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Special delta beams are now available in FEM-Design 19. They can be analysed as any other beam (in space), and their utilizations are checked for z' shear force and y' bending moment resistance.

This feature is available in 3D Structure, 3D Frame and Plate module.

Definition

Delta beam definition is accessible in Beam tool, where the cross-section needs to be Delta type. and DR type delta beams are implemented.The cross-sectional data listed in the dialog are basic cross-sectional sizes, bar stiffnesses (EA, EIy, EIz, GIt), cross-sectional resistances (z' shear force TRd, y' bending moment MyRd+/MyRd-) and unit mass.

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Material cannot be assigned to delta beams!

Due to the specified cross-sectional mechanical properties of delta beam, only force loads can act on it.

Analysis

In FEM-Design, several calculation types and limit states analysis can be performed which are using different creep factors and deformation parameters (see further information about the subject here, and here). In these calculations the program uses the same cross-sectional stiffnesses to delta beams which were adjusted in their property dialogs.

All beam type analysis results are available for Delta beams, except stress results, because the exact cross-sectional geometry is not defined.

Design

The design calculations are performed in the new Composite design tab.

In the Utilization the shear force and bending moment checks are available, where the shear force (in z’ direction) is compared to the shear resistance, and the y' bending moment compared to the corresponding bending moment resistance. If the bending moment from analysis is positive the utilization is based on the positive bending moment resistance, and if the bending moment is negative the utilization is based on the negative bending moment resistance.

Manual and Auto design functions work in the same way, as for steel or timber bars.

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List

Utilizations can be listed in Composite design/Delta beam utilization, where the shear and moment checking are visible.

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