Development and Validation for Double-Core Self-Centering Energy Dissipative Braces
Date Issued
2011
Date
2011
Author(s)
Chen, Ying-Chuan
Abstract
Self-Centering Energy Dissipative Brace is a kind of brace which uses tendons to constrain compression elements of the brace and provide self-centering properties under tension and compression force (restore to zero residual deformation). Traditional self-centering energy dissipative brace’s deformation capacity relies on the elastic deformation capacity of the tendons used inside the brace, and results in limitation of the braces’ deformability. Traditional SCED brace has a maximum strain of 1.3% when the tendons reach 1.9% strain and the frame reaches 2% inter-story drift. Tendons required to have large elastic strain mainly uses composite material. However, tendons having over 2% elastic strain material properties are rare and seldom used or researched.
This research develops a new kind of SCED brace by adding a second core element and another group of tension elements which doubles the deformation capacity compared to traditional SCED brace while using tension elements comprised of the same material properties (or largely reduce the elastic strain demand of the tendon elements to 1% under the same brace deformation when compared to traditional SCED brace). This research designed four specimens to validate the double core SCED brace which uses different materials for its tendons. Four specimens’ tendon uses D16 steel strand, D22 glass fiber, D29 glass fiber and D13 carbon fiber respectively. The results show that the mechanism of double core SCED brace is consistent with prediction. The test results and prediction of tendon strain is close which is 0.8%, 1.05%, 0.9% and 1.09% for specimen 1 to 4 respectively while the brace has a 1.2% strain corresponding to 2% inter-story drift. The result shows that double core SCED brace can significantly reduce the demand for tendon elastic strain. Except specimen 1 due to loss of pre-tension force has poor behavior in self-centering, specimen 2 to 4 have good behavior in self-centering with no pre-tension loss.
This research also uses the finite element software ABAQUS to analyze double core SCED brace behavior and compare with the testing results which is proved similar. The parametric study of double core SCED brace we choose different pre-tension force, different friction force, and different tendons to observe the difference in brace behavior. Results indicate that the lager the friction force is the larger the energy dissipation there will be, yet in order to have full self-centering behavior, the pre-tension force should be larger than friction force. However the larger the pre-tension force is the smaller the deformation capacity there is left. Unlike pre-tension force and friction force, the difference of tendons only effect the post-stiffness of the response and limits the deformation capacity due to its limitation in elastic strain.
Subjects
Double-Core
Self-Centering
Energy Dissipative
Brace
Composite Material
Glass Fiber
Carbon Fiber
Type
thesis
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