An Alternative Approach to Earthquake-Hazard Evaluation for Concrete Building Structures

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9314197 Sozen Research is proposed to develop an alternative earthquake-hazard evaluation technology for regions with infrequent earthquake occurrence. The proposed work includes (a) development of procedures specifically designed to identify buildings that will threaten life, (b) calibration of the new as well as current state-of-the-art procedures with data from buildings subjected to a strong earthquake and (c) analysis of the strengths and weaknesses of current and proposed technologies in formulation of risk-reduction strategies for regions of low to moderate seismicity. The research is designed to focus on field experience. The information from 31 partially damaged buildings, with lateral- force resisting systems ranging from effectively none to barely acceptable, will be used. The important attributes of the buildings for the project are that they all survived a strong ground motion (Amax = 0.5G) without leading to life-threatening damage and they all would have been evaluated to be hazardous by state-of-the art evaluation procedures. The project will include six tasks: Task !-Selection and determination of parameters to be used to define the structures and the ground motion. These will include standard quantitative and qualitative indices such as framing descriptors, calculated translation periods, and base shear strength coefficients as well as those reflecting the combined effect of structural and nonstructural elements. Task II-Studies to select a set of five to nine structures for analysis. The selection will be made so that the set includes examples covering suitable ranges of the parameters established in phase I. Task III-Detailed studies of the selected set of structures. Each selected structure will be evaluated in each direction using standard analysis and evaluation methods use in Turkiye, the U.S. and Japan. Analyses will range from two-dimensional linear to three-dimensional nonlinear, depending on the quality of the information , type of framing and perception of return. Task IV-Identification of incompatibilities between evaluation results and observations. In this critical phase, incompatibilities between results of evaluation and observation will be studied to identify which differences can be reconciled by credible modifications of the input or modeling and which cannot be so reconciled. Task V- Synthesis. This phase will involve work either to modify the standard techniques to suite (by far the preferable option) or to develop totally new approaches. Task VI-Recalibration. The sanctioned procedures will be calibrated using (a) the entire set of 31 buildings, (b) the six buildings in Erzincan that collapsed in the March 1992 event, and (c) typical nonmetallic buildings in central and eastern U.S. Two reports will be prepared for dissemination. The first will document tasks 1 to IV. The second will present results of tasks V and VI. ***