Shake Table Studies of a Steel Girder Bridge System with ABC Connections
Civil and Environmental Engineering
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Accelerated bridge construction (ABC) reduces the onsite construction time by utilizing prefabricated elements. Connections between prefabricated elements are critical in high seismic areas to maintain the integrity of the bridge system. Various ABC connections have been investigated at the component level to build a solid understanding of their local seismic response. However, to confidently recommend ABC bridges for adoption in standard bridge design and construction, they should be tested as a system. This study was aimed at addressing this issue by conducting experimental and analytical investigations of a 0.35-scale two-span steel girder bridge system with six ABC connection types: (1) column-to-footing rebar hinge pocket connection, (2) column-to-hybrid cap beam grouted duct connection, (3) steel girder-to-cap beam connection, (4) girder-to-deck grouted pocket connection, (5) ultra-high performance concrete (UHPC)-filled joints between the deck panels, and (6) UHPC-filled joint over the pier. The bridge system was tested to failure on shake tables under successive motions simulating scaled versions of the 1994 Northridge-Sylmar earthquake. Results demonstrated that the performance of the bridge model was comparable to cast-in-place bridges as columns underwent 6.9% resultant drift ratio in a ductile manner while cap beam, deck, footing, and four ABC connections in the superstructure responded as capacity protected elements. The analytical model was found to be was adequate to capture the overall seismic response of the bridge model. The effects of vertical ground motions and bi-axial excitations on seismic response of bridge elements and connections were investigated and found that some of the response parameters can be significantly affected by near-fault earthquakes.