3.3.2: Shell Cross Sections
In Karamba3D there are four different kinds of shell cross sections:
The components “Shell Const” and “Shell Var” only differ in the data structures expected at the inputs “Material(s)” and “Height(s)”. In case of “Shell Const” these are data items. The “Shell Var”-variant expects two lists. The descriptions below refer to the “Shell Var”-component.
Fig. 18.104.22.168 shows a shell consisting of two elements. Triangular meshes form the basis for defining a shell geometry (see section 3.1.9) and specify the sequence of faces (i.e. shell elements). The list of element thicknesses in fig. 22.214.171.124 corresponds to that order. Be aware of the fact that meshes containing quads will be automatically triangulated. In case that there are more mesh faces than thickness specifications, the last item (
in this case) acts as the default value. The same holds for the supplied list of materials. Make sure to graft the “Materials”- and “Heights”-input when you want to define a list of shell cross sections. Otherwise one cross section results where one would expect several. For the “Shell Const” definition no data tree manipulation is necessary in such a case.
Fig. 126.96.36.199: Shell made up of two elements with different thicknesses
When rendering the shell cross sections (see fig. 188.8.131.52) thicknesses get linearly interpolated between the nodes. The cross section height at each node results from the mean thickness of shell elements attached to it.
The design of reinforced concrete cross sections in Karamba3D is based on linear elastic cross section forces. The “Optimize Reinforcement”-component takes these and computes the necessary reinforcement assuming cracked concrete cross sections. Thus defining reinforced concrete cross sections does not alter the mechanical behavior of the structure. They rather serve as input to the reinforcement design procedure.
Similar to shell cross sections there exist two variants of components for reinforced cross sections:
Further below variant two will be explained. The “ShellRC Std Const”-component works similar to the variable-variant. The only difference are the data structures expected at the inputs.
Fig. 184.108.40.206: Shell made up of two elements with different properties
Fig. 220.127.116.11 shows the definition for a reinforced concrete shell with two faces with different thicknesses, materials and reinforcement definitions. The geometry corresponds to that of fig. 18.104.22.168. A standard reinforced concrete cross sections consists of five layers: Layer zero is the concrete cross section. The layers one to four correspond to reinforcement. The top layer (with respect to where the local z-axis points to) comes first, the bottom layer last. Their orientation with respect to layer zero is 0°, 90°, 90° and 0°.
Besides the standard inputs of cross sections (“Family”, “Name”, “Elem|Id” and “Color”) the “ShellRC Std Var”-component offers these:
With the input-plug “LayerInd” of the “ShellView”-component one can select specific layers for visual inspection and results retrieval.