Flexural Behavior of the Composite Girder of a Prestressed Segmental UHPC Channel and a Reinforced Conventional Concrete Deck

The present study was conducted to clarify the flexural behaviors of the Composite Girders of a Prestressed Segmental Ultra-High-Performance Concrete (UHPC) Channel and a Reinforced Conventional Concrete Deck (PSUC-RCCD). The girders can be used as bridge superstructures with the advantages of structural efficiency, cost-effectiveness, and easy construction. A total of five specimens were tested. Three of them were PSUC-RCCD specimens, including two semi-segmental girders (the channel beams were composed of five segments with dry-joints) and one integral girder (the channel beams were integral ones without dry-joints). The two other specimens were P-UHPC girders composed of PSUC and UHPC deck slabs; one was semi-segmental and the other was integral. The flexural behaviors of the specimens were investigated, including the load-displacement curves, crack distribution, cracking moments, and ultimate flexural capacity. The study compared the influence of the segment number and deck material on the flexural behaviors of semi-segmental girders and introduced and validated methods for calculating the cracking moment and flexural capacity of both semi-segmental and integral sections in PSUC-RCCD and P-UHPC girders. The results show that the entire loading process of all the specimens can be classified into the elastic phase, the cracks development phase, and the failure phase. Compared to the integral girders, the number of segments has little effect on the flexural behavior of the semi-segmental girders, but it has a significant effect on the cracking moments. The cracking moments of the semi-segmental girders is only 0.58~0.60 of the integral girders. Reducing the strength of the deck slab by changing the material from UHPC to CC does not significantly affect their flexural behaviors. Based on the test results, this work proposes a method for predicting the cracking moment and flexural capacity of the semi-segmental girders, the results of which fit well with the test results, and it is applicable in the structural design of such members.

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