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Abstract:
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An experimental program was conducted at the Ferguson Structural Engineering Laboratory of The University of Texas at Austin , under the auspices of Texas Department of Transportation (TxDOT ) Research Project 5831 , to investigate the tensile stresses that develop in the end regions of pretensioned concrete U -beams at transfer of prestress . Understanding the effect of these “bursting” and “spalling” stresses is essential in order to design standard details that might lead to reliably -serviceable end regions .
Two full -scale beam specimens , designed to be worst -case scenarios for bursting and spalling , were fabricated . Each beam had one square and one highly skewed end . Extensive instrumentation , including strain gages on transverse and lateral reinforcing bars , was employed in the end regions of these U -beams . Experimentally determined bursting and spalling stresses in these bars were compared to results of past projects (from the literature ) investigating I -beams and inverted T -beams .
Preliminary recommendations are made for changes in the standard reinforcing details for U -beam end regions . Such recommended details will be tested in the upcoming phase of Research Project 5831 . |