Damage evaluation in gap tubular truss ‘K’ bridge joints using SFEM

Abstract

A damage stiffness parameter α of the shell element is calculated analytically using the fracture mechanics concept. A smooth quad T4 element was modified using the calculated parameter α. The modified element was introduced at the junction between the chord/brace connection where welding defect had taken place, while the unmodified same element was used elsewhere on the joint. Thereafter, a finite element analysis was carried out using thin shell theory and the smooth element formulation to investigate the effect of brace spacing on the distribution of stress concentrations in the welded tubular ‘K’ joint. This was done in order to investigate the level of stress concentrations and damage in the welded connection in the tubular joint. The joint was first modelled with no gap between the braces and a finite element computer run was made. Thereafter, the joint was modelled with brace gaps from 10mm to 70mm and finite element computer runs were made. The results obtained were then compared with those published in the literature. It was found that the presence of variable gaps between braces of the joint together with pre-crack affects the strength of tubular ‘K’ joints appreciably.