Numerical/experimental research on welded joints in aluminium truss girders

Welded joints in a 30 meter span aluminium truss girder were investigated numerically and experimentally. Since aluminium design rules for welded K-and N-joints in CHS truss girders were lacking the joints were checked using steel design rules. Calculations showed that the N-joints were governing for chord and brace sizes. Further numerical analysis on the N-joints using ANSYS 11.0 was carried out. Full scale experimental research was successfully carried out for validation of the numerical calculations. It is concluded that steel design rules predict the failure behavior and failure mode of the considered aluminium N-joints well. However, steel design rules overestimate the failure load by 8% for the truss configurations investigated

Analytical and experimental research on strength properties of adhesive bonded joints in aluminium structures

The structural use of adhesives in the building industry is growing in interest, due to successful applications in automotive and aerospace industry. However, the potential of adhesive joints is not yet fully utilized in building structures due to a lack of design rules c.q. building regulations. In particular the limited knowledge on the joint strength characteristics as well as the durability of the joint is a restriction for the use in practice. For these reasons analytical and experimental research projects have been carried out at Eindhoven University of Technology (see [1] to [3]). In the present paper only the static strength prediction is worked out in further detail. The project focused on the static failure load prediction of single lap joints using the singularity approach [1]. The lap joint is worked out analytically and numerically. Several elastic models for stress analysis were examined. The Allman-method [4] was worked out further into a singular stress failure criterion. The failure load prediction was verified by experiments on single lap joints with varying overlap length and width

Extended design method for in-plane stability of haunched sway portal frames

In current design rules the effect of a haunch on the sway in-plane stability of a steel portal frame only takes into account the influence of the haunch dimensions on the beam-to-column connection strength and stiffness. The effect of the haunch dimensions on the beam behavior, and thus on the frame behavior, is not included. The paper describes the effect of this phenomenon by regarding current design methods and comparing these with analytical solutions. The validity of the methods is covered by numerical simulations. For a vertical beam loading, the larger the span of the portal frame, the higher the compressive force in the beam becomes. In addition, the longer the span of the frame, the smaller the critical buckling load of the beam becomes. This decreases the stability of the overall frame significantly. In fact, the compressive force in the beam of a portal frame has a significant effect on the additional stiffness the haunch provides to the column. Due to the adjusted center line of the haunch causing an eccentricity, an additional first order moment is generated. This additional internal moment reduces the additional stiffness the haunch provides. For some spans this may even cause the additional stiffness of the haunch to be negligible. The research has given more insight, also on the effect of the shift of the compressive force in the beam, which depends on the geometry of the haunch. The study resulted in two simple correction factors for the current design rules, where these correction factors cover amplification factors for the original stiffness of the beam. The factors depend on the kind of loading (point load or equally distributed load) and on the haunch to rafter ratio (with regard to the length of the haunch as well as with regard to the height of the haunch)

Design imperfections for steel beam lateral torsional buckling

To perform geometrically and materially nonlinear analyses including imperfec-tions for steel beam lateral torsional buckling, the size and shape of the geometric imperfec-tion can be obtained from EN 1993-1-1. The shape is prescribed as an initial bow along the weak axis of the section, excluding torsion of the cross-section. The shape of the imperfection can alternatively be taken equal to the lateral torsional buckling mode, including torsion. Sev-eral tables and formulas exist to determine the size of the imperfection. Different imperfection approaches were applied in finite element simulations to evaluate the lateral torsional nonlin-ear buckling resistances and to compare them to the results obtained with design rules

Lateral torsional buckling design imperfections for use in non-linear FEA

\u3cp\u3eTo perform geometrically and materially non-linear analyses including imperfections for steel beam lateral torsional buckling, the size and shape of the geometric imperfection can be taken from EN 1993-1-1. The shape is prescribed as an initial bow along the weak axis of the section, excluding torsion of the cross-section. Alternatively the shape of the imperfection can be taken equal to the lateral torsional buckling mode, including torsion. Several tables and formulae exist for the determination of the size of the imperfection. In this article, different imperfection approaches are presented for finite element simulations to evaluate lateral torsional non-linear buckling resistances and to compare these to results obtained with design rules. Based on the comparisons made, the article concludes with a proposal for design imperfections to be used in non-linear Finite Element Analyses (FEA) for lateral torsional buckling of beams.\u3c/p\u3