Research on the Prevention of Brittle Fracture in High-Rise Steel Buildings

本研究旨在阐明在1995年日本现代城市发生的地震中观察到的钢框架脆性断裂的原因。本研究的最终目的是提出一种预防城市地震多发区高层建筑脆性断裂的设计方法。本研究涉及以下几个问题：1)脆性断裂对钢结构的安全性影响有多大？2)现代建筑高层钢结构的脆性断裂可能的形式是什么？3)钢材对脆性断裂的支配作用是什么？4)焊接对钢节点的脆性断裂有什么影响？5)地震时的滞回变形对脆性断裂有什么影响？6)建筑物发生脆性断裂后，失效安全机制是如何可能的？7)根据本研究和现有的相关知识，可以提供多么复杂的设计方法来防止脆性断裂。本研究，在试验测试和分析模拟相结合的基础上，对上述问题提出了解决方案，并提供了脆性断裂的基本信息。综合这些数据，提出了初步的设计和施工方法。但同时也认识到，地震中的脆性断裂现象是一个非常复杂的现象，包含了许多物理因素，还需要进一步的研究才能得出最终的结论。

This research aims at clarifying the cause of brittle fracture in steel building frames as observed during the 1995 Hyogoken-Nanbu Earthquake which hit the modern urban city. The final target of this research is to propose a design method to prevent the brittle fracture which is anticipated in high rise buildings in earthquake-prone urban areas. This research deals with the following subjects :1) How much degree of safety degradation is anticipated in steel structures by brittle fracture?2) What is the possible mode of brittle fracture in tall steel buildings of modern architecture?3) What is the governing property in steel material on brittle fracture?4) What effect is given by welding on brittle fracture of steel connections?5) What effect is given by hysteretic deformation during earthquake on brittle fracture?6) How failsafe mechanism is possible after occurrence of brittle fracture in buildings?7) How sophisticated design methodology can be provided for preventing brittle fracture from this research and current related knowledge.This research, on the basis of the combination of experimental test and analytical simulation, has provided resolutions to the above questions as well as basic information on brittle fracture. From synthesizing these data, a tentative design and construction method is proposed. However, it is also understood that the phenomenon of brittle fracture during earthquake is a very complicated one including many physical factors, then further research is required to attain the final conclusions.