What safety features are used to protect bridges from earthquakes?

Bridges are vulnerable to earthquakes because of their dynamic characteristics, the ground motion imposed by earthquakes, and their structural details. Several safety features are employed to protect bridges from earthquake damage:

Seismic Isolation: This involves introducing a layer of flexible material, such as rubber or lead-rubber bearings, between the bridge's superstructure and the substructure. These isolators absorb and dissipate seismic energy, reducing the amount of force transferred to the bridge.

Energy Dissipation Devices: These devices are incorporated within the bridge's structure to absorb and dissipate seismic energy. They may include viscous dampers, friction or metallic yielding dampers, tuned mass dampers, and others. These devices help reduce the bridge's vibration and absorb energy during an earthquake.

Reinforced Concrete Columns and Piers: Columns and piers supporting the bridge deck are often reinforced with steel reinforcement and/or concrete jacketing to enhance their ductility and strength. This helps them resist the lateral forces and deformations caused by earthquakes.

Ductile Design: Bridge elements are designed to behave in a ductile manner, allowing for controlled plastic deformation without sudden brittle failure. This is achieved by using appropriate detailing and reinforcing, ensuring adequate ductility in critical regions of the bridge.

Redundancy: Bridges are often designed with redundant structural elements, so if one element is damaged or fails during an earthquake, other elements can redistribute the loads and maintain the structural integrity of the bridge.

Seismic Monitoring: Some bridges are equipped with seismic monitoring systems that can measure the bridge's response during an earthquake. This data can provide valuable information for post-earthquake inspections and damage assessment.

By implementing these safety features and adhering to seismic design codes, engineers can enhance the resilience and safety of bridges during seismic events.