This command converts a Frame model to a Truss. This is done by adding hinges to the ends of some Elements of the Model. A Truss Model has only axial tension (no shear, no bending moment).
Important: Please note that if a Body (Acceleration) Load is present, then a Truss model in EngiLab Frame.2D can have also shear and bending, for example bending of a truss element due to its self weight. In this case, each element acts as a simply supported beam with a distributed load on it. The same is true if there are any Elemental Loads (distributed loads) acting on the Elements.
For dedicated 2D Truss analysis, EngiLab also offers EngiLab Truss.2D software, which works with 2 Degrees of Freedom per Node and is dedicated to the analysis of 2D Trusses, offering more pre- and pro-processing features for this type of structures, such as stress and strain diagrams, color plots and others.
In EngiLab Frame.2D, in order to convert a Frame model to a Truss model, the program automatically makes the following changes to the Model:
1.Every node where elements are connected is converted to a Hinge. When N elements are connected to a node, N-1 hinges are added to the N elements, as explained in detail in the following picture.
2.Supports are converted to Truss-Model supports, by releasing any constraints on the rotational Degree of Freedom (RZ-Con). The other two DOFs of each node are not affected. The picture below explains this conversion for every support case in EngiLab Frame.2D.
See the example below.
The picture below shows the initial Frame Model. If you analyze this Frame model, you will get axial forces, shear forces and bending moments in all elements.
The picture below shows the Model after it has been converted to a Truss. If you analyze this Truss model, you will get ONLY axial forces. No shear forces and bending moments will be present in the elements.
