Ductile Concrete End-Diaphragms of Slab-on-Girder Concrete Bridges

In this paper, the results of the proposed ductile precast concrete end-diaphragm beams for the transverse seismic resistance and protection of the substructure of slab-on-girder concrete bridges, tested at the facilities of LanammeUCR structural laboratory, University of Costa Rica, are detailed and discussed. The proposal can be used as part of an accelerated bridge construction (ABC) solution for moderate-to high-risk seismic areas. The hysteretic results showed adequate energy dissipation performance of the transverse end-diaphragm beams system; however, the envelopes obtained in both load directions evidenced a marked difference: the negative envelope showed a more noticeable ductile behavior and close enough to the predicted theoretical monotonic curve than the positive envelope. The damage observed at the precast concrete diaphragm beams was negligible, and the concrete deterioration was concentrated in the corners of the connections with the bridge girders, where the grout mortar at the joint gap evidenced a poor performance. Even if the bridge girders showed cracking both due to shear and flexure, the residual crack width was low: on average 0.10 mm. The final conclusion is that even if the test showed some issues that have to be revised, the system has the potential to demonstrate an outstanding performance under lateral seismic load.