Earthquake sensors may improve building safety
In an effort to improve the design of structures to better withstand earthquakes, researchers at UCLA are developing testing and monitoring equipment that will serve as the 'eyes and ears' of a nationwide earthquake engineering research network.
The George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES), an $87 million project funded by the National Science Foundation, brings together 11 institutions in a cooperative network that will allow them to share data and equipment. The field-testing and monitoring equipment -- being designed at UCLA's Henry Samueli School of Engineering and Applied Science -- will provide researchers with real-time information on what happens to structures such as buildings, dams and bridges during simulated earthquakes.
According to John Wallace, professor of UCLA's civil and environmental engineering department and principal investigator on the project, sensors capable of monitoring up to 100 different conditions, including acceleration, strain and displacement, will be placed in the buildings and the soil surrounding the buildings. Information from these sensors will be transmitted wireless to a mobile command center that, in turn, will transmit the data via satellite to the Internet. That way, other researchers elsewhere in the country 'will be able to read our data almost as quickly as we can,' Wallace said.
By attaching large masses to a roof or floor of a building, and then using control systems to rotate these masses, the researchers will be able to exert forces up to 200,000 pounds and use the sensors to measure how the structure shakes. In addition to the rotating shakers, Wallace said, they will also be obtaining a 'linear shaker,' which creates a random vibration pattern more typical of what you would see in an earthquake, but has lower force capacity.
By using different types of shakers, according to Wallace, researchers will be able to create 'small-to-moderate, and in some cases, significant building vibrations' to address a spectrum of important issues relating to the response of structures to earthquakes. Along with new buildings and those being remodeled, Wallace said, they also hope to experiment on structures that are to be demolished -- some of which they may destroy in the process.
Many of today's computer simulations or laboratory tests are done on what Wallace calls 'idealized buildings,' that is, the simulations do not include a realistic model of the foundation system, or the influence of partitions, windows or the exterior facade. 'Using real buildings as a laboratory has the potential to greatly improve the accuracy of these computer simulations,' Wallace said. And more accurate simulations will reduce the loss of life and property by producing safer buildings that can better withstand earthquakes.
In addition, the researchers will use the equipment to vibrate a number of structures and catalog the results so that 'in the very likely event of another earthquake, the sensors can be quickly reattached to measure the vibrations during earthquake aftershocks,' Wallace said. 'We certainly want to take advantage of these extremely valuable real-life opportunities to reduce the damage caused by earthquakes.'
Because the equipment is mobile, it can be moved to the site of earthquakes throughout the region and lent to other institutions. In fact, sharing equipment and data are major objectives of the project, Wallace said. This way, all interested researchers will have access to a vast array of equipment and data.