Earthquake Monitoring of Structures
In the San Diego, California VA Medical Center, the recently retrofitted main hospital building is equipped with earthquake monitoring systems. Red arrows in the schematic diagram show the locations and indicate the directional sensitivity of the seismic sensors from the basement through the building’s seven stories to the roof. The triaxial sensor on the ground floor (at lower right) monitors the input motions in three orthogonal directions.
After a major earthquake it is imperative to check the condition of structures in order to be able to assess their structural integrity for public safety.
Recordings from structures instrumented with sensors help engineers assess the structure’s safety and functionality in a timely fashion. Such recordings are also critical to designing safer infrastructure, and to preventing loss of life.
In particular, monitoring structures helps engineers to:
- assess a structure’s safety immediately following a damaging quake,
- understand how damage to structural and nonstructural components (such as equipment and pipes) occurs from strong shaking,
- evaluate and improve earthquake-resistant design techniques and also methods for predicting the seismic performance of structures, and
- improve earthquake-resistant design provisions in seismic codes.
More than 250 structures through¬out the United States have been outfit¬ted with seismic sensors by the USGS National Strong Motion Project (NSMP) to improve the overall understanding of earthquakes and their effects on the built environment.
The instrumentation and monitoring of structures by NSMP is only one part of USGS efforts to protect peo¬ple’s lives and property from earthquake hazards in all of the Nation’s seismically active regions.