Damage Concentration Effect of Multistory Buckling-Restrained Braced Frames

Due to the low postyield stiffness of buckling-restrained braces (BRBs), multistory buckling-restrained braced frames (BRBFs) subjected to earthquakes are prone to lateral deformations and damage concentrations at certain stories, which is deemed a damage concentration effect (DCE). A series of nonlinear pushover analyses and response history analyses are conducted to investigate the key factors affecting the DCE of BRBFs. Two comparisons of the DCE are performed for different types of structures and different beam-to-column connections in the main frame (MF). These comparisons show that BRBFs equipped with BRBs as the main earthquake resistance system have a more serious DCE than the traditional moment-resisting frame or conventional braced frame and that the MF stiffness significantly affects the structural residual displacement and DCE. Then, parametric analyses are performed to investigate the influence of two stiffness distribution parameters (in the horizontal and vertical directions) on the DCE of a 6-story BRBF dual system designed according to the Chinese seismic code. The results show that increasing the MF stiffness and avoiding abrupt changes in the BRB stiffness between stories can effectively mitigate the DCE of BRBFs. Finally, the correlations between various damage performance indices are analyzed. A low statistical correlation between the peak and residual drift responses can be observed in BRBFs. Therefore, it is recommended that the DCE be considered in BRBF design.

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IMPACT OF INTRODUCING SEMI-RIGID MOMENT FRAMES ON SEISMIC RESPONSE OF BRACED FRAMES

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2019.88 ◽

2019 ◽

Vol 6 (1) ◽

Author(s):

Mahmoud Faytarouni ◽

Onur Seker ◽

Bulent Akbas ◽

Jay Shen

Keyword(s):

Braced Frames ◽

Seismic Evaluation ◽

Moment Frames ◽

Moment Frame ◽

Braced Frame ◽

Shear Connections ◽

Seismic Force ◽

Steel Building ◽

Story Drift ◽

Moment Resisting

Maximum seismic inelastic drift demand in a steel building with braced frames as primary seismic-force-resisting (SFR) system tends to concentrate in few stories without considering inherent participation of designed gravity-force-resisting (GFR) system in actual structural stiffness and strength. The influence of GFR system on stiffness and strength can be taken into account by considering the composite action in beam-to-column shear connections that exist in modern steel building construction to form actual semi-rigid moment-resisting frames. Therefore, modeling semi-rigid moment frames as an equivalent to the GFR system in braced frame buildings could be utilized as a representative to the strength provided by gravity frames. This paper presents a seismic evaluation of a six-story chevron braced frame, with and without semi-rigid moment frame. Four different cases are investigated under a set of ground motions and results are discussed in terms of story drift distribution along the height. The results pointed out that the current findings lay a foundation to conduct further investigation on the seismic performance of braced frames as designed SFR system together with GFR system.

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A Comparative Study on the Behavior of Steel Moment-Resisting Frames with Different Bracing Systems Based on a Response-Based Damage Index

Civil Engineering Journal ◽

10.28991/cej-0309178 ◽

2018 ◽

Vol 4 (6) ◽

pp. 1354 ◽

Cited By ~ 1

Author(s):

Kamran Karsaz ◽

Seyed Vahid Razavi Tosee

Keyword(s):

Damage Index ◽

Steel Structures ◽

Braced Frames ◽

Initial Stiffness ◽

Concentrically Braced Frames ◽

Braced Frame ◽

Under Five ◽

Seismic Rehabilitation ◽

Moment Resisting Frames ◽

Moment Resisting

Seismic rehabilitation of existing buildings is one of the most effective ways to reduce damages under destructive earthquakes. The use of bracings is one of techniques for seismic rehabilitation of steel structures. In this study we aimed to investigate the seismic performance of three 5, 10 and 15-storey steel structures with moment-resisting frames designed three dimensionally in ETABS 2015 application based on first edition of Iranian Standard 2800. Their damage under five ground motions was evaluated using response-based damage model proposed by Ghobara et al. (1999). Then, the structures were rehabilitated with different bracing systems (X, eccentric and concentric V and inverted-V) and, again, their damage under five earthquakes were evaluated and compared with those of moment resisting frames. The pushover analysis results indicated that X-braced frame was the least ductile system but had highest initial stiffness and yield stress. In low-rise building, X-braced frames showed better performance among studied bracing systems compared to moment resisting frames, while mid and high-rise buildings with eccentrically braced frame (EBF) showed the best behavior against earthquakes with the least damage. Moreover, it was found out that EBFs’ performance increases by increasing storey height, but for concentrically braced frames (CBFs) it was decreased. We concluded that the use of response-based damage models can be a suitable procedure for estimating the vulnerability of steel structures rehabilitated with bracing system.

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.284-287.1446 ◽

2013 ◽

Vol 284-287 ◽

pp. 1446-1449 ◽

Cited By ~ 1

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.

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Probabilistic seismic demand assessment of residual drift for Buckling-Restrained Braced Frames as a dual system

Structural Safety ◽

10.1016/j.strusafe.2015.08.004 ◽

2016 ◽

Vol 58 ◽

pp. 31-39 ◽

Cited By ~ 10

Author(s):

A. Deylami ◽

M.A. Mahdavipour

Keyword(s):

Dual System ◽

Seismic Demand ◽

Braced Frames ◽

Residual Drift ◽

Demand Assessment ◽

Probabilistic Seismic Demand ◽

Buckling Restrained Braced Frames

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Special Moment Resistant Steel Buildings

International Journal of Advanced Research in Science, Communication and Technology ◽

10.48175/ijarsct-2214 ◽

2021 ◽

pp. 444-448

Author(s):

Deepan Dev B ◽

Dr V Selvan

Keyword(s):

Pushover Analysis ◽

Time History ◽

Nonlinear Time History Analysis ◽

Building Structures ◽

Braced Frames ◽

Steel Buildings ◽

Braced Frame ◽

Moment Resisting ◽

Frame Systems ◽

Nonlinear Time History

The seismic response of special moment-resisting frames (SMRF), buckling restrained braced (BRB) frames and self-centering energy dissipating (SCED) braced frames is compared when used in building structures many stories in height. The study involves pushover analysis as well as 2D and 3D nonlinear time history analysis for two ground motion hazard levels. The SCED and BRB braced frames generally experienced similar peak interstory drifts. The SMRF system had larger interstory drifts than both braced frames, especially for the shortest structures. The SCED system exhibited a more uniform distribution of the drift demand along the building height and was less prone to the biasing of the response in one direction due to P-Delta effects. The SCED frames also had significantly smaller residual lateral deformations. The two braced frame systems experienced similar interstory drift demand when used in torsional irregular structures.

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Seismic performance of dual systems coupling moment‐resisting and buckling‐restrained braced frames

Earthquake Engineering & Structural Dynamics ◽

10.1002/eqe.3332 ◽

2020 ◽

Cited By ~ 1

Author(s):

Fabio Freddi ◽

Enrico Tubaldi ◽

Alessandro Zona ◽

Andrea Dall'Asta

Keyword(s):

Seismic Performance ◽

Braced Frames ◽

Dual Systems ◽

Moment Resisting ◽

Buckling Restrained Braced Frames

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Seismic Stability of Buckling-Restrained Braced Frames

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.763.924 ◽

2018 ◽

Vol 763 ◽

pp. 924-931 ◽

Cited By ~ 2

Author(s):

Santiago R. Zaruma ◽

Larry A. Fahnestock

Keyword(s):

Elastic Stability ◽

Seismic Stability ◽

Code Design ◽

Braced Frames ◽

Design Strategies ◽

Axis Orientation ◽

Residual Drift ◽

Seismic Force ◽

Story Drift ◽

Buckling Restrained Braced Frames

Buckling Restrained Braced Frames (BRBFs) are widely used as seismic force resisting systems due to their ductility and energy dissipation. However, because of the modest overstrength and relatively low post-yielding stiffness, BRBFs subjected to seismic loading may be susceptible to concentrations of story drift and global instability triggered by P-∆ effects. Due to the use of simplistic methods that are based on elastic stability, current code design provisions do not address seismic stability rigorously and do not consider the particular inelastic response of a system. Design strategies are needed to prevent undesirable seismic response in BRBFs, such as drift concentration and large residual drift. This study used the FEMA P-695 Methodology to evaluate the response of current U.S. code-based BRBF designs and to study the effect on seismic stability of three potential enhancements: strong-axis orientation for BRBF columns, gravity column contribution, and a BRBF-SMRF dual system. Results from nonlinear static and dynamic analyses allowed assessment of seismic behavior. Results from collapse performance evaluation quantify the improvement that is achieved with each alternative and provide a means of comparison.

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Frame and Brace Action Forces on Steel Corner Gusset Plate Connections in Buckling-Restrained Braced Frames

Earthquake Spectra ◽

10.1193/1.4000007 ◽

2012 ◽

Vol 28 (2) ◽

pp. 531-551 ◽

Cited By ~ 19

Author(s):

Chung-Che Chou ◽

Jia-Hau Liu

Keyword(s):

Axial Strain ◽

Free Edge ◽

Braced Frames ◽

Element Analysis ◽

Gusset Plate ◽

Braced Frame ◽

Test Frame ◽

Force Components ◽

Buckling Restrained Braced Frames ◽

Plate Connections

This work presents test and finite element analysis results for a steel buckling-restrained braced frame (BRBF). The objectives are to evaluate the forces of frame and brace actions on the corner gusset plate and to develop a method that considers both actions in design. The BRBF test frame exhibited excellent performance up to a drift of 2% with a maximum axial strain of 1.7% in the buckling-restrained brace. Without free-edge stiffeners, the corner gusset plate buckled at a significantly lower strength than that predicted by the American Institute of Steel Construction (AISC) specifications ( AISC 2005a ). By idealizing the corner gusset plate as a strut, a strut model can be used to determine the forces resulting from frame action, which are on the same order as the brace forces. Considering the stress distributions and force components from the frame and brace actions, the maximum stresses in the gusset tips are used as an additional design parameter for sizing gusset connections.

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