materials, such as ultra-high-performance concrete (UHPC), and slender cross-sectional shapes in bridge girders can result in high susceptibility to shear failure during fire exposure. Shear limit state is usually not considered in fire design, which can be a major risk for I-shaped girders with slender webs. This paper presents the development of an approach to evaluate the shear capacity of UHPC bridge girders during fire through extension of room temperature capacity equations to elevated temperatures. Four types of standard AASHTO concrete bridge girders are analyzed under both standard and hydrocarbon fire scenarios. The output results are utilized to evaluate the progression of temperatures and deflections throughout fire exposure, as well as estimate degradation in flexural and shear capacities. Results show that the fire resistance of UHPC bridge girders are significantly affected by fire severity and concrete mass and that these factors should be taken into consideration in fire design of UHPC bridge girders.