Precast RC Blocks with Detachable Connections for Emergency Temporary Bridges: Wave-Shaped Concrete Shear Keys Fabricated from 3D-Printed Molds and Steel Couplers

Although structural design and technology remain challenges in preventing bridges, especially their superstructure, from being washed out by hydrodynamic forces due to tsunamis, floods, and storm surges, bridges must be functional after disasters to ensure rapid recovery. Consequently, countermeasures that account for the potential for bridge failure are crucial for enhancing resilience. This paper proposes a temporary bridge using precast reinforced concrete (RC) blocks with connections composed of wave-shaped concrete shear keys fabricated using three-dimensional (3D)-printed molds and mechanical couplers. The proposed RC blocks can be easily assembled and disassembled for reuse in future disasters. Loading test results demonstrate that RC blocks joined with adequately waved concrete shear keys, classified as the 1.0 cosine shape in this study, exhibit an expected flexural failure and an equivalent load–deflection relationship to the reference specimen without any connections (i.e., ordinary RC beam). The maximum load and corresponding displacement of the integrated full-scale RC blocks are 1.01 and 4.46 times those of the ordinary RC beam, respectively. A two-dimensional finite-element (FE) model incorporating Coulomb friction between concrete shear keys is developed and validated by comparing results with bending test data. The FE model is used to explore the effects of the amplitude of the wave-shaped concrete shear key on the entire structural performance.