The safe and reliable implementation of seismic isolation requires verifying the properties and capacities of the bearings through testing.

Quality Control Tests are performed on every bearing to verify the bearing properties used in the design of the isolated structure.

Prototype Bearing Tests
are performed on two representative bearings of each bearing size and type, to verify the adequacy and properties of the isolation system. The Prototype Bearing Tests include Real-Time Property Tests and Bearing Capacity Tests.

Real-Time Property Tests measure the dynamic properties of the prototype bearings over the range of applicable loads and displacements used in the design. The measured bearing properties from these tests are used in the modeling of the bearing properties in the design and analysis of the structure.

Bearing Capacity Tests ensure that the prototype bearings exhibit safe structural behavior during the strongest earthquake shaking considered in the structure design. To prevent the collapse of a seismically isolated structure, it is very important that the seismic isolation bearings have the strength and stability to withstand Maximum Considered Earthquake (MCE) shaking without structural bearing failures. The Bearing Capacity Tests check the prototype bearings for significant structural degradation caused by the combined design compression and shear loading under MCE conditions. Bearings need to be able to dissipate the energy from long duration MCE shaking when tested at the isolated natural period TM. They also need to be able to safely accommodate short duration uplift displacements or tension loads, and afterwards maintain their lateral strength and stiffness when loaded again at the design compression loading. While supporting the design vertical load, the bearing should maintain a positive incremental lateral stiffness as the lateral loads are incrementally increased up to the calculated MCE shear load and displacement. If a positive incremental lateral stiffness is not maintained, bearing displacements larger than the calculated design displacement will occur, which may cause isolation system instability and complete structure collapse.

Detailed testing requirements are given for Buildings and Bridges.

Click here to see video of Bearing testing in real time, at full loads, and total displacement.
 

 
 
     
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