Experimental Study of Seamless Bridge Transition System for U.S. Practice

Abstract

Expansion joints are one of the main causes for high maintenance costs in bridges. In this paper, a seamless bridge system is presented that provides for bridges with long service lives by eliminating the joints over the length of the bridge, the approach slab, and a segment of the adjoining roadway. Bridge movements in seamless systems are dissipated in a transition zone located at the bridge ends beyond the abutments. Thermal compression forces are transferred to the base soil, and thermal tensile forces are handled through opening and closing of microcracks in the transition zone. Crack width and spacing are important parameters in the design of seamless bridge systems. In the seamless system presented, the transition zone consists of a top slab and a secondary slab installed a few feet deep in the base soil. The two slabs are connected via small piles. At the end of the transition zone where it interfaces the roadway, which can be either jointed rigid or flexible pavement, there is a joint called an end joint. The bridge and transition zone movements should be reduced to amounts small enough so that no mechanical joint or grade beam would be required at the end joint. Development of the design provisions for the seamless bridge system is presented in a companion paper. A small pile–concrete slab connection detail has been proposed. In this paper, parametric studies have been carried out on a prototype bridge to develop an experimental program that simulates a segment of the proposed transition system. The experimental program studies the general behavior of the proposed transition system under cyclic loading, its stiffness, and capability in effectively reducing the bridge movements at the end joint, the development of cracks, the behavior of the proposed small pile-concrete slab connection detail, and the effect of geomaterial on the transition behavior. Finite-element analysis using Abaqus and SAP2000 computer programs was used to further study the behavior of the experimental system.