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    Evaluation of the Performance of Passive TMDs in Damage Reduction of 2-D Concrete Structure from Energy Point of View

    , M.Sc. Thesis Sharif University of Technology Ardalan, Amir Khosro (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
    Up to now, many seismic design methods and construction technologies have been investigated to reduce the seismic responses of bridges, buildings and potentially vulnerable structures. [1] Introducing a new effective systems aim to control of vibration caused by earthquake on the structures will be useful. This system is based on repelling of imposed force to the structures with tuned mass dampers (TMDs), to gain minimum damage. The detuning of the structures by equipped with TMDs resulted from nonlinear behavior due to dynamic loads such as strong ground motions are real concern in the practical applications. The application of TMDs, as expected, can reduce the deformation of the... 

    Development of Fragility Curves for Tehran Multi-Cell Box Girder Bridges

    , M.Sc. Thesis Sharif University of Technology Salili, Sahand (Author) ; Bakhshi, Ali (Supervisor)
    Bridges are one of the most important parts of the transportation network and play an important role in relief after earthquakes. Therefore, detecting where and how much damage take place is vital. Bridge structure is consist of two parts: substructure and superstructure. Usually, superstructure remains intact during earthquake because of rigidity and high strength of it. In the other hand, damage localizes to substructure. We also use high safety factor to piles and cap piles so they experience little or no damage. As a result, columns suffer damage more than other parts. In this study, the focus is on columns damage. This study also is limited to non-prestressed multi-cell box girder... 

    Seismic performance of a variable stiffness system

    , Article Asian Journal of Civil Engineering ; Volume 12, Issue 3 , June , 2011 , Pages 375-393 ; 15630854 (ISSN) Tabeshpour, M. R ; Golafshani, A. A ; Monzavi, M ; Sharif University of Technology
    In this paper a new ribbed bracing system (RBS) is proposed capable of performing as a variable stiffness system that can be used for controlling structural deformations and frequency shifting to compensate seismic energy. RBS has two important advantages. Because of ribbed system, the compressive member is rigidly moved like a piston and a cylinder and therefore it is a buckling prevented system. Also it is possible to use this system as a semi-active system by considering the story drifts and global structural damage and control the system if it is necessary to be open or closed based on the operational criteria assigned in the system. RBS has no need to any actuator and large power... 

    Evaluation of the Performance of Passive TMDs in Damage Reduction of 2-D Concrete Structures

    , M.Sc. Thesis Sharif University of Technology Abtahi, Pooya (Author) ; Rahimzadeh Rofooei, Fayaz (Supervisor)
    The detuning of the structures equipped with Tuned Mass Dampers (TMDs) caused by their nonlinear behavior under strong ground motions is a real concern in their practical application. This thesis presents a feasibility study on the effectiveness of TMDs in reducing the seismic response and the resulting structural damage of reinforced concrete structures under intense ground motion. A number of 2-D concrete moment resisting frames with different numbers of stories are considered. TMDs are used as a mean to protect these structural models against ground excitation. The mass of TMDs are varied from 1% to 5% of the first effective modal mass of the structural models. IDARC 2-D program is used... 

    Damage in RC Moment Frames under near Field Earthquakes using Damage Index Criterion

    , M.Sc. Thesis Sharif University of Technology Zinati Yazdi, Morteza (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Heavy damage developed from near field earthquake in resent years cause serious attention to this problem. Investigation shows that these records include large energy pulse, unlike far field earthquake. Overall effect of near field earthquakes ignored in the most building codes. The purpose of this investigation to find effect of near field earthquake on reinforced concrete moment frames. To achieve this goal Erduran damage index is efficient way to calculate damage. Two 4th and 8th story reinforcement concrete moment frame buildinges with moderate and high ductility designed by strength criterion. Seven pairs of near field earthquakes and seven pairs of far field earthquakes scaled and use... 

    Developing Fragility Curves for Seismic Isolated Reinforced Concrete Structures

    , M.Sc. Thesis Sharif University of Technology Mostafavi, Ahmad (Author) ; Bakhshi, Ali (Supervisor)
    Nowadays, base isolation technique is widely used in the old and new structures, so it is necessary to assess the seismic performance of base-isolated buildings probabilistically, it is also essential to assess their performance during near-source versus far-field earthquakes.
    Developing the fragility curves is useful probabilistic method for the seismic assessment of structures. These curves define the probability of exceedance of different damage states for a given level of seismic intensity parameter. Former investigations has been done to assess the seismic behavior of base isolation systems consider base isolated highway bridge piers.
    In this thesis fragility curves are derived... 

    Application of Damage Spectra in the Estimation of Steel Moment Frames Damage by ET Method

    , M.Sc. Thesis Sharif University of Technology Maleki Amin, Mohammad Jalal (Author) ; Esmaeil Pourestekanchi, Homayun (Supervisor)
    In new method of performance-based design, the behavior of structure during earthquake is considered more realistically, and applying damage parameters like plastic ductility and inter-story drift to determine the seismic performance of structures is suggested. Damage indexes, the contribution of damage parameters to damage capacity of structural members, are defined to specify damage level of each element. In addition, damage spectrum which is the diagram of values of certain damage index versus natural period of single-degree-of-freedom system will be useful to seismic assessment of existing structures and seismic design of new ones. By the way, endurance time (ET) method can be... 

    Development of Fragility Curves for Confined Masonry Buildings

    , Ph.D. Dissertation Sharif University of Technology Yekrangnia, Mohammad (Author) ; Ghannad, Mohammad Ali (Supervisor) ; Bakhshi, Ali (Supervisor)
    The present study deals with the development of development of fragility curves for confined masonry buildings with the emphasis on masonry school buildings by means of numerical simulation. In doing so and based on the results of several previously-performed tests in Iran, simple analytical models for confined masonry walls capable of predicting various failure modes and also simulating different behavioral characteristics of these walls in the form of cyclic force-displacement curves were presented. In order to endure the ability of the proposed analytical models in simulation of seismic response of existing confined masonry buildings, a static-cyclic in-situ test on a real typical... 

    Development of Seismic Fragility Curves for Reinforced Concrete Tall Buildings

    , M.Sc. Thesis Sharif University of Technology Ansari, Mojtaba (Author) ; Bakhshi, Ali (Supervisor)
    This study focuses on the risk assessment of reinforced concrete tall buildings subjected to ground motion excitation. In order to assess the vulnerability of tall buildings, twelve-, and twenty-four-story four-bay reinforced concrete moment resisting frames are studied. This evaluation is done through developing fragility curves. These fragility curves provide the probability of exceeding the multiple damage states for a given intensity (e.g. CAV) of ground motion excitation. To develop the fragility curves, a great number of nonlinear dynamic analyses were conducted in the open-source platform OpenSees. Since the PEER Guidelines for Performance-Based Seismic Design of tall buildings (PEER,... 

    Investigation of strong-motion duration consistency in Endurance Time excitation functions

    , Article Scientia Iranica ; Vol. 20, issue. 4 , 2014 , p. 1085-1093 ; 10263098 Mashayekhi, M ; Estekanchi, H. E ; Sharif University of Technology
    The Endurance Time (ET) method is a dynamic analysis procedure using intensifying excitation. The ET excitation functions are generated so that structural performance can be assessed at different excitation levels in a single response history analysis. ET accelerograms, which have been generated so far, possess response spectra consistency; this means that the duration consistency has not been directly considered. Strong-motion duration can influence the response of structures which have stiffness or strength degrading characteristics. In this paper, several well-known strong-motion duration definitions are studied in the context of the ET method. Ground motions are scaled to spectral... 

    Structural damage estimation using seismic and spectral parameters

    , Article 10th International Conference on Civil, Structural and Environmental Engineering Computing, Civil-Comp 2005, Rome, 30 August 2005 through 2 September 2005 ; 2005 ; 1905088000 (ISBN); 9781905088003 (ISBN) Bakhshi, A ; Tavallali, H ; Karimi, K ; Sharif University of Technology
    Estimation of damage to structures after severe earthquakes is important for loss estimation and is an essential step for rescue program. Using seismic or spectral parameters could be a quick method for this purpose. In this article damage estimation for some world's destructive earthquakes has been carried out. For this purpose some earthquake seismic parameters, response spectra and damage indices have been calculated and compared. Damage indices are calculated for three types of intermediate sway concrete frame buildings, i.e. low-rise, mid-rise and high-rise, designed according to Iranian Seismic Code and ACI 318-95. Finally the trend between earthquake seismic parameters, response... 

    Evaluating the damage in steel MRF under near field earthquakes from a performance based design viewpoint

    , Article Procedia Engineering ; Volume 14 , 2011 , Pages 3111-3118 ; 18777058 (ISSN) Rofooei, F. R ; Imani, R ; Sharif University of Technology
    This study is about the performance assessment of steel moment resisting frame structures under nearfield strong ground motions. A number of 3 and 9-story, 3-D structural models being designed using the strength method, are considered. A set of 7 near-field earthquake records, scaled according to ASCE- 7(05), are considered for nonlinear dynamic time history analyses using OpenSees program. Park and Ang damage index is considered for quantitative measurement of the performance of structural models. Maximum values of inter-story drifts along with the local and global damage indices are determined to be used in the performance assessment process. Considering the average results of different... 

    Correlation between structural performance levels and damage indexes in steel frames subjected to earthquakes

    , Article Scientia Iranica ; Volume 16, Issue 2 A , 2009 , Pages 147-155 ; 10263098 (ISSN) Arjomandi, K ; Estekanchi, H ; Vafai, A ; Sharif University of Technology
    Various damage indexes have been introduced in recent years incorporating different parameters for estimating structural damage. Amongst these indexes, Plastic Ductility and Drift have been the center of attention of standards and building codes, like FEMA-356, because of their straightforward physical interpretation and ease of calculation. In this paper, several steel moment frames have been considered and their responses have been evaluated under a set of scaled earthquakes. A group of various damage indexes, which included cumulative and non cumulative, cyclic fatigue based, deformation based and modal parameter based, has been considered and the damage to structures has been evaluated... 

    Introducing a response-based duration metric and its correlation with structural damages

    , Article Bulletin of Earthquake Engineering ; Volume 17, Issue 11 , 2019 , Pages 5987-6008 ; 1570761X (ISSN) Mashayekhi, M ; Harati, M ; Ashoori Barmchi, M ; Estekanchi, H. E ; Sharif University of Technology
    Springer Netherlands  2019
    This study proposes a response-based parameter for strong motion duration which is computed for structures and is the total time they are nonlinear during an earthquake. Correlation between structural response and duration for structures, subjected to a set of spectrum matched ground motions, is employed to examine the efficiency of the proposed method. The spectral matching procedure ensures that the influence of amplitude and frequency content of motions on structural response variability is significantly removed. Four concrete building type systems are studied and correlation coefficients of structural response with the proposed duration definition are examined. Comparison of the proposed... 

    Study of Endurance Time Analysis Method in Seismic Evaluation of Steel Moment Resisting Frames

    , Ph.D. Dissertation Sharif University of Technology Tajmir Riahi, Hossein (Author) ; Esmaeil Pourestekanchi, Homayun (Supervisor)
    In this research the capability of a new method named Endurance Time analysis in seismic assessment of single and multi degree of freedom structures in nonlinear range is investigated. Endurance Time analysis is based on time history analysis but in this method structure is subjected to an intensifying acceleration function and different damage indices of the structure are evaluated through analysis time. This method can be a useful tool for executing Performance Based Design of structures. Firstly the Endurance Time criterion is defined and the progress of the generation of Endurance Time acceleration functions is described. Also the optimization procedure used for the generation of... 

    Comparison of Endurance Time Method with Time History Dynamic Analysis in Evaluating Irregular Concrete Structure

    , M.Sc. Thesis Sharif University of Technology Akbari, Reza (Author) ; Esmaeil Pourestekanchi, Homayuon (Supervisor)
    The Endurance Time Method is reprehensively new and comprehensive method for analyzing and designing the structure quality in based on performance that is related on time history analysis for investigating structure systems under dynamical instigation in result of earthquake. In this evaluation the index comparison in based on endurance time against of applied acceleration function. The result of the structure will plot against time, until the structure will achieve to a special amount of damage. The high endurance time means high performance. While the damage index will maintain less than allowable limit until endurance time, the structure will be approvable.In this project the ability of... 

    Two Novel Shear Fuses for Moment Resisting Frames

    , M.Sc. Thesis Sharif University of Technology Rezazadeh Kalehbasti, Pouya (Author) ; Mohtasham Dolatshahi, Kiarash (Supervisor)
    Based on the code specifications, in moment-resisting frames the span-to-depth ratio has to be larger than a minimum value to make sure of adequate plastic hinging at beam-ends. This provision poses a restriction on the use of deep beams with short spans, especially for the framed-tube system in tall buildings. In this thesis, a new energy dissipation method is introduced for moment-resisting frames by modifying the mid-span of the beam by two different methods, resulting in: (i) Perforated Shear Links (PSLs) and (ii) Slit Shear Links (SSLs). The links dissipate energy through shear yielding of the web, weakened by perforation or slitting, respectively. A thorough study is conducted on the... 

    Minimizing the Level of Damage of Structures and Improving their Performance through Optimal Design of Semi-Active Tuned Mass Damper

    , M.Sc. Thesis Sharif University of Technology Chenari, Mohammad Reza (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
    The aim of this study is to evaluate the seismic performance of structures using a semi-active tuned mass damper minimizing the amount of structural damage caused by earthquakes. One of semi-active control mechanisms, which has been studied in recent years, is the damper with fluid controlled by a magnetic field (Magnetorehological Damper, MR). These type of dampers react to the magnetic fields that cause significant changes in the behavior of fluid flow. These dampers are acknowledged because of their simplicity, broad operating range as well as not requiring high-power energy sources. In this thesis, a MR damper is used instead of the existing viscous element of tuned mass damper. To... 

    Application of Damage Indices In Seismic Analysis of Concrete Frames Using Endurance Time Method

    , M.Sc. Thesis Sharif University of Technology Baniassadi, Arash (Author) ; Esmaeil Pourestekanchi, Homayoun (Supervisor)
    In most places in the world as it is in our country, structural vibration caused by earthquakes are among the most destructive menaces for the building. For this reason one of the main goals for civil engineers is constructing structures that can perform properly in an earthquake-exposed situation. For moving toward this goal it is necessary to estimate structural responses considering probable earthquake excitation and use these data for design of new structures or retrofitting of existing ones. In this research, the capability of a new method named Endurance Time analysis in seismic assessment of concrete moment frame is investigated in nonlinear range. ET is a new dynamic time history... 

    Seismic evaluation of cemented material dams - A case study of tobetsu dam in Japan

    , Article Earthquake and Structures ; Volume 10, Issue 3 , 2016 , Pages 717-733 ; 20927614 (ISSN) Arefian, A ; Noorzad, A ; Ghaemian, M ; Hosseini, A ; Sharif University of Technology
    Techno Press  2016
    Trapezoidal Cemented Sand and Gravel Dam, namely Trapezoid CSG, is a new type of dam. Due to lack of dynamic studies in the field of CSG dam, this research was performed to analyze Trapezoidal CSG dam using dynamic Finite element method with ABAQUS Software. To investigate possible earthquake-induced damages, fragility curves are plotted based on damage index, the length of the cracks created at the dam base and the area of cracked elements in the dam. The seismic analysis indicated that minimum and maximum tensions are generated in the heel and toe of the dam, respectively. According to the fragility curves, with increase in PGA, the possibility of the exceeding the defined limit state is...