Document Type : Research Article
Authors
1
M.Sc. Student, Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran
2
Associate Professor, Structural Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran
Abstract
As one of the most common lateral load-resisting systems, X-braced Frames have low energy dissipation. In this study, performance of a new energy dissipation system in X-brace frames (XBFs), which can be thought of as a passive control system, is investigated. The Rubber-Fuse Damper (RFD) is a new damper with a rubber core, steel plates, adhesive, and four bolts. The use of a rubber core for energy dissipation is a key feature of the damper's. The monotonic and cyclic behavior of a single-span and single-story XBF with varying frame height-to-span ratios equipped with the proposed RFD is investigated using finite element modeling and validated with experimental data. The RFD is either single or in pairs in each XBF specimen. In addition, the ductile damage method (DDM) revealed damage to the main structural components, such as bracing members. The results revealed that X-braced frames with single and double rubber-fuse dampers (XBF-RFDs) performed better under cyclic and monotonic loading than X-braced frames without rubber-fuse dampers (XBFs). Furthermore, because the bracing members did not buckle in the XBF-RFD specimens, there was no rapid loss in the stiffness and strength of the X-braced frames.
The monotonic loading reduced the stiffness of the XBF-RFD specimens by 93% to 98% to XBF specimens at various height-to-span ratios. In comparison to the XBF specimens, the yield and ultimate base shear of the XBF-RFD specimens dropped as well, with the highest reductions of 91% and 82%, respectively. When compared to XBF specimens under monotonic loading, the reduction in base shear and stiffness avoided buckling, resulting in more stable behavior and smaller nonlinear deformations of the XBF-RFD specimens.
Furthermore, the XBF-RFD specimens showed no sudden stiffness or strength drop. The results of the cyclic loading of the XBF-RFD specimens demonstrated that no rapid drop in stiffness or strength was detected due to no buckling of the bracing members under the cyclic loading, as was the case with the monotonic loading. Additionally, in comparison to the XBF specimens, the drifts corresponding to the first plastic hinges of the XBF-RFD specimens show that the bracing members experienced nonlinear deformation at greater drifts, with the plastic hinges created in them at bigger displacements.
The RFD also reduced Von Mises stress and damage in the bracing members of the XBF-RFD specimens, according to the cyclic loading results. At height to span ratios of 0.5, 1, and 1.5, the ultimate Von Mises stress reduction in the bracing members was 26%, 42%, and 36%, respectively, and this decrease was a reason to prevent the buckling phenomenon. Unlike the XBF specimens, which lost seismic functionality at low drifts, the XBF-RFD specimens maintained their seismic functionality up to a 4% drift of the cyclic loading, and they dissipated a greater quantity of energy.
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