Finite Element Analysis of Eccentrically Braced Frames with Removable Link

Abstract

Steel eccentrically braced frames (EBFs) are expected to sustain damage during an ultimate limit state design level earthquake through repeated cyclic plastic deformation of the active link. Traditionally the active link has been integral with the collector beam, but following the 2010/2011 Canterbury earthquakes, the benefit of having a readily replaceable active link became apparent. The development of this was undertaken by New Zealand Heavy Engineer Research Association (HERA) and Steel Construction New Zealand (SCNZ), with input from the University of Auckland. This paper describes the finite element analyses performed to determine the behaviour of the system including the bolted endplate connections through the range of inelastic cyclic loading expected. The numerical simulations answer a number of questions, like at which loading cycle the von Mises stress is above 300MPa in collector beam adjacent to the removable link; history of all bolt forces; component forces (shear) in slab and removable link; rotation of the link versus cycles; equivalent plastic strain contour for the last cycle and others. This paper also describes how the interaction with the concrete slab was modelled in the elastic and inelastic range.