地震受损房屋结构自振特性测试

Field test to natural characteristics of earthquake damaged building structures

采用底部剪力法对结构进行抗震计算的重要一步就是确定结构的基本自振周期,抗震设计规范为此提供了自振周期计算和相应的折减方法。对于新建结构,规范经验公式是合理的,但对于地震受损结构,当需要进行抗震加固设计计算时,针对完好建筑结构给出的规范经验公式就不再适用。由于缺乏实测资料,无论是抗震鉴定标准还是加固技术规程,都没有给出可以参考的方法。作者在玉树地震后,利用环境脉动测试方法,对在玉树地震中受到破坏的20余栋不同结构类型的房屋建筑结构进行了现场测试,获得了这些受损房屋结构的实测基本自振特性,给出了对结构震害程度与结构自振周期变化之间关系的初步认识。为震损结构鉴定与加固设计提供了可参考数据,同时,实测结果也可为结构非线性分析方法的发展和结果的验证提供重要参考。

One of the important steps is to determine the natural period of structure in the preliminary seismic design by using the base shear method. The seismic design codes provide empirical formula as well as the reduction approach to estimate the natural period of the newly designed building. It’s usually reasonable and reliable to a new building or an intact existing building. But for a seismically damaged structure, especially in the retrofitting design, the code formula is not suitable anymore.Due to the lack of real test data, the period estimation formula is not provided in either seismic evaluation code or retrofitting code for existing buildings. Immediately after the 2010 Yushu Ms7.1 earthquake, in the field investigation, more than 20 different structural type of damaged building were selected by the authors to carry out the natural period field test by using the ambient-vibration test. By comparing of the tested natural period and the damage status of these building structures, the relationship between the period change and the structural damage level was preliminary established. The test results will provide useful reference to seismic retrofit design of earthquake damaged buildings as well as nonlinear analysis and model verification.