Simplified Analytical Nonlinear Model for Contact Problem between Precast Concrete Beams and Elastomeric Bearing Pads

Abstract

This paper presents an advance in the analytical prediction of the contact interaction between bearing pads and precast beams. Contact problems are typically nonlinear, and until recently, there was no analytical proposition to predict the nonlinear moment-rotation relation of bearing pads accounting for the loss of contact (lift-off) between the parts. It should be pointed out that lift-off governs the lateral stability of beams supported from below during erection. The energy method is utilized to determine a closed-form nonlinear equation. The nonlinear results for the proposed solution are in close agreement with experiments and finite-element analysis. Also, the initial rotational stiffness predicted by the current solution is 40% smaller than the solution available in the literature. The difference occurred due to the assumed nonlinear contact stress distribution between the beam and pad in the proposed formulation. From the results it was found that the relation WL3 and the level of precompression governs the moment-rotation capacity of bearing pads. Furthermore, the study highlights that lift-off occurs for small rotations, meaning that beams can have no full contact with pads. Therefore, the use of the secant stiffness is a safer choice to determine the rotational stiffness for verification of the lateral stability of beams.