Techno Press
Tp_Editing System.E (TES.E)
Login Search


eas
 
CONTENTS
Volume 13, Number 1, July 2017
 

Abstract
This article is all about using the MR damper with an external lever system for mitigation torsional and transitional lateral displacements by using of PID control algorithm. The torsional modes are so destructive and can be varied during an earthquake therefore, using a semi-active control system mostly recommended for them. In this paper the corner lateral displacement of each floor obtains and then it equivalents in a solid member and it connects to an MR damper, which relies to a rigid structure to reduce the response. An MR damper is a semi-active control system, which can absorb a lot of energy by injecting current to it. This amount of current is very low and needs low power supply, but it increases the amount of damper force, rather than inactive systems like viscous dampers. This paper will show the appropriate algorithm for current injection into MR damper when the eccentricity of the load is changed by using of Bouc-Wen and Bingham´s methods and illustrates the coincidence of them.

Key Words
MR damper; semi-active control system; torsion; Bingham model; Bouc-Wen model

Address
Kambiz Takin: Department of Civil Engineering, Safadasht Branch, Islamic Azad University, Tehran, Iran

Behrokh Hosseini Hashemi: Structural Engineering Research Center (SERC), International Institute of Earthquake Engineering & Seismology(IIEES),
Tehran, Iran, Member of IEEA

Masoud Nekooei: Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

Abstract
In this paper, the influence of the rotational component, about a vertical axis, of earthquake ground motion on the response of building structures subjected to seismic action is considered. The torsional component of ground motion is generated from the records of translational components. Torsional component of ground motion is then, together with translational components, applied in numerical linear dynamic analysis of different reinforced concrete framed structure of three stories buildings. In total, more than 40 numerical models were created and analyzed. The obtained results show clearly the dependence of the effects of the torsional seismic component on structural system and soil properties. Thus, the current approach in seismic codes of accounting for the effects of accidental torsion due to the torsional ground motion, by shifting the center of mass, should be reevaluated.

Key Words
torsional rigidity; translational rigidity; accidental eccentricity; seismic torsional component; torsional coupling

Address
Abderrahmane Ouazir, Asma Hadjadj and Abdelkader Benanane: epartment of Civil Engineering and Architecture, Abdel Hamid Ibn Badis University, Faculty for Sciences and Technology,
Av. Hamadou Hossine, Mostaganem 27000, Algeria


Abstract
In this study, the characteristics of site amplification at seismic observation stations in Japan were estimated using the attenuation relationship of each station´s response spectrum. Ground motion records observed after 32 earthquakes were employed to construct the attenuation relationship. The station correction factor at each KiK-net station was compared to the transfer functions between the base rock and the surface. For each station, the plot of the station correction factor versus the period was similar in shape to the graphs of the transfer function (amplitude ratio versus period). Therefore, the station correction factors are effective for evaluating site amplifications considering the period of ground shaking. In addition, the station correction factors were evaluated with respect to the average shear wave velocities using a geographic information system (GIS) dataset. Lastly, the site amplifications for specific periods were estimated throughout Japan.

Key Words
attenuation relationship; station correction factor; average shear wave velocity; site amplification

Address
Yoshihisa Maruyama: Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan

Masaki Sakemoto: Nippon Koei Co., Ltd., 1-14-6 Kudankita, Chiyoda-ku, Tokyo 102-8539, Japan


Abstract
Stone masonry is one of the oldest construction types due to the natural and free availability of stones and the relatively easy construction. Since stone masonry is brittle, it is also very vulnerable and in the case of earthquakes damage, collapses and causalities are very likely to occur, as it has been seen during the last Italian earthquake in Amatrice in 2016. In the recent years, some researchers have performed experimental tests to improve the knowledge of the behaviour of stone masonry. Concurrently, there is the need to reproduce the seismic behaviour of these structures by numerical approaches, also in consideration of the high cost of experimental tests. In this work, an alternative simplified procedure to numerically reproduce the diagonal compression and shear compression tests on a rubble stone masonry is proposed within the finite element method. The proposed procedure represents the stone units as rigid bodies and the mortar as a plastic material with compression and tension inelastic behaviour calibrated based on parametric studies. The validation of the proposed model was verified by comparison with experimental data. The advantage of this simplified methodology is the use of a limited number of degrees of freedom which allows the reduction of the computational time, which leaves the possibility to carry out parametric studies that consider different wall configurations.

Key Words
stone masonry; numerical modelling; finite element; experimental tests

Address
Nicola Tarque: Division of Civil Engineering, Pontificia Universidad Catolica del Peru, Av. Universitaria 1801, Lima, Peru

Guido Camata, Enrico Spacone: Department of Engineering and Geology, University G. D´Annunzio, Viale Pindaro 42, Pescara, Italy

Andrea Benedetti: Department of Civil, Chemical, Environmental, and Materials Engineering, University of Bologna, Via Zamboni 33, Bologna, Italy

Abstract
Displacement response and corresponding maximum response energy of structures are key parameters to assess the dynamic effect or even more destructive structural damage of the structures. By employing them, this research has compared the structural responses of jacket supported offshore wind turbine (OWT) subjected to seismic excitations apprehending earthquake incidence, when (a) soil-structure interaction (SSI) has been ignored and (b) SSI has been considered. The effect of earthquakes under arbitrary angle of excitation on the OWT has been investigated by means of the energy based wavelet transformation method. Displacement based fragility analysis is then utilized to convey the probability of exceedance of the OWT at different soil site conditions. The results show that the uncertainty arises due to multi-component seismic excitations along with the diminution trend of shear wave velocity of soil and it tends to reduce the efficiency of the OWT to stand against the ground motions.

Key Words
offshore wind turbine; soil-structure interaction; incident angle; wavelet transformation; fragility curve

Address
Faria Sharmin, Mosaruf Hussan, Dookie Kim: Department of Civil Engineering, Kunsan National University, 558 Daehak-ro, Kunsan, Jeonbuk 54150, Republic of Korea

Sung Gook Cho: Innose Tech Company Limited, Republic of Korea

Abstract
Passive dynamic vibration absorbers (DVAs) are often used to suppress the excessive vibration of a large structure due to their simple construction and low maintenance cost compared to other vibration control techniques. A new type of passive DVA consists of two pendulums connected with spring and dashpot element is investigated. This research evaluated the performance of the DVA in reducing the vibration response of a two degree of freedom shear structure. A model for the two DOF vibration system with the absorber is developed. The nominal absorber parameters are calculated using a Genetic Algorithm(GA) procedure. A parametric study is performed to evaluate the effect of each absorber parameter on performance. The simulation results show that the optimum condition for the absorber frequencies and damping ratios is mainly affected by pendulum length, mass, and the damping coefficient of the pendulum´s hinge joint. An experimental model validates the theoretical results. The simulation and experimental results show that the proposed technique is able be used as an effective alternative solution for reducing the vibration response of a multi degree of freedom vibration system.

Key Words
vibration; structure; damping; building; earthquake

Address
Mulyadi Bur, Lovely Son, Meifal Rusli: Department of Mechanical Engineering, Faculty of Engineering, Andalas University, Kampus Limau Manis 25163, Indonesia

Masaaki Okuma: Department of Mechanical and Aerospace Engineering, Tokyo Institute of Technology, 2-12-1-I3-15 Ookayama, Meguro-ku, Tokyo 152-8552, Japan


Abstract
Modern seismic codes rely on performance-based seismic design methodology which requires that the structures withstand inelastic deformation. Many studies have focused on the inelastic deformation ratio evaluation (ratio between the inelastic and elastic maximum lateral displacement demands) for various inelastic spectra. This paper investigates the inelastic response spectra through the ductility demand µ, the yield strength reduction factor Ry, and the inelastic deformation ratio. They depend on the vibration period T, the post-to-preyield stiffness ratio α, the peak ground acceleration (PGA), and the normalized yield strength coefficient η (ratio of yield strength coefficient divided by the PGA). A new inelastic deformation ratio Cη is defined; it is related to the capacity curve (pushover curve) through the coefficient (η) and the ratio (α) that are used as control parameters. A set of 140 real ground motions is selected. The structures are bilinear inelastic single degree of freedom systems (SDOF). The sensitivity of the resulting inelastic deformation ratio mean values is discussed for different levels of normalized yield strength coefficient. The influence of vibration period T, post-to-preyield stiffness ratio α, normalized yield strength coefficient η, earthquake magnitude, ruptures distance (i.e., to fault rupture) and site conditions is also investigated. A regression analysis leads to simplified expressions of this inelastic deformation ratio. These simplified equations estimate the inelastic deformation ratio for structures, which is a key parameter for design or evaluation. The results show that, for a given level of normalized yield strength coefficient, these inelastic displacement ratios become non sensitive to none of the rupture distance, the earthquake magnitude or the site class. Furthermore, they show that the post-to-preyield stiffness has a negligible effect on the inelastic deformation ratio if the normalized yield strength coefficient is greater than unity.

Key Words
deformation ratio; yield strength reduction factor; ductility; inelastic spectra; earthquakes; seismic response

Address
Benazouz Chikh, Nacer Laouami, Youcef Mehani, Abderrahmane Kibboua: National Earthquake Engineering Research Center, CGS, Rue Kaddour Rahim, BP 252 Hussein-Dey, Algiers, Algeria

Ahmed Mebarki: University Paris-Est, Laboratoire Modelisation et Simulation Multi Echelle (MSME), UMR 8208 CNRS, 5 Bd Descartes,
77454 Marne-La-Vallee, France

Moussa Leblouba: Department of Civil & Environmental Engineering, College of Engineering, University of Sharjah, P.O. Box 27272 Sharjah, United Arab Emirates

Mohamed Hadid: National School of Built and Ground Works Engineering (ENSTP), 01 Rue SidiGaridi, Vieux Kouba 16003, Algiers, Algeria

Djillali Benouar: University of Science & Technology HouariBoumediene (USTHB), Faculty of Civil Engineering, BP 32, 16111 El-Alia / Bab Ezzouar, Algiers, Algeria

Abstract
Oil storage tanks are vital life-line structures, suffered significant damages during past earthquakes. In this study, a numerical model for an unanchored vertical vaulted-type tank was established by ANSYS software, including the tank-liquid coupling, nonlinear uplift and slip effect between the tank bottom and foundation. Four actual earthquakes recorded at different soil sites were selected as input to study the dynamic characteristics of the tank by nonlinear time-history dynamic analysis, including the elephant-foot buckling, the liquid sloshing, the uplift and slip at the bottom. The results demonstrate that, obvious elephant-foot deformation and buckling failure occurred near the bottom of the tank wall under the seismic input of Class-I and Class-IV sites. The local buckling failure appeared at the location close to the elephant-foot because the axial compressive stress exceeded the allowable critical stress. Under the seismic input of Class-IV site, significant nonlinear uplift and slip occurred at the tank bottom. Large amplitude vertical sloshing with a long period occurred on the free surface of the liquid under the seismic wave record at Class-III site. The seismic properties of the storage tank were affected by site class and should be considered in the seismic design of large tanks. Effective measures should be taken to reduce the seismic response of storage tanks, and ensure the safety of tanks.

Key Words
storage tank; seismic response; tank-liquid coupling; site class; uplift; liquid sloshing

Address
Rulin Zhang, Xudong Cheng, Youhai Guan: College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao Shandong 266580, People´s Republic of China

Alexander A. Tarasenko: Industrial University of Tyumen, 38 Volodarskogo st., Tyumen, 625000, Russia

Abstract
Seismic analysis of local site conditions is fundamental for a reliable site seismic hazard assessment. It plays a major role in mitigation of seismic damage potential through the prediction of surface ground motion in terms of amplitude, frequency content and duration. Such analysis requires the determination of the transfer function, which is a simple tool for characterizing a soil profile by estimating its vibration frequencies and its amplification potential. In this study, numerical simulations are carried out and are then combined with a statistical study to allow the characterization of design sites classified by the Algerian Building Seismic Code (RPA99, ver 2003), by average transfer functions. The mean transfer functions are thereafter used to compute RPA99 average site factors. In this regard, coming up seismic fields are simulated based on Power Spectral Density Functions (PSDF) defined at the rock basement. Results are also used to compute average site factor where, actual and synthetic time histories are introduced. In absence of measurement data, it is found that the proposed approach can be used for a better soil characterization.

Key Words
transfer function; simulation; RPA99; site factor; Power Spectral Density; random vibrations

Address
Mohamed Beneldjouzi: Water, environment, Geomaterials and structures laboratory (LEEGO), Faculty of Civil Engineering, University of Science and Technology Houari Boumediene, Algiers, 16111, Algeria

Nasser Laouami and Abdennasser Slimani: Earthquake Engineering Applied Research Center (CGS), Rue Kaddour Rahim, Algiers, 16040, Algeria


Abstract
The focus of this paper is the study on the seismic performance of RC buildings with two different connections at the base level under near-fault earthquakes. It is well-known that the impulsive nature of the near-fault ground motions causes severe damages to framed buildings especially at base connections. In the scope of this study, two types of 3-dimensional RC Moment Frames with Fixed Support (MFFS) and Hinged Support (MFHS) containing 5 and 10 stories are assessed under an ensemble of 11 strong ground motions by implementing nonlinear response history analysis. The most vulnerable locations of MFFS, are the connections of corner columns to foundation especially under strong earthquakes. On the other hand, using beams at the base level as well as hinged base connections in MFHS buildings, prevents damages of corner columns and achieves more ductile behavior. Results denote that the MFHS including Base Level Beams (BLB) significantly shows better behavior compared with MFFS, particularly under pulse-type records. Additionally, the first story beams and also interior components undergo more actions. Role of the BLBs are similar to fuses decreasing the flexural moments of the corner columns. The BLBs can be constructed as replaceable members which provide the reparability of structures.

Key Words
seismic performance; RC moment frame; hinged base; base level beam; near-fault ground motions

Address
Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran, 15719-14911, Iran


Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2018 Techno-Press
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Tel: +82-42-828-7996, Fax : +82-42-828-7997, Email: info@techno-press.com