List of Articles Nonlinear time history

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  1 - Evaluation of Steel Braced Frames under Vertical and Horizontal Components of Near Field Earthquake
  علی گل افشار متین روشنی محمد حسین ثقفی
  In the common practice design of structures, Often the effect of vertical component of earthquake is ignored, but this component is important parameter especially in near field Earthquakes. The objective of this paper is study the effect of vertical and horizontal compo More

  In the common practice design of structures, Often the effect of vertical component of earthquake is ignored, but this component is important parameter especially in near field Earthquakes. The objective of this paper is study the effect of vertical and horizontal component of earthquake ground motion in steel braced frames. First verification of numerical models through finite element software package (ABAQUS) is carried out. Comparison of the result of load displacement curve for numerical and experimental model shows matching result. After this, two concentrically braced frames with X-configuration are selected from previous researches. Four earthquake records have been used for this study. Kobe, Northridge, Tabas and Imperial Valley. Two components of earthquake are applied simultaneously to frames under nonlinear time history analysis. The results that extract from the analysis content of vertical and horizontal displacement of roof and plastic dissipated energy during earthquakes. the intensity of the former parameters is depend of earthquake intensity and frequency content of them. Assessing the result reveal that in the three story frame, the ratio of maximum vertical displacement to maximum horizontal displacement is crucial parameter with respect to seven story braced frame. Also the time of plastic energy dissipated for frames is short because of nature of near field earthquake. Manuscript profile
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  2 - Performance of Mid-rise Buildings with Tubular Structure Under the Effect of Near Field Earthquakes
  Hooman Mazlooma Maryam Firoozi Nezamabadi
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  3 - Probabilistic Evaluation of Seismic Performance of RC Bridges in Iran
  Mehran Seyed Razzaghi M. Safarkhanlou
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  4 - The Effect of Compressive Strength Reduction of Column Section Expose due to Freezing-Thawing Cycles on the Seismic Performance of Bridges
  Saeideh Alsadat Mousavi Mehran Seyed Razzaghi
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  5 - The Effect of SMA Damper on Energy Dissipation and Eduction of Vibration Amplitude of Multi-Story Steel Frames
  Ali Seyedkazemi milad esmaeili saman eftekhar ardabili morteza hoseinali beygi
  In recent years, the idea of ​​using durable materials which are capable of absorbing energy and have high ductility are highlighted in structural engineering. One example of these materials is shape memory alloys which show predefined physical properties in different c More

  In recent years, the idea of ​​using durable materials which are capable of absorbing energy and have high ductility are highlighted in structural engineering. One example of these materials is shape memory alloys which show predefined physical properties in different conditions. These materials show little residual strain under loading and unloading cycles even when passing through the yield area. In fact, they create regenerative forces in structures. In this study, the effect of shape memory alloys on energy dissipation and reducing vibration amplitude of multi-story steel frame is investigated. For the present purpose, shape memory alloy rebars are used in the middle of the diagonal elements of braces. ABAQUS software is used in the present study. To validate models, first, two-story braced frame with shape memory alloy used in the laboratory studies of Han et al (2003) is modeled and analyzed in the software. The results obtained by the two laboratory and analytical methods are in acceptable agreement. To investigate the effect of height on the seismic performance of the buildings equipped with this type of dampers, 3- and 12-story buildings were considered and reciprocating nonlinear analysis and nonlinear dynamic time history analysis using Tabas accelerogram were performed. Results show that using this type of dampers cause quick energy dissipation and a significant reduction in the vibration amplitude and base shear so that the existence of shape memory alloy in 3-story building makes the ability of the structural system in dissipating energy and the initial stiffness of the system increase 2.5 and 2 times respectively. Moreover, with an increase in height, its effectiveness in controlling the seismic response of structure is reduced between 10-15 percent. Manuscript profile
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  6 - A Comparison of Modal Analysis of Ritz Vector Mode (Ritze) and Eagan Vector (Eigen) based on nonlinear Time History (NTH) Dynamic Analysis
  seyed ali mousavi davoudi Morteza Naghipour
  Nowadays, the requirements of designing structures based on low weight and high strength in structural engineering science, have increased the possibility of unwanted and destructive vibrations in these systems. Also, using of computer softwares for modeling alone canno More

  Nowadays, the requirements of designing structures based on low weight and high strength in structural engineering science, have increased the possibility of unwanted and destructive vibrations in these systems. Also, using of computer softwares for modeling alone cannot accurately predict the dynamic behavior of structures. For this reason, a fundamental approach to experimental techniques was developed and made progress in the field of modal analysis. In recent years, modal analysis has been applied as a tool to determine and enhance the dynamic properties of structures. The vibrational modes obtained from the modal analysis, are useful for understanding the behavior of the structure correctly. Modal analysis is also used in modal time history analyzes and quasi-dynamic analysis of response spectrum. An important point in modal analysis is that when using modal analysis there are two types of analytical models named special vector state and Ritz vector state. Finding the best method for modal analysis of structural responses is very important in modal analysis, so far no comprehensive studies have been conducted to date. Considering the importance of this issue, in this study the evaluation of the accuracy between the two modes of vectors (Ritz) and (Eigen) in modal analysis is done. It is concluded that the modal analysis of Eigen vector is more accurate than Ritz vector and the results of Eigen modal              analysis are closer to reality. Manuscript profile
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  7 - Investigation of the Effect of Soil Structure Interaction on the Response of Structures with Viscoelastic Damper under Different Damping
  masoud pourbaba saeid javaherzadeh fariba seyyedi mohammadi
  Using additional dampers for reducing input energy of structures is an effective way for dissipating input energy of structures. Including appropriate tools in dissipating the input energy of structures is viscoelastic damper. Generally, according to the structural anal More

  Using additional dampers for reducing input energy of structures is an effective way for dissipating input energy of structures. Including appropriate tools in dissipating the input energy of structures is viscoelastic damper. Generally, according to the structural analysis, the soil under structures is assumed to be rigid and the effect of soil structure interaction has been ignored. However, in reality, this soil is not rigid and the soil beneath the structures changes the dynamic specifications of structures and thus response of it. Structural response and damper performance depend on various components including type of earth movement and soil specifications. In this research, a few two-dimensional special concrete frames were examined. For frame modeling of additional damper, we used Kelvin method and for modeling of soil structure interaction effects with additional damper we used spring and damper equivalent method in the OpenSees app. Studied frames after rehabilitation with damper have been analyzed under dynamic nonlinear time history analysis. This analysis was done in three damping 5%, 10% and 15%. And at the end the results of soil-structure interaction impact with viscoelastic damper under different damping are studied. Manuscript profile
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  8 - Optimal intensity measures for probabilistic seismic demand modeling of multi-span continuous concrete box girder bridges subjected to near-field earthquakes
  Hoodean Malekzadeh Hassan Abbasi Mahmood Hooseini Armin Aziminejad Mohammadreza Adib Ramezani
  10.30495/civil.2021.684416
  Seismic intensity measures (IMs) perform a pivotal role in probabilistic seismic demand modeling. Past studies investigated appropriate IMs for structures, including the vital component of the transportation system, the highway bridges. These studies were mainly focused More

  Seismic intensity measures (IMs) perform a pivotal role in probabilistic seismic demand modeling. Past studies investigated appropriate IMs for structures, including the vital component of the transportation system, the highway bridges. These studies were mainly focused on far-field earthquakes and did not consider the strong vertical component of ground motions in near-field earthquakes.  In order to evaluate the optimal IMs for the multi-span continuous concrete box girder bridges subjected to near-field earthquakes, ten sample bridges were modeled and then subjected to three-component records of 164  near-field earthquakes applying the OpenSees software framework. In the present research, 5 engineering demand parameters considering the most critical response parameters related to columns and deck were selected, along with 24  intensity measures considering the horizontal and vertical components of ground motions. Base on the optimality investigation method, parameters such as efficiency, practicality, proficiency, sufficiency, and relative sufficiency were considered. In total, 8200 nonlinear time-history analyses were conducted. The results presented that the peak ground velocity of the horizontal component (PGVH), velocity spectrum intensity of the horizontal components(VSIH), and Housner intensity of horizontal components (HIH) were the optimal intensity measures, and vertical component of ground motions in near-field earthquakes should be considered in optimality investigation. Manuscript profile
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  9 - Seismic Control of Structures Using Tuned Liquid Dampers (TLD) Adaptable with Water Level
  Nakisa Azari Farshid Fathi
  10.30495/civil.2021.681672
  Tuned Liquid Dampers (TLD) are widely utilized today because of their simple structure, no need for external energy sources and low construction and implementation costs. They have also been used effectively to reduce the responses of structures against the earthquake e More

  Tuned Liquid Dampers (TLD) are widely utilized today because of their simple structure, no need for external energy sources and low construction and implementation costs. They have also been used effectively to reduce the responses of structures against the earthquake excitation. By adjusting the water level, inside the TLD tank, so that the vibration frequency of the fluid is equal to the main frequency of the structure, the best efficiency is obtained for this passive control system in reducing the response of the structures. Many efforts have been undertaken to make this type of damper usable even under normal conditions, so that to be used as a water storage tank for the buildings. However, in such case, due to the variable level of water consumption in the damper tank, its efficiency will not necessarily be high at the time of an earthquake. Therefore, the purpose of this paper is to introduce an improved model, instead of conventional TLD, that perform the best efficiency in reducing structural responses at the different water levels in the reservoir. For this purpose, by applying seven earthquake records to the studied analytical model, the efficiency of two control systems has been compared with each other. The results of nonlinear time history analyses indicate that the maximum building responses in the proposed control system have been effectively reduced, for the different reservoir water levels, compared to the conventional TLD system. Manuscript profile
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  10 - Investigation of Nonlinear Seismic Behavior of High-rise Reinforced Concrete Buildings and their Improvement by Viscoelastic Dampers
  Faraz Kazemi ashkan khodabandehlou
  10.30495/civil.2022.689974
  Owing to the destruction of high-rise buildings during recent earthquakes, the use of a structural system of reinforced concrete moment frame with viscoelastic damper causes a loss of seismic energy and consequently reduces lateral displacement. In this study a high-Ris More

  Owing to the destruction of high-rise buildings during recent earthquakes, the use of a structural system of reinforced concrete moment frame with viscoelastic damper causes a loss of seismic energy and consequently reduces lateral displacement. In this study a high-Rise, 20-Storey, three-dimensional reinforced concrete frame with 8 Models, of which 4 models with moment frame structural system and 4 models with moment frame + viscoelastic damping system in two directions of X, Y located in the high seismic zone (A=0.3g) on the soil type III is considered. The aim of the present study is to investigate the horizontal lateral displacement (absolute and relative) of the stories, the base shear of frames under gravity loads, and lateral loads of the earthquake.  In order to modeling the viscoelastic materials, the Kelvin-Voigt model and to determine damping ratio(ζ) of frames with viscoelastic damper, stiffness coefficient (Kv) and damping coefficient (Cv) of viscoelastic dampers, the modal strain energy method have been applied. For seismic analysis of models without and with dampers, dynamic analysis of nonlinear time history via direct integration and modal (FNA) methods have been utilized, respectively.  Geometric modeling of all frames was done using the SAP2000-V15 software. The results indicate that with increasing span length (model 2 compared to model 1 and model 4 compared to model 3) and increasing the height of stories (model 3 compared to model 1 and Model 4 compared to model 2), the maximum absolute lateral and relative displacement of stories, and base shear along with X, Y without and with viscoelastic damper have an increasing trend. Also, the maximum percentage increase of the mentioned models with damper compared to without damper along with X, Y has decreased Manuscript profile
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  11 - Evaluation of the Simultaneous Application of Vertical and Horizontal Mass Isolation Techniques in the Moment Steel Frame Structures
  Noosheen Ghorbani Farshid Fathi
  10.30495/civil.2021.684725
  In the recent decades, many efforts have been made to reduce the damages caused by strong earthquakes to the structural and non-structural systems of buildings utilizing various methods of seismic control of structures (active and passive). One of the most common passiv More

  In the recent decades, many efforts have been made to reduce the damages caused by strong earthquakes to the structural and non-structural systems of buildings utilizing various methods of seismic control of structures (active and passive). One of the most common passive seismic control systems is the horizontal isolation of buildings at their base level or base isolation. Another type of seismic isolation system, which is called vertical mass isolation and has been proposed in recent years, tries to separate the stiffness system and mass sub-system of the structures in some way.  In this research, the more efficient Simultaneous application of the horizontal base isolation together with the vertical mass isolation techniques, along with the use of a damping devices (such as viscous dampers), to improve the seismic performance of moment steel frame structures, has been investigated. For this purpose, the performance of the proposed hybrid system was evaluated by performing nonlinear time history dynamic analysis under the horizontal component of earthquake acceleration records. The results of the analysis obviously presented significant reductions in the maximum seismic responses of the studied structures especially for displacements, drifts and base shears compared to those responses of the other types of conventional structural systems with similar characteristics Manuscript profile
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  12 - Seismic Reliability Evaluation of the Jacket Structure of an Offshore Platform Based on Nonlinear Time History Analyses
  M Hosseini S Karimiyan
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