On Design of Eccentrically Braced Frames

1989 ◽  
Vol 5 (3) ◽  
pp. 495-511 ◽  
Author(s):  
Michael D. Engelhardt ◽  
Egor P. Popov
Keyword(s):  
Current Practice ◽  
Specific Reference ◽  
Braced Frames ◽  
Steel Buildings ◽  
Capacity Design ◽  
Link Length ◽  
Eccentrically Braced Frames ◽  
Overall Design ◽  
Design Requirements ◽  
Code Format

Seismic-resistant Eccentrically Braced Frames (EBFs) are becoming a widely used lateral resisting system for steel buildings, with even wider application anticipated as design requirements are put into building code format. This paper addresses a number of EBF design issues, which in the opinion of the authors are inadequately considered either in current practice or in the emerging code provisions. The overall design philosophy for EBFs is reviewed, with specific reference to the concept of “Capacity Design”. Application of capacity design principles assures that yielding will be restricted primarily to the ductile link elements, an important goal of EBF design. Further, through careful choice of frame geometry and link length at the preliminary stages, many potential design difficulties can be avoided. The paper also presents some important observations from experimental work currently underway on EBFs with long, flexural yielding links.

scholarly journals Advances in design of eccentrically braced frames

1987 ◽  
Vol 20 (1) ◽  
pp. 22-29 ◽  
Author(s):  
Egor P. Popov ◽  
Kazuhiko Kasai ◽  
Michael D. Engelhardt
Keyword(s):  
Design Procedure ◽  
Preliminary Design ◽  
Braced Frames ◽  
Link Length ◽  
Eccentrically Braced Frames ◽  
Short Beam ◽  
Different Types ◽  
Proper Design ◽  
Seismic Forces ◽  
The University

Eccentrically Braced Frames (EBFs) have attained recognized status as a viable structural steel system for resisting lateral seismic forces. Sustained research at the University of California, Berkeley, since 1977 and numerous field applications provide a
good database for their proper design. In this paper the different types of EBF are critically evaluated, and the kinematics of their inelastic deformation are examined with particular reference to the behaviour of isolated short beam segments or links. Desirable link length and web stiffening are recommended. A preliminary design procedure for hand-calculation of EBFs is described and some suggestions for brace connection details are advanced.

A Discussion on some Key Issues for Seismic Design of Concentrically Braced Frames According to Canadian and Chinese Codes

2010 ◽  
Vol 163-167 ◽  
pp. 211-221
Author(s):  
Wen Yuan Zhang ◽  
Constantin Christopoulos
Keyword(s):  
Seismic Design ◽  
Braced Frames ◽  
Capacity Design ◽  
Concentrically Braced Frames ◽  
Main Design ◽  
Seismic Force ◽  
Concentrically Braced ◽  
Key Issues ◽  
Design Requirements ◽  
Insight Into

To gain further insight into the seismic design of concentrically braced frames as defined by the Canadian and Chinese codes, a comparison of the main design requirements contained in each code is carried out in this paper. The comparison emphasizes on the differences existing in these two code provisions, and the reasons behind them. The issues that are examined include the seismic force resisting systems for braced frames, the height restrictions, the force transferred to the beams in chevron configurations, the slenderness ratios of the bracing members, the width-to-thickness ratios of the brace sections, and the influence of brace connections on the columns. Some additional issues that still remain undefined on the seismic response of these systems and some proposals for further studies are also discussed. It is concluded through this comparison that a number of modifications are still required in order to fully implement a capacity design approach of these systems in both codes.

scholarly journals Validation of a Design Procedure for Failure Mode Control of EB-Frames: Push-Over and IDA Analyses

2013 ◽  
Vol 7 (1) ◽  
pp. 193-207 ◽  
Author(s):  
Luigi Mastrandrea ◽  
Elide Nastri ◽  
Vincenzo Piluso
Keyword(s):  
Seismic Response ◽  
Failure Mode ◽  
Design Procedure ◽  
High Energy ◽  
Collapse Mechanism ◽  
Braced Frames ◽  
Link Length ◽  
Eccentrically Braced Frames ◽  
Ductility Demand ◽  
Global Type

The paper is devoted to the investigation of the seismic response of eccentrically braced frames characterised by links having different length. In addition, the analysed structures have been designed according to a methodology, already proposed by the authors, aiming to guarantee a collapse mechanism of global type. Therefore, the results of the nonlinear analyses herein presented provide the validation of the proposed design procedure, by testifying that all the designed structures exhibit a global failure mode where all the links are yielded while all the columns remain in elastic range with the exception of the base section of first storey columns, leading to high energy dissipation capacity and global ductility. Furthermore, two different distributions of the link lengths are examined. The first one is characterised by short links with uniform lengths along the height of the structure. The second one is characterised by the use of link elements having different length at the different storeys which are selected to assure the same value of the non-dimensional link length. The seismic response of EB-Frames with such distributions of the link length is investigated by means of both push-over analyses and dynamic non-linear analyses. The comparison of the performances is mainly carried out in terms of plastic hinges distribution, local ductility demand and frame lateral stiffness.

A Risk-Based Approach to Determine the Optimal Service Life of Steel Buildings in Seismically Active Zones

2013 ◽  
Vol 284-287 ◽  
pp. 1446-1449 ◽  
Author(s):  
Chien Kuo Chiu ◽  
Heui Yung Chang
Keyword(s):  
Service Life ◽  
Braced Frames ◽  
Steel Buildings ◽  
Eccentrically Braced Frames ◽  
Optimal Service ◽  
Probable Maximum Loss ◽  
Moment Resisting ◽  
Structural Fragility ◽  
Active Zones ◽  
Buckling Restrained Braced Frames

The object of this study is to propose, develop and apply a risk-based approach to determine the optimal service life for steel framed buildings in seismically active zones. The proposed framework uses models for seismic hazards, structural fragility and loss functions to estimate the system-wide costs owing to earthquake retrofitting and recovery. With the seismic risk curves (i.e. the expected seismic loss and probability of exceeding the loss), the optimal service life can be determined according to the probable maximum loss (PML) defined by the building’s owner. The risk-based approach is further illustrated by examples of 6- and 20-story steel framed buildings. The buildings have three kinds of different lateral load resisting systems, including moment resisting frames, eccentrically braced frames and buckling restrained braced frames. The results show that for the considered PML (i.e. 40% initial construction cost) and risk acceptance (e.g. 90% reliability), steel braced frames can effectively improve seismic fragility and lengthen service life for a low-rise building. However, the same effects cannot be expected in a high-rise building.

Advances in Design of Eccentrically Braced Frames

1987 ◽  
Vol 3 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Egor P. Popov ◽  
Kazuhiko Kasai ◽  
Michael D. Engelhardt
Keyword(s):  
Design Procedure ◽  
Preliminary Design ◽  
Braced Frames ◽  
Link Length ◽  
Eccentrically Braced Frames ◽  
Short Beam ◽  
Different Types ◽  
Proper Design ◽  
Seismic Forces ◽  
The University

Eccentrically Braced Frames (EBFs) have attained recognized status as a viable structural steel system for resisting lateral seismic forces. Sustained research at the University of California, Berkeley, since 1977 and numerous field applications provide a good database for their proper design. In this paper the different types of EBF are critically evaluated, and the kinematics of their inelastic deformation are examined with particular reference to the behavior of isolated short beam segments or links. Desirable link length and web stiffening are recommended. A preliminary design procedure for hand-calculation of EBFs is described and some suggestions for brace connection details are advanced.

Seismic analysis of links of various lengths in eccentrically braced frames

1991 ◽  
Vol 18 (1) ◽  
pp. 140-148 ◽  
Author(s):  
A. Ghobarah ◽  
T. Ramadan
Keyword(s):  
Seismic Analysis ◽  
Element Model ◽  
Elastic Stiffness ◽  
Lateral Loads ◽  
Braced Frames ◽  
Link Length ◽  
Eccentrically Braced Frames ◽  
Braced Frame ◽  
Shear Link ◽  
Inelastic Behaviour

Eccentrically braced steel frames have excellent elastic stiffness under moderate lateral loads and good ductility when subjected to severe seismic loading conditions. Under extreme loading, the inelastic behaviour is designed to be confined to a ductile link element. The behaviour of links of various lengths in eccentrically braced frames is evaluated using a finite element model. The link is subjected to extreme cyclic loading simulating a severe earthquake. The effect of the link length on its performance, capacity for energy dissipation, plastic mechanisms, and mode of failure are investigated. Measures for improving the performance of long links are examined. It was found that the most efficient link is the short shear link. However, the short link deformation is characterized by large angles of deformation, which may cause substantial damage to the nonstructural elements. On the other hand, long links were found to have smaller angles of deformation than short links, but with reduced ductility levels. An effective approach to improve the performance of long links is by increasing the flange thickness of the link section with the appropriate adjustment to the stiffener design. This technique can be applied to links of length up to 1.4 times the critical shear link length. Key words: steel, eccentric, braced, frame, link, seismic, ductility, design.

Seismic Response of Composite Eccentrically Braced Frames with Short Dissipative Element

2018 ◽  
Vol 763 ◽  
pp. 846-853
Author(s):  
Adina Vătăman ◽  
Adrian Ciutina ◽  
Daniel Grecea
Keyword(s):  
Structural Integrity ◽  
Concrete Slab ◽  
Plastic Hinge ◽  
Bending Moment ◽  
Eurocode 8 ◽  
Lateral Loads ◽  
Braced Frames ◽  
Link Length ◽  
Eccentrically Braced Frames ◽  
Good Energy

Eccentrically braced frames (EBF) in steel and composite solution are very well suited structural assemblies for buildings in areas with high seismicity. Due to their good energy dissipation capacity, they can undergo important lateral deformations by plastic hinge formation in the dissipative element (link element) without impacting the structural integrity of the system. The dissipative link elements can be short, medium or long (according to modern design norms, such as Eurocode 8), based on the ratio between shear force and bending moment. If the dissipative element length is smaller than 1.6(Mpl/Vpl) [mm], it is considered to be a short element and is predominantly subjected to shear. The links can be realized on steel solutions or composite with the concrete slab. However, the steel behavior is assumed for composite link. The current article presents the results of extensive numerical testing based on experimental results on the behavior of composite EBF with short link elements subjected to seismic-like lateral loads. The results will present the main differences in strength, stiffness and ductility between the responses of steel and composite EBFs. Finally, a parametrical study will show the influence of link length, influence of number of stiffeners and of the web slenderness.

Sign in / Sign up

Export Citation Format

Share Document