Experimental Investigation of a Full-Scale Spread Slab Beam Bridge

The Texas Department of Transportation (TxDOT) uses precast prestressed concrete slab beams in a side-by-side configuration for short-span bridges in low-clearance areas. To reduce costs, a new bridge type called a spread slab beam bridge was recently developed using the same concept as spread box beam bridges in which the beams are spaced apart. A full-scale spread slab beam bridge was constructed and tested under static and dynamic vehicular loads to evaluate constructability and structural performance. The load-distribution behavior was investigated through field testing, and experimental live-load distribution factors (LLDFs) were evaluated using alignments that provided the most adverse loading cases. The measured response provides detailed experimental data to validate computational modeling techniques for this new class of bridge systems. Research findings show that spread slab beam systems provide a viable construction method for short-span bridges, and that the desired performance was achieved for in-service loading. During field testing, the beam live-load deflections were within the design limits, and no significant cracking or reduction in the overall stiffness of the bridge was observed.