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Seismic behavior of concentrically braced steel frames.
Seismic design of low- and medium-rise chevron braced steel frames.
Seismic demand on brace-intersected beams in two-story X-braced frames.
Seismic performance and new procedure for chevron braced frames.
Plastic design of seismic Resistant V-Braced frames.

A design procedure for seismic retrofitting of eccentrically braced frames (EBFs) by rocking walls and viscous dampers is proposed.
A design procedure for retrofit of eccentrically braced frames by means of rocking walls and viscous dampers is here proposed.
First, single-story eccentrically braced systems in k-braced configuration have been defined.
Beams, columns and braces are modelled by elastic members.
The internal forces in links are determined by the lateral force method of analysis and a behavior factor equal to 5 is used to reduce the seismic forces.

the core unit + constraint element=brb Fig.4 Behavior of conventional brace Fig.3 Schematic diagram of buckling restrained brace versus buckling restrained brace brb has the following advantages[4]: (1 ) axial stiffness and flexural stiffness separation; (2) the higher capacity of brb; (3) the ductility and hysteretic performance; (4) protecting the main structure, the adjacent beams.
Connecting member should have the durability and easy maintenance. 3 Buckling restrained brace layout of different effects on the seismic effect In the layout of frame structure, We have two lines of defence in the structure under the horizontal load, the first line is the vertical support, the second is the framework.
(a)Compressive Buckling Behavior of ordinary support (b) Anti compression buckling stability behavior support Fig.6 Compression behavior of ordinary brace and brb (2) simpler Flexible structure design ①The brb can easily adjust the support stiffness by changing the core length support according to the strength of selection section, as a result ,the design more flexible. ②For the irregular plane structure, the stiffness center and the center of mass are often incon-sistent, the brb can be obtained better effect than the common support by adjusting the structure of the torsional stiffness. ③The brb can also give structure to provide adequate stiffness and damping, without the use of large support, the space utilization rate is higher. ④In the structure design, brb can be simplified as two force model, the constitutive relation of the bilinear model, mechanical model is more simple
Seismic Performance of Buckling-Restrained Braced Frame with Masonry Walls and Design Method Concerning Energy Dissipation Ratio[D].Dalian: Dalian University of Technology,2013.
Performance based seismic design method of steel frame with bucking restrained braces[D].Hunan: Hunan University,2012.

Analyses in seismic responses of different types of eccentrically braced steel frames Ying Hu 1, a, Jinsong Lei 1, 2, b and Wenxia Luo 1,c 1 College of Civil Engineering and Architecture, Southwest University of Science and Technology; Mianyang, Sichuan, China; 2College of Civil Engineering, Hunan University, Changsha, Hunan, China a ross8109@hotmail.com, b leijinsong2003@163.com, c luoxia886@163.com Key words: Eccentrically braced steel frames, finite element analysis, seismic behaviors, time history analysis.
Abstract: In order to research the seismic behaviors of the eccentrically braced steel frames, used finite element software SAP2000 to build 20-storey single frame models with type D, K, and Y eccentrically braces, and did the seismic time history analyses to them.
The results reveal that: type K is able to control the moments and displacements of the layers; while type Y is good at restricting the acceleration amplified effect, and the seismic behavior of type D is between the former two types.
Introduction By using frame-brace system, it is able to overcome the disadvantage of the pure frame like stiffness is low; storey drifts and lateral displacements are large.
Based on the forms and the ways of energy consumption, the system can be divided into concentric braced and eccentrically braced frames.

Current retrofitting methods like using Fibre-reinforced plastic (FRP) material to strengthen columns and beams [3], setting frames outside the structure to increase lateral stiffness of the original building or setting isolated mechanisms to reduce seismic actions.
Application to Single Story Frame under Seismic Analysis Nonlinear deployable brace model is applied in a single-storey, single-bay V-bracing frame model to analyse the effects of brace configuration under monotonic static load subject at the left top of the frame model.
Fig. 6 Frame models under Pushover Analysis case The deployable model still has a similar behaviour during the elastic stage but the buckling strength is only 50% of the conventional type.
Compared with conventional frame model, the deployable model has more ductility after the frame buckles and the plastic behaviour lasts longer than the other two models.
Conclusions Nonlinear deployable brace member models with different joint clearance and strut eccentricities are investigated to simulate the behaviour under cyclical load cases.

Next, the influence of staircases on the seismic behavior of concrete frames is studied.
Stairs change the seismic behavior of the whole system.
Seismic responses of the stairs and their influence on overall seismic behavior of structures are neglected in the current design practice.
The third approach is to consider the effect of stairs on seismic behavior and stiffness of the frame.
Axial forces of the columns connected to the staircase are also increased due to bracing effect of the stair slab.

Studies found in the literature [2, 4, 5, 6, 9 and 11] about the structural behavior of frames with energy dissipating devices concentrate on problems related to the global response of these systems.
In this paper, the influence of the seismic loads on the force distribution in the columns and bracing elements is evaluated with some detail.
The frame-bracing system with TPEA damping devices gives us the best results from the point of the reduced forces in the columns.
check[%] Column forces[kN] Capac. check[%] Bracing forc.
Králik, jr. : Seismic Analysis of Reinforced Concrete Frame-Wall Systems Considering Ductility Effects in Accordance to Eurocode.

A new braced steel frame system was suggested, which was energy dissipating eccentrically brace.
Considering the shortcomings of current eccentrically braced frames, this paper proposed a new type of framework – energy dissipating eccentrically braced frames [6].
In order to study the seismic behavior of this new frame, experiments were carried out to compare the new frame (D-G2) with common eccentrically braced frame (hereinafter called D-G1[7] for short).
So specimen of D-G2 had great bearing capacity and deformation behavior.
References [1] Taichiro Okazaki: Seismic Performance of Link-to-Column Connections in Steel Eccentrically Braced Frames (Proquest Information and Learning Company, the University of Texas of Austin, 2004)

This paper uses finite element software ANSYS to do non-linear time history analysis for Center Braced Steel Frame, Eccentrically Braced Steel Frame, Buckling-restrained Braced Steel Frame under the earthquake.
Elastic-plastic time history analysis method has been adopted to analysis the damping energy dissipation capacity of center braced steel frame, eccentrically braced steel frame, buckling-restrained braced steel frame under the earthquake.
Fig. 8 Curve of acceleration power amplification coefficient 3 Conclusions (1) Through the nonlinear time-history analysis of concentrically braced frames, eccentrically braced frames and buckling restrained brace frames, buckling restrained brace can significantly contain the increase of the frame structural lateral displacement, and amplification effect of seismic action is also lesser when peak acceleration is input.
The Practice and Research Development of Buckling-Restrained Braced Frames (I) [J].
[7] Luo Kai-hai, Cheng Shao-ge , Bai Xue-shuang , Rong Wei-sheng, Analysis of Mechanical Behavior of the Buckling Restrained Energy-dissipation Braces[J].

Floors have a key role in the seismic behaviour of structures, especially in multi-story buildings.
The seismic behaviour of structures subjected to earthquake ground motions may significantly change due to the occurrence of torsional effects [9, 10].
Effects of torsion on seismic behaviour of structural systems have been studied by many researchers however, the effect of torsion on in-plane forces in diaphragms has not been studied comprehensively.
Nonlinear actions in the structural elements changed the stiffness of the inelastically responding braced frame and, as a result, the elastic frame and the inelastic frame demonstrated a different stiffness.
Ryan, Effects of torsion on the behavior of peripheral steel‐braced frame systems.