Author: Clifford Astill at NOTE Date: 3/22/98 6:21 PM Priority: Normal TO: acoles at nsf18 Subject: Abstract: CMS-9733113, Jonathan Stewart, UCLA Message Contents Abstract: CMS-9733113, Jonathan Stewart, UCLA Recent improvements in seismological source modeling, in the analysis of travel path effects, and in the characterization of local site effects on strong ground shaking, have led to significant advances in both code-based and more advanced procedures for evaluating earthquake ground motions. Concurrently, seismic structural design practice is evolving towards consideration of performance-based criteria, which provide more reliable representations of structural behavior during earthquakes. A missing link, however, is empirically verified design procedures for assessing the effects of soil-structure interaction (SSI) on both the strong motions transmitted to structures and the structural response to these motions. Fortuitously, a significant amount of strong motion data has become available over the last decade which affords the opportunity to obtain this empirical verification. This is the objective of this CAREER project. The research component of this project utilizes strong motion data in system identification analyses to evaluate the effects of inertial and kinematic interaction on the seismic response of buildings through more fundamental representations of SSI; namely impedance and transfer functions. These empirical results are compiled from analyses of data having suitable combinations of structural and free-field strong motion recordings. Empirical results derived from strong motion data are combined with data from forced vibration testing of structures and results of numerical analyses to develop a framework for understanding the factors influencing impedance and transfer functions. These results will elucidate several important sources o f uncertainty in SSI analysis procedures, such as the modeling of non-uniform site conditions, and the effects of foundation embedment and/or deep foundation elements (i.e. piles and piers) on foundation performance. The educational component of this project seeks to improve the teaching of earthquake engineering at UCLA, to enhance knowledge transfer to practicing engineers, and to encourage pre-college students to pursue careers in science and technology. The teaching of earthquake- and geotechnical-engineering at UCLA is improved at the undergraduate and graduate levels through curriculum reform (including the addition of new courses), and the utilization of an instructional style which blends fundamental theory with "field" data and practical design problems. Knowledge transfer to practicing engineers is facilitated through continuing education workshops and service on professional committees. Outreach to pre-college students consists of lectures and demonstrations in local middle- and high-school science classes. The research plan compliments these educational objectives by providing "field" data that can be utilized in classroom instruction. These unified educational and research plans reflect the philosophy that research and teaching of complex seismic and geotechnical phenomena must blend sound physical principles with well documented field performance data in order to gain insight into a problem. +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+= + Clifford J. Astill Ph:703-306-1362 Fax:703-306-0291 castill@nsf.gov Nat'l Science Fdn 4201 Wilson Blvd., Rm545 Arlington, VA 22230 <www.eng.nsf.gov/cms/castill.htm>
