A design procedure for pin‐supported rocking buckling‐restrained braced frames

Bosco, Melina; Marino, Edoardo M.; Rossi, Pier Paolo

doi:10.1002/eqe.3112

Cited by 15 publications

(22 citation statements)

References 31 publications

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“…Like shear walls and rocking-braced frames, higher modes have been identified as the cause of near-elastic force demands in pivoting strongback-braced frames (SBFs) that employ an elastic truss, or strongback. [15][16][17][18][19][20] SBFs are composed of an elastic and nonlinear truss; see Figure 2B. The strongback-comprised of the elastic truss including the elastic braces, tie, and column shaded in gray in Figure 2B-is proportioned to remain essentially elastic, resulting in a relatively stiff and strong vertical backbone that engages every story in a pivoting displaced shape.…”

Section: Introductionmentioning

confidence: 99%

Higher‐mode force response in multi‐story strongback‐braced frames

Simpson

2020

Earthq Engng Struct Dyn

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Strongback-braced frames employ an essentially elastic steel truss, or strongback, that distributes demands more uniformly to delay or prevent story mechanisms. Because inertial forces are no longer limited by the formation of a story mechanism, strongback-braced frames can exhibit large elastic force demands, particularly in the higher modes. This paper characterizes the higher-mode force response of strongback-braced frames. Four-story archetypes were designed using nonlinear dynamic analyses to incorporate higher-mode force demands into the design process. The response of the archetypes was compared with that of reference buckling-restrained braced frames that were allowed to form story mechanisms. The force demands in the strongback were then described using equivalent-static forces to represent the inertial forces induced by the higher modes. Force demands in the strongback arise from a yielding first-mode 'pivoting' and elastic higher-mode 'bending' response. These higher-mode force demands are elastic, ill-constrained by the strength of the yield mechanism, and depend significantly on the choice of ground motion record used for the analysis. In remaining elastic in the higher modes, the strongback distributes demands more uniformly and mitigates the formation of story mechanisms. Consequently, design and analysis methods for strongback-braced frames need to include estimates for these near-elastic higher-mode force demands.

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Section: Introductionmentioning

confidence: 99%

Higher‐mode force response in multi‐story strongback‐braced frames

Simpson

2020

Earthq Engng Struct Dyn

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“…Effective and economical structural systems that mitigate damage concentration and residual deformation after major earthquakes are essential for enhancing the resilience of building structures toward earthquakes. Earlier studies 1–10 have verified the efficacy of pin‐supported high stiffness steel braced frames or reinforced concrete (RC) walls, i.e., structural spines, to improve structural integrity and avoid deformation or damage concentration for various structural systems, such as reinforced concrete buildings, 1,2 deficient concentrically braced frames, 3 buildings with various heights, 4 ‐ 6 strongback system for steel‐braced frames, 7 and several other configurations 8–10 …”

Section: Introductionmentioning

confidence: 99%

“…Earlier studies 1-10 have verified the efficacy of pin-supported high stiffness steel braced frames or reinforced concrete (RC) walls, i.e., structural spines, to improve structural integrity and avoid deformation or damage concentration for various structural systems, such as reinforced concrete buildings, 1,2 deficient concentrically braced frames, 3 buildings with various heights, 4-6 strongback system for steel-braced frames, 7 and several other configurations. [8][9][10] Structural spines are generally designed to be able to pivot around the base without a self-centering mechanism. Therefore, this system is not expected to control residual deformation.…”

mentioning

confidence: 99%

Super elastic system using parallel spine frames with steel braces

Chen

Tagawa

2020

Earthq Engng Struct Dyn

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To reduce the seismic response and residual deformation of structures, this study proposes a super elastic bracing system comprising parallel spine frames with steel rods acting as the braces connecting adjacent spine frames. The brace‐end connections are located on the outer side of the pin supports of spine frames to ensure that the axial deformation of the braces is lower than that of a regular bracing system with identical brace angles. To verify the feasibility and elastic range of the proposed system, cyclic loading tests were conducted using scaled specimens consisting of two spine frames with four different brace configurations. Numerical models created in OpenSees were used to simulate the loading tests appropriately. Four evaluation methods were developed for predicting the force and deformation relation considering the geometrical nonlinearity of the proposed system. Through parametric analyses, the influence of key parameters on structural behaviors is clarified, and the applicability of the evaluation methods is investigated.

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“…The key aspect of rocking systems, including rocking walls [3,4] and rocking braced frames [5,6], is the gap-opening mechanism taking place between the structure and foundation, which softens the structural lateral response without any residual deformations. The gap-opening mechanism can also be applied to beam-column interface to form a post-tensioned moment frame in which the beam is compressed to the side of a column by using post-tensioning (PT) technology [7,8].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Seismic Response of Multistory Steel Frames with Self-Centering Tension-Only Braces

et al. 2020

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The self-centering tension-only brace (SC-TOB) is a new and innovative bracing system that provides both a flag-shaped recentering hysteresis and load mitigation to structures. This paper presents an extensive investigation of the nonlinear seismic response of multistory steel frames built with SC-TOBs to internal force, drift, and energy dissipation. Pushover analysis subjected to two lateral load distributions and nonlinear dynamic analysis under ground motion ensembles corresponding to four hazard levels were conducted. The SC-TOBs can be designed to serve as conventional tension-only braces (TOBs) only providing lateral stiffness during minor earthquakes, to function with energy dissipation as intensity increases, and to fully recenter a structure even after severe earthquakes. The findings show that with an increase in the earthquake intensity, both the force response and drift response of the SC-TOB frames (SC-TOBFs) increased; however, the force distribution and drift distribution shapes of the SC-TOBFs remained almost constant. The SC-TOBFs generally experienced more energy dissipation in the lower parts of the building, while the upper stories dissipated almost no energy under certain load conditions, suggesting that the bracings on those stories could be replaced by conventional TOBs for economy. It is demonstrated that the SC-TOBs have immense potential to effectively improve seismic resilience to structures such that rehabilitation costs and operational disruptions after earthquakes are minimized.

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A design procedure for pin‐supported rocking buckling‐restrained braced frames

Cited by 15 publications

References 31 publications

Higher‐mode force response in multi‐story strongback‐braced frames

Higher‐mode force response in multi‐story strongback‐braced frames

Super elastic system using parallel spine frames with steel braces

Nonlinear Seismic Response of Multistory Steel Frames with Self-Centering Tension-Only Braces

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