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Design and Performance of Combined Basic Devices to Control Undesirable Bridge Deck Displacements and Damage, During Major Earthquakes

Abstract:

This paper describes criteria and parameters employed in the design of neoprene shock absorbers, concrete shear keys and vertical steel bar anchors, used together in the Los Caras Bridge, to control damage and bridge deck displacements, during major earthquakes. There is a focus on construction details, because of the importance of this factor on overall system performance. The authors assess and report on the actual performance of these design features under the April 16, 2016 Mw 7.8 Muisne earthquake in Manabí, Ecuador. Isolated and non-isolated segments of the 2 km long Los Caras Bridge remained fully operable after a peak ground acceleration (PGA) of 0.90 g was generated by the Muisne earthquake. Neoprene compression shock absorbers were used at the end of bridge segments. Transverse reinforced concrete shear keys and vertical steel bar anchors were included on top of piers. The shear resistance of neoprene bearing pads is also analyzed. Special attention was paid to performance of the neoprene bearing pads, since their stability is essential to the whole displacement control system. Displacement control of shear keys, and bridge deck displacements in other bridges of Manabí were also studied. After the earthquake, general details and design criteria are proposed. Improved design criteria and details for concrete shear keys and steel bar anchors, based on actual seismic performance, are presented.