Stability formulations and design of buckling-restrained braces considering stiffness degradation

Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.

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Improved empirical model for the strut efficiency factor and the stiffness degradation coefficient for the strength and the deflection prediction of FRP RC deep beams

Structures ◽

10.1016/j.istruc.2020.12.039 ◽

2021 ◽

Vol 29 ◽

pp. 2044-2066

Author(s):

Job Thomas ◽

S. Ramadass

Keyword(s):

Empirical Model ◽

Efficiency Factor ◽

Stiffness Degradation ◽

Deep Beams ◽

Rc Deep Beams ◽

Degradation Coefficient

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Experimental study on stiffness degradation of Crts Ⅱ ballastless track-bridge structural system under fatigue train load

Construction and Building Materials ◽

10.1016/j.conbuildmat.2021.122794 ◽

2021 ◽

Vol 283 ◽

pp. 122794

Author(s):

Ling-Yu Zhou ◽

Lei Zhao ◽

Akim D. Mahunon ◽

Ying-Ying Zhang ◽

Hua-Yong Li ◽

...

Keyword(s):

Experimental Study ◽

Stiffness Degradation ◽

Structural System ◽

Ballastless Track ◽

Track Bridge

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Numerical modelling of glulam frames with buckling restrained braces

Engineering Structures ◽

10.1016/j.engstruct.2021.112338 ◽

2021 ◽

Vol 239 ◽

pp. 112338

Author(s):

Wenchen Dong ◽

Minghao Li ◽

Chin-Long Lee ◽

Gregory MacRae

Keyword(s):

Numerical Modelling ◽

Buckling Restrained Braces

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Study on the stiffness degradation in concrete continuous beam with externally prestressed CFRP tendons under fatigue loading

Advances in Structural Engineering ◽

10.1177/1369433221992492 ◽

2021 ◽

pp. 136943322199249

Author(s):

Xing Li ◽

Jiwen Zhang ◽

Jun Cheng

Keyword(s):

Fatigue Life ◽

Fatigue Loading ◽

Load Level ◽

Fiber Reinforced Polymer ◽

Stiffness Degradation ◽

Test Results ◽

Reinforced Polymer ◽

Continuous Beams ◽

Practical Engineering ◽

Good Agreement

This paper presents fatigue behaviors and the stiffness degradation law of concrete continuous beams with external prestressed carbon fiber-reinforced polymer (CFRP) tendons. Three specimens were tested under fatigue loading, and the influence of different load levels on the stiffness degradation and fatigue life were studied, and it was found that the stiffness degradation of three test specimens exhibited a three-stage change rule, namely rapid decrease, stable degradation, and sharp decline, but there are obvious differences in the rate and amplitude of stiffness degradation. The load level has a significant influence on the fatigue life of the test specimens. An analytical model with load level considered was proposed to calculate the residual stiffness and predict the stiffness degradation, which is in good agreement with the test results. The model of stiffness degradation presents a possible solution for practical engineering applications of concrete continuous beams with externally prestressed CFRP tendons subjected to different fatigue loadings.

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Bending fatigue of single-wall and double-wall corrugated paperboards under sinusoidal and random loads

Journal of Sandwich Structures & Materials ◽

10.1177/10996362211020420 ◽

2021 ◽

pp. 109963622110204

Author(s):

Zhi-Wei Wang ◽

Yang-Zhou Lai ◽

Li-Jun Wang

Keyword(s):

Energy Dissipation ◽

Fatigue Failure ◽

Fatigue Tests ◽

Stiffness Degradation ◽

Random Load ◽

Bending Fatigue ◽

Random Loads ◽

Vibration Fatigue ◽

Sinusoidal Load ◽

Double Wall

The bending fatigue tests of single-wall and double-wall corrugated paperboards were conducted to obtain the εrms– N curves under sinusoidal and random loads in this paper. The εrms– N equation of corrugated paperboard can be described by modified Coffin–Manson model considering the effect of mean stress. Four independent fatigue parameters are obtained for single-wall and double-wall corrugated paperboards. The εrms– N curve under random load moves left and rotates clockwise compared with that under sinusoidal load. The fatigue life under random load is much less than that under sinusoidal load, and the fatigue design of corrugated box should be based on the fatigue result under random load. The stiffness degradation and energy dissipation of double-wall corrugated paperboard before approaching fatigue failure are very different from that of single-wall one. For double-wall corrugated paperboard, two turning points occur in the stiffness degradation, and fluctuation occurs in the energy dissipation. Different from metal materials, the bending fatigue failure of corrugated paperboard is a process of wrinkle forming, spreading, and folding. The results obtained have practical values for the design of vibration fatigue of corrugated box.

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