美国UBC97与中国建筑抗震设计规范近断层系数对比

Comparison of the near fault factor between Chinese building seismic design code and American Uniform Building Code

本文介绍了美国《Uniform Building Code》1997使用Ca和Cv双参数确定抗震设计反应谱的方法。UBC97中规定,同时满足4个方面的条件:(1)建筑位于抗震设防4区;(2)断层是发震断层;(3)断层具备发生不小于M_w6.5级地震的能力;(4)断层距小于15 km,才需考虑近断层系数。近断层反应谱与非近断层反应谱主要有等效峰值加速度、等效峰值速度和反应谱特征周期3个方面的增大。隔震结构的近断层增大系数不小于传统抗震结构的近断层增大系数。中国建筑抗震设计规范只规定了隔震结构和进行性能抗震设计的结构,在同时满足发震断层和断层距2个方面的条件,才需考虑近断层增大系数。通过对比发现,UBC97关于近断层系数的规定更加系统、明确和全面。

The method of determining the seismic design response spectrum of the Uniform Building Code 1997 u- sing Ca and Cv in the United States was introduced. If the site meets the 4 conditions ： （ 1 ） The building is located in seismic fortification zone 4 ; （2） The fault is active fault; （3） Faults are capable of producing large magnitude e- vents Mw〉6.5; （4） The fault distance is less than 15 km, and the near fault factors should be considered in the UBC97. The effective peak acceleration, the effective peak velocity and characteristic period of the near fault design response spectrum are larger than the non near fault. The near fault factors of the seismic isolation structure are not less than the traditional structure. For the only isolated structures and the structure using the performance-based seismic design, the near fault factors should be considered in the Chinese building seismic design code. For the tra- ditional structures, the factors must not be required. If the site meets the 2 conditions of active fault and fault dis- tance, the near fault factors should be considered in the Chinese building seismic design code. Through compari- son, it is found that the provisions on the near fault factors in UBC97 are more svstematic, clear and comnrthensiwthan Chinese building seismic design code.