Vahid Saberi; Hamid Saberi; Davood Sohrabi; Romina Nourian
Abstract
Passive control method, which is one of the solutions for strengthening and designing structures under earthquake loadings, has different sub-branches. One of these methods is to improve the existing weak buildings by using different types of damper. The seismic behaviour of the strengthened structure ...
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Passive control method, which is one of the solutions for strengthening and designing structures under earthquake loadings, has different sub-branches. One of these methods is to improve the existing weak buildings by using different types of damper. The seismic behaviour of the strengthened structure with different type of dampers is one of the main issues in choosing the strengthening method. Due to the energy absorption property, dampers have many applications in both construction and retrofitting. During an earthquake, these devices are activated and convert the earthquake input energy into heat energy, in other words, it absorbs the incoming energy. In previous studies, the use of this damper in various structures has been evaluated, but there is no specific category to investigate its effect on various types of steel structures in terms of height and type of damper. In this paper, the performance of this type of dampers in steel structures with different heights is discussed. The effect of using this type of dampers on the response of the structure such as the story drifts and the base shear is investigated and its performance is compared in steel structures with different heights. In the study of displacement, base shear and energy absorption parameters for three structures of 3, 6 and 12 floors, it was observed that viscous dampers had the best response to friction dampers and ADAS.
Pouya Akbari; Vahid Saberi; Hamid Saberi; Faezeh Eslami; Abbasali Sadeghi
Volume 2, Issue 9 , December 2021, , Pages 11-21
Abstract
One of the most important and fundamental issues that civil engineers always deal with today due to its importance is the study of the performance and behavior of structures under different conditions. In addition, in many cases, buildings are analyzed and designed separately and without considering ...
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One of the most important and fundamental issues that civil engineers always deal with today due to its importance is the study of the performance and behavior of structures under different conditions. In addition, in many cases, buildings are analyzed and designed separately and without considering the effect of other elements, including the foundation and soil of the infrastructure, which in many cases creates irreparable risks; Therefore, it is necessary to study and evaluate the effect of soil-structure interaction on the performance and design of buildings in order to manage the cost and time of construction projects. In this study, the performance of steel structures with concentric brace of 5, 10 and 15 floors by considering the interaction of soil structure in three different soil modes using nonlinear dynamic analysis of time history under 3 near-fault earthquakes has been done. The results show that considering the interaction of soil and structure increases the accuracy of structural responses.
seyedali seyedmahmoud; Hamid Saberi; Vahid Saberi
Volume 3, Issue 9 , December 2021, , Pages 84-101
Abstract
Application of dual SMRF-BRBF system can be considered as an appropriate choice for resisting seismic loads in high seismicity regions. Taking advantage of having buckling resistant braces which can resist high axial compressive forces without local and global buckling, buckling restrained bracing frame ...
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Application of dual SMRF-BRBF system can be considered as an appropriate choice for resisting seismic loads in high seismicity regions. Taking advantage of having buckling resistant braces which can resist high axial compressive forces without local and global buckling, buckling restrained bracing frame (BRBF) system can be used as an efficient alternative for conventional bracing system. Response modification factor (R factor) is required for seismic design of structures. Therefore, in this research, performance-based R factor is evaluated for dual SMRF-BRBF structures. Considering the fact that in addition to structural properties the seismic load characteristics effect on the load-carrying capacity and R factor, R factor is evaluated specifically for near fault ground motions. To consider the effect of performance level, the R factor is calculated distinctly for Life Safety (LS) and Collapse Prevention (CP) limit states. Nonlinear time history and pushover analysis results are employed for determination of ductility, over-strength and R factor of the sample structures. According to the obtained results, the average of R factor coincident to LS and CP performance levels is 6.1 and 7.9, respectively. The comparison of results obtained for near fault records with those obtained for far fault motions reveals that the R factor is averagely 25% lower for near fault ground motions.
Vahid Saberi; Hamid Saberi; Faezeh Eslami; Abbasali Sadeghi
Volume 2, Issue 8 , November 2020, , Pages 38-54
Abstract
In this study, the effect of steel damper with vertical slits on chevron braced frames with the number of different stories is investigated and pushover and cyclic analyses are performed . To evaluate and compare the results, a parametric study is carried out on a steel damper with and without slit. ...
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In this study, the effect of steel damper with vertical slits on chevron braced frames with the number of different stories is investigated and pushover and cyclic analyses are performed . To evaluate and compare the results, a parametric study is carried out on a steel damper with and without slit. Eight model frames such as a single-story in ordinary moment frame, braced frame, chevron braced frame with gusset plate, chevron braced frame equipped by a damper with vertical slits, chevron braced frame with silt damper and three-story chevron braced frame equipped by a damper with vertical slits, five-story chevron braced frame equipped by a damper with vertical slits, eight-story chevron braced frame equipped by damper with vertical slits are modeled and analyzed by finite element method in Abaqus software. The results showed that the braced frame equipped by a damper with vertical slits by its ductile behavior, dissipated a large amount of earthquake input energy and reduced the base shear. The hysteresis curves were stable and without any loss, indicating high energy absorption by chevron braced frame equipped by a damper with vertical slits. In all the chevron braced frame equipped by a damper with vertical slits, the plastic hinges are not formed in the members of structures, and the failure mechanism is concentrated in the damper. The damper with vertical slits reduced the elastic stiffness, secondary stiffness and carrying capacity, which in addition to controlling the drift of the structure, increased the energy absorption capability. The chevron braced frame equipped by a damper with vertical slits had more ductility than other specimens, and according to the results, damper with vertical slits had good seismic performance.
Vahid Saberi; Hamid Saberi; Pouya Akbari; Faezeh Eslami; Abbasali Sadeghi
Volume 2, Issue 8 , November 2020, , Pages 55-71
Abstract
In construction of high-rise buildings, one of the major and effective factors is the final cost of structure. Due to high volume of materials in such sort of projects, the smallest changes in the type and method of joining between the different structural components of these systems may have substantial ...
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In construction of high-rise buildings, one of the major and effective factors is the final cost of structure. Due to high volume of materials in such sort of projects, the smallest changes in the type and method of joining between the different structural components of these systems may have substantial impact on the amount of consumed materials and hence the final cost of the project. Structural systems applied in construction of high-rise buildings must be able to transfer the lateral wind force into the earth. One the systems used in construction of high buildings is outrigger system and truss belt. Optimized location of truss belt and shape of architectural plan have crucial effect on structural performance of the system. The aim of this study is to find the appropriate shape for building plan. In this regard, rectangular shaped plans with different width-to-length ratios, similar areas and different number of caps along the height of the building were constructed. After modeling and sample analysis, different parameters such as shear moment, lateral displacement, base shear, relative lateral displacement and …, were compared. Comparison of curves and analysis of obtained results showed that application of rectangular plan with width-to-length ration of 0.64 has better structural performance efficiency. Also, when lateral wind force is applied, application of truss belt resulted in creation of an inflection point in axial force curve of the columns surrounding the central core in the interval between two belts.
Vahid Saberi; Hamid Saberi; Erfan Alipour; Abbasali Sadeghi
Volume 2, Issue 3 , June 2020, , Pages 39-50
Abstract
Due to the seismic dangers in the buildings, it is necessary that engineers consider newer and more suitable ways to resist against the seismic forces regularly. The Buckling Restrained Brace (BRB) are almost the new systems against the seismic forces that generally have more ductility in comparison ...
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Due to the seismic dangers in the buildings, it is necessary that engineers consider newer and more suitable ways to resist against the seismic forces regularly. The Buckling Restrained Brace (BRB) are almost the new systems against the seismic forces that generally have more ductility in comparison with other lateral loading systems. In this study, the building 5 story with eccentric buckling restrained braces are designed by ETABS software and then two dimensional side frame is modelled by ABAQUS software in order to investigate the effect of material and specifications of link beam variations on the cyclic performance of eccentric buckling restrained brace. Therefore, first its link beam was modeled with soft steel ST37, then with high strength steel ST52 and finally with hardening bond and reduced surface area by 20%, 40% and 60% (6 models totally). The results show that the highest resistance is related to the sample whose link beam is with the stiffener. Also, the highest plasticity belongs to the model whose link beam is modeled with ST52.
