The Experts below are selected from a list of 3072 Experts worldwide ranked by ideXlab platform
Reza Rahgozar - One of the best experts on this subject based on the ideXlab platform.
-
Seismic Performance of Outrigger-Braced System Based on Finite Element and Component-Mode Synthesis Methods
Iranian Journal of Science and Technology Transactions of Civil Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:Determining the optimum location of Outrigger-belt truss system is of the most important challenges in tall structures. In this paper, two numerical methods, finite element method (FEM) and component-mode synthesis (CMS), are evaluated to determine the seismic performance of two buildings with different heights: one with 20 stories and the other with 30 stories. To find the optimum location of the Outrigger, seismic performance of 2D Outrigger-braced buildings in terms of inter-story drift ratio, roof displacement, base shear, and base moment is investigated. It is concluded that CMS as a model reduction method is very effective and useful in reducing the required analysis time as well as having good concordance with FEM results. The seismic responses of the two buildings change significantly as the Outrigger location changes from the first to the last story. The accuracy of the results is verified through the OpenSees program. Results show that the component-mode synthesis method is able to reduce the analysis time significantly, and also the efficiency and impotence of this method are more obvious as degrees of freedom are increased. In addition, placing the Outrigger system at 0.6 H to 0.8 H of the total height of the building improves the seismic performance of the structure.
-
Seismic performance of Outrigger–belt truss system considering soil–structure interaction
International Journal of Advanced Structural Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:The focus of this study is to investigate the seismic behavior of Outrigger-braced building considering the soil–structure interaction based on finding the best location of Outrigger and belt truss system. For this purpose, a central Outrigger-braced frame of a steel tall building is considered. A layered soil deposit underlied this frame and the resulting soil–structure system is subjected to seismic excitation. To analyze this system, direct method is employed in OpenSees. Also, elastic and in-elastic analyses are both considered and a comparison is made between current results and the results related to the system with fixed base. The best location of Outrigger–belt truss system is determined by considering the maximum roof displacement, base moment and base shear with and without soil–structure interaction. It is shown that considering SSI affects the location of Outrigger–belt truss system. Elastic analysis of both systems, namely with fixed base and with soil–structure interaction, showed that locating the belt truss at higher stories caused lower amounts of roof displacement.
-
seismic performance of Outrigger belt truss system considering soil structure interaction
International Journal of Advanced Structural Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:The focus of this study is to investigate the seismic behavior of Outrigger-braced building considering the soil–structure interaction based on finding the best location of Outrigger and belt truss system. For this purpose, a central Outrigger-braced frame of a steel tall building is considered. A layered soil deposit underlied this frame and the resulting soil–structure system is subjected to seismic excitation. To analyze this system, direct method is employed in OpenSees. Also, elastic and in-elastic analyses are both considered and a comparison is made between current results and the results related to the system with fixed base. The best location of Outrigger–belt truss system is determined by considering the maximum roof displacement, base moment and base shear with and without soil–structure interaction. It is shown that considering SSI affects the location of Outrigger–belt truss system. Elastic analysis of both systems, namely with fixed base and with soil–structure interaction, showed that locating the belt truss at higher stories caused lower amounts of roof displacement.
-
Determination of optimum location for flexible Outrigger systems in tall buildings with constant cross section consisting of framed tube, shear core, belt truss and Outrigger system using energy method
International Journal of Steel Structures, 2017Co-Authors: Reza Kamgar, Reza RahgozarAbstract:In this paper, based on maximizing the Outrigger-belt truss system’s strain energy, a methodology for determining the optimum location of a flexible Outrigger system is presented. Tall building structures with combined systems of framed tube, shear core, belt truss and Outrigger system are modeled using continuum approach. In this approach, the framed tube system is modeled as a cantilevered beam with box cross section. The effect of Outrigger and shear core systems on framed tube’s response under lateral loading is modeled by a rotational spring placed at the location of belt truss and Outrigger system. Optimum location of this spring is obtained when energy absorbed by the spring is maximized. For this purpose, first derivative of the energy equation with respect to spring location as measured from base of the structure, is set to zero. Optimum location for Outrigger and belt truss system is calculated for three types of lateral loadings, i.e. uniformly and triangularly distributed loads along structure’s height, and concentrated load at top of the structure. Accuracy of the proposed method is verified through numerical examples. The results show that the proposed method is reasonably accurate. In addition, for different stiffness of shear core and Outrigger system, several figures are presented that can be used to determine the optimum location of belt truss and Outrigger system.
J.c.d. Hoenderkamp - One of the best experts on this subject based on the ideXlab platform.
-
Preliminary design of Outrigger braced shear wall structures on flexible foundations
2020Co-Authors: J.c.d. Hoenderkamp, M.c.m. Bakker, H.h. SnijderAbstract:This paper presents a graphical method to optimise the position of Outriggers on shear walls with flexible foundations. This location for the Outriggers will cause a maximum reduction in lateral deflection at the top of the building. The method can be used for preliminary design of high-rise structures subjected to horizontal loading. The method requires the calculation of six structural parameters: bending stiffnesses for the shear wall and Outrigger structure, an overall bending stiffness contribution from the exterior columns, rotational stiffnesses for the shear wall and column foundations in addition to a newly suggested bending stiffness parameter representing the structural behaviour of the flexible foundation beam connecting the foundation of the shear wall to the exterior column foundations. These parameters allow the derivation of two compatibility equations for rotations at the intersections of the neutral lines of the shear wall with the Outrigger and foundation structures. They yield expressions for the restraining moments at Outrigger and foundation levels that act in the opposing direction to the bending moment from the horizontal loading on the structure. Maximising the influence of the restraining moments on the horizontal deflections leads to the optimum location of the Outrigger structure. Combining all stiffness parameters into two non-dimensional characteristic structural parameters allows the optimisation procedure for this type of structure to be represented by a single graph that directly gives the optimum level of the Outrigger. It is concluded that all six stiffness parameters need to be included in the preliminary analysis of a proposed tall building structure as the optimum location of the Outrigger as well as the reductions in horizontal deformations and internal forces in the structure can be significantly influenced by all the structural components.
-
Analysis of high‐rise braced frames with Outriggers
Structural Design of Tall and Special Buildings, 2020Co-Authors: J.c.d. Hoenderkamp, Mcm Monique BakkerAbstract:A graphical method of analysis for the preliminary design of tall building structures comprising braced frames with Outrigger trusses subjected to horizontal loading is presented. For this method of analysis it is necessary to determine five stifnesses for the uniform structure: bending and racking shear stiffnesses of the braced frame and Outriggers in addition to a stiffness parameter representing the axial lengthening and shortening of the exterior columns. The analysis allows a simple procedure for obtaining the optimum location of the Outrigger up the height of the structure and a rapid assessment of the impact of the Outrigger on the behaviour of the high-rise structure. It is concluded that all five stiffnesses should be included in the preliminary analysis of a proposed tall building structure as the reductions in horizontal deflections and bending moments of the braced frame are influenced by all stiffness parameters
-
Periods of Vibration of Braced Frames with Outriggers
Procedia Engineering, 2020Co-Authors: Mp Monica Nicoreac, J.c.d. HoenderkampAbstract:This paper presents simple equations for the natural lateral and rotational periods of vibration for high-rise steel structures comprising braced frames with Outrigger trusses. The structural floor plan can be symmetric or asymmetric combinations of identical bents. Each braced frame is modelled by a cantilever with a bending stiffness and racking shear stiffness. The Outriggers are represented by a rotational spring. The stiffness of the Outrigger spring is dependent on three specific modes of behaviour: bending and racking shear in the Outrigger truss and axial lengthening or shortening of the exterior columns. This yields a simple calculation of the maximum horizontal deflection of the structure. For the rotational frequencies, the bending, racking shear and spring stiffness parameters of the steel structure each are combined to yield a torsional stiffness, a warping stiffness and a warping spring stiffness which allow an assessment of the rotation at the top. The approximate method of analysis relates the natural frequencies of the structure to the top deflection and rotation when the self-weight is taken as a distributed horizontal load. In the calculations a braced frame is represented by a rigid stick model with its overall flexibility assigned to a rotational spring at the base. Results obtained by the simplified method are compared to those from a finite element analysis. The approximate method gives acceptable conservative results for preliminary analysis.
-
second Outrigger at optimum location on high rise shear wall
Structural Design of Tall and Special Buildings, 2008Co-Authors: J.c.d. HoenderkampAbstract:This paper presents a simple method of analysis for preliminary design of Outrigger braced high-rise shear walls subjected to horizontal loading. The shear wall has Outriggers at two levels. One Outrigger has a fixed location up the height of the structure, while the second can be placed at an optimum location. This position will cause a maximum reduction in lateral deflection at the top of the building. A single diagram allows for a rapid assessment of the optimum location for the second Outrigger. The suggested method of analysis for use in the initial stages of the design of an Outrigger structure for a proposed tall building offers a simple and rapid means of locating a second Outrigger at an optimum location up the height of the structure, thereby allowing optimum dimensions for the individual structural members. Copyright © 2007 John Wiley & Sons, Ltd.
-
Shear wall with Outrigger trusses on wall and column foundations
Structural Design of Tall and Special Buildings, 2004Co-Authors: J.c.d. HoenderkampAbstract:A graphical method of analysis is presented for preliminary design of Outrigger truss-braced high-rise shear wall structures with non-fixed foundation conditions subject to horizontal loading. The method requires the calculation of six structural parameters: bending stiffness for the shear wall, bending and racking shear stiffnesses for the Outrigger, an overall bending stiffness contribution from the exterior columns, and rotational stiffnesses for the shear wall and column foundations. The method of analysis employs a simple procedure for obtaining the optimum location of the Outrigger up the height of the structure and a rapid assessment of the influence of the individual structural elements on the lateral deflections and bending moments of the high-rise structure. It is concluded that all six stiffnesses should be included in the preliminary analysis of a proposed tall building structure as the optimum location of the Outrigger as well as the reductions in horizontal deformations and internal forces in the structure can be significantly influenced by all the structural components.
Reza Kamgar - One of the best experts on this subject based on the ideXlab platform.
-
Reducing static roof displacement and axial forces of columns in tall buildings based on obtaining the best locations for multi-rigid belt truss Outrigger systems
Asian Journal of Civil Engineering, 2019Co-Authors: Reza Kamgar, Peyman RahgozarAbstract:In this paper, energy method as a robust method has been used to compute the optimum locations of belt truss and Outrigger systems. To achieve this aim, a tall building of constant stiffness along its height, reinforced with a framed tube, shear core and belt truss with Outrigger systems has been considered. An equivalent cantilevered beam has been used to model the framed tube system. Here, Outrigger–belt truss systems are modeled by rotational springs placed at their spatial position. Utilizing the energy method, belt truss systems are placed at particular positions along the structure’s height, selected so to maximize energy absorption and dissipation. Applicability and accuracy of the proposed method are verified via a numerical example (50-story concrete building) and the results are compared with Stafford Smith’s method. The proposed method demonstrated for several belt truss and Outrigger systems a reduction in the values of the roof displacement and axial force in comparison with Stafford Smith’s method. The results show that the structure with two belt–Outrigger systems has a better performance in reduction of roof displacement and axial forces (2.3% and 4% reduction, respectively) rather than the one- and three-belt truss systems.
-
Seismic Performance of Outrigger-Braced System Based on Finite Element and Component-Mode Synthesis Methods
Iranian Journal of Science and Technology Transactions of Civil Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:Determining the optimum location of Outrigger-belt truss system is of the most important challenges in tall structures. In this paper, two numerical methods, finite element method (FEM) and component-mode synthesis (CMS), are evaluated to determine the seismic performance of two buildings with different heights: one with 20 stories and the other with 30 stories. To find the optimum location of the Outrigger, seismic performance of 2D Outrigger-braced buildings in terms of inter-story drift ratio, roof displacement, base shear, and base moment is investigated. It is concluded that CMS as a model reduction method is very effective and useful in reducing the required analysis time as well as having good concordance with FEM results. The seismic responses of the two buildings change significantly as the Outrigger location changes from the first to the last story. The accuracy of the results is verified through the OpenSees program. Results show that the component-mode synthesis method is able to reduce the analysis time significantly, and also the efficiency and impotence of this method are more obvious as degrees of freedom are increased. In addition, placing the Outrigger system at 0.6 H to 0.8 H of the total height of the building improves the seismic performance of the structure.
-
Seismic performance of Outrigger–belt truss system considering soil–structure interaction
International Journal of Advanced Structural Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:The focus of this study is to investigate the seismic behavior of Outrigger-braced building considering the soil–structure interaction based on finding the best location of Outrigger and belt truss system. For this purpose, a central Outrigger-braced frame of a steel tall building is considered. A layered soil deposit underlied this frame and the resulting soil–structure system is subjected to seismic excitation. To analyze this system, direct method is employed in OpenSees. Also, elastic and in-elastic analyses are both considered and a comparison is made between current results and the results related to the system with fixed base. The best location of Outrigger–belt truss system is determined by considering the maximum roof displacement, base moment and base shear with and without soil–structure interaction. It is shown that considering SSI affects the location of Outrigger–belt truss system. Elastic analysis of both systems, namely with fixed base and with soil–structure interaction, showed that locating the belt truss at higher stories caused lower amounts of roof displacement.
-
seismic performance of Outrigger belt truss system considering soil structure interaction
International Journal of Advanced Structural Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:The focus of this study is to investigate the seismic behavior of Outrigger-braced building considering the soil–structure interaction based on finding the best location of Outrigger and belt truss system. For this purpose, a central Outrigger-braced frame of a steel tall building is considered. A layered soil deposit underlied this frame and the resulting soil–structure system is subjected to seismic excitation. To analyze this system, direct method is employed in OpenSees. Also, elastic and in-elastic analyses are both considered and a comparison is made between current results and the results related to the system with fixed base. The best location of Outrigger–belt truss system is determined by considering the maximum roof displacement, base moment and base shear with and without soil–structure interaction. It is shown that considering SSI affects the location of Outrigger–belt truss system. Elastic analysis of both systems, namely with fixed base and with soil–structure interaction, showed that locating the belt truss at higher stories caused lower amounts of roof displacement.
-
Determination of optimum location for flexible Outrigger systems in tall buildings with constant cross section consisting of framed tube, shear core, belt truss and Outrigger system using energy method
International Journal of Steel Structures, 2017Co-Authors: Reza Kamgar, Reza RahgozarAbstract:In this paper, based on maximizing the Outrigger-belt truss system’s strain energy, a methodology for determining the optimum location of a flexible Outrigger system is presented. Tall building structures with combined systems of framed tube, shear core, belt truss and Outrigger system are modeled using continuum approach. In this approach, the framed tube system is modeled as a cantilevered beam with box cross section. The effect of Outrigger and shear core systems on framed tube’s response under lateral loading is modeled by a rotational spring placed at the location of belt truss and Outrigger system. Optimum location of this spring is obtained when energy absorbed by the spring is maximized. For this purpose, first derivative of the energy equation with respect to spring location as measured from base of the structure, is set to zero. Optimum location for Outrigger and belt truss system is calculated for three types of lateral loadings, i.e. uniformly and triangularly distributed loads along structure’s height, and concentrated load at top of the structure. Accuracy of the proposed method is verified through numerical examples. The results show that the proposed method is reasonably accurate. In addition, for different stiffness of shear core and Outrigger system, several figures are presented that can be used to determine the optimum location of belt truss and Outrigger system.
Reihaneh Tavakoli - One of the best experts on this subject based on the ideXlab platform.
-
Seismic Performance of Outrigger-Braced System Based on Finite Element and Component-Mode Synthesis Methods
Iranian Journal of Science and Technology Transactions of Civil Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:Determining the optimum location of Outrigger-belt truss system is of the most important challenges in tall structures. In this paper, two numerical methods, finite element method (FEM) and component-mode synthesis (CMS), are evaluated to determine the seismic performance of two buildings with different heights: one with 20 stories and the other with 30 stories. To find the optimum location of the Outrigger, seismic performance of 2D Outrigger-braced buildings in terms of inter-story drift ratio, roof displacement, base shear, and base moment is investigated. It is concluded that CMS as a model reduction method is very effective and useful in reducing the required analysis time as well as having good concordance with FEM results. The seismic responses of the two buildings change significantly as the Outrigger location changes from the first to the last story. The accuracy of the results is verified through the OpenSees program. Results show that the component-mode synthesis method is able to reduce the analysis time significantly, and also the efficiency and impotence of this method are more obvious as degrees of freedom are increased. In addition, placing the Outrigger system at 0.6 H to 0.8 H of the total height of the building improves the seismic performance of the structure.
-
Seismic performance of Outrigger–belt truss system considering soil–structure interaction
International Journal of Advanced Structural Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:The focus of this study is to investigate the seismic behavior of Outrigger-braced building considering the soil–structure interaction based on finding the best location of Outrigger and belt truss system. For this purpose, a central Outrigger-braced frame of a steel tall building is considered. A layered soil deposit underlied this frame and the resulting soil–structure system is subjected to seismic excitation. To analyze this system, direct method is employed in OpenSees. Also, elastic and in-elastic analyses are both considered and a comparison is made between current results and the results related to the system with fixed base. The best location of Outrigger–belt truss system is determined by considering the maximum roof displacement, base moment and base shear with and without soil–structure interaction. It is shown that considering SSI affects the location of Outrigger–belt truss system. Elastic analysis of both systems, namely with fixed base and with soil–structure interaction, showed that locating the belt truss at higher stories caused lower amounts of roof displacement.
-
seismic performance of Outrigger belt truss system considering soil structure interaction
International Journal of Advanced Structural Engineering, 2019Co-Authors: Reihaneh Tavakoli, Reza Kamgar, Reza RahgozarAbstract:The focus of this study is to investigate the seismic behavior of Outrigger-braced building considering the soil–structure interaction based on finding the best location of Outrigger and belt truss system. For this purpose, a central Outrigger-braced frame of a steel tall building is considered. A layered soil deposit underlied this frame and the resulting soil–structure system is subjected to seismic excitation. To analyze this system, direct method is employed in OpenSees. Also, elastic and in-elastic analyses are both considered and a comparison is made between current results and the results related to the system with fixed base. The best location of Outrigger–belt truss system is determined by considering the maximum roof displacement, base moment and base shear with and without soil–structure interaction. It is shown that considering SSI affects the location of Outrigger–belt truss system. Elastic analysis of both systems, namely with fixed base and with soil–structure interaction, showed that locating the belt truss at higher stories caused lower amounts of roof displacement.
Joo-won Kang - One of the best experts on this subject based on the ideXlab platform.
-
Smart Outrigger damper system for response reduction of tall buildings subjected to wind and seismic excitations
International Journal of Steel Structures, 2017Co-Authors: Joo-won KangAbstract:The Outrigger damper system has recently been proposed to reduce the dynamic response of tall buildings subjected to lateral loads. Previous studies have shown that the Outrigger damper system could effectively increase the response reduction capacity of tall buildings. The Outrigger damper system was used not only for a response reduction of tall buildings, but also for adjusting the differential column shortening. When an Outrigger damper system is designed optimally for wind or earthquake loads, it shows good control performance against each target excitation. On the other hand, the Outrigger damper system designed for the wind load cannot effectively control the seismic responses and vice versa. This study examined the control performance of a smart Outrigger damper system for reducing both the wind and seismic responses. The smart Outrigger damper system was comprised of magnetorheological dampers. A fuzzy logic control algorithm, which was optimized by a multi-objective genetic algorithm, was used to control the smart Outrigger damper system. Numerical analysis showed that the smart Outrigger damper system could provide superior control performance for the reduction of both wind and earthquake responses compared to the general Outrigger system and passive Outrigger damper system.
-
Semi-active Outrigger Damping System for Seismic Protection of Building Structure
Journal of Asian Architecture and Building Engineering, 2017Co-Authors: Joo-won KangAbstract:The Outrigger structural system is one of the most widely used lateral load-resisting structural systems for high-rise buildings. To increase the energy dissipation capacity of the Outrigger system...
-
Evaluation of Vibration Control Performance of Outrigger Damper System for Tall Buildings Subjected to Seismic Load
2015Co-Authors: Sung Wook Yoon, Joo-won KangAbstract:Recently, the concept of damped Outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of Outrigger damper has been analyzed. To this end, a simplified analysis model with Outrigger damper system has been developed. An artificial wind of 1000 seconds with 0.1 second time steps was generated by using a Kaimal spectrum. Analysis results show that Outrigger damper system is more effective up to 20-23% in the control of dynamic response compared to conventional Outrigger system. The increase of Outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the Outrigger damper system because, the Outrigger damper having large capacity is result in heavy financial burden.
-
optimal design of Outrigger damper using multi objective genetic algorithm
JOURNAL OF THE KOREAN ASSOCIATION FOR AND SPATIAL STRUCTURES, 2014Co-Authors: Sung Wook Yoon, Joo-won KangAbstract:Recently, a concept of damped Outrigger system has been proposed for tall buildings. Structural characteristics and design method of this system were not sufficiently investigated to date. In this study, control performance of damped Outrigger system for building structures subjected to seismic excitations has been investigated. And optimal design method of damped Outrigger system has been proposed using multi-objective genetic algorithm. To this end, a simplified numerical model of damped Outrigger system has been developed. State-space equation formulation proposed in previous research was used to make a numerical model. Multi-objective genetic algorithms has been employed for optimal design of the stiffness and damping parameters of the Outrigger damper. Based on numerical analyses, it has been shown that the damped Outrigger system control dynamic responses of the tall buildings subjected to earthquake excitations in comparison with a traditional Outrigger system.
