Numerical investigation of seismic behavior system of braced frame with innovative two level dampers system: Friction slotted bolt connection and Horizontal Shear panel

Document Type : Original Research

Author
A. M. Rousta
Yasouj Uni./ Faculty of Civil Eng./ Dept. of Civil Eng.
10.22034/21.6.11
Abstract
Structural vibration control has become a controversial topic among researchers today.In recent years passive dampers have been proposed as an effective and reliable method against these vibrations. In this paper, an innovative configuration for steel braced frames using energy dissipaters is presented. The proposed bracing system includes two-level slotted bolted connection (SBC) dampers with slipping performance and a horizontal shear panel system (H-SPS) or eccentrically braced frames (EBF) which is called CS+EBF.The proposed model consists of four structural parts, including horizontal shear link beam, beam, bracing and columns, which other structural components were designed based on the shear capacity of horizontal shear link beam. The brace provides the rigidity of the frame and remains elastic until the end of the loading, like columns and beam. The SBC fuse with frictional movement of the end of the brace in the slot hole and the H-SPS fuse with shear yield can dissipate energy at low, medium and severe earthquake levels, respectively, and prevent or delaying the bracing member from buckling. Past experience has shown that dampers designed for an earthquake energy level also start working in low level earthquakes than that level, which has hampered the ability of these dampers to dissipate energy in more severe earthquakes. Therefore, the SBC fuse is considered as an auxiliary fuse in this innovative two-level system to prevent the main fuse from operating in mild earthquakes. Also, the SBC fuse, unlike the yielding fuses after the earthquake, does not need to be replaced and is repaired by applying prestressed load to the connection screws, which distinguishes the proposed two-level system from other similar systems. The samples are modeled with 1/2 scale and solid elements to achieve accurate results.

The proposed configuration and other similar samples, in addition to push over loading, were also subjected to cyclic SAC loading protocol to compare the behavior of the proposed sample and other samples properly. The results obtained in this study indicate that in the push over analysis, in addition to maintaining the strength and stiffness of the proposed sample (CS+EBF), the ductility of this sample compared to other similar single-level systems, SCBF and EBF has increased. In addition based on cyclic loading, it was found that two-level proposed system has more ductility and energy dissipation than similar single- level systems and also shows that with increasing shear thickness of shear panel beam, energy dissipation and final strength of braced frame increases. The energy dissipation of the proposed configuration is 88% and 33% higher than that of SCBF and EBF single-level systems, respectively, and the share of energy dissipation of the first fuse (SBC) and second fuse (H-SPS) is 33% and 30% of the total energy dissipated by the CS+EBF2 braced frame respectively.

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Modares Civil Engineering journal
Volume 21, Issue 6
November and December 2021
Pages 143-156