Design and Constructability of Wide-Flange UHPC Bridge

Abstract

Construction of highway bridge girders using conventional prestressed concrete is a widely accepted norm in the state of Texas. But the limited life and the lengthy on-site construction work is a serious concern to the travelling public. This research looks into the design and constructability of slab-on-girder Ultra High-Performance Concrete (UHPC) bridge spans using different configurations. One associated feature is to minimize the number of field activities in the construction process. Therefore, the use of wide flanges of varying thicknesses are investigated. The thesis evaluates five UHPC design scenarios, which are compared to the standard TxDOT way of constructing highways with Tx54 girders using normal concrete. Because the wide flange topped girders are entirely cast off-site, deflection control is important to ensure the ride surface remains as flat as practicable. The different longitudinal girder-to-girder connection options are investigated. For each design, detailed estimates are made together with construction engineering schedules. Results show that the most economical solution that may be rapidly constructed following the principles of accelerated bridge construction (ABC) used a full-thickness flange. By contrast, the most enduring solution had a half-depth field cast topping which was transversely post-tensioned to actively tie all units together to mitigate the possibility of longitudinal cracking at the girder-to-girder connections.