Volume 17, Issue 4 (2017)                   IQBQ 2017, 17(4): 141-152 | Back to browse issues page

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Ghassemieh M, hasani sokhtesarae M, bastami M. Suitable Remote Range Strong Motion Accelerograms for three-dimensional non-linear analysis for Tehran,Iran. IQBQ. 2017; 17 (4) :141-152
URL: http://journals.modares.ac.ir/article-16-1002-en.html
1- Professor of Structural Engineering School of Civil Engineering University of Tehran
Abstract:   (1399 Views)
In regions that are susceptible to earthquake occurrence, designing large and engineering developed structures such as tall buildings, dams and bridges most often requires quantitative dynamic analysis. Engineers discuss important questions on possible magnitude of earthquake in the zones under construction and require knowledge on the movements or the spectrums enforces and/or defining parameters. Time history analysis is the most natural analytical method compatible with the physical behaviors in the course of earthquake in a way that structures are performed by including the effects of earth acceleration as a function of time being applied in the structural base. The accelerograms which are used in analyzing the chronological history in determining the impacts of earth movement must reveal the actual movements of earth in the construction site of the structure during earthquake; As a result, selecting accelerogram is very important in analyzing the chronology. Unfortunately, the point that suitable records must be selected with respect to the conditions that govern seismic source, the geological characteristics, tectonic distance from fault and the largeness of the zone is usually neglected. Our country is located in one of the most active seismic regions in the world. According to the scientific information and documents, Iran is one of the riskiest regions of the world and is exposed to serious damage from earthquake. In the recent years, there has been an earthquake with large physical and financial casualties in one of the regions of the country once every five years in average. Presently, Iran is on top of the list of countries where earthquake is associated with life casualties. It is very difficult to fully prevent damages caused by high magnitude earthquakes. This is especially important in the city of Tehran with the very large population that lives in it, and is encircled by several active faults. The main goal of this research is to prepare a suitable list of remote range strong motion accelerograms to be used in nonlinear analysis in Tehran. The main focus of this research is to study all parameters that are effective in selecting suitable strong motion accelerogram in Tehran and for this purpose, 1000 strong motion accelerograms from earthquakes that occurred in Iran between 1978 through 2007 were studied and the entire parameters effective in selecting suitable strong motion accelerograms for the city of Tehran including distance, magnitude, frequency contents, earthquake mechanism, soil and specifications of earth strata were reviewed. Ultimately, a suitable list of strong motion accelerograms is presented to be used in nonlinear three-dimensional analysis. To achieve this goal, the geological and geotechnique features of the region were studied. In addition, the mechanism of active faults in the region were studied as well and by considering the parameters of magnitude, the focal depth, the distance of registry stations to the earthquake place, the geology studies of the records registry stations, mechanism and the frequency contents of a series of the accelerograms are suggested to reveal the actual movement of earth in Tehran as much as possible; if modeling and chronological history analysis are bi-dimensional, it will be possible to use 28 categories alongside and orthogonal with the faults in the suggested list. It should be noted that to analyze the chronology, only those accelerograms were used which could be scaled with the spectrum of the standard plan of the region and prove compatible with the frequency period of the structure. Minimum moment magnitude in the mentioned list is equal to 5.6 and maximum moment magnitude is 7.4. The mean magnitude in this list is 6.45. The mean maximum earth acceleration for the list was equal to 0.191g. The dominant mean period in the list is 0.64 seconds. The dominant frequency in this collection of accelerogram includes a large frequency range; therefore, suitable stimulation could be anticipated from this list for various structures.
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Article Type: Technical Note | Subject: ---------
Received: 2016/01/29 | Accepted: 2017/03/13 | Published: 2017/10/23

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