FINITE ELEMENT MODELLING OF GAP JOINTS WITH SEPARATED RHS DOUBLE CHORDS.

Finite element modelling of the elasto-plastic behaviour of separated double chord gap joints of hollow structural sections (HSS) is presented. The joint has the form of a short beam that sandwiches two reactive stub columns with a central load column between the inner webs of the chord members. The model treats the HSS member as composed of a thin plate representing the inner web and a channel representing top and bottom flanges and the outer web. The twelve degrees of freedom (DOF) nonconforming plate bending element and the eight DOF plane stress element are used to form a plate element for the inner web. The channel is made of a grillage of beam-column elements and shear beam elements in the transverse and longitudinal directions, respectively. The analysis beyond the elastic limit takes into account the strain hardening effect and material nonlinearity.