Experimental study of strand splice connections in UHPC for continuous precast prestressed concrete bridges

Current infrastructure demands require bridging larger spans while maintaining construction and structural simplicity. The use of standard prestressed concrete girder elements which might be spliced in situ has been regarded as an appealing solution. This study investigated the performance of strand lap splices embedded in ultra high performance concrete (UHPC) and their further implementation in structural continuity connections for spliced girder bridges. The results of an initial experimental program suggested that the full development length of 12.7 mm and 15.2 mm diameter unstressed prestressing strands embedded in a steel fiber reinforced UHPC is approximately 510 and 610 mm (40 ds), respectively. The implementation of the splice strand connection concept for girder spliced bridges was further developed and experimentally assessed. Two full scale box beam tandems were spliced and tested. It was demonstrated that large flexural capacity can be achieved with relatively short lap splice lengths. Approximately 90% of the ultimate flexural capacity estimated for the fully prestressed and continuous girder was reached by the spliced box beam tandem connected using a strand splice length of 762 mm (50 ds). Additional detailing of the structural system and the reinforcing scheme is discussed to improve the performance of the system in general and the connection in particular.