Posttensioned Concrete Bridge Beams Exposed to Hydrocarbon Fire

Abstract

This paper presents the experimental and numerical investigations of two types of bonded posttensioned concrete bridge beams under hydrocarbon fire, including the box and tee beams. The factors considered included the load level and fire exposure duration. Six specimens were tested. The surface temperatures, strand temperatures, and midspan deflection of specimens were measured. Results showed that the box beam under service load could sustain fire for 184 min, while the tee beam could only endure for 105 min before collapse. The overloaded box beam could withstand fire for around 165 min. For exposure to fire for 90 min followed by cooling down to ambient temperature, the box and tee beams lost 11% and 38% of load-carrying capacity, respectively. Postfire observation also showed severe spalling at the midspan and support regions of the specimens. The test results were also used to validate the finite element models established for predicting the thermal and structural responses of the bridge beams under hydrocarbon fire.