Performance evaluation of self-centring steel-braced frame

Moghadam, Abdolreza S.; Rahgozar, Navid; Aziminejad, Armin

doi:10.1680/jstbu.15.00136

Cited by 11 publications

(7 citation statements)

References 11 publications

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“…8, RCBF and RZBF have less residual roof drifts comparing with CBF and ZBF which indicate the better seismic performance for these systems. This result is in line with the results of previous studies [43].…”

Section: Roof Drift Ratio and Residual Driftsupporting

confidence: 94%

“…The mean value of residual roof drift for the RCBF and RZBF is 0.0014 and 0.00016 radians, which showed the reliable self-centering behavior of these frames. This result is identical with the result of past researches [40,43,44]. They presented that the residual roof drift for fixed base frame is 46 and 54 times larger than the residual roof drift for rocking frame under DBE and MCE earthquakes, respectively.…”

Section: Roof Drift Ratio and Residual Driftsupporting

confidence: 90%

“…Also, RCBF experiences first damage at higher drifts comparing with CBF system, resulting in better seismic performance in terms of drift ratio and residual drift as presented in different experimental and analytical studies [10,40]. Recent studies presented that RCBFs like rocking concentrically braced frame [10,41,42], dual rocking frames [31,43,44], using multiple rocking joint through the height of the frame [11], rocking braced frames with energy dissipating elements and various story numbers [45] and tension-only concentrically braced frames with rocking core [46] are able to decrease damage under severe earthquakes and enhance the seismic performance of ordinary CBFs in terms of uniform distribution of inter story drifts. Huang et al showed that RCBFs are economically better systems comparing to CBFs for low and mid-rise building under severe earthquakes [47].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of Seismic Performance of Improved Rocking Concentrically Braced-frames with Zipper Columns

Sarand¹,

Jalali²

2020

Period. Polytech. Civil Eng.

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Concentrically braced frames (CBFs) as one of well-known stiff and common lateral force resisting systems often show limited ductility capacity under severe earthquakes. This study proposes rocking zipper braced frame (RZBF) to improve the drift capacity of CBFs which is based on combination of rocking behavior and zipper columns. In the RZBF system, rocking behavior permit the braced frame to uplift during the earthquake and then restoring force induced through post-tensioned bars self-center the frame to its initial state.Also, zipper columns can decrease the concentration of damage by distributing the unbalance force at the mid bay over the frame's height. To assess the performance of RZBF, a comparison study is carried out considering CBF, rocking concentrically braced frame, zipper braced frame and RZBF. For this purpose, some frames structures are designed and nonlinear time history analysis conduct under a set of earthquake records. Seismic responses such as roof drift ratio, gap opening at the column-base interface, forces of top story braces and post-tensioned bars are taken into consideration. The results show that the proposed RZBF has better performance among the others and zipper columns can improve the behavior of rocking systems.

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Section: Roof Drift Ratio and Residual Driftsupporting

confidence: 94%

Section: Roof Drift Ratio and Residual Driftsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of Seismic Performance of Improved Rocking Concentrically Braced-frames with Zipper Columns

Sarand¹,

Jalali²

2020

Period. Polytech. Civil Eng.

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“…The presented papers continue the tradition of this journal to provide results useful for the professional development of its readers. This issue contains papers that have passed the usual rigorous peer review procedure adopted by the journal and contribute to the areas of knowledge discussed in this Editorial.This first paper presents the performance evaluation of selfcentring steel-braced frames (Rahgozar et al, 2016). A modern self-centring braced frame equipped with post-tensioned cables and replaceable fuses is capable of rocking on its foundation during an earthquake.…”

mentioning

confidence: 99%

“…This first paper presents the performance evaluation of selfcentring steel-braced frames (Rahgozar et al, 2016). A modern self-centring braced frame equipped with post-tensioned cables and replaceable fuses is capable of rocking on its foundation during an earthquake.…”

mentioning

confidence: 99%

Editorial

Hussain¹

2017

Proceedings of the Institution of Civil Engineers - Structures

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This issue of Structures and Buildings contains the performance evaluation of self-centring steel-braced frame, plastic design of eccentrically braced frames with shear panels, fluid viscous dampers locations in reinforced-concrete core wall buildings, correlation of a new index with energy-based damage indices and seismic progressive collapse of momentresisting frames and eccentrically braced frames (MRF-EBF) dual steel systems. The presented papers continue the tradition of this journal to provide results useful for the professional development of its readers. This issue contains papers that have passed the usual rigorous peer review procedure adopted by the journal and contribute to the areas of knowledge discussed in this Editorial.This first paper presents the performance evaluation of selfcentring steel-braced frames (Rahgozar et al., 2016). A modern self-centring braced frame equipped with post-tensioned cables and replaceable fuses is capable of rocking on its foundation during an earthquake. The aim of this paper is to evaluate the seismic performance of a controlled rocking braced frame and compare its efficiency with a similar fixed-base braced frame. A non-linear time history analysis is conducted for a set of archetypes, varying in height, seismic design category and seismic frame type. A sensitivity analysis is performed to examine the effects of modelling and ground motion parameters. Results indicate that the rocking system is capable of enhancing the performance of a conventional braced frame by features such as the controlled rocking mode, self-centring and concentrated damage to replaceable fuses.The second paper presents the plastic design of eccentrically braced frames with shear panels (Hamed and Mofid, 2016). This paper introduces a new earthquake-resistant building design featuring eccentrically braced frames with steel wall shear panels. It also proposes closed-form expressions for analysis and extension of the existing failure mode control design method for the new structural system. Closed-form equations for internal forces were obtained, and probable failure mechanisms and corresponding lateral load multipliers for secondary effects were identified. Selection of member profiles was completed by the mechanism equilibrium curve concept. Pushover modelling was then performed with plastic hinge distribution corresponding to failure mechanisms. Only small differences were found between the analytical and modelled values of lateral force multipliers, meaning that the closed-form equations are a valid alternative approach for plastic analysis and design of eccentrically braced frames with shear panels.The third paper is about the fluid viscous damper locations in reinforced-concrete core wall buildings (Ahmed, 2016). A flexural plastic hinge is assigned and detailed at the core wall base and coupling beams ends to control seismic responses. This strategy is based on allowing damage to main structural components. To avoid damage to main structural components, an alternative strategy using ene...

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Equivalent linear model for fully self‐centering earthquake‐resisting systems

Rahgozar

Moghadam

2018

Structural Design Tall Build

Self Cite

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Modern rocking and stepping cores have been known as the efficient self-centering earthquake-resisting systems (SC-ERSs). The current article proposes an approximate equivalent linear (EL) model for rapid estimation of the SC-ERS displacement. An equivalent damping ratio and effective stiffness are formulated for flag-shaped hysteresis of a fully SC-ERS. The approximate EL model is first established using secant stiffness and Jacobsen's damping model. Nonlinear response history analyses are carried out to compare exact and approximated peak displacements. Findings reveal that EL analysis of the SC-ERS based on Jacobsen's damping leads to underestimation of the maximum inelastic displacement. Accordingly, a new optimal damping formula is proposed using a genetic algorithm and nonlinear regression analyses. The improved EL model is validated by practical examples, and the results show acceptable accuracy in design-level displacement estimation. KEYWORDS equivalent linear model, flag-shaped hysteresis, optimization analysis, secant stiffness, selfcentering systems, viscous damping model 1 | INTRODUCTIONOn the basis of the traditional ductility-based design concept, structural members allow for sustaining of uniform damage. Nevertheless, buildings experience severe damage following a large earthquake, which lead to socioeconomic losses due to business downtime and repair costs. In recent years, self-centering earthquake-resisting systems (SC-ERSs) have been developed to provide a sustainable system through directing seismic damage to replaceable devices. Figure 1a shows examples of rocking and stepping self-centering systems including single or coupled stepping braced frames, [1][2][3][4][5][6][7][8] pin-supported rocking frame or wall, [9][10][11] rocking precast concrete wall, [12][13][14][15] and self-centering timber frames. [16,17] These lateral resisting systems are generally composed of bounded or unbounded posttensioning (PT), replaceable energy dissipation (ED) devices, rigid strut beam, bumper, and special diaphragm connections. Regardless of the SC-ERS components, a flag-shaped hysteresis is representative of their total seismic responses. Figure 1b depicts a sample of push-pull curves of the system characterized by uplift ( F up − Δ up ) and yield ( F y − Δ y ) parameters along with postyield stiffness (α) and ED index (β). Prior to unloading the system ( F d − Δ d ), the response is generally composed of three main branches. In the first branch that terminates when the system is uplifted, the SC-ERS has a large initial elastic stiffness and behaves as conventional buildings. Nevertheless, in the second branch, the system stiffness is reduced and sways on its foundation, which leads to the system yielding point. The yielding point is the beginning of the third branch with the hardening stiffness of α. Note that geometric nonlinearity is controlled using PT and ED devices. Accordingly, the PT cable provides adjustable restoring forces, and the ED device produces required ED capacity during the unloading ph...

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Performance evaluation of self-centring steel-braced frame

Cited by 11 publications

References 11 publications

Evaluation of Seismic Performance of Improved Rocking Concentrically Braced-frames with Zipper Columns

Evaluation of Seismic Performance of Improved Rocking Concentrically Braced-frames with Zipper Columns

Editorial

Equivalent linear model for fully self‐centering earthquake‐resisting systems

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