11.51: Numerical investigation of short seismic links in shear

Abstract

It is well known that seismic links are usually designed to remain in elastic region during ordinary loading but withstand nonlinear deformation during seismic event having capability to dissipate seismic energy. The use of short seismic links is recommended because they are capable of dissipating seismic energy in larger quantity by shear, while the webs in these links are expected to yield in shear during large seismic events, i.e. dissipation of seismic energy by bending in links is negligible. Shear deformations are basically plane deformations of the cross section web of the link, without any significant tendency towards lateral torsional buckling. To achieve the required plastic rotation, local instabilities such as flange or web buckling should be delayed. The flange local buckling is delayed by specifying width to thickness ratio, while the web local buckling will be prevented by adding number of transverse stiffeners along the web of the link. The main purpose of the stiffeners is to preserve buckling of the seismic link web, i.e. to achieve plastification of the cross section by shear. Dissipation of energy in the stiffened link will occur sooner through inelastic shear deformations than through inelastic web buckling. The seismic links were chosen having the same cross section and the same length, but with different number of stiffeners, i.e. with three couples of stiffeners, two, one and without any stiffener respectively. A finite element modelling approach in investigating the structural behaviour of short links is presented. Both the material and geometric nonlinearities are considered in the FE modelling using the software ABAQUS and the Shear force -Displacement relationships was obtained. The FEA results are validated against the test results and the comparisons indicated that the FE analysis procedures agree well with the test results.

Seismic Response of 2-D Plane Framed Buildings Eccentrically Braced with Vertical Shear Links

“…This process guarantees the dissipation of large amount of earthquake input energy, thereby keeping the main structural elements (columns and beams) within the elastic range without any sort of significant damage. After earthquake event takes place, VSL can be easily replaced since all inelastic deformations are localized in it [1], [11], [12]. Additionally, experimental testing results found in literature proved that inelastic deformation is confined in VSLs, therefore confirming that the VSLs act as ductile fuses to absorb energy [12].…”

“…Structures seismic protection systems should satisfy two fundamental criteria. The first is that the structure should have adequate stiffness to keep deflections within the limit of non-structural damage during minor earthquake ground motions, the second is the structures capability to possess enough ductility to avoid collapse in the case of a rare overload which may occur during the major seismic events [1]. One of the efficient seismic protection techniques is to install vertical shear links (VSLs) between chevron braces and the floor beam in certain bays of the buildings thus transforming them into vertical eccentrically braced frames (V-EBFs).…”