پژوهشنامه زلزله شناسی و مهندسی زلزله
سال هفدهم شماره 1 (پیاپی 64، 1393)

LOTOS Code-12 was submitted in December 2012 by Ivan Koulakov. This code can operate on regional and local scales and can be applied to very different data sets without complicated tuning of parameters. It is used to calculate the three-dimensional velocity model and the parameters of sources simultaneously. Location of sources is determined by probabilistic method using Goal Function which reflects the probability of the source location in the current point. The ray tracing is according to Fermat principle of travel time minimization which uses its own modification of bending algorithm to find the shortest ray path. Besides the inversion for Vp and Vs there is a possibility for Vp-Vp/Vs inversion. The algorithm of this code consists of 3 main steps: first of all it optimizes the 1D velocity model and finds the preliminary location of sources simultaneously then relocates the sources in 3D velocity model, and finally the simultaneous inversion for the sources parameters and velocity model will be found. In this code there are two different choices to parameterization of the velocity distribution: parameterization with nodes and grids. In the absence of rays, no nodes are installed and the least the ray density is, the most the distances between nodes are. This code has a parameter for describing the minimum distance between nodes to avoid the excessive concentration of nodes in the parts with high ray density. To reduce the artificial effects of nodes and cells distribution on the final result, LOTOS applies the inversion on several grids with different orientation then it computes the result for each grid and finally averages them into one summary model. This code has some free inversion parameters such as “Damping”, “Smoothing coefficients” and “Iteration”. The most effective and unbiased way to evaluate optimal values of these free inversion parameters is by performing synthetic modeling that reproduces the real situation. For this purpose, one should apply the inversion on different values of a free parameter and by using synthetic tests, choose the best value for each. The most important and difficult task in inverse problems is not only showing the result, but also providing convincing arguments shows that the results conforms to the real structure. For this reason researches take the benefits of synthetic tests. These tests are also useful to test the accuracy of the final results. This code has different options to make synthetic tests. The different ways to introduce synthetic models are synthetic horizontal and vertical checkerboard and synthetic vertical and horizontal free anomalies tests. Beside these different options of making synthetic models, this code has the ability to produce artificial noise which synthetic data can be perturbed with them. This option helps us to be more confident about the results, because the real data always has noises from various sources. We used LOTOS12 code for local tomographic study of most eastern Zagros, and todetermine the optimum values of free inversion parameters. We used 2 synthetic tests, synthetic horizontal and vertical checkerboard and oblique strips. Finally to check the end result these test were used too.

Tsunamis happen when seismic waves pass through water in deep seas and make high marine waves. These waves proceed very fast to shoreline and by decreasing the depth of water, grow in height in a wave shoaling process. The fast and high marine waves when reaching to offshore, cause lots of damages. Although most part of Caspian Sea is shallower than tsunamis can be happened, in south part and near to Iranian shorelines, depth increase more than 1000 meter. Therefore, it is necessary that danger of tsunami in this sea to be considered and studied. In this study, first, mechanism of and effective parameters on tsunami is presented. Tsunamis can be stimulated by earthquakes, submarine landslides, mud volcanos ormeteorites. In the earthquake stimulated cases, the main parameters affect the intensity of tsunamis including: magnitude, mechanism and focal depth. In the Caspian Sea, historical studies decelerate thatsome suspicious phenomenon reported which can be interpreted as tsunami. Here, the modeling studies were done for tsunami prediction in Caspian Sea, also reviewed. Based on these studies, tsunami with 3 m waves can be expected in Caspian Sea.

Recent advances in evaluation of earthquake-induced permanent displacement of earth systems are addressed herein. Currently, seismic design of geotechnical structures emphasize on the quantification of system performance with the prescribed levels of permanent displacements. Accordingly, evaluation of earthquake-induced permanent displacement in geotechnical structures such as earth embankments and slopes is a topic of consideration for the geotechnical engineers. Different studies are available for estimating earthquake-induced permanent deformation of earth slopes and embankments. In general, these studies can be divided into three categories: analytical and semi-analytical, empirical and semiempirical, and numerical studies. Analytical and semi-analytical studies are simplified dynamic methods based on Newmarkian rigid block analogy. Based on this analogy, the rigid block displaces once the exciting acceleration exceeds the critical (or yield) acceleration. The original Newmarkian analogy assumes the sliding mass as the rigid block directly subjected to the input acceleration. The decoupled analysis is based on a rigid block but dynamic response of the system is calculated to obtain the equivalent acceleration as the input motion for the sliding block analysis. The decoupled analysis does not consider dynamic response of the slipped mass, while this response affects the overall behavior of the system. In a fully coupled analysis, dynamic response of the sliding mass and the permanent displacement are modeled together so that the effect of sliding displacement on the ground motions is taken into account. Through the empirical approaches, researchers developed correlations to predict seismicallyinduced displacement of slopes using databases of field case histories. These studies make clear that traditional rigid block analysis does not yield acceptable results for the seismic performance of large engineered earth structures. Besides, they provided detailed treatments of specific combinations of site and shaking conditions that are and are not adequately modeled by rigid-block analysis. Furthermore, other semi-empirical correlations have been presented based on the results of the analytical and semianalytical approaches. The third category aims to incorporate advanced constitutive models and numerical procedures such as finite difference, finite element, discrete element, and hybrid methods. This category soon began to be applied to slopes, particularly earth dams, and it provided a valuable tool for modeling the static and dynamic deformation of soil systems. However, advanced constitutive models, which are capable for simulation of soil behavior under dynamic loading, commonly require many parameters such as a high density of high-quality data and sophisticated soil-constitutive models. This problem may prevent prevalent usage of the advanced numerical approaches for estimation of earth slope displacement. For this reason, use of simplified method is preferable for evaluation of seismic permanent displacement. In this paper, major studies and recent developments on the methods of seismic slope displacement are explained based on the aforementioned categories. Moreover, advantages and disadvantages of the recent approaches are explained.

Mass dampers have been used in recent years as a device for passive control of structures subjected to lateral load due to wind and earthquake. This device, which consists of a mass connected to a spring and a damper, is usually installed at the upper story of the building, and its mass is relatively small compared to the mass of the building and even building’s story. In this study, the control mass is very large and is resting on rollers at the building’s foundation level, and its inertia force is transferred into the building’s structure by a relatively stiff structure, connected to the upper story of the building, and can decrease the seismic response of the building by its interactive effect. It is assumed that the building has a large void at its middle, which can place the relatively stiff structure connecting the control mass to the building roof. In this research, three buildings, having five, eight, and eleven stories equipped with the proposed control mass have been studied. For this purpose, seven three-component accelerograms with PGA values of 0.3g to 0.8g have been used for a series of time history analysis (THA). The considered buildings have been designed based on Iranian Standard No. 2800 for seismic loading, assuming type II for site soil, and AISC89-ASD for design of steel members, considering moment frames as the load bearing system. Compatible with the site soil, the selected records for THA cover a relatively wide range of input frequencies to make it possible to investigate the performance of the proposed control system with relatively high generality. The used earthquake for this purpose include San Fernando, Friuli (Italy), Tabas, Coyote Lake, Northridge (from two stations), and Kobe. The PGA values of the selected records varies from o.27g to 0.88g for horizontal components and from 0.15g to 0.40g for vertical component, and their duration varies between 23.78 sec and 47.94 sec. Various amounts have been considered for the control mass and its corresponding stiffness and damping to find the optimal values for each building. Maximum roof displacements in two main horizontal directions, and in two states of without and with the control mass have been used as the response value for comparing different cases. Results of THA show that using the proposed control mass with appropriate stiffness and damping corresponding values can decrease the seismic response of buildings around 40% in average.

In a dual system, the total seismic resistance is to be provided by the combination of the moment frames and the shear walls or braced frames in proportion to their lateral rigidities. Shear force distribution between the frame and the shear walls in the wall-frame system is an important issue in the earthquake engineering; and therefore, it has been considered in different building codes such as the Iranian Standard No. 2800 or ASCE7. Based on Standard No. 2800 or ASCE7, a wall frame system can be considered as a dual system if the moment frames shall be capable of resisting at least 25 percent of the design seismic forces. There are some different methods in professional engineering for application of this code regulation. In this paper, these methods and their effects on the strength of the structure and lateral force distribution between the frames and the shear walls have been evaluated. In these methods, in order to eliminate the load resisting ability of the shear walls, shear walls are eliminated from the finite element model or without eliminating shear walls, their characteristic parameters are modified. Moreover, to evaluate the effect of the above mentioned code regulation, some building structures have been modeled without considering this regulation. For this purpose, two-dimensional reinforced concrete wall-frame models with different number of stories (5, 10 and 15 stories) have been designed and analyzed. Each frame model has three spans. Shear wall is in the inner span with a length of 4 m. The height of stories and the length of outer spans are 3 m and 6 m, respectively. The frames were designed due to the gravity and lateral loads according to the specifications of Iranian codes. At first, linear static analyses of the frames were performed by the EATABS2000 software. Then nonlinear static and nonlinear time-history analyses were done on the frames subjected to different strong ground motions using PERFORM-3D. The results of the pushover and time history analyses show that in some of these methods to apply the above mentioned regulation, there are not significant differences in the results, whereas in some other methods to eliminate the load resisting ability of the shear walls with modification of wall and adjacent columns parameters, changes in the results are remarkable. In the latter method, the number of elements with inelastic behavior decreases. In all methods, the contribution of shear walls is lower in the upper stories in comparison with the lower stories. In all structural models in which the moment frames have capable of resisting at least 25 percent of the design seismic forces, the contribution of the moment frames in the absorption of the base shear is between 1.7 to 7.2 percent in linear analyses and between 1.9 to 7.3 percent in nonlinear dynamic analyses.

Knowing the behavior of Bam people in the time of earthquakes, can be an effective factor in revising the educational methods and behavioral patterns of people during earthquakes. In this paper, the ideas and perspectives of those who have experienced the 2003 Bam Earthquake, will be evaluated. In this research, the behavior and condition of Bam people in the time of the earthquake, their awareness about sheltering, the causes of earthquake and the safety issues have been assessed after ten years. At the end, the effect of this earthquake on people’s degree of attention in learning correct sheltering, and their reaction in the time of a probable earthquake is assessed. In this research, survey research and simple random sampling have been used. The necessary information has been analyzed and discussed based on interviews and questionnaires. The findings revealed that most of the people experience fear during the earthquake. Most of these people have received their information about earthquake through formal education (school and school textbooks). They believed that face to face education can be very effective. In this research, it was revealed that even in the countries with high disaster education knowledge, only half of the people take the correct sheltering at the time of earthquakes. The DCH method has been advised in Iran as correct sheltering.