|
|
|
| Fundamental period formula for horizontal layered soil profiles |
| QI Wen-hao1, BO Jing-shan2, LIU Hong-shuai1 |
| 1. Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, CEA, Harbin 150080, China; 2. Department of Disaster Prevention Engineering, Institute of Disaster Prevention, Sanhe 065201, China |
|
|
|
|
Abstract The current formula can not calculate the fundamental periods of the sites containing soft soil layers accurately. In order to solve the problem, a fundamental period formula for a horizontal layered site, on which the effect of soil layer construction is considered, is deduced based on the vibration theory. According to the rules of natural vibration periods being equal, a single layer site is simplified into a SDOF system by means of the lumped mass method, and the equivalent height coefficient between their heights is deduced. A horizontal multi-layer site can be simplified into a SDOF system based on any one soil layer, and the height of the SDOF system is equal to that of the soil layer multiplied by the equivalent height coefficient. The natural vibration period of the SDOF system is called contributing fundamental period of the soil layer here, and the fundamental period of the site should be equal to the square root of sum square (SRSS) of the contributing fundamental periods of all the soil layers in the site, and its formula is also deduced. The test results show that (a) the proposed formula can reflect the effect of soil layer construction on fundamental periods of sites very well, and (b) by comparing the calculated fundamental periods with the test ones of 5 engineering sites by use of the microtremor method, the proposed formula is of higher accuracy and reliability than the current formula. A conclusion is drawn that the deduced formula can be adopted to estimate the fundamental period of a layered horizontal site.
|
|
Received: 18 June 2012
|
|
|
|
|
|
[1] 《工程地质手册》编委会. 工程地质手册[M]. 4版. 北京:中国建筑工业出版社, 2006.Editorial Board of Engineering Geology Manual. Engineering geology manual[M]. 4th ed. Beijing
[2] 薛素铎,赵 均,高向宇. 建筑抗震设计[M]. 2版. 北京:科学出版社, 2007.XUE Su-duo, ZHAO Jun, GAO Xiang-yu.
Seismic design of building[M]. 2nd ed. Beijing: Science Press, 2007.(in Chinese)
[3] 熊建国,许贻燕. 分层土自振特性分析[J]. 地震工程与工程振动, 1986,64:21-35. XIONG Jian-guo, XU Yi-yan.
Analysis of the behavior of natural vibration of layered soil deposits[J]. Chinese Journal of Earthquake Engineering and Engineering Vibration, 1986, 64: 21-35. (in Chinese)
[4] 童广才,刘康和. 场地卓越周期的确定[J]. 电力勘测, 2000,2:43-46. TONG Guang-cai, LIU Kang-he.
Determine predominant period of site[J]. Chinese Journal of Electric Power Survey, 2000, 2: 43-46. (in Chinese)
[5] MOTAZEDIAN D, BANAB K K, HUNTER J A,et al. Comparison of site period derived from different evaluation methods[J]. BSSA, 2011,1016:2942-2954.
[6] DOBRY R, OWEIS I, URZUR A. Simplified procedures for estimation the fundamental period of a soil profile[J]. BSSA, 19764:1293-1321.
[7] 林 通. 场地自振周期计算方法的比较[J]. 福建建筑, 2009,1293:70-71. LIN Tong. The comparison of some solution used in natural ground period calculate[J]. Chinese Journal of Fujian Architecture & Construction, 2009, 1293
[8] 胡聿贤. 地震工程学[M]. 2版. 北京: 地震出版社, 2006:145. HU Yu-xian. Earthquake engineering[M]. 2nd ed. Beijing:EarthquakePress, 2006
[9] IDRISS I M, SEED H B. Seismic response of horizontal soil layers[J]. Journal of the Soil Mechanics and Foundation Division, ASCE,1968, 944:1003-1034.
[10] 中国地震局工程力学研究所. 西安市阎良区地震小区划工作报告[R]. 西安: 中国地震局工程力学研究所, 2007.Institute of Engineering Mechanics, China Earthquake Administration. Seismic microzonation report of Yanliang district, Xi'an[R]. Xi'an
|
|
|
|
