Seismic performance analysis of socket prestressed assembled UHPC block

Monolithic reinforced concrete (RC) shear keys are commonly utilized in small- and medium-span bridges. However, these traditional shear keys have inherent limitations that make them highly susceptible to earthquake damage. In addition, post-earthquake repairs of these monolithic RC shear keys are often challenging and arduous. This study designs a socket prestressed assembled Ultra-High-Performance Concrete (UHPC) block structure based on the prestressing system, assembly construction, and the sacrificial concept. This innovative block structure consists of UHPC blocks, convex falcons, a prestressed anchorage system, and cast-in-place cover beams. Scaled specimens and a control group of specimens are thoughtfully designed and fabricated to investigate the operational performance and damage patterns of the socketed UHPC block. The specimens' mechanical properties, failure modes, and self-resetting abilities are evaluated through quasi-static tests and rigorous finite element analysis. In addition, the influence of the convex falcon's socket height on the novel block's seismic performance is analyzed. A strength prediction model corresponding to the failure mode of the socketed block is constructed, considering the contributions of UHPC and steel reinforcement to the block's strength. The results indicated that the failure modes of the socketed UHPC block and the monolithic RC block are shear rotation and typical oblique shear damage, respectively. The designed socketed UHPC block exhibits an impressive load-bearing capacity, self-resetting capability, and energy dissipation potential. The numerical analysis shows that compared to traditional RC blocks, the horizontal displacement capacity of the novel block is increased by about 130 %, the energy consumption capacity is increased by about 35 %, and the ductility coefficient is increased by about 12 %. The active design of the plastic damage position within the novel block can be achieved by appropriately modifying the socket height of the convex falcon. The established strength calculation model shows a high level of predictability. The prestressed assembled structure facilitates rapid replacement and repair of the socketed UHPC block after an earthquake, ensuring the bridge's continued safety and operational reliability.