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    Resilience Assessment of Buildings with Considering Aftershocks

    , M.Sc. Thesis Sharif University of Technology Khanjari, Madiheh (Author) ; Bakhshi, Ali (Supervisor) ; Kashani, Hamed (Co-Supervisor)
    Abstract
    The development of the methods to evaluate the seismic resilience of communities, infrastructures, and structures has attracted many researches. To estimate the resilience with accuracy, developing a model that can simulate the events during the recovery time is very important. For the same, modelling the aftershocks with their accumulative effects on the damaged buildings during the recovery time has been the main focus of the current study. The proposed approach to simulate the aftershocks’ effect utilizes the Monte-Carlo sampling, in which each sample includes the two following steps. The first step is the simulation of the cumulative damage caused by the mainshock-aftershocks sequence... 

    Statistical evaluation and probabilistic modeling of aftershock sequences of Iranian plateau

    , Article Journal of Seismology ; Volume 22, Issue 5 , 2018 , Pages 1249-1261 ; 13834649 (ISSN) Khansefid, A ; Bakhshi, A ; Sharif University of Technology
    Springer Netherlands  2018
    Abstract
    The present research focuses on the statistical evaluation of Iranian plateau aftershocks from an engineering perspective and presents probabilistic models applicable for generating random earthquake scenarios. Accordingly, a comprehensive earthquake data catalog including the period from 1964 to 2016 is prepared. Data are declustered into 37 separate mainshock-aftershock sequences by considering the completeness moment magnitude of the database. The well-known modified Omori occurrence rate formula is adopted to determine the recurrence time of the events, considering the effect of secondary aftershocks. In addition to computing the probability density functions of the parameters of the... 

    Development of declustered processed earthquake accelerogram database for the Iranian Plateau: including near-field record categorization

    , Article Journal of Seismology ; Volume 23, Issue 4 , 2019 , Pages 869-888 ; 13834649 (ISSN) Khansefid, A ; Bakhshi, A ; Ansari, A ; Sharif University of Technology
    Springer Netherlands  2019
    Abstract
    In this paper, a comprehensive accelerogram database of the Iranian plateau containing 3585 data with all three components is gathered. The raw data are processed by the wavelet-based denoising method, and results are compared with the contaminated data. All the data are classified into mainshock and aftershock categories using the time and spatial window method. Afterward, the data are categorized into the pulse-like and non-pulse-like events based on the detection of velocity pulse in any of horizontal and/or vertical directions. Eventually, among 3585 data, the ones with an average shear wave velocity of top 30 m of subsurface soil profile are selected and their important ground motion... 

    New model for simulating random synthetic stochastic earthquake scenarios

    , Article Journal of Earthquake Engineering ; Volume 26, Issue 2 , 2022 , Pages 1072-1089 ; 13632469 (ISSN) Khansefid, A ; Bakhshi, A ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    This research attempts to propose a new simulating model capable of generating synthetic stochastic earthquake scenario including both seismological, and acceleration signal properties. The Iranian plateau is selected as a mainland for developing the model due to the existence of high-quality earthquake databases. This model is composed of two sub-models. The first one generates random seismic event scenarios including mainshocks and aftershocks. The second one procreates 3-dimensional synthetic stochastic accelerograms for each of the previously simulated events. This scenario-based predictive model offers a powerful tool to the risk modelers interested in lifetime seismic risk assessment... 

    Advanced two-step integrated optimization of actively controlled nonlinear structure under mainshock–aftershock sequences

    , Article JVC/Journal of Vibration and Control ; 2018 ; 10775463 (ISSN) Khansefid, A ; Bakhshi, A ; Sharif University of Technology
    SAGE Publications Inc  2018
    Abstract
    In this paper, an attempt is made to examine a new method for designing and applying the active vibration control system to improve building performance under mainshock–aftershock sequences. In this regard, three different structures are considered; 5-, 10-, and 15-story buildings. Seven mainshock–aftershock sequences are selected from the Iranian accelerogram database for analyzing the structures. By implementing an advanced two-step optimization method, buildings equipped with the active vibration control system (linear–quadratic regulator (LQR) algorithm) are designed to withstand all events of mainshock–aftershock sequences. In the first optimization step, a multi-objective optimization... 

    Advanced two-step integrated optimization of actively controlled nonlinear structure under mainshock–aftershock sequences

    , Article JVC/Journal of Vibration and Control ; Volume 25, Issue 4 , 2019 , Pages 748-762 ; 10775463 (ISSN) Khansefid, A ; Bakhshi, A ; Sharif University of Technology
    SAGE Publications Inc  2019
    Abstract
    In this paper, an attempt is made to examine a new method for designing and applying the active vibration control system to improve building performance under mainshock–aftershock sequences. In this regard, three different structures are considered; 5-, 10-, and 15-story buildings. Seven mainshock–aftershock sequences are selected from the Iranian accelerogram database for analyzing the structures. By implementing an advanced two-step optimization method, buildings equipped with the active vibration control system (linear–quadratic regulator (LQR) algorithm) are designed to withstand all events of mainshock–aftershock sequences. In the first optimization step, a multi-objective optimization... 

    seismic performance assessment of SMRF structures subjected to mainshock-aftershock seismic sequences by endurance time method

    , Article Journal of Earthquake Engineering ; 2020 Farivarrad, A. H ; Estekanchi, H. E ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    Abstract
    Seismic performance of postmainshock buildings considering seismic mainshock-aftershock sequences are studied. The case studies correspond to three SAC steel MRF buildings of three, nine and twenty stories. The 2-D models are able to capture important properties of deterioration of strength and stiffness. Endurance time method is used to predict the response of structures in different hazard levels. Results are compared with those from of nonlinear incremental dynamic analysis. Maximum dynamic seismic responses of structures are captured during synthetic mainshock-aftershock seismic sequences which are produced by endurance time method. Interactional-conceptual curves for different seismic... 

    Seismic performance assessment of SMRF structures subjected to mainshock-aftershock seismic sequences by endurance time method

    , Article Journal of Earthquake Engineering ; Volume 26, Issue 7 , 2022 , Pages 3281-3299 ; 13632469 (ISSN) Farivarrad, A. H ; Estekanchi, H. E ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    Seismic performance of postmainshock buildings considering seismic mainshock-aftershock sequences are studied. The case studies correspond to three SAC steel MRF buildings of three, nine and twenty stories. The 2-D models are able to capture important properties of deterioration of strength and stiffness. Endurance time method is used to predict the response of structures in different hazard levels. Results are compared with those from of nonlinear incremental dynamic analysis. Maximum dynamic seismic responses of structures are captured during synthetic mainshock-aftershock seismic sequences which are produced by endurance time method. Interactional-conceptual curves for different seismic... 

    Seismic Hazard Assessment in the Lifetime Duration of Steel MRF Structures Considering Aftershocks

    , M.Sc. Thesis Sharif University of Technology Farivarrad, Amir Hooshang (Author) ; Esmaeil Pourstekanchi, Homayoon (Supervisor)
    Abstract
    Following a large earthquake, numerous aftershocks can be triggered due to the complex stress interaction between and within tectonic plates. The aftershocks have the potential to cause severe weakening of mainshock-damaged buildings, threaten life safety, hamper reoccupation and restoration of buildings, and increase financial loss. The probability of aftershocks has not been included in the description of seismic hazard in performance-based earthquake engineering. This study proposes methodologies and a framework to investigate the seismic performance in the lifetime of steel MRF structures subjected to mainshock-aftershock sequences. The case studies correspond to three SAC 2D steel MRF... 

    Evaluating the Effects of Aftershocks on Increasing the Structural Damages in Special Steel Moment Frame Building

    , M.Sc. Thesis Sharif University of Technology Hajili, Ronak (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor) ; Ghods, Babak (Co-Supervisor)
    Abstract
    The purpose of this study is to investigate the effect of consecutive earthquakes by considering different levels of structural damage intensity index. The cumulative damage of structures caused by the sequence of main earthquake and aftershock is a combination of the initial damage caused by the main earthquake and the increased damage caused by the aftershock. The evaluation process of the main earthquake and aftershock is divided into two parts: evaluation of the fragility of the main earthquake and evaluation of the fragility due to the aftershock. This investigation was carried out using a 4-story steel building with special moment resisting frame. The results for the case of only the... 

    Empirical predictive model for generating synthetic non-stationary stochastic accelerogram of the Iranian plateau: including far- and near-field effects as well as mainshock and aftershock categorization

    , Article Bulletin of Earthquake Engineering ; Volume 17, Issue 7 , 2019 , Pages 3681-3708 ; 1570761X (ISSN) Khansefid, A ; Bakhshi, A ; Ansari, A ; Sharif University of Technology
    Springer Netherlands  2019
    Abstract
    This work proposes comprehensive empirical predictive equations for generating stochastic synthetic 3-dimensional accelerograms for the Iranian plateau based on the existing database. First, the databank of Iranian accelerograms is collected, sorted, processed, declustered and categorized into the pulse-like and non-pulse-like data. To simulate the artificial accelerograms, a stochastic model capable of handling both the temporal and spectral non-stationarity of accelerograms is adopted. By implementing nonlinear curve fitting, parameters of the stochastic model are estimated. Then, the recorded events are categorized into eight distinct groups based on the existence of pulse-like... 

    Seismic Risk Assessment of Transmission Towers under Mainshock-Aftershock sequence Pardis-Vardavard 400 KV transmission line Case Study

    , M.Sc. Thesis Sharif University of Technology Paktinat, Mohaddeseh (Author) ; Bakhshi, Ali (Supervisor)
    Abstract
    The main purpose of this research is to evaluate the impact of mainshock and aftershocks on the response and fragility of power transmission towers and to provide an approach to assess the risk of transmission lines under mainshock-aftershock sequence. The transmission line studied in this research has 27 self-supported 400 kV transmission towers. The reason for choosing this line is the proximity of the line to the active faults of Tehran like Mosha and North-Tehran, as well as the service of the line to a large residential and industrial area, which, in case of damage by an earthquake, will cause considerable direct and indirect loss to the society. In the three-dimensional models...