This study was carried out systematically to identify the potential sources of discrepancies between the design and measured camber from release to the time of erection, in order to improve accuracy of camber estimation and avoid related problems in the field.
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Scope:
The scope of this research is to improve both short-term and long-term camber predictions, and minimize the error between the expected and actual camber of PPCBs especially at the time of erection. The project scope was achieved through systematically investigating the short-term and long-term material behavior, examining the camber measurement techniques, and quantifying the camber from the time of construction of PPCBs until the completion of bridges using these beams.
Background:
The current method of predicting camber of Precast, Prestressed Concrete Beams (PPCBs) used by Iowa has been observed to frequently over-predict the long-term camber of long bulb-tee beams, while underpredict the long-term camber of shorter PPCBs. Overpredicting or underpredicting camber typically causes difficulty in the field during bridge construction, causing delays in construction schedule and increase in the construction costs. Both over and under prediction of camber requires additional unplanned haunch reinforcement, while under predicting camber can also cause unexpected flexural cracking in the girder top flange and require changes to the bridge deck elevation.
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Final Report
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