Thus, by visualization thicknesses of elements the user can define support condition in details instead of working on the line mesh having point P43 supported only. In that case the sectional forces at the bottom chord is not correct at the 300mm end.
Figure: Lusas 3D deformation for vertical load 2.5kN/m2. See animation. The most important in FEM work is the correct FEM model, regrading to all elements have been connected to each other. This correctness can be easily checked by deformation figure, already at the deadload earliest stage in the analysis. Above shown deformed shape where the roof carrying 2.5kN/m2 to give some deformed values large than 1mm. The deformed values itself are not important in this single loadcase but the ratio between them are useful to estimate the entire structure. The vertical displacement 1mm at center of the bottom chord where the strongest section 300x80mm are used. The displacement is bigger 2mm at the end of the top chord cantilever. The displacement is also 2mm at center of the lath having 1.2m span between two top chords, and a section of only 73x38mm. In the animation one can clearly the outer frame deforms in X-direction (3mm) more than the inner frames (0mm). This 3rd dimension will not be see if the frame is modeled in 2D ZY-Plan. As the model is deformed correct, the user can model other load cases and load combinations on the structure to verify the timber dimensions according to Eurocode 5.
Modify automated model from ICDAS *.cmd file The beams model is automated when import the *.cmd file in LUSAS. The following additional manual works are needed for a beams model in LUSAS interface:
› Create User Sections (Tools > Section Property Calculator).
› Double click on a cross section automated in Geometric folder. The ‘Geometric Line’ dialog open, navigate to the associated user-defined-section created from above. Set the eccentricity ez here and click ‘Apply’. The model will update all beams with that section.
› Rotate the laths with beta angle arctan(tan(H/B)) so they are perpendicular to the top chords (left side with angle b, right side with angle -b). In Geometric folder right-click on the section name ‘Laths Left’ > Select Assignments. When all the laths on the left side are selected > go to Mesh folder > right-click on ‘Elem 0.250m’ and press ‘Assign’ (again). The ‘Line Mesh Assignment’ dialog open, set beta angle = b and click OK. All laths on the left side will rotate with the angle b in once. Do the same for the laths on the right side.
Revit Robot Integration Options In this option the roof construction is created in with Revit standard beam elements. The crossing of two top chords on top needed to modify so it looks like ICDAS generic model creation. When integrate to Robot, the user need to check all elements have been connected to each other as they are in ICDAS Revit LUSAS Option. Robot does not show the deformed shape in 3D cross section. Load combinations need to create in Robot manually and there is no smart combination in Robot (favour/disfavour).
Updated 13-04-2022 |