9416276 Uang This project addresses seismic performance of instrumented steel moment-resisting frames. The 1994 Northridge earthquake caused widespread damage of beam-to-column moment connections in more than fifty buildings. This earthquake shook not only steel framed buildings but also confidence that the seismic design profession has long held for this type of premier system. Although design, detailing, and welding issues of steel moment connections remain to be investigated experimentally, to improve seismic design of this type of framing system it is also important to re examine current seismic provisions. The main objective of this research project is to investigate factors that contribute to damage of this type of frames at the structural system level. Many steel moment-resisting frames in the Los Angeles area have been instrumented by the California Division of Mines and Geology (CDMG). Because of the high level of ground shaking, the recorded response from this earthquake represents the most valuable data of actual building performance up to date. Three instrumented buildings (two office and one hospital buildings, ranging from 5 to 19 stories high) are selected for intensive study. Time history correlation and nonlinear dynamic analysis re conducted to evaluate actual deformation demand (story drifts, member and panel zone rotational demands). The relationship between the response modification factor and the structural redundancy, which has not been addressed in current seismic codes, is also addressed. The results of this research project will provide information on realistic deformation demand on moment connections. This information is essential for providing guidelines for future testing of steel moment connections. The research results on structural redundancy will further provide a basis for developing a next-generation seismic code. This is a Northridge earthquake project. ***
