Journal of Seismology and Earthquake Engineering
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Journal of Seismology and Earthquake Engineeringendaily1Sat, 01 Jan 2022 00:00:00 +0330Sat, 01 Jan 2022 00:00:00 +0330Structural Analysis of the Western Part of Shotori Mountain Range; Eastern Iran
http://www.jsee.ir/article_704788.html
NW-SE trending Shotori range has some structural elements such as folds and fractures (including thrust and strike-slip faults), following almost a similar trend. Based on the plotted stereograms, the predominant mechanism of the region&rsquo;s faults is thrust with a dextral strike slip component which implies overcoming compressive stresses in the region. On the other hand the strike-slip horizontal component of the faults may also be due to the Nayband fault activities on Shotori and Esfandiar thrust zones. The steep dip of these faults may also be due to some normal faults converted to reverse faults as a result of stress phase change from tensional to compressional. Based on planar axis perpendicular compression or stretching axis &sigma;1= 34, 10 and &sigma;3= 296, 38 were obtained for the study area. striogram axial surface folds&nbsp; dominantly show&nbsp; NW-SE direction, which is indicates&nbsp; compression axis which is equal N53, 12.Aeromagnetic data analysis revealed two magnetic lineaments with the same trends as surveyed lineaments in the field. The relatively high magnetic intensity of these lineaments could be due to basement faults in the region. With regards to obtained stereo plots, trend of the folds&rsquo; axis are parallel to the regional thrust faults and folds&rsquo; contour diagrams apply asymmetric folds with faulting in the area.Crustal Structure of the Northern Lut Block in Eastern Iran Using P Wave Receiver Function Migration
http://www.jsee.ir/article_704816.html
To investigate the crustal structure of the northeast of Lut block and Eastern Iranian Ranges, we deployed 31 seismic stations along a 230 km profile for a period of approximately 9 months. Using the migration of P-wave receiver functions, we analyzed changes in the Moho depth along this profile. Our results indicate that the boundary between the crust and upper mantle is nearly flat, with a depth of approximately 40 km. Furthermore, we found that the thickness of the crust is relatively high beneath the Lut-Afghan Block boundaries and Bagheran Mountain, where receiver functions suggest the presence of more complex structures including inclined interfaces. Our findings suggest that the collision of Lut-Afghan blocks has not significantly increased the crustal thickness in the northeast Iran compared to the Zagros collision zone in the southwest of Iran. Rather, we propose that the observed shortening in this region is primarily due to the interaction of strike-slip motions, which can accommodate shortening through mechanisms such as rotation and wedge escaping.Liquefaction-induced settlement and lateral spreading effects on buried pipelines by using shaking table tests
http://www.jsee.ir/article_704494.html
Due to the importance of buried pipelines, as one of the types of lifelines, it is necessary to consider all possible seismic hazards in their operation. Settlement and lateral spreading caused by liquefaction are among these risks. In this research, their effects have been investigated using two series of 1-g shaking table tests. Results show that the maximum displacement applied to the pipe occurs during the shake is greater than the residual displacement after the shake. Also, by investigating the shear stress-shear strain curves (hysteresis loop), the reduction of shear stiffness due to the shake was observed. After liquefaction occurs, the soil loses its shear strength and the slope starts to move downstream. It is observed that the contribution of cyclic strains due to ground vibration is far less than the contribution of strain due to monotonic displacement. According to the findings of this research, the deformation of the pipe is less than the settlement of the ground due to the liquefaction.Equivalent Linear Analysis of Semi-Infinite Free-Field Column Using PML
http://www.jsee.ir/article_704993.html
One of the important factors in determining the response of the structures is the correct evaluation of the input motion. This input excitation can be affected by various factors such as the propagation of waves in different layers, site effects, interaction of soil-structure, etc. Another problem with the numerical analysis is the use of appropriate absorbing boundaries to prevent the return of scattered waves into the analysis environment. Besides, the non-linear behavior of construction materials can also change the propagated waves, which makes the problem more complicated. One of the simple methods to estimate the nonlinear behavior of materials is to use the equivalent linear analysis method, which is still used due to its simplicity and ease of use. In this research, by preparing the finite element time domain dynamic analysis code using C programming language, the response of the free field, which is the first step in estimating the soil-structure interaction effect, has been evaluated using the equivalent linear analysis method. In addition, to increase the accuracy of the results, radiation damping simulation by perfectly matched layers (PML) has been implemented. This program uses four-nodded quadrilateral elements and the implicit Newmark method to solve the dynamic equation. For using PML in the equivalent linear method, the PML properties were updated based on adjacent elements to avoid reflection from boundaries. The results showed that the nonlinear behavior of materials can change responses significantly in a way that it be far away from results of the linear analysis. Furthermore, the results showed that the procedure adopted to perform equivalent linear analysis using PML is efficient.A Novel Numerical Iterative Procedure for Ground Motion Simulation
http://www.jsee.ir/article_704889.html
Time history analysis of structures require some carefully selected earthquake records to be employed as the input for dynamic analysis. Despite the increase in number of recorded earthquake ground motions, the need for generation of artificial accelerograms are highly demanded in some areas for some reasons. As a result, many efforts have been made to develop mathematical methods for simulating ground motions by various researchers. Since most of the methods for generation of spectrum compatible signals use relatively complex mathematical approaches, it requires engineers to make more effort and spend time to deal with these complicated methods. In order to meet engineers&rsquo; demand for generation of the above-mentioned signals while maintaining an applicable tool that is easy to utilize, a simple, numerically iterative novel procedure has been proposed which is based on linear combination of intrinsic mode functions (IMF) of recorded seismic signals evaluated by empirical mode decomposition (EMD). The proposed method requires only basics of structural dynamics and definitely all engineers are familiar with them and simply can apply the method, while it leads to results as accurate and efficient as benchmark methods such as random vibration theory and time-frequency analysis techniques. The results of this study prove the applicability of the developed approach.Blast Mitigation: Review
http://www.jsee.ir/article_704733.html
These days, an increase in terrorist attacks and advanced techniques for creating small explosive devices using powerful, high-explosive materials are causing massive building collapses, economic losses, and death. Protecting and mitigating the effects of explosions on structures and the people in them have become important to scientists. In this article, the effect of different parameters on the target structure, such as standoff distance, charge weight, and the use of protection systems, have been reviewed. It is not economical to design the main parts of the structure so that they can withstand different hazards, therefore the use of different protection systems and materials such as walls, fences, sacrificial claddings, sandwich panels, and FRP, to mitigate the blast pressure and diffracted waves, and the results of their analysis have been discussed. The role of these protection systems is to absorb high kinetic energy in the form of strain energy through deformation. It is sometimes possible to replace these systems with a new one after failure at a lower cost than structures without a protection system. This paper presents an overview for beginner researchers to study the effects of the explosion on the structures and investigate solutions to reduce these harmful effects and protect the structures, and their inhabitants.