Beam-in-Slab Low-Volume-Road Bridge System

Abstract

Funding for the repair and replacement of structurally deficient and functionally obsolete bridges is a nationwide problem. This problem is magnified for the managers of low-volume-road (LVR) systems who have limited budgets; thus, innovative replacement alternatives are always being sought. The beam-in-slab bridge (BISB) is an alternative replacement bridge developed in Iowa. The bridge consists of W-beam sections spaced 24 in. (610 mm) on center, with concrete filling the void space between them. Spans up to 50 ft (15.24 m) can be constructed with this low-cost alternative. Field and laboratory testing confirmed that the system is capable of handling legal loads. Modifications to the BISB have been investigated to improve its structural efficiency to make it possible to use the system in longer spans. An alternative shear connector (ASC) has been developed to provide composite action in the BISB. The ASC consists of holes, either torched or drilled, through the web of the girder for the formation of concrete dowels that provide for composite action. Ongoing research promises more structural efficiency with the development of an arched formwork system, which will make possible wider girder spacings and reduced self-weight. Combining the ASC with the arched formwork should result in an essentially steel-free system that is relatively easy to construct. From initial results, it should be possible to construct spans up to 75 ft (22.86 m) to carry legal loads in Iowa with these modifications.