Experimentally and analytically study on eccentrically braced frame with vertical shear links

Abstract

The excellent hysteretic behavior of eccentrically braced frames (EBFs) using shear links have made these systems an effective alternative for both moment resisting frame as well as concentrically braced structures. Generally, horizontal shear links are located either at the middle or at the ends of the beam. However, large deformation of the shear links in those beam must be accepted under severe earthquakes. In those instance in which the beam have to remain elastic, vertical shear links should be designed underneath the beam thereby transferring the region of plastic deformation to location where they are tolerable and post-earthquake repair or replacement of damaged parts is easier. In this paper, seismic behavior of vertical-EBF (V-EBF) have been considered experimentally and analytically. The required relation to design of the system have been proposed. In addition, to predict nonlinear behavior of V-EBF systems, an analytical model including kinematic-isotropic strain hardening for shear, only kinematic strain hardening for moment, has been presented. Results showed a good convergence of the presented analytical model (with an upper bound for yielding surface to the V-EBF) with experimental results. KEYWORDS cyclic loading, ductility, dynamic response, experimental, shear yielding, strain hardening 1 | INTRODUCTION Eccentrically braced frames (EBFs) have been used as a seismic load resisting system, primarily in buildings. The system, which relies on the yielding of a horizontal link beam between eccentric braces, has been shown to provide ductility and energy dissipation under seismic loading, and its behavior in various configurations has been investigated. In other hand, the EBF systems are metallic passive energy dampers under seismic loading.Despite high seismic energy dissipation, horizontal-EBF (H-EBF) has substantial disadvantages. It is no simple replace or repair of link beam in the H-EBF after a severe earthquake. This problem is the main disadvantage of this system. In addition, in industrial structures such as power plants, deep beams are sometimes used to carry the loads of heavy and highly sensitive equipment. In these cases, to assure the efficiency and accuracy of the equipment, load-bearing members such as beams and columns should remain in the elastic range as much as possible. Therefore, the use of horizontal link beams is not convenient. To overcome the problems in the EBF system, a new system called the vertical-EBF (V-EBF) system was proposed. [1] In this system, reversed-V braces are attached to the story beam through a shear panel. Intensive inelastic deformations are localized in the shear panel, and the internal energy is dissipated by this member. Figure 1 shows plastic hinge formation in the EBFs and V-EBFs. Because all inelastic deformation is localized in the shear panel, there is no damage to the main members of the frame, and repairs after a strong earthquake are easier than in H-EBF systems because this member can be replaced. Using the vertical links for seismic rehabilit...

Seismic behavior of highly irregular structures with multiple passive energy dissipation system: Case study of a single‐column elevated station

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