Hydrocarbon Fire Performance of Reinforced Elastomeric Bridge Bearing Pads

Abstract

Elastomeric bearing pads are commonly used to support precast prestressed bridge girders. Previous studies on such pads have been conducted only at ambient temperatures. Bridges are susceptible to fire due to the potential for crashed or overturned vehicles, and the pad behavior at such elevated temperatures should be explored. A typical bridge fire in the vicinity of girder supports can have a significant effect on the performance of the bearing pads. In this study, a one-span full-scale bridge comprised of standard precast concrete I-girders and composite deck with elastomeric bearing pads was tested under a combined hydrocarbon pool fire and simulated live load. The test was conducted for 60 min, and the fire temperature at the bearing pads reached as high as 400°C. The affected bearing pads were then tested for hardness, shear modulus, compression set, and adhesion strength as per current standards. All material properties except for the compression set indicated small changes and were within the acceptable limits. Numerical simulation using a linear elastic model and thermomechanical analysis was also conducted with nonlinear finite element software. The pad shear strain, tensile stress, and bond stress increased by up to 30–50% for 50, 60, and 70 elastomer hardness levels at 200°C temperature exposure. The effect of fillers on bearing pad performance is negligible.