SMART Shear Keys for Tsunami/Storm Surge-Hazards Mitigation of Concrete Girder Bridges

In recent years, transportation infrastructures have been exposed to increasing hydraulic hazards, such as tsunamis and storm surges. In 2011, a devastating tsunami triggered by a Mw 9.0 earthquake struck Japan, 252 bridges were severely damaged. Most of the bridges worked normal after the earthquake load but failed after its associated tsunami loading due to the combination effect of buoyancy and overturning. Storm surges associated with the 2005 Hurricane Katrina floated and displaced many superstructures of bridges when end diaphragms and girders trapped air under water, dropping the bridge spans into water.<br /><br />The goal of this multi-phase proposal is not only to prevent the floated-and-displaced bridge superstructures but also to limit the damage of bridge substructures under tsunami/storm surge events by exploring and developing a novel concept of concrete-girder bridges with Sliding, Modular, Adaptive, Replaceable, and Two-dimensional (SMART) shear keys. Each key is composed of three precast concrete modules arranged in L-shape that are horizontally and vertically post-tensioned with replaceable unbonded steel bars to form two wedged sliding surfaces. When installed next to a girder and anchored into its capbeam support, the key provides controllable horizontal and vertical friction forces during natural hydraulic hazards and regulate corresponding displacements over time. This shear key will not only constrain the displacement of the bridge superstructure under floating and overturning loads, but also dissipate hysteresis energy to enhance the safety of the bridge substructure.

The objectives of this multi-phase proposal are to conduct an experimental study of a reinforced concrete girder bridge with end diaphragms and SMART shear keys in a large flume to simulate the effects of tsunami and hurricane events and to analyze the test data to understand the underlying behavior of the shear keys.

Developing an innovative measure to mitigate natural hydraulic hazards including tsunami/storm surge effects could potentially save both bridge structures and the lives of travelers who drive through the affected bridges. The outcomes and benefits resulting from such an enabled measure could have direct impact on the MATC’s theme on promoting safety. In addition, effective measures that can address the mitigation of multiple hazards are limited in the literature. This study could bridge the gap between research and the growing need for hydraulic hazards mitigation.

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