PSI - Issue 57

Philipp Ladendorf et al. / Procedia Structural Integrity 57 (2024) 589–597 Ladendorf, Herion, Winkler, Dürr / Structural Integrity Procedia 00 (2019) 000 – 000

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3. Numerical investigations 3.1. General remarks

The numerical static system is the same as in the preceding research project FOSTA P1132 (Fig. 3) and the load cases consist of axially loaded braces (AX), axially loaded chord (GN) and in-plane-bending of the braces (IPB). The chord and the braces have lengths of 5 × b j /d j (j = 0,1,2), where the chord-length is based on the joint-center and the brace-length is defined from the topside of the chord to the brace-end.

Fig. 3. Investigated load-cases

All numerical investigations are carried out with Abaqus/CAE 6.11-1 using hexahedral elements (C3D8R) with activated hour-glass-control and at least 2 Elements over the wall-thickness and an element size ratio between 0.8 and 1.0 (Herion 1994) . The Young’s modulus is set to E = 210,000 N/mm² and the Poisson’s ratio to ν = 0.3. While the braces and the gusset-plates are discretized in a monolithic manner, their connection with the chord is modelled using TIE-constraints. The nodal degrees of freedom at the brace- and chord-ends are kinematically coupled to reference points located at the position of the pinned supports (cp. Fig. 4). While the exact locations of all Hot-Spots are shown in the final report of P1442, in this article, the maximum SCF is used to show the influence of the gusset-plates.

Fig. 4. Kinematic coupling and example of numerical mesh

3.2. Results

3.2.1. General remarks The representation of the SCFs of the conventional as well as the form-optimized gusset-plate variants uses two types of colormaps. The first type shows the actual calculated maximum SCFs reaching from green (1.0) to brown (5.0) with white as dividing color and a designated SCF of 2.0, which is considered the minimum advisable SCF. The second type of colormap shows the maximum SCF of the gusset-plate variants as percental deviation from the con ventional K-joint reaching from -100 % with a blue color to +100 % with a red color and with white as color for no deviation. All three investigated load-cases are shown together with the five RHS respectively three CHS geometries at the Hot-Spot-locations for the chord and the brace. As optical guidance, the net-cross-section geometries are dis played by scaling the chord heights/diameters to the geometries no. 3 for RHS and CHS.