The ground may feel solid beneath our feet, but the strong ground motion that occurs during an earthquake can cause the ground to suddenly become unstable and behave like liquid. This change of seemingly solid earth to a loose, shifting soil is called liquefaction. It is not enough to study how to construct earthquake safe structures. Engineers also need to understand how the ground beneath a structure will react. To conduct research where structures already exist - or to test the soil where future building may be planned - researchers need to conduct experiments outside of the traditional laboratory, or "in situ" (a Latin term meaning "in the original place").
The NEES program's three field and mobile laboratories make it possible to test on-site and relay the data directly from the field. Lab vehicles carry equipment that can generate ground vibrations, plus sensors with recording devices to measure the effects. The study of how a structure will react to the ground it stands on during an earthquake-like force is called Soil-Foundation-Structure Interaction, or SFSI.
University of California, Los Angeles
The UCLA mobile lab can conduct testing on full-scale structural and foundation systems. UCLA NEES program has developed a state-of-the-art mobile field laboratory to enable detailed, seismic performance characterization of full-scale structural and foundation systems. Through use of this equipment, it is possible to develop an inventory of field test results that provide new insights into nonlinear response of full-scale structural systems, as well as soil structure interaction effects.
University of California, Santa BarbaraThe University of California at Santa Barbara, in partnership with the University of Southern California and Brigham Young University, has established a permanent field-testing site in the seismically active area of Garner Valley.
Facility Specifications: Technical information
- Equipment Site Homepage: NEES@UCSB
University of Texas, AustinThe nees@UTexas equipment includes five mobile shakers that have diverse force and frequency capabilities, an instrumentation van that houses state-of-the-art data acquisition systems, and a large collection of field instrumentation.