Clarification of Impulsive Failure in Structural Damage due to the Hyogoken-nanbu Erathquake

日本建筑研究所成立了一个合作研究小组，研究了地震冲动性作用对小古肯-南部地震造成的部分结构破坏的可能性，迄今为止得出的结果如下：1。2.足滨住宅小区发生的钢筋断裂等重大结构破坏，不可能是由普通结构设计中采用的常规地震波造成的，而是由本应发生在现场的地震节约造成的。在同一层楼中同时出现塑性铰不能保持相应的抗震性能。为了保证结构的抗震可靠性，应限制塑性铰的出现次数。结构框架的开裂后性能不仅与裂缝附近的周向条件有关，还与框架的整体结构和荷载条件有关。在脉冲加载过程中出现的高应变率和塑性预应变显著降低了钢构件的断裂韧性。有可能过去的地震记录没有包含足够精确的高频内容。

In order to investigate the possibility that some of structural damages due to the Hyogoken-nanbu Earthquake were caused by impulsive action of the earthquake, a cooperative research group was formed in Architectural Institute of Japan, and have derived to date such results as follows :1.Significant structural damage such as steel fracture experienced at Ashiyahama residential complex cannot be caused by such conventional seismic waves as adopted in ordinary structural design, but by the seismic save which would have occurred at the site.2.Pertinent earthquake resistance cannot be maintained through simultaneous occurrence of plastic hinges in an identical story. The number of the occurrence of plastic hinges should be limed for structural reliability against earthquakes.3.The post-cracking behavior of a structural frame depends not only on the circumferential condition near the crack but also on the over-all configuration and loading condition of the frame.4.Such a high strain-rate and plastic pre-strain as occur in impulsive loading reduce fracture toughness of a steel member significantly.5.There is a possibility that past earthquake records do not contain high-frequency contents to sufficient accuracy.