Design and Constructability of Spread Slab-Beam Bridges
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2016 American Society of Civil Engineers. A new bridge type called a spread slab-beam bridge was developed recently by using the same concept as that used for spread box beam bridges, in which the beams are spaced apart. This paper presents an evaluation of the new bridge system in terms of design and constructability and investigates the challenges encountered during construction. Forty-four bridge geometries were designed by using standard Texas DOT (TxDOT) slab-beam types to determine the feasible design space. One of the most aggressive geometries with widely spaced slab beams was constructed at full scale. On the basis of the research findings, it was concluded that spread slab beams with a topped panelized deck provide a viable construction method for short-span bridges. Results of a shear-design check show that the standard interface shear reinforcement must be doubled for the first quarter of the span length for more aggressive designs. Larger-than-expected camber of the precast slab beams might cause construction challenges and delays. A 30% increase in standard camber estimates can be used for construction purposes. High differential temperatures together with drying shrinkage might lead to early-age longitudinal deck cracking. Care should be taken during concrete curing to avoid factors that contribute to large temperature changes in the deck.
