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Non-linear analysis of disposable knee bracing
, Article Computers and Structures ; Volume 75, Issue 1 , 2000 , Pages 65-72 ; 00457949 (ISSN) ; Khosravi, P ; Sharif University of Technology
2000
Abstract
An approximate method is presented that can be used to determine the non-linear behaviour of a new structural bracing system called the `Disposable Knee Bracing'. In this framing system, a special form of diagonal brace connected to a knee element instead of beam-column joint, is investigated. The diagonal element provides lateral stiffness during moderate earthquakes. However, the knee element is designed to have three plastic joints for dissipation of the energy caused by strong earthquake. This article demonstrates the transformation of a complex problem into a new, practical set of design charts and graphs. First, by studying of the elastic behaviour of the system, a suitable shape and...
Experimental evaluation of pinned frame equipped with ribbed bracing system
, Article Journal of Earthquake Engineering ; 2017 , Pages 1-21 ; 13632469 (ISSN) ; Toufigh, V ; Golafshani, A. A ; Arzeytoon, A ; Sharif University of Technology
Abstract
This study presents the experimental investigation of half-scale, one-story, one-bay pinned frames equipped with a ribbed bracing system (RBS). The RBS is a newly developed passive control system designed to eliminate buckling and enhance the seismic behavior of structures. Here, mechanical models of this bracing system were designed and constructed. Pinned frames equipped with the RBS were cyclically tested. The hysteretic behavior and energy absorbing capacities of the frames were evaluated. Based on the results, the full plastic capacity of the brace was achieved and no buckling occurred. The RBS frame illustrated proper hysteretic behavior and energy dissipation capacity up to 4% story...
Arthrometric evaluation of stabilizing effect of knee functional bracing at different flexion angles
, Article Journal of Sports Science and Medicine ; Volume 8, Issue 2 , 2009 , Pages 247-251 ; 13032968 (ISSN) ; Farahmand, F ; Karimi, H ; Kamali, M ; Sharif University of Technology
2009
Abstract
Previous in-vivo investigations on the stabilizing efficacy of knee bracing for ACL reconstructed patients have been often limited to 20-30 degrees of knee flexion. In this study, the effectiveness of a uniaxial hinged functional brace to improve the knee stability was assessed at 30, 60 and 90 degrees of knee flexion. Arthrometry tests were conducted on 15 healthy subjects before and following wearing the brace and the tibial displacements were measured at up to 150 N anterior forces. Results indicated that functional bracing has a significant stabilizing effect throughout the range of knee flexion examined (p < 0.05). The rate of effectiveness, however, was not consistent across the...
Experimental evaluation of pinned frame equipped with ribbed bracing system
, Article Journal of Earthquake Engineering ; Volume 23, Issue 8 , 2019 , Pages 1297-1317 ; 13632469 (ISSN) ; Toufigh, V ; Golafshani, A. A ; Arzeytoon, A ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
This study presents the experimental investigation of half-scale, one-story, one-bay pinned frames equipped with a ribbed bracing system (RBS). The RBS is a newly developed passive control system designed to eliminate buckling and enhance the seismic behavior of structures. Here, mechanical models of this bracing system were designed and constructed. Pinned frames equipped with the RBS were cyclically tested. The hysteretic behavior and energy absorbing capacities of the frames were evaluated. Based on the results, the full plastic capacity of the brace was achieved and no buckling occurred. The RBS frame illustrated proper hysteretic behavior and energy dissipation capacity up to 4% story...
On the optimal shape of new ductile knee bracing
, Article Second International Conference on High Performance Structures and Materials: HIGH PERFORMANCE STRUCTURES AND MATERIALS II, Ancona, 31 May 2004 through 2 June 2004 ; Volume 7 , 2004 , Pages 599-608 ; 14690071 (ISSN) ; Lotfollahi, M ; Sharif University of Technology
2004
Abstract
In this paper a particular structural bracing system, called the Chevron Knee Bracing (CKB), is introduced. In this framing system, a special form of diagonal braces that are connected to knee elements instead of beam-column joints is investigated. The braces provide required stiffness during moderate earthquakes, while the knee elements yield in flexure or shear to dissipate energy during a severe earthquake, whereby buckling of the braces or yielding of the main structure is prevented. First, elastic analysis is applied to the new system and a suitable shape and angle for the knee and the brace elements is proposed, using new and practical parameters. Then, by developing a nonlinear...
On the characteristics and seismic study of Hat Knee Bracing system, in steel structures
, Article Steel and Composite Structures ; Volume 13, Issue 1 , 2012 , Pages 1-13 ; 12299367 (ISSN) ; Mofid, M ; Sharif University of Technology
2012
Abstract
In this study, a new structural bracing system named 'Hat Knee Bracing' (HKB) is presented. In this structural system, a special form of diagonal braces, which is connected to the knee elements instead of beam-column joints, is investigated. The diagonal elements provide lateral stiffness during moderate earthquakes. However the knee elements, which is a fuse-like component, is designed to have one plastic joint in the knee elements for dissipation of the energy caused by strong earthquake. First, a suitable shape for brace and knee elements is proposed through elastic studying of the system and several practical parameters are established. Afterward, by developing applicable and highly...
Investigating the Application of y-Braced Frames in Seismic Performance of Steel Structures
, Ph.D. Dissertation Sharif University of Technology ; Vafai, Abolhassan (Supervisor)
Abstract
Finding suitable locations for installing conventional concentric bracings such as X and V, without interfering with building architecture and its openings, is a routine challenge in building design. One of the less known forms of concentric bracings which can be used to solve this issue, is the y-shaped bracing composed of three braces. In the current thesis, results of analytical studies, computer modeling and experimental tests are presented to extend the knowledge of structural behavior of y-bracings. As the first step, effective buckling lengths of braces with rigid connections were found from equilibrium equations incorporating the effect of axial force on rotational stiffness of...
Seismic performance of ribbed bracing system in passive control of structures
, Article JVC/Journal of Vibration and Control ; Volume 23, Issue 18 , 2017 , Pages 2926-2941 ; 10775463 (ISSN) ; Golafshani, A. A ; Toufigh, V ; Mohammadi, H ; Sharif University of Technology
Abstract
In this article, a novel passive control system, ribbed bracing system (RBS), has been proposed to deal with the buckling problem. RBS is a bracing system with a simple mechanism that can be installed in braces as a supplemental part. The behavior of RBS is similar to that of conventional braces under tensile loading. However, under compressive force, it endures an insignificant force and prevents the braces from buckling through length reduction. In addition, seismic damage is concentrated in the bracing system of the structures equipped with RBS, decreasing the dissipated hysteretic energy in other structural members. There are two different mechanisms for RBS: 1) completely-closed RBS...
Experimental and numerical studies on ribbed bracing system
, Article Structural Design of Tall and Special Buildings ; Volume 27, Issue 13 , 2018 ; 15417794 (ISSN) ; Toufigh, V ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
Ribbed bracing system (RBS) is an innovative structural system designed to eliminate the buckling of braces and enhance the behavior of structures under seismic loads. In this study, a collaborative performance of 2 RBS devices bracing a frame was assessed numerically and experimentally. In the numerical phase, the collaboration of ribbed braces at various stages of reversal loading was elaborated mathematically and was used for representing the system using finite element modeling. In the next phase, the numerically observed behavior was validated experimentally by conducting cyclic quasistatic tests of the proposed configurations. Two alternative RBS configurations—called completely closed...
Nonlinear seismic behavior of RC frames with RC braces
, Article Asian Journal of Civil Engineering ; Volume 9, Issue 6 , 2008 , Pages 577-592 ; 15630854 (ISSN) ; Mohseni, M. M ; Sharif University of Technology
2008
Abstract
Braced frames, besides other structural systems, such as moment resisting frames or shear walls, have been an effective and valuable method to enhance structures against lateral loads. In wind or seismic excitations, inclined elements react as truss web elements which would bear compression or tension stresses. This axial reaction results in less moments and therefore smaller sizes in beam and column sections with respect to members in similar moment resisting frame. However, low tensile strength of concrete material, made it a challenge to use in inclined members. In practice, there have been various methods to consider this defect such as disengagement of brace elements in tension or...
Experimental investigation into the behaviour of a new replaceable bracing system
, Article Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE ; Volume 2 , 2012 , Pages 427-437 ; 9780791844892 (ISBN) ; England, G. L ; Moradi, M ; Farahani, H ; Zarei, D ; Sharif University of Technology
2012
Abstract
A new bracing system with new features somewhat different from those of the existing ones was devised and is presented. These features comprise some of the advantages of eccentric bracing systems including their ability to dissipate energy through bending of flexural elements while lacking some of the disadvantages of such systems including their inability of being replaced upon damage during events such as earthquakes, etc. While in traditional types of braces, including both concentric and eccentric ones, braces are under axial loading, in this new system they work in a bending capacity. As a result, the sort of flexibility which is introduced in the system in the presence of eccentric...
Assessment of Seismic Behavior Factor of Irregular Midrise Steel Structure
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
The Overstrength, Ductility and the Response Modification Factor (R) for 70 steel X-braced , Inverted-V-Braced and Offcenter Bracing System frames were evaluated by performing pushover analysis of model structure with various stories (3,6,9,12&15 story) and span length (4,6&8 meter). Some result were compared with those from nonlinear dynamic analysis. According to the analysis result the R factors obtained from nonlinear dynamic analysis are 15% more than obtained from pushover analysis and R factors computed from pushover analysis were generally smaller than the values given in the design codes. R factors in Irregular structure in height are about 90% of R values in regular structure in...
Investigating the Behavior of a Type of Energy Absorbing Bracing System
, M.Sc. Thesis Sharif University of Technology ; Khonsari, Vahid (Supervisor)
Abstract
Bracing Systems are usually a set of inclined members that are embedded in structures to resist lateral forces and control lateral displacements. There are different types and behaviors for Bracing Systems depending on the way of assembling and locating them in the structure. Braced Frames, such as Concentrically Braced Frames (CBFs), generally have high stiffness and low ductility. Another Type of Braced Frames is Eccentrically Braced Frames (EBFs) which improves CBFs by establishing suitable ductility as well as stiffness. Inelastic behavior of Links involved with EBFs caused this in EBFs. Nevertheless, these systems have no efficiency in next earthquake, because links are parts of beams...
Seismic Response of Zipper Inverted-V Braced Frame with Unequal Buckling-Restrained Braces
, M.Sc. Thesis Sharif University of Technology ; Ahmadizadeh, Mehdi (Supervisor)
Abstract
This study presents the advantages of using unsymmetrical buckling restrained braces in zipper frames for simultaneous improvement of peak and residual response of low- and mid-rise buildings. It is demonstrated that such combination allows for the usage of benefits of each of these systems, namely the significant energy dissipation capacity of buckling restrained braces and better distribution of hysteretic energy dissipation demands through the elevation observed in zipper frames. It has already been shown that using buckling restrained braces of varying yield strengths within each story of a building can improve the residual response of buckling-restrained-braced frames without severely...
Performance of BRBF System and Comparing it with the OCBF System
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Buckling-Restrained Braced Frame system (BRBFs) are a new type of steel seismic-load-resisting system that has found use in several countries because of its efficiency and its promise of seismic performance far superior to that of conventional braced frames. The system is addressed in the 2005 edition of the AISC Seismic Provisions for Structural Steel Buildings, also a set of design provisions has been developed by NEHRP. This thesis illustrates the seismic design of buckling-restrained braced frames and compares its seismic performance with the performance of ordinary bracing systems. This work investigates the advantage and disadvantages of this new type of seismic resisting. By having...
Investigating the Behaviour of A Type of Energy Absorbing Bracing System
, M.Sc. Thesis Sharif University of Technology ; Khonsari, Vahid (Supervisor)Performance-based assessment of an innovative braced tube system for tall buildings
, Article Bulletin of Earthquake Engineering ; 2017 , Pages 1-22 ; 1570761X (ISSN) ; Toufigh, V ; Golafshani, A. A ; Arzeytoon, A ; Sharif University of Technology
Abstract
In this paper, an innovative seismic lateral force resisting system for tall buildings is introduced. In this system, a novel supplemental part, ribbed bracing system (RBSyst), is attached to Braced Tube System, creating a modified BTS. RBSyst is a supplemental part which is attached to the conventional bracing members to eliminate buckling problem. The behavior of RBSyst under tensile force is similar to that of the conventional braces. However, in compression, it prevents the braces from buckling by length reduction. In order to evaluate the efficiency of this new BTS system by performance-based assessment, two typical 40-story tall buildings with different story modules equipped with this...
Local and global buckling condition of all-steel buckling restrained braces
, Article Steel and Composite Structures ; Volume 23, Issue 2 , 2017 , Pages 217-228 ; 12299367 (ISSN) ; Nazeryan, M ; Bahrani, M. K ; Nooralizadeh, A ; Montazerian, L ; Naserifard, M ; Sharif University of Technology
Techno Press
2017
Abstract
Braces are one of the retrofitting systems of structure under earthquake loading. Buckling restrained braces (BRBs) are one of the very efficient braces for lateral loads. One of the key needs for a desirable and acceptable behavior of buckling-restraining brace members under intensive loading is that it prevents total buckling until the bracing member tolerates enough plastic deformation and ductility. This paper presents the results of a set of analysis by finite element method on buckling restrained braces in which the filler materials within the restraining member have been removed. These braces contain core as the conventional BRBs, but they have a different buckling restrained system....
On the effect of large deflection on nonlinear behavior of an eccentric bracing system
, Article Structural Design of Tall and Special Buildings ; Volume 17, Issue 4 , 2008 , Pages 795-808 ; 15417794 (ISSN) ; Mofid, M ; Khezrzadeh, H ; Sharif University of Technology
2008
Abstract
In this article, a particular off-center bracing system is introduced. In this system, the tensile diagonal strut is not straight. When the load is applied, the original geometry changes and thus causes the system to harden. Based on this behavior, a step-by-step analytical method is developed. Using this method, a Geometrically Nonlinear Analysis Program (GNAP) is designed to analyze the elastic force-displacement relation. Extension of this program to dynamic analysis led to a Dynamic Nonlinear Analysis Program (DNAP). The object of this article is to show that such bracing systems will lead to less seismic force on such structures compared to classic concentric bracing systems. On the...
On the design of new ductile knee bracing
, Article Journal of Constructional Steel Research ; Volume 62, Issue 3 , 2006 , Pages 282-294 ; 0143974X (ISSN) ; Mofid, M ; Sharif University of Technology
2006
Abstract
An approximate method is presented that can be used to determine the nonlinear behavior of a new structural bracing system called the 'Chevron Knee Bracing' (CKB). In this framing system, an especial form of diagonal brace connected to a knee element instead of a beam-column joint is investigated. The diagonal element provides lateral stiffness during a moderate earthquake. However, the knee element is designed to have three plastic joints or two yielded specimens in flexural and shear yielding mode, respectively, for dissipation of the energy caused by a strong earthquake. This article demonstrates the transformation of a complex problem into a new, practical set of design charts and...