Journal of Seismology and Earthquake Engineering
Volume:23 Issue: 4, Autumn 2021

In this study, a new method is introduced for visualizing the vector data for the first time. This method is based on RGB attributing each rectangular cell within a grid with a specific square mesh size. Two different quantities are introduced, namely unidirectional and bidirectional, which will be illustrated using the two color circle types 1 and 2 as color scales. Seeking the correct illustration of the directions with a color scale, the opposite directions (SHmax) should be of the same color, making the problem more sophisticated so that the usual color wheel cannot be used. As an example, the SHmax variations in the Zagros Makran transition zone was mapped by using this new approach. Maximum horizontal stress directions are extracted from available earthquake focal mechanism data. The results show important variations in SHmax direction, which reflect the complicated tectonic environment of the study area. Several anomalies in the direction of SHmax are observed in the study area for the first time by implementing the proposed new method. Some of the anomalies take place in the areas where deeper earthquakes occur. This may imply the decoupling between the shallow seismogenic zone within the sedimentary cover and the crystalline basement, responsible for deeper events.

The first step in many seismological studies is identifying and locating the seismic events. The small magnitude earthquakes, due to their rate of occurrence and abundance, are of great importance to seismologists, contrary to the engineers and city residents. However, due to the attenuation of seismic waves and the unavoidable noise in the seismic stations, very dense seismographic networks are required for detecting small events. The Matched-Filter technique is an approach based on signal processing, which makes it possible for seismologists to identify the seismic phases with very low signal-to-noise ratios by improving the detection capability of the seismic networks in case of repeating events. The goal of this study is to depict the points that must be considered when employing the Matched-Filter approach. As a result, sensitivity tests were performed on each parameter to demonstrate their importance and effectiveness in influencing the outcomes of utilizing this technique on a local seismic network. The statistical studies revealed that selecting incorrect values reduces the quality of the identifications and may potentially result in mistakes. Finally, depending on the assessments and settings chosen, this method utilized to process 95 days of continuous data from a local temporary seismographic network demonstrates the technique's capability.

Gas transmission pipelines will expand when they are put into operation under the influence of increased internal pressure and temperature. The movement due to such expansion is significant for large diameter pipelines which operate at high pressure and elevated temperature. The pipeline needs to be restrained near compressor stations in order to prevent the transmission of such movement to equipment and facilities within the station. Concrete anchor blocks are commonly used to restrain the movement of buried pipelines on both sides of compressor stations. Anchor blocks for transmission pipelines are usually massive because of the high axial stress in the pipe which results in large thrust force. Current design procedures are usually based on providing an adequate margin of safety against block sliding, block overturning and soil bearing pressure.This paper presents the results of an analytical study on the response of soil, pipeline and anchor block at different operating pressure and temperatures. Nonlinear finite element analyses which include modeling of soil-pipe and soil-block interactions are carried out to evaluate the design procedures. The results indicate that the concept used in current design procedures is fundamentally flawed because it is based on controlling forces rather displacements. Furthermore, both the thrust force and the resistance capacity are grossly miscalculated. The thrust force is significantly overestimated because it is based on a fully restrained anchor. The resistance capacity of the block which is calculated based on full mobilization of the passive resistance of soil is also drastically miscalculated because only a fraction of the passive resistance is mobilized.

In this paper, the seismic performance of concentrically braced steel frames equipped with TADAS damper has been investigated with emphasis on earthquake uncertainties. For this purpose, first, relying on laboratory and finite element results, the behavioral model of TADAS damper has been presented and verified. Afterwards, adopting the TADAS damper connection model and non-linear conditions, two-dimensional moment frames were used with 4 m floor height and length of different spans in FEMA P695 regulations and also 10 records were used that have the highest PGA in FEMA P695. To reflect the uncertainties associated with earthquakes, the incremental dynamic analysis procedure was performed.The procedure outcomes, which consist of more than2500nonlinear dynamic analyzes, Thus, nonlinear dynamic analysis of the studied structures was performed and the results of these analyzes were used to estimate the performance of the frames in terms such “limit-state frequencies”, “seismic demand hazard curve”. The results may be used in comparing the studied structures with similar other structures and also as a crisis to the prescriptions issued by design guidelines for the structures under consideration and reveal the difference between the collapse behaviors of low and high-rise structures.

This study aimed to explore the seismic responses of the water-filled prestressed concrete cylindrical tanks. To this end, a number of dynamic-explicit studies are carried out in order to investigate the implications that the water sloshing phenomenon has on the behavior of the prestressed concrete tank when it is subjected to earthquake inputs. Using previous research demonstrates that our numerical analysis is capable of representing the sloshing waves. In addition, a shaking table test is carried out to verify the accuracy of the numerical analysis. The main highlight of the numerical simulation method is to consider all components and elaborate detailing of prestressed tanks. The novelty of this study is to model the 3D sloshing of the liquid in the prestressed concrete tanks. Comparing the experimental and numerical results demonstrates a reasonable agreement between them. Also, in this research, the dynamic-explicit method is applied accompanying the Arbitrary Lagrangian–Eulerian (ALE) adaptive meshing to enhance the numerical model for nonlinear sloshing wave simulation. An experiment is performed on a prestressed concrete containment sample in the shaking table of the Amirkabir University of Technology to assess the efficiency of numerical analysis. The numerical results show the robustness of the water simulation method in which almost shows realistic motions of water mass points in the ALE method.

The seismic design of buildings in approximately all common seismic design codes is based on the equivalent static force procedure this procedure has failed to provide insight into how the building behaves during earthquakes. The nonlinear analyses in performance-based design procedure provide the tools for calculating structural response beyond the elastic limit. Hence, nonlinear analysis has an important role in the design of existing and new buildings. In this study, a performance-based procedure for the seismic design of reinforced concrete (RC) special moment frames is presented. The proposed method includes nonlinear static analysis in accordance with appendix 2 of BHRC and nonlinear dynamic analysis in accordance with chapter 16 of FEMA P-2082-1. The proposed method has been systematically applied to the design of a regular multistory 3-dimensional (3D) RC special moment frame then; its seismic performance has been compared with that of a similar frame designed according to BHRC under an ensemble of 22 near-fault and far-fault ground motions. The results show that the proposed method can better achieve the optimal strength distribution pattern over conventional method. Buildings designed with the proposed method showed better seismic performance than those designed according to the standard code. In addition, this method has been shown to be more economical than conventional design methods.