Stress triaxiality is proposed as one of the key parameters to discuss the cause of brittle fracture during earthquakes in steel structures. This study analytically investigated the features of stress triaxiality in steel bridge bent subjected to earthquakes. The target structure is a steel bridge bent actually fractured during the South Hyogo prefecture Earthquake. From the investigations, it was confirmed that high stress triaxiality was generated at a point supposed as fracture origin. There is a possibility that the triaxiality was involved in the fracture strongly through the increase of maximum principal stress. Moreover, from the analyses accounting for several kinds of large earthquake waveforms, it was indicated that threre is possibility that the distribution of triaxiality around the fracture origin was not affected by significantly by each cycle and each waveform.

中文翻译：

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钢桥弯曲处地震脆性断裂中应力三轴性的参与

提出了应力三轴性作为讨论钢结构地震中脆性断裂原因的关键参数之一。该研究分析性地研究了地震作用下钢桥弯曲时的应力三轴性特征。目标结构是在南兵库县地震中实际断裂的弯曲钢桥。通过研究，证实了在假定为断裂起点的点处产生了高应力三轴性。三轴性可能通过最大主应力的增加而强烈地参与了断裂。此外，根据对几种大地震波形的分析，