3.1.6.1 Line to Beam
Last updated
Last updated
The “LineToBeam” component converts lines into beam elements. Fig. 3.1.6.1 illustrates how the component takes two lines as input, determines their connections, and outputs beams and a set of unique points representing their endpoints. Lines with identical endpoints are automatically removed.
The “LineToBeam” component accepts straight lines, polylines, and splines as geometric input. Polylines are exploded into segments, and splines are divided based on the parameters "ToPAng", "ToPTol", and "ToPMinL" - see the description below for their meaning. All coordinates are in meters (or feet for Imperial units).
For cross-section design, the buckling length assumed for individual elements is crucial. By default, if “SetBkl” is "True", the distance between the endpoints of a line, polyline, or spline is used as the initial buckling length assumption for all created elements. An automatically assumed value for the buckling length is marked with a negative sign but is taken as an absolute value in the design procedures. This assumption can be overridden via a "ModifyBeam"-component by the user by supplying a positive buckling length. In case that the simplified buckling length calculation done by Karamba3D (see section 3.6.8: Optimize Cross Section) leads to a larger value than the initial assumption then the larger value is applied. A User defined positive buckling length always wins over any assumptions.
The “Color” input allows defining a color for rendering elements. To display the colors, activate the “Elements” button in the “Colors” submenu of the “ModelView” component and ensure the “Cross section” option in the “Render Settings” submenu of the “BeamView” component is enabled.
Elements can have non-unique names via the “Id” input, accepting a list of strings as identifiers. The default is an empty string. Each beam has a default name: its zero-based index in the model. Identifiers help group beams for modification or display. To assign multiple names to an element, use the notation '&"id1"|"id2"|"id3"|...' or shorter '&id1|id2|id3|...'.
Cross-sections can be attached to elements with the “CroSec” input. Cross-section definitions via the “Assemble” component override these settings.
A click on the “Options” submenu heading reveals additional input-options of the “LineToBeam”-component:
Beams that meet at a common point are by default connected rigidly in the structural model like they were welded together. See section 3.3.6 on how to define joints at the end of beams. The “Info” output-plug informs about the number of removed nodes and beams.
Beams come with several default properties to be immediately useful. These can be seen in the top right string-output of Fig. 3.1.6.1: “active” means that a beam will be included in the structural model. The default cross-section is a circular hollow profile with a diameter of 114 mm and a wall thickness of 4 mm. The default material is steel of grade “S235” according to Eurocode 3.
Input
Property
“Pts”
The order in which points appear in the output node list is random by default. However, it is sometimes advantageous to identify certain points by their list index to apply loads or define supports. This can be achieved by feeding a list of coordinates into the “Points” plug. They will be placed at the beginning of the output node list. For example, to ensure the endpoints of the structure in Fig. 3.1.6.1 have index 0 and 1, input a list of points with coordinates (0/0/0) and (4/0/0).
“New”
If this plug is “False”, only lines that start and end at one of the points given in the input points list will be added to the structure.
“Remove”
If this option is “True”, the "LineToBeam" component checks for lines that overlap and merges such duplicates into one. This prevents an error that is hard to detect visually: two lines on the same spot mean double member stiffness in the structural model. Alternatively, apply the “Remove Duplicate Lines” component from the Karamba3D utilities section to the list of incoming lines to ensure a one-to-one correspondence between lines and elements.
“LDist”
Sets the limit distance for two points to be merged into one. Points supplied via lines are considered identical if their distance is less than that specified in “LDist”. The default value of “LDist” is 5 mm. Snapping nodes does not apply to points supplied via the “Pt” input plug. The mechanism for attaching duplicate nodes to elements is identical to that used by the “Assemble” component (see section 3.1.1).
“Z-Ori”
The default orientation of beams and trusses is described in section 3.1.14. The “Z-Ori” input allows defining a non-standard direction for the local Z-axis.
“Bending”
Allows switching off the bending stiffness of beams, turning them into trusses. For details, see section 3.1.10.
"SetBklL"
Set Buckling Length: If "True" (the default), the buckling length in local Y- and Z- as well as for lateral torsional buckling is set as the distance between the endpoints of the input curve. If this length is smaller than the automatic estimate based on the connectivity of the element's endpoints, it will be replaced by the larger value.
"ToPAng"
To Polyline Max Angle: For converting splines into polylines: Maximum angle (0 to pi) between tangents at adjacent vertices.
"ToPTol"
To Polyline Tolerance: For converting splines into polylines: If tolerance = 0, the parameter is ignored. This parameter controls the maximum permitted distance from the curve to the polyline.
"ToPMinL"
To Polyline Min Edge-length: For converting splines into polylines: If maxEdgeLength = 0, the parameter is ignored. This parameter controls the maximum permitted edge length in the base unit for geometry input.
