International Institute of Earthquake Engineering and Seismology
Journal of Seismology and Earthquake Engineering
1735-1669
2821-2541
21
3
2019
08
01
Statistical Analysis of the Inter-Event Time, Distance, and Migrating Trend Distribution of Successive Large Earthquakes in Iran
1
12
EN
Seyed Naser
Hashemi
School of Earth Sciences, Damghan University, Damghan
hashemi@du.ac.ir
10.48303/jsee.2019.241705
In this study, the waiting time, spatial distance, and migrating trend pattern of<br />successive large earthquakes in Iran have been investigated. In order to carry out<br />this work, the earthquake data of Iran with M >= 4.5 (1976-2018) have been<br />obtained from the USGS catalog. Then, the statistical distribution of the Interevent<br />time, migrating distance, and directional trend of migration of successive<br />events were studied using different lower magnitude thresholds. The statistical and<br />probability distributions of inter-event times of earthquakes were assessed and<br />modelled by different distribution models. Furthermore, the directional analysis<br />of migrating trends, as well as the spatial distances of successive events with<br />different lower magnitude, was carried out. It is observed that the inter-event time<br />distribution of earthquakes can be quite well fitted by the Gamma distribution<br />model. The results obtained also indicate a decreasing trend in spatial distance<br />distribution and a meaningful correlation between the directional pattern of the<br />migrating trends of successive events and the dominant trends of the active faults of<br />the region. The results of this study can be considered as an effective step to better<br />understanding the temporal-spatial pattern of seismicity in Iran and also as an<br />attempt to achieve earthquake prediction in this country, in a regional scale.
Inter-event time distribution,Statistical distribution of earthquakes,Spatio-temporal analysis,Seismicity,Seismotectonics
http://www.jsee.ir/article_241705.html
http://www.jsee.ir/article_241705_8fd2e6e8e1745c2fbd689e04d3224c5a.pdf
International Institute of Earthquake Engineering and Seismology
Journal of Seismology and Earthquake Engineering
1735-1669
2821-2541
21
3
2019
08
01
An Experimental Study of Insufficient Free Board Effect on Fixed-Roof Cylindrical Tank Seismic Loads
13
30
EN
Mojtaba
Moosapoor
International Institute of Earthquake Engineering and Seismology
m.moosapoor09@gmail.com
Mohammad Mehdi
Yousefi
Babol Noshirvani University of Technology (BUT)
Mohammad Ali
Goudarzi
International Institute of Earthquake Engineering and Seismology
goudarzi.ma@gmail.com
10.48303/jsee.2019.241706
Cylindrical tanks are fundamental structures used for the storage of liquids.<br />Sloshing caused by earthquakes in tanks without enough freeboard leads to a<br />liquid impact on the roof of tanks. This study aims to explore the base shear<br />variation due to insufficient freeboard using experimental and numerical methods.<br />The experimental tests are performed using a cylindrical liquid tank excited by<br />various harmonic loads. The impact of some parameters such as the water height to<br />tank radius ratio and freeboard on base shear force are investigated by conducting<br />90 tests. Impulsive and convective masses for simplified mass-spring are modified<br />in numerical models so that experimental and numerical base shear results<br />are consistent. Finally, a simple analytical solution to estimate the reduction of<br />convective mass due to insufficient freeboard is suggested and validated using<br />experimental results.
Liquid Tanks,Strengthening,Seismic Behavior,Numerical Methods
http://www.jsee.ir/article_241706.html
http://www.jsee.ir/article_241706_8cb38d9b808db26d950f8f3cf971c371.pdf
International Institute of Earthquake Engineering and Seismology
Journal of Seismology and Earthquake Engineering
1735-1669
2821-2541
21
3
2019
08
01
Friction-Slip Connections for Moment Frames with Continuous Beams
31
48
EN
Fereshteh
Seifan
University of Tehran, Tehran
fereshteh.saifan@gmail.com
Seyed Rasoul
MirGhaderi
University of Tehran, Tehran
Mehdi
Ghassemieh
University of Tehran, Tehran
10.48303/jsee.2019.241707
This paper presents an assessment on a friction-slip connection for moment frames<br />with continuous beams based on the current detail. It also proposes a new configuration<br />for rigid connections in moment frames with continuous beams, which<br />can be developed as a friction-slip connection. In conventional moment frames,<br />beams are placed between two adjacent columns and connected to the column<br />flanges faces. However, in moment frames with continuous beams, two beams are<br />continuously passed next to the column. In the existing practice for connections in<br />these frames, two vertical connection plates placed on column flanges, and the<br />beams are connecting to these plates via their wings. In the mentioned detail, it was<br />assumed that the load transfers with in-plane action between connection plates<br />and column; therefore, the design force is pure shear, and based on the design<br />procedure, it should have been able to be developed for a friction-slip connection.<br />However, the results showed that the out-of-plane action of RPLs could be significant;<br />although this action provides extra capacity in moment connections, it<br />is not desirable in friction connections due to changes in the developed forces<br />in pretension bolts. Based on this action, a locking occurs, which changes the<br />performance of the connection considerably. As an alternative to this detail, a new<br />configuration is proposed in this paper, which can also be used as a friction-slip <br />connection and provides a friction connection in moment frames with continuous<br />beams. In new detail, by eliminating the effect of connection plate thickness, the<br />friction joint works as expected. Thus, instead of the plastic behavior of structural<br />elements, these friction joints can be used as an energy-dissipating system.
Friction-slip connection,Bolted connection,Continuous beams,Moment frame
http://www.jsee.ir/article_241707.html
http://www.jsee.ir/article_241707_4165ebfdf706cbbbafe869278ba377ef.pdf
International Institute of Earthquake Engineering and Seismology
Journal of Seismology and Earthquake Engineering
1735-1669
2821-2541
21
3
2019
08
01
Design of Mass Isolated Structures with Consideration of Stability Constraints
49
63
EN
Mohammad
Boujary
International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran
m.boujary@iiees.ac.ir
Mansour
Ziyaeifar
International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran
mansour@iiees.ac.ir
10.48303/jsee.2019.241708
Vertical mass isolation is one of the new techniques in the seismic design of<br />structures that consists of two stiff and soft substructures connected by viscous dampers.<br />Adding to the flexibility and energy dissipation potential of the system is the main<br />feature of some new approaches in the seismic design of structures. Extra flexibility<br />helps to reduce earthquake-induced forces and accelerations in the building and<br />provides higher energy dissipation potential for the system (by creating large<br />relative deformations in the structure). Mass subsystem possesses low lateral<br />stiffness but carries the major part of the mass system. Stiffness subsystem, however,<br />controls the deformation of the mass subsystem and attributes with much higher<br />stiffness. In this paper, the aim is to find the limitation of the stability of a<br />soft structure and to obtain the maximum period available for a soft structure.<br />According to the studies, the most important obstruction in increasing the period<br />of the soft structure, assuming control of its deformation by connecting to the<br />stiff substructure, is to maintain the stability of the structure. In this paper, first, a<br />relationship has been presented to calculate the period of the structure in terms of<br />the stability factor that estimates the period of structure with good agreement by<br />analytical results. This paper deals with presenting a procedure for designing the<br />Mass Isolation System (MIS) with consideration of stability constraints. To this end,<br />the paper presents mathematical solutions to calculate the period of the structure<br />followed by proposing a design procedure of the soft substructure.
Mass isolation,Structural stability,P-Delta effect,Collapse prevention
http://www.jsee.ir/article_241708.html
http://www.jsee.ir/article_241708_28feb50fb53d5a1f6393681ddb029cdf.pdf
International Institute of Earthquake Engineering and Seismology
Journal of Seismology and Earthquake Engineering
1735-1669
2821-2541
21
3
2019
08
01
Detection of Long-Range Correlations and Trends Between Earthquakes in California
65
75
EN
Yasaman
Maleki
Alzahra University
y.maleki@alzahra.ac.ir
Mostafa
Allamehzadeh
International Institute of Earthquake Engineering and Seismology
zadeh66@hotmail.com
10.48303/jsee.2019.241709
In this paper, we investigate the long-range correlations and trends between<br />consecutive earthquakes by means of the scaling parameter so-called locally Hurst<br />parameter, H(t), and examine its variations in time, to find a specific pattern that<br />exists between Earthquakes. The long-range correlations are usaully detected<br />by calculating a constant Hurst parameter. However, the multi-fractal structure of<br />earthquakes caused that more than one scaling exponent is needed to account<br />for the scaling properties of such processes. Thus, in this paper, we consider the<br />time-dependent Hurst exponent to realize scale variations in trend and correlations<br />between consecutive seismic activities, for all times. We apply the Hilbert-Huang<br />transform to estimate H(t) for the time series extracted from seismic activities<br />occurred in California during 12 years, from 2/24/2007 to 9/29/2017. The superiority<br />of the method is discovering some specific hidden patterns that exist between<br />consecutive earthquakes, by studying the trend and variations of H(t). Estimationg<br />H(t) only as a measure of dependency, may lead to misleading results, but using this<br />method, the trend and variations of the parameter is studying to discover hidden<br />dependencies between consecutive earthquakes. Recognizing such dependency<br />patterns can help us in prediction of future main shocks.
Long-range dependence,Time-dependent Hurst exponent,Hilbert-Huang transform,Empirical Mode Decomposition,Seismic activities
http://www.jsee.ir/article_241709.html
http://www.jsee.ir/article_241709_4f9810e968789cc379d7b862c8d36934.pdf
International Institute of Earthquake Engineering and Seismology
Journal of Seismology and Earthquake Engineering
1735-1669
2821-2541
21
3
2019
08
01
Seismic Response Evaluation of Kashan Historical Bazaar Structure Including Soil-Structure Interaction
77
93
EN
Amirhossein
Lazizi
Civil Engineering Department, The University of Kashan, Kashan
Hossein
Tahghighi
Civil Engineering Department, The University of Kashan, Kashan
tahghighi@kashanu.ac.ir
10.48303/jsee.2019.241710
Historical heritage structures are especially vulnerable to earthquakes because<br />they were designed only for gravity loads without any consideration of lateral<br />loads. For this reason, the preservation and maintenance of these structures are of<br />great cultural, economic, and social importance. The present study investigates the<br />seismic vulnerability of a historical structure called Kashan Bazaar, located in<br />Kashan (central Iran), dating back to the 17th century. The detailed 3D geometrical<br />model of this structure was drawn using SolidWorks software. Finite element<br />numerical method was used to evaluate the response of Bazaar structure using<br />macro-modeling approach. Static, modal, and nonlinear static (pushover) analyses<br />were carried out using two cases, with soil-structure interaction (SSI) and without<br />SSI (fixed-base). According to the results, considering the SSI has a significant<br />influence on the mode shapes, vibration frequencies, and the structural responses.<br />The structure of Bazaar can withstand gravity loads as well as DBE demands<br />in fixed-base model. However, the results of the SSI analyses show the structure<br />weakness against lateral loads.
Kashan historical Bazaar,finite element method,Nonlinear Static Analysis,Soil-Structure Interaction,Seismic Assessment
http://www.jsee.ir/article_241710.html
http://www.jsee.ir/article_241710_cd8bad5da8208a0fbce894568aa2c0c0.pdf