Performance of CFRP-Strengthened Concrete Bridge Girders under Combined Live Load and Hydrocarbon Fire

Highway bridges may encounter various extreme events during their design lives, and the effect of accidental, natural, or artificial fire on bridges is one of the least investigated hazard types. To bridge this knowledge gap, a full-scale one-span prestressed concrete composite bridge was tested under a combined hydrocarbon pool fire in an open environment and simulated AASHTO live load. This is believed to be the first testing of its kind in the world. The objective was to study the response of a concrete bridge superstructure, the carbon fiber-reinforced polymer (CFRP) strengthening, and associated fireproofing protection against the fire hazard. Unlike the standard fire tests, which are conducted in a controlled environment, the 60-min event resulted in fluctuating and high-intensity fire temperatures on the girders due to the prevailing wind. This characteristic showed that results from standard fire tests should not be used to justify the fire performance of concrete bridge components. Of the three tested girders, the girder with CFRP and no fireproofing sustained severe damage, indicating that the nation's concrete bridges with such girders are highly vulnerable and unprotected for extreme fire events. The fireproofing was helpful in lowering the temperature at the CFRP-concrete interface, preserving the integrity of the CFRP bonding, the concrete substrate, and the prestressing steel.