| dc.description.abstract | When constructing prestressed concrete girder bridge structures, the high initial pretensioned force at the bottom of the girder causes it to camber upwards. This hogging of girders may be reduced slightly after casting the deck slab, any residual camber becomes locked-in. The upward deflection is generally mitigated by providing haunches or variable slab thickness. Such adjustments lead to construction delays, increased costs, and if not properly dealt with, rider discomfort. Because of loss of prestress over time, increase in strength of concrete after release and variations in production factors, the accurate estimation of long-term deflections may be complicated. Therefore, accurate predictions and minimization of camber and deflections should be, ideally incorporated into the design process. The aim of this research is to achieve the deck profile as flat as possible under the dead load (after long-term losses). The magnitude of camber is analyzed, and methods devised to minimize the after-losses deflections by manipulating the prestress in terms of profile and magnitude of force. The proposed relations between optimum force and eccentricity for different harping points, provide significant improvements to the long-term deflections of precast prestressed concrete beams compared to the currently observed deflections for eccentric and harped tendon profiles. | en |
