Experimental investigation of a low‐prestressed self‐centering energy dissipative brace

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Self‐centering energy dissipative (SCED) braces are designed to limit the maximum story drifts in buildings during earthquakes and to nearly eliminate residual drifts. SCED braces that have been developed in the past face three major challenges: they require high levels of prestressing force, they have limited elongation capacity, and their energy dissipative systems have inadequate reliability or excessive complexity. This paper proposes a new SCED brace that addresses these three challenges with the use of a mild‐steel dissipative element that never experiences compression, so it will not buckle. The feasibility of the new system was demonstrated with a set of experiments in a configuration that uses a series combination of post‐tensioned steel tendon and Belleville springs for re‐centering. The paper develops equations that govern the brace's performance, identifies key parameters and develops a numerical modeling method. The design of an example building shows that the new brace only requires approximately 6% of the prestressing force required for existing SCED braces to achieve similar hysteretic relationships. Numerical analysis confirms that a braced frame equipped with the new brace would control the maximum response to about the same extent as would for existing SCED braces and buckling‐restrained braces, while effectively eliminating residual drift under severe earthquakes. Meanwhile, the new system generates 18–26% smaller axial forces than existing SCED braces and appears to have a large elongation capacity. Based on these findings, it is concluded that the proposed brace successfully addresses the major challenges of previous SCED braces.

Section: Introductionmentioning

confidence: 94%

“…A validation experimental report is presented in Xiao et al 19 Differs from Ref. [19] this paper presents the following:…”

Section: Introductionmentioning

confidence: 94%

Section: Lp-sced Brace Behaviormentioning

confidence: 99%

Section: Physical Configurationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

See 3 more Smart Citations

Low‐prestressing, self‐centering energy dissipative brace

Xiao

Eberhard

Zhou

et al. 2022

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Experimental investigation of a low‐prestressed self‐centering energy dissipative brace

Xiao

Eberhard

Zhou

et al. 2022

Self Cite

Self‐centering energy dissipative (SCED) braces have the potential to contribute greatly to building resiliency, because the braces can limit both maximum and residual story drifts during earthquakes. An obstacle to widespread adoption of existing SCED systems is that they require high prestressing forces, corresponding to more than half of the brace yield strength. To address this problem, a new low‐prestressed SCED (LP‐SCED) system has been proposed, which has a flag‐shaped force–deformation hysteresis but needs only a low level of prestressing force. This paper presents the results of an experimental investigation to establish the properties of the new system's key components, as well as prototypes of the full brace specimen. The tested system had a prestressing force equal to only 3∼4% of the brace yield force. The tested systems had a stable, flag‐shaped force–deformation hysteresis relationship, even after being subjected to deformations corresponding to 3.4% story drift. Eventually, when the imposed deformations were sufficiently large, the brace stiffness increased dramatically, which helps to reduce drift concentrations that may be critical in braced‐frame structures under extreme earthquakes. The yielding and damage were restricted to the mild‐steel dissipaters, which could be replaced easily after each test, and in practice, they could be replaced easily after an earthquake.

Experimental and mathematical model of the variable friction adaptive self‐centering energy dissipative brace

Liu

Zhu

Dong

et al. 2023

The self‐centering energy dissipative (SCED) brace can limit the maximum story drift and eliminate residual drift during an earthquake. The inadequate reliability or excessive complexity of the energy dissipative system, the contradiction between the energy dissipative system and self‐centering system, the limited elongation capacity, and the difficulty in replacement and reuse are the main challenges faced by the existing developed SCED brace. To solve these problems, a variable friction adaptive self‐centering energy dissipative (VFA‐SCED) brace has been proposed. First, the details of the VFA‐SCED brace are introduced, and the force analysis of each component and the working mechanism of the brace are expounded. Then, the equations that govern the brace performance have been derived, key parameters and mathematical models have been identified. Finally, the feasibility of the new system was demonstrated with a set of experiments, in which five specimens with different key parameters were fabricated, tested, and analyzed. The test results show that the hysteretic curve of the VFA‐SCED brace is typically flag‐shaped, and there is almost no residual deformation after multiple cyclic loadings, which means that the brace has good energy dissipative capacity and self‐centering ability, replaceable and recyclable for each component, and stable working performance. The elongation capacity, friction, energy dissipative capacity, and self‐centering ability can be changed by adjusting the relevant key parameters of the spring and wedge block, and the proposed mathematical model can well predict the force‐deformation hysteresis of the brace with different parameters. The results show that the VFA‐SCED brace successfully avoids the main obstacles of previous SCED braces.