scholarly journals An Alternative Approach for the Design of Chevron-Braced Frames

2021 ◽  
Vol 11 (22) ◽  
pp. 11014
Author(s):  
Francesca Barbagallo ◽  
Melina Bosco ◽  
Marco Caragliano ◽  
Edoardo M. Marino ◽  
Pier Paolo Rossi
Keyword(s):  
Seismic Performance ◽  
Design Procedure ◽  
Eurocode 8 ◽  
Braced Frames ◽  
Limit States ◽  
Alternative Approach ◽  
Significant Damage ◽  
Internal Forces ◽  
Ductility Capacity ◽  
Elastic Design

The design of steel chevron-braced frames as per Eurocode 8 is based on the idea that only the braces should buckle and yield during ground motions, while other members should remain elastic. The elastic design of the braced frames is also allowed. However, in both cases, the seismic performance of the frame may be compromised because of premature yielding/buckling of columns. This paper proposes an alternative design procedure that promotes yielding of beams in addition to yielding of braces. This mitigates the vertical unbalanced force transmitted by compressive and tensile braces to the beam and in turn reduces the internal forces of the columns. The result is the overall improvement of the seismic performance owing to the reduction of the number of cases in which failure of the columns occurs before full exploitation of the ductility capacity of the dissipative members. The proposed design procedure is validated by incremental dynamic analyses performed on a set of chevron-braced frames. In particular, the peak ground accelerations of the frames designed by the proposed procedure at the attainment of Significant Damage and Collapse Prevention limit states are determined and compared to those of frames designed according to Eurocode 8. Furthermore, frames designed according to the Eurocodes and to the proposed method are compared in terms of structural cost.

scholarly journals On the European Norms of Design of Buckling Restrained Braced Frames

2017 ◽  
Vol 11 (1) ◽  
pp. 513-530 ◽  
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.

scholarly journals Evolution of EC8 Seismic Design Rules for X Concentric Bracings

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1807
Author(s):  
Alessia Campiche ◽  
Silvia Costanzo
Keyword(s):  
Seismic Design ◽  
Structural Engineering ◽  
Design Procedure ◽  
Eurocode 8 ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Design Rules ◽  
Factor Ii ◽  
And Behavior ◽  
Seismic Area

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.

Seismic performance and new design procedure for chevron-braced frames

2006 ◽  
Vol 35 (4) ◽  
pp. 433-452 ◽  
Author(s):  
Edoardo M. Marino ◽  
Masayoshi Nakashima
Keyword(s):  
Seismic Performance ◽  
Design Procedure ◽  
Braced Frames

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

Buildings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 196 ◽  
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.

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

2018 ◽  
Vol 763 ◽  
pp. 1147-1154 ◽  
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.

scholarly journals Dual-concentrically Braced Frames Using High Strength Steel – Seismic Response

2017 ◽  
Vol 11 (1) ◽  
pp. 496-512 ◽  
Author(s):  
André Tenchini ◽  
Carlos Rebelo ◽  
Luis Simões da Silva ◽  
Luciano Lima
Keyword(s):  
Seismic Performance ◽  
High Strength Steel ◽  
Steel Production ◽  
High Strength ◽  
High Yield ◽  
Eurocode 8 ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Concentrically Braced ◽  
Steel Grades

The recent technological advances on steel production process allowed introducing in construction market steel grades with significantly high yield strength. These new materials are known as High Strength Steel (HSS). The use of these steel grades offers economical and mechanical benefits compared with mild carbon steel (MCS). Consequently, their use is constantly increasing especially for seismic applications that are the rational field to exploit the high performance of HSS, by means of the “dual-steel” concept, which combines the HSS with MCS in order to provide overstrength to non-dissipative element and ductility to dissipative ones, thus controlling the global frame behaviour into a ductile overall failure mode. In this paper, a comprehensive parametric study devoted to investigate the seismic performance of Eurocode 8 compliant dual-steel chevron Dual-Concentrically Braced Frames (D-CBF) is presented and discussed. This structural typology is composed of two dissipative sub-systems acting in parallel, namely Moment Resisting Frames (MRFs) and Concentrically Braced Frames (CBFs). Static nonlinear pushover analyses were carried out in order to assess the seismic performance of the D-CBFs. The examined parameters cover both geometric and mechanical variables, as the type columns, span length, number of storeys and spectral shape. The analyses showed that the use of HSS in Eurocode 8 compliant D-CBFs is effective to avoid the damage in non-dissipative members. On the other hand, the use of HSS leads to design flexible members, especially for the braced-intercepted beams, resulting in poor performance of bracing members due to significant damage concentration. The economic evaluation shows that the use of HSS allows reducing the material consumptions and dropping the total constructional costs.

scholarly journals A Capacity Design Procedure for Columns of Steel Structures with Diagonals Braces

2014 ◽  
Vol 8 (1) ◽  
pp. 196-207 ◽  
Author(s):  
M. Bosco ◽  
A. Ghersi ◽  
E.M. Marino ◽  
P.P. Rossi
Keyword(s):  
Design Procedure ◽  
Steel Structures ◽  
Building Structures ◽  
Axial Deformation ◽  
Braced Frames ◽  
Capacity Design ◽  
Concentrically Braced Frames ◽  
Design Spectrum ◽  
Internal Forces ◽  
Seismic Forces

According to modern seismic codes, in concentrically braced frames the seismic input energy should be dissipated by means of the hysteretic behaviour of braces while all the other members (i.e. beams and columns) have to remain elastic. Accordingly, the design internal forces of braces are determined in these codes by elastic analysis of the structure subjected to seismic forces obtained by the design spectrum. The internal forces of the non-dissipative members, instead, are calculated by means of specified rules for the application of capacity design principles. According to some recent numerical analyses, the yielding or buckling of columns may take place before braces achieve their axial deformation capacity. This paper investigates the reasons of this unsatisfactory behaviour and proposes technological suggestions and a design procedure to improve the seismic performance of columns of building structures with diagonal braces.

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