UBC Theses and Dissertations
Anchorage of stirrups in prestressed concrete I-girders Hui, Macarious Kin Fung
The current research investigates the performance of commonly-used non-code-compliant stirrup detailing in concrete I-girder bridges, specifically when the lower hooks on the stirrups are oriented parallel to the longitudinal prestressing strands and are not bent around any longitudinal bars. Such detailing does not meet the specifications in the Canadian Highway Bridge Design Code CSA S6-06. An experimental investigation was conducted on full-scale partial sections of a concrete I-girder to evaluate the performance of such non-code-compliant stirrup anchorages by comparing their performance to the performance of code-compliant stirrup anchorages. An analysis of an example concrete I-girder bridge was conducted to determine the demands on the stirrup anchorage during the tests. In the tests, the flexural tension force was applied to the prestressing strand while a diagonal force was applied to the web of the test specimens at approximately 30° to the longitudinal axis of the specimen. Two pairs of stirrups were fixed to a support as the diagonal force was applied. The ratio of the slip of the stirrup to the strain along the exposed length of the stirrup, which equals to the debonded length, was monitored in order to observe the performance of the stirrup anchorage. After applying many cycles of the diagonal force, including about 100 cycles after yielding of the stirrups, the non-code-compliant hooks were found to perform adequately.
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