Structural Behavior of Thin Prestressed Slab Beams in Bridges
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In recent years, the need to rehabilitate or replace many short-span old bridges in the most economical way has given rise to the idea of designing a wide-and-shallow beam, so called Thin Prestressed Slab Beams (TPSBs). TPSBs are cost-effective owing to: (1) simple formwork, (2) simple reinforcement detailing, (3) ease of quality control, and (4) overall performance given that their behavior is more like slabs (governed by flexure) than beams (governed by flexure/shear). The Texas Department of Transportation (TxDOT), in 2003, officially introduced TPSBs with 305 mm (12 in.) and 381 mm (15 in.) in height, 1.22 m (4 ft.) and 1.52 m (5 ft.) in width, and up to 12.2 m (40 ft.) in length. The shear reinforcement design in TPSBs is guided by the AASHTO LRFD Specification. No tests on such TPSBs, however, had been performed in the past. This research had four main objectives: (1) to characterize the behavior of TPSBs and their failure modes, i.e., flexure, shear, and/or anchorage bond; (2) to evaluate the effectiveness of shear reinforcement; (3) to check whether the shear design provisions in AASHTO LRFD are applicable to the design of TPSBs; and (4) to provide design recommendations for TPSBs. The test results of full-scale TPSBs showed that the failure mode of TPSBs was governed by either a non-ductile anchorage bond failure or flexural failure. Anchorage bond failure resulted in lower capacity than those failing in flexure and/or shear.