Roll Stiffness of Reinforced Neoprene Bearing Pads under Imposed Skew and Slope Angles

Abstract

During bridge construction, the flexible support conditions provided to precast, prestressed concrete girders by steel reinforced neoprene bearing pads allow for a rolling motion about an axis parallel to the span of the girders and may lead to girder instability. Imposed skew and/or slope angles significantly reduce the roll stiffness of bearing pads, which reduces the ultimate buckling capacity of the girders under the gravity loading condition. In this paper, roll stiffnesses for bearing pads under skew and slope conditions are derived from experimental data gathered from a test device designed to measure such values. The test device reproduces the forces acting on a bearing pad in the field while simultaneously permitting axial load, skew angle, and slope angle to be controlled independently, isolating the influence that each parameter has on bearing pad roll stiffness. A total of 108 tests were performed on three different standard bearing pads, with varying severity of imposed skew and slope angle.