NEHRP Clearinghouse

A Comprehensive Research Program in Earthquake Engineering.
National Science Foundation, Washington, DC. Engineering and Applied Science., August 22, 1968, 19 p.
Laboratory tests of two new strong-motion accelerographs have resulted in significant improvements in accuracy and reliability. A new manually operated vibration test table with long period and permanent displacement capabilities has made it possible to extend studies of accelerograph accuracy. Contributions have been made to improvements in the Southern California Strong-Motion Accelerograph Network by supplying additional instruments and through studies of optimum location. In cooperation with the U.S. Coast and Geodetic Survey, improved methods for data processing of accelerograms have been worked out, and significant progress has been made towards a uniform treatment of past earthquake records. An improved set of artificial earthquake accelerograms based on statistical studies of past records has been produced which will facilitate structural dynamics and soils investigations. Computer studies of yielding systems have been extended to include more realistic damping conditions, and digital computer models for prestressed concrete beams have been developed. Structural dynamic tests of full scale structures have been carried out for a multi-story building and for a rockfill dam. Interaction effects in yielding structures loaded simultaneously in several directions have been examined. Soil dynamics studies have concentrated on soil-structure interactions. Calculations of dynamic response of structures founded on an elastic half-space have defined the conditions under which higher modes of vibration can be neglected. The earthquake response of a flexible retaining wall has been investigated.
Seismic waves; Earth movements; Seismology; Dynamic response; Ground motion; Earthquake engineering; Computer aided analysis; Soil dynamics; Soil structure interactions; Accelerometers; Earthquakes; Dynamic structural analysis