Dynamic Testing of Large-Size Seismic Moment Connections

9416276 uang本项目研究仪表钢抗弯框架的抗震性能。1994年的北岭地震造成了50多座建筑的梁柱弯矩连接的广泛破坏。这场地震不仅动摇了钢框架建筑，也动摇了抗震设计专业长期以来对这种主要系统的信心。虽然钢弯矩节点的设计、细节和焊接问题仍有待试验研究，但为了改进此类框架体系的抗震设计，重新审查现有的抗震规定也是很重要的。本研究项目的主要目的是在结构体系水平上调查导致这类框架结构破坏的因素。洛杉矶地区的许多钢结构抗弯矩框架已经由加州矿业和地质部(CDMG)安装了仪器。由于地面震动程度很高，这次地震的反应记录代表了迄今为止最有价值的实际建筑性能数据。三栋仪表化建筑(两栋办公楼和一栋医院楼，高度从5层到19层不等)被选作深入研究的对象。采用时程关联法和非线性动力分析法对实际变形需求(层间位移、杆件和板区转角需求)进行了评估。文中还讨论了反应修正系数与结构冗余度之间的关系，这是现行抗震规范中没有考虑到的。本课题的研究成果将为弯矩节点的实际变形需求提供参考。这些信息对于为今后钢结构弯矩连接的测试提供指南是非常重要的。结构冗余度的研究成果将进一步为新一代抗震规范的制定提供依据。这是一个北岭地震项目。***

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. ***