Evolution of EC8 Seismic Design Rules for X Concentric Bracings

Eurocodes are currently under revision within a six-year program by CEN/TC 250. In this framework, concentric bracings, particularly in cross configuration, have been largely debated; indeed, several criticisms affect the seismic design procedure currently codified within Eurocode 8, entailing significant design efforts and leading to massive and non-economical structural systems, even characterized by poor seismic behavior. The efforts of SC8 have been aimed at improving the codified seismic design criteria for concentrically braced frames, by providing requirements and detailing rules conceived to simplify the design process and to improve the seismic performance. The current paper provides recent advances in the field of computational and structural engineering focusing on symmetric X concentrically bracings in seismic area, outlining the evolution of Eurocode 8 (EC8) seismic design rules, by examining the following aspects: (i) ductility class and behavior factor, (ii) analysis and modelling aspects, (iii) design of dissipative members; (iv) design of non-dissipative zones; (v) brace-to-frame connections.

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Remarks on Seismic Design Rules of EC8 for Inverted-V CBFs

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.763.1147 ◽

2018 ◽

Vol 763 ◽

pp. 1147-1154 ◽

Cited By ~ 3

Author(s):

Silvia Costanzo ◽

Mario D'Aniello ◽

Raffaele Landolfo ◽

Attilio de Martino

Keyword(s):

Design Procedure ◽

Eurocode 8 ◽

Structural System ◽

Braced Frames ◽

Concentrically Braced Frames ◽

Design Rules ◽

Concentrically Braced ◽

Dynamic Analyses ◽

Study Case ◽

Nonlinear Dynamic Analyses

Chevron concentrically braced frames (C-CBFs) are expected to provide limited ductility in the framework of Eurocode 8: differently from North American codes, lower values of behavior factors are recommended by EN 1998 for C-CBFs than for other concentric bracing configurations (namely diagonal and cross bracings). The research presented in this paper is aimed at revising the design rules and requirements provided for by EN 1998-1 for C-CBFs in order to improve the ductility and the dissipative capacity of this structural system. The proposed design criteria are validated by means of nonlinear dynamic analyses performed on a study case. The results confirm the effectiveness of developed design procedure.

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Code provisions for seismic design for concentrically braced steel frames

Canadian Journal of Civil Engineering ◽

10.1139/l92-122 ◽

1992 ◽

Vol 19 (6) ◽

pp. 1025-1031 ◽

Cited By ~ 4

Author(s):

R. G. Redwood ◽

A. K. Jain

Keyword(s):

Seismic Design ◽

Structural Engineering ◽

Steel Frames ◽

Braced Frames ◽

Concentrically Braced Frames ◽

Braced Frame ◽

Concentrically Braced ◽

Interstorey Drift ◽

Available Information ◽

Steel Braced Frame

Extensive research into the inelastic seismic response of concentrically braced frames and their components has been carried out in the last two decades. This knowledge has now been incorporated into seismic design practice in several countries, notably the U.S.A., Canada, and New Zealand. In this paper, design specifications from these three countries, which derive largely from the same body of research, are compared. The basic design philosophy for concentrically braced steel frames, loading, and member detailing are examined. It is concluded that, in general, the Canadian specifications are in conformity with the available information and have many similar features to codes of the other countries. Significant differences exist in the classification of braced frames, between interstorey drift requirements, in the treatment of dual structural systems, and to a lesser extent in member detailing requirements. Some features of Canadian codes meriting review are identified. Key words: structural engineering, earthquakes, standards, steel, braced frame, ductility, concentric bracing, dual system.

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On the European Norms of Design of Buckling Restrained Braced Frames

The Open Civil Engineering Journal ◽

10.2174/1874149501711010513 ◽

2017 ◽

Vol 11 (1) ◽

pp. 513-530 ◽

Cited By ~ 1

Author(s):

Ádám Zsarnóczay ◽

Tamás Balogh ◽

László Gergely Vigh

Keyword(s):

Seismic Design ◽

Structural Reliability ◽

Design Procedure ◽

Material Model ◽

Eurocode 8 ◽

Braced Frames ◽

Reliability Indices ◽

Buckling Restrained Braces ◽

Buckling Restrained Braced Frames ◽

Ground Motion Records

The application of buckling restrained braced frames is hindered in Europe by the absence of a standardized design procedure in Eurocode 8, the European seismic design standard. The presented research aims to develop a robust design procedure for buckling restrained braced frames. A design procedure is proposed by the authors. Its performance has been evaluated for buckling restrained braced frames with two-bay X-brace type brace configurations using a state-of-the-art methodology based on the recommendations in the FEMA P695 document. A special numerical material model was developed within the scope of this research to represent the behavior of buckling restrained braces more appropriately in a numerical environment. A total of 24 archetype designs were prepared and their nonlinear dynamic response was calculated using real ground motion records in incremental dynamic analyses. Evaluation of archetype collapse probabilities confirms that the proposed design procedure can utilize the advantageous behavior of buckling restrained braces. Resulting reliability indices suggest a need for additional regulations in the Eurocodes that introduce reasonable structural reliability index limits for seismic design.

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Seismic Behaviour of EC8-Compliant Moment Resisting and Concentrically Braced Frames

Buildings ◽

10.3390/buildings9090196 ◽

2019 ◽

Vol 9 (9) ◽

pp. 196 ◽

Cited By ~ 5

Author(s):

Silvia Costanzo ◽

Roberto Tartaglia ◽

Gianmaria Di Lorenzo ◽

Attilio De Martino

Keyword(s):

Design Procedure ◽

Eurocode 8 ◽

Braced Frames ◽

Concentrically Braced Frames ◽

Research Activity ◽

Seismic Behaviour ◽

Concentrically Braced ◽

Dynamic Analyses ◽

Moment Resisting ◽

Energy Dissipation Capacity

The design procedure codified within current Eurocode 8 for dissipative moment resisting and concentrically braced frames have led to the design of massive systems characterized in the most of cases by poor energy dissipation capacity. The research activity presented in the current paper addresses the identification of the main criticisms and fallacies in the current EN 1998-1 for those seismic-resistant typologies. In this regard, the design provisions and codified rules for both moment resisting frames (MRFs) and chevron concentrically braced frames (CCBFs) are critically discussed and numerically investigated. Static and incremental dynamic analyses were performed on a set of 3 and 6-story frames designed compliant to EN 1998-1. The results from the numerical analyses are reported and discussed.

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