Proposed Design Provisions for a Seamless Bridge System: Cases of Flexible and Jointed Pavements

Abstract

Expansion devices are one of the main causes for high maintenance costs in bridges. In this paper, a seamless bridge system is presented that results in bridges with long service lives by eliminating the joints over the bridge length, approach slab, and a segment of the roadway. The idea of a seamless system was originally developed in Australia for use with continuously reinforced concrete pavements (CRCP). In this system, bridge movements are dissipated in the transition zone located at the bridge ends beyond the bridge abutments. Thermal compression forces are transferred partly to base soil and partly to the CRCP, and the thermal contractions are handled by opening and closing microcracks in the transition zone. Crack width and spacing are important parameters in the design of seamless bridge systems. This paper presents the modification to the Australian seamless system so that it could be extended to U.S. practice, where most pavements are either jointed plain concrete or flexible. Analyses and design procedures are presented. The main difference between the Australian version of the seamless system and the proposed version for U.S. practice is in the type of transition region. The main challenge for U.S. practice is to have almost zero movement and force at the end of the transition zone. This objective is achieved by constructing a secondary slab below the transition region and connecting the two using closely spaced small piles. Numerical and analytical studies have been carried out to comprehend the performance of the proposed system, and an experimental study was carried out to provide proof of the concept and merits of the proposed design recommendations. Results of this experimental work are presented elsewhere.