THE STATIC STRENGTH OF MULTIPLANAR TUBULAR TX-JOINTS UNDER AXIAL LOADING EXCLUDING THE EFFECTS OF OVERALL CHORD BENDING MOMENTS

Since no experimental data exist for multiplanar TX-joints, non-linear FE analyses are carried out on axially loaded multiplanar TX-joints i n order to study the local static behaviour of this type of joint (i.e . excluding the effects of overall chord bending moments at the inters ection between the chord and the braces). The influence of the chord l ength parameter alpha has been excluded by applying compensating momen ts to the chord ends. The individual influences of the geometric param eters beta and 2 gamma and the load ratio J (= load on out-of-plane br aces divided by the load on the in-plane brace) on the static strength are made clear. In addition, the effects on the joint behaviour due t o different end conditions of the out-of-plane braces (i.e. the out-of -plane braces were either free or restrained against rotations) are sh own for various beta values. Based on the FE results and the expressio ns derived from the analytical 'ring model' approach, ultimate strengt h formulae are established for the local strength of multiplanar TX-jo ints with J = 0.0 and infinity. Based on the numerical results of the TX-joints subjected to load ratios J different from 0.0 and oo, anothe r set of two equations is developed describing the multiplanar interac tion effects for axially loaded multiplanar TX-joints excluding the in fluences of overall chord bending moments. (C) 1998 Published by Elsev ier Science Ltd. All rights reserved.