Research Spotlight: Lateral Torsional Buckling of Butterfly-Shaped Shear Links (2017 Vinnakota Award Winner)

2017 Annual Stability Conference Presentation
Vinnakota Award Winner – Alireza Farzampour 

Session S10 – Stability of Plates
Friday, March 24, 2017
8:00 am

Lateral Torsional Buckling of Butterfly-Shaped Shear Links

A promising type of hysteretic damper used for seismic energy dissipation consists of a set of butterfly-shaped links subjected to shear deformations. Prior research has been conducted on shear panels with straight links, also referred to as steel slit panels or slit steel plate shear walls. Butterfly-shaped links have been proposed more recently to better align bending capacity with the shape of the moment diagram. The links have linearly varying width between larger ends and a smaller middle section.  These links have been shown in previous tests to be capable of substantial ductility and energy dissipation, but can also be prone to lateral torsional buckling.  In this article, the lateral torsional buckling of a butterfly-shaped link subjected to shear loading is conceptualized, and differential equations governing the links’ buckling behavior are formulated. The differential equations are numerically solved for a useful range of link geometries. The resulting critical moment, and related critical shear, are provided in a useful format for use in butterfly link design. Strategies for controlling lateral torsional buckling in butterfly links are recommended and are validated through comparison with finite element models.

Alireza Farzampour and Matthew R. Eatherton, Virginia Polytechnic Institute and State University, Blacksburg, VA