Tying behaviour of fin-plate connection to concrete-filled rectangular steel tubular column — Development of a simplified calculation method

Abstract

This paper presents the results of numerical and theoretical studies into the behaviour of simple welded fin-plate to concrete-filled tubular (CFT) columns loaded by tensile force. Such connections represent a simple single-sided joint solution to steel CFTs. The current design method for similar connections under purely tensile load, in CIDECT Guide 9, based on a deformation limit of 0.03 of the tube width is shown to be inadequate when evaluating the ultimate strength of such connections. Hence numerical models have been developed and used to perform extensive parametric studies from which a simple hand calculation method has been developed for evaluating the strength of the column component of rectangular CFTs under tensile load imparted through a fin-plate connection. The ranges of parameters encompassed by the model include column cross-section size, column thickness and fin-plate length. The simple hand calculation procedure is based upon defining a rigid plate deformation pattern for the column face and then applying the virtual work principle. The column face deformation corresponding to the maximum load has been found to be strongly related to the column width to thickness ratio and a method for evaluating this relationship has been proposed based on extensive numerical results. The load–deflection curve consists of two segments: the first representing the elastic behaviour from classic plate theory, the second obtained by plotting the deflection at failure against failure load — both of which are obtained through the simple hand calculation procedure. The simple hand calculation method is compared favorably with a large range of finite element simulations. The proposed method may be used in the component based method for joints involving a fin-plate component in tension.