A model consists of structural objects, loads and finite elements. This chapter summarizes the definition ways, the properties and the features of the structural objects.

Depending on the current FEM-Design Module (license you have), the available Object types are different. Although the structural objects are real 3 dimensional objects, they are 1D members and 2D planar elements (because of the finite element method) having sectional (thickness, profile etc.) and material properties. So, they can be defined as lines or regions. Some elements like point supports can be defined as points.

Type	Icon	Modules where available	Definition mode	Position	Material	Profile	Load bearing	Default Short Command
Soil			Region	Horizontal	Arbitrary	-	Arbitrary	SO
Borehole			Point	-	-	-	-	BH
Pile			Point/Line	Vertical	Arbitrary	Arbitrary	Arbitrary	PILE
Isolated foundation			Regular shape/Solid	Horizontal	Concrete	Arbitrary	Arbitrary	FIS
Wall foundation			Line	Horizontal	Concrete	Arbitrary	Arbitrary	FWL
Foundation slab			Region	Horizontal	Concrete	Arbitrary	Arbitrary	FSL
Beam			Line	Horizontal Arbitrary	Arbitrary	Arbitrary	Arbitrary	BM
Column			Point Point/Line	Vertical	Arbitrary	Arbitrary	(Support) Arbitrary	CL
Truss member			Line	Arbitrary	Arbitrary	Arbitrary	Axial	TR
Intermediate section			Point	-	Arbitrary	Arbitrary	-	ISEC
Apex			Line	Vertical / Horizontal	Timber	Rectangle	Arbitrary	APEX
Column corbel			Point	Horizontal	Arbitrary	Arbitrary	Arbitrary	CCOR
Wall corbel			Line	Horizontal	Arbitrary	Arbitrary	Arbitrary	WCOR
Plate			Region	Horizontal Arbitrary	Arbitrary	Constant / variable thickness	Vertical Axial	PL
Wall			Line Region Line	Vertical	Arbitrary	Constant/ variable thickness	(Support) Planar Arbitrary	WL
Profiled panel			Line/Region	Vertical/Horizontal	Arbitrary	Constant	Arbitrary	PPR / WPR
Timber panel			Line/Region	Vertical/Horizontal	Timber	Constant	Arbitrary	PTM / WTM
Point support Point support group			Point	Vertical Arbitrary	-	-	-	SPT SPG
Line support Line support group			Line	Vertical Arbitrary	-	-	-	SLN SLG
Surface support group			Region	Vertical Arbitrary	-	-	-	SSF
Point-point connection			Line	Horizontal Arbitrary	-	-	-	CPT
Line-line connection			Lines	Horizontal Arbitrary	-	-	-	CLN
Fictitious bar			Line	Horizontal Arbitrary	-	-	-	FICB
Shell model			Regions	Arbitrary	Steel	Constant/ variable web height	Arbitrary
Fictitious shell			Regions	Arbitrary	-	-	-	FICS
Post-tensioned cable (PTC)								BPTC

Table: Structural Objects and their main properties

The commands for defining structural objects can be started from the  Tabmenu. Each command has a Tool palette with the customizable element properties (cross-sections, materials, stiffness values etc.) and the definition tools of the element geometry and position (direction).

Properties

Tool palette contains all customizable structural properties. The main properties can be set directly in the tool palette and all properties can be set in the dialog opens by clicking on the Default settings button. The settings dialog and fields keep the last set property values by element types (beams, columns, plates etc.)

Figure: Setting part of Tool palette

Cross sections

FEM-Design offers the possibility to add any cross-section type/shape (Section) to beams, columns and truss members.

To avoid design failures of concrete, steel and timber bars (section type and material do not fit), the program checks the section type - material compatibility while setting the properties. The program sends an error message when it finds incompatibility definition at closing the settings dialog. But, the so-called General material (defined by the user) can be added to each section types.

The Section tabpage of the settings dialog contains predefined cross-sections. Unique profiles and shapes can be define by their parameters (parametric shapes) in New> Size or with the  FEM-Design Section Editor. The following table sums the available cross-section types.

Type	Description	Section library	Compatible material
Standard steel profiles	Not editable, built-in steel profiles depending on the applied national code		Steel (or General)
Often used concrete profiles	Not editable, built-in square, rectangular and circular concrete profiles		Concrete (or General)
Often used timber profiles	Not editable, built-in square timber profiles		Timber (or General)
Common parametric concrete shapes	Predefined concrete shapes to create required profiles by defining the shape parameters		Concrete (or General)
Common parametric rolled steel shapes	Predefined rolled steel shapes to create required profiles by defining the shape parameters		Steel (or General)
Common parametric cold-formed steel shapes	Predefined cold-formed steel shapes to create required profiles by defining the shape parameters		Steel (or General)
Common parametric welded steel shapes	Predefined welded steel shapes to create required profiles by defining the shape parameters		Steel (or General)
Common parametric timber shapes	Predefined timber shapes to create required profiles by defining the shape parameters		Timber (or General)

Table: Section types

Defining a new (e.g. parametric) section in the settings dialog, the program calculates automatically the parameters need for later analysis and design. Each bar element has a local coordinate-system which y and z axes define the plane of its cross-section.

Parameter	Meaning	Example
A	Area
P	Perimeter
A/P	Area/Perimeter
Yg, Zg	Center of gravity
Ys, Zs	Shear center position
Iy, Iz	Moment of inertia
Wy, Wz	Section modulus
ez max, ey max	Maximum distance of extreme fiber
ez min, ey min	Minimum distance of extreme fiber
iy, iz	Radius of inertia
Sy, Sz	Maximum statical moment
It	Torsion moment of inertia
Wt	Torsion section modulus
Igamma	Warping parameter
Iyz	Centroidal product of inertia
z omega	Wagner warping parameter
alpha1, alpha2	Angle of principal direction
I1, I2	Principal moment of inertia
W1 min, W2 min	Principal minimum section modulus
W1 max, W2 max	Principal maximum section modulus
e2 max, e1 max	Maximum distance of extreme fiber
e2 min, e1 min	Minimum distance of extreme fiber
i1, i2	Radius of principal inertia
S1, S2	Principal maximum statical moment
So1, So2	Principal statical moment of half area
c1, c2	Plastic/elastic moment capacity
Rho1, Rho2	Principal shear factor
z2, z1	Wagner parameter

Table: Sectional characteristics

A cross-section is stored in the following tree structure: group > type > size. New library items can be defined or previous ones can be edited (renamed, modified or deleted) by the following settings options.

Figure: Section library structure

Cross-sections used in the project and defined as parametric profiles are grouped in Used sections library, but they are available only in the current project.

Figure: “Used sections” library

You can Import and Export the Section Library to share the content of the Library.

Composite sections

Composite sections can be set for beams, columns and piles.

The available composite section types:

Click Default settings/Section tab/Composite/New to open the settings of Composite sections.

For the time being only above listed composite sections can be selected, there is no choice to create alternative section.

Materials

The Material tabpage of the settings dialog contains predefined materials according to the current national standard.

A model may include mixture of elements with different materials, and analysis can be done for the complete model, but design can be done for elements having proper materials.

Table: Available and design materials

Material library stores the available materials by material type groups. Materials used in the project are grouped in Used materials library, but they are available only in the current project.

Figure: Material library

Above the standard materials, user can define concrete, steel, timber and general materials. The new materials are also stored in the Material library in the proper material type group. To define a new (e.g. concrete) material, select the required material group name (e.g. Concrete), click New and set the required material properties starting with the material name first.

Figure: Material types

The properties of the current (selected in the list) material can be edited with the Modify tool.

Customized material database can be shared between projects and users with the Export and Import tools. Click Export to save all materials of the current project in a named database file (.fdlmat). To load an exported material database to a project, just apply Import and browse for it.

Figure: Material export/import

Just one click on Quantity estimation (Tools menu), and a fast process collects all structural elements of the current project with their applied materials, material qualities, identifiers, main geometric parameters (e.g. profiles), quantities etc.

Modifying the national standard for a model the program shows a dialog where you can convert the material property of the structural elements and the reinforcing steel, so the materials will automatically change after switching the code.

Figure: Material conversion dialog

Information Pop-up

Moving the cursor over a structural object, an Information pop-up appears with its main properties. For example, the pop-up displays the ID, the material, the thickness, the alignment and orthotropic features for Plates.

Figure: Information pop-up example

Information pop-up appears only for elements on visible layers and if there is not running command.

Pop-up is enabled by default. To unable it, uncheck the Display information pop-up at Settings > All > Environment > General >View.

“Properties” Tool

       With the Properties tool of a tool palette, the properties of a selected object or objects can be inquired and edited in dialog format (similar to Default settings).

Figure: Modifying object properties (e.g. cross-section of a selected beam)

Modify properties by “Quick menu”

Alternative way of modifying object properties is to select any object by right click, or more objects of the same type by box, then click “Properties  ” in the Quick menu to check/modify its/their properties. This function works for structural objects, loads or design elements.

“Pick properties” and “Copy properties”

With these functions the properties of an object can be copied to others of the same type, or picked to use as default. Both can be found in the Tools menu and in the toolbar as well.

To copy properties with the Copy properties ( ) function, first select the source object, then one or more objects to which the properties are to be applied.

Pick properties ( ), when used on an object (of the same type as in the active editing dialogue) will update the default settings for its type.

Pick properties can only be used when Define is selected in an editing window, otherwise it is disabled.

Copy and Pick properties work according to the following rules:

• Generally, the properties defined by the property dialogue will be picked or copied.
• They are only available in the 3D Structure and Plate modules.
• ID will not be copied.
• Load case of loads will not be copied.
• Varying shell thickness and surface load value will not be copied.

Numbering

Structural elements with an ‘Identifier (. position number)’ will have an automatically or manually assigned position number.

The position number will be 0 upon creating the object and will be automatically set to another value in the following cases:

• before creating a list
• using the Find tool
• before calculation

User can manually set position numbers by Tools/Numbering…  tool.

Use   for Manual position numbering

1. type required position number into the Position no. textbox
2. select option for handling position number conflicts
3. select object(s) to set position number for

In case more objects are selected, the first one gets the position number typed by the user and for the next ones it is increased automatically.

To set position number of component objects, like edge connections, corbels, post-tensioned cables, punching regions, the Select component (…)  auxiliary option has to be checked.

Objects with manually set position number can be highlighted by checking the last option of the tool window.

The position number can be reset to zero by choosing Reset   option then selecting one or more objects.

Automatic numbering   sets position number automatically for all objects in the database except the ones with manually set position number.

The option to Lock numbering can be accessed by clicking its icon   in the same Tool window.

When the numbering of a selected object type is locked, the position number of individual elements will remain the same. The maximum position number is saved for all IDs, so position numbers less than that will not be used in the future, even if some items are deleted.

This means all the element types with their numbering locked will retain their original ID, even after refreshing the numbering (either manually, or automatically).

Display Settings of Structural Elements

The display properties of the structural elements can be set at the Settings > All… > Display.

The available options depend on the current FEM-Design module.

Figure: Settings options affect on the appearance of the structural elements

• Drawing elements
  With the Show end points of line option you can show (or hide) the insertion points of planar structural objects, their holes and bar objects (beams, columns etc.). These points are visible in all display modes, but the Wireframe mode without displaying the elements’ thickness gives the clearest appearance of them.
  
  Figure: Insertion points displayed in Wireframe mode

  By showing the insertion points you can also detect the unnecessary (for example accidentally) defined points, which may cause “too refined” finite element mesh in planar structural elements. The unnecessary points can be deleted with editing tools (Edit menu) which can be applied for region elements (such as plate, wall regions etc.). For example, stretch the unnecessary points outside the host region, and then cut the stretched region part(s) with the Split tool of the Modify region (Edit menu) or with the Hole tool of the structural planar object. Figure: Unnecessary definition points detected visually

  With the Fill-up with color option the planar objects (plate, wall, drawing regions) can be displayed with their reference plane as colored surface or with their contour lines only. Applying the fill colors is useful to display holes/openings clearly. The filling color of an element is the default color of the Object layer includes the element. It can modified at the layer settings by element types (Plate, Wall etc.) or with the Color option of the Change properties tool (Edit > Properties) by elements (independently from their types).
  
  
  
  Figure: Planar objects displayed with their colored surface or without it in Wireframe mode
   

• Structure and load labels
  Information of structural elements (such as ID, position number, material properties, section names etc.) and load (such as intensity, Comment etc.) can be displayed on the screen by element types in Wireframe display mode.
  
  Figure: Info labels displayed on screen by element types
   
• Storey
  In this section the User can select how the objects can be displayed within the storey.

Every object is displayed which is in the plane of the storey or if it is crossing the range of the storey above or below according to the setting.

To display one of the defined storeys click on the    icon in the Toolbar, then choose the storey you wish to be displayed:

The pictures below show the whole structure and how its displayed parts depend on the selected option in Settings/Display/Storey dialog.

• Display local system
  The local co-ordinate system of the structural elements can be displayed with the Display local system option by element types. The size of the local system symbol can be set at the Size option. The color of the local system axes can be set at Local systems setting. The default colors are: green for the local x’ axis, red for the local y’ axis and blue for the local z’ axis.
  
  Figure: Local co-ordinate system displayed on screen by element types
   
• Special display settings of walls
  With the Display wall base line option (3D Structure and Predesign modules only) the bottom end of the walls can be displayed as a hatched surface.
  By inactivating the Display wall height option (Plate module only) only the reference support line (as hatched surface) can be displayed without showing the height-extension that is out from the plates’ calculation 2D plane.
  
  
  Figure: Special display options of walls

• Special display settings of bar elements
  The Display section shape option shows the applied section of the bar elements as a colored symbol in the middle of the bar reference lines. The size (Scale), the filling (Fill) and contour (Border) colors are customizable. Although, section shape symbols are visible in most of the different display modes, their “best” display mode is the Wireframe mode without displaying the elements’ thickness.
  
  The Display connections option shows the end connection property (see Beam, Column or Fictitious bar connection settings) of the bar elements. Only the free end motion components can be displayed as arrows, where a simple arrow shows a motion component by its direction and a double-headed arrow shows the axis direction of a rotation component. The fix (rigid) end connection components are never displayed. The color of an end motion component equals with the color of the proper axis of the host bar element’s local system (see before, Display local system). The size of the symbols can be set at the Size option.
  
  Figure: Special display options of bar elements
   
• Layer, color and pen width
  All elements are placed (and grouped) on Object layers according to their type. So, for example, columns are on the “Columns” layer and the walls are on the “Walls” layer. The default color and pen width of elements’ contours/reference lines are represented by their host layers. For example, by default, walls are red, if the color of the “Walls” layer is also red.
  
  Figure: Layer-system of structural objects

The default color of an object can be modified independently from their types with the Color option of the Change properties tool (Edit > Properties).

Color schema

This feature lets the users to navigate a model easier, by allowing them to fully customize element colors. These options can be accessed through the Tools à Colors menu command, or by clicking on their icon ( ) in the toolbar.

Mode determines the attribute on which the color coding is based. When None is selected, the default colors for object types will be used.

For each object type, the following attributes are available:

The Manage button can be used to save a specified color coding system. These can be selected afterwards from the drop-down list to the left from the Manage button. Schema color is saved only for a given project.

Clicking the Apply button will apply the color code to the model. Enabling the Auto apply checkbox will apply any changes automatically.

When a custom color scheme is in use, a legend window will be displayed. With the Position button, the placement of this window can be specified; it can even be hidden. By default, the legend is displayed in the bottom left corner of the screen.

Colors, borders, and their line types (with thickness) can be modified by clicking on the Edit palette button. In the dialog box, all parameters can be set for every value of the specified attribute (ID, Material or Thickness). It is possible to save these settings separately to be used in another color scheme.

The Settings button will allow you to save your color scheme to a file (*.cpal) or as default, or load another schema.

When a color scheme is saved, only the colors and their order will be stored, values need to be specified each time.

Pen (line weight) can use pixels as well as millimeters. A positive number means millimeters, while a negative one will give the line width in pixels. A line weight given in millimeters will remain the same in the documentation. When pen size is given in pixels, the line weight will remain the same on-screen, regardless of zoom level.

Geometry

The definition modes and the available shapes of structural elements’ reference line or reference plane depend on:

• The structural type: 1D Member or Planar Object, and
• The current FEM-Design module.

The Tool palette of a structural element contains only the available modes. The next table summarizes the geometry possibilities by structural elements.

Type	Icon	Modules where available	Definition mode	Geometry
Soil			Reference region	Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
Borehole			Reference point	- (Insertion point)
Pile			Reference line	Pile by point (Geometry)  Vertical line (Geometry)  Select point (Geometry)  Line by selection (Geometry)  Array Rectangular (Geometry)  Array Polar (Geometry)
Isolated foundation			Regular shape	Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
			Reference solid	Pick existing solid (Geometry)
Wall foundation			Line	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Foundation slab			Region	Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
Column			Reference point	- (Insertion point)
			Reference line	Line by insertion point (Geometry)  Vertical line (Geometry)  Select axes (Geometry)  Select point (Geometry)  Line by selection (Geometry)
Truss member			Reference line	Straight line (Geometry)  Line by selection (Geometry)
Intermediate section			Reference point	- (Insertion point)
Apex			Reference beams	-
Column corbel			Reference point on a column	- (Insertion point)
Wall corbel			Reference line	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Plate			Reference region	Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
Wall			Reference line	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
			Reference region	Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
			Reference region	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Profiled plate			Reference region	Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
Profiled wall			Reference region	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Timber panel			Reference region	Use as plate:  Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
			Reference region	Use as wall:  Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Point support Point support group			Reference point	- (Insertion point)
Line support Line support group			Reference line	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Surface support			Reference region	Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
Point-point connection			Reference points	- (Insertion points)
Line-line connection			Reference lines	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Fictitious bar			Reference line	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Cover - Wall type			Reference line	Straight line (Geometry)  Arc by center, start and end points (Geometry)  Arc by 3 points (Geometry)  Arc by start, end point and tangent (Geometry)  Line by selection (Geometry)
Cover - Slab or roof type			Reference region	Rectangular (Geometry)  Circular (Geometry)  Polygonal (Geometry)  Pick lines (Geometry)  Pick existing region (Geometry)
Building cover			Reference plane shape	-

Table: Structural Objects and their geometry definition

Hole

       Holes, openings and cuttings can be added to reference regions (Plate, Wall and Surface support) with the Hole tool. The following geometries can be used for holes:

The steps of a hole definition:

1. Select the host region with mouse-clicking. Clicking a region places the UCS into the region plane, so giving hole coordinates needs only X and Y values from the UCS origin.
2. Define the geometry of the hole with one of the following geometry modes:
     Rectangular
     Circular
     Polygonal
     Pick lines

Figure: Examples for holes

Figure: Hole tool can be used to edit region geometries as cuttings

Holes can be easily copy inside a region or among regions with same reference plane position with the Copy command (Edit menu). It is recommended to display only the regions’ reference plane (inactive Display thickness option) to easily select the contour of the hole you would like to copy. To set the distances/new positions, the UCS has to be in the plane of the host region(s).

Figure: Copying holes in a Wall

Direction

Numerous objects need direction settings for their positioning (bar elements) or their components definition (supports). The next table summarizes the direction possibilities by structural elements.

Type	Icon	Modules where available	Direction for	Direction Modes
Soil			-	-
Borehole			-	-
Isolated foundation			Solid position: Direction of local x’ axis	Predefined direction (Geometry)  Local system (Geometry)
Wall foundation			-	-
Foundation slab			-	-
Beam			Cross-section position: Direction of local y’ axis	Predefined direction (Geometry)  Parallel with line (Geometry)  Perpendicular to plane (Geometry)
Column			Cross-section position: Direction of local y’ axis	Predefined direction (Geometry)  Parallel with line (Geometry)  Perpendicular to plane (Geometry)
Truss member			Cross-section position: Direction of local y’ axis	Predefined direction (Geometry)  Parallel with line (Geometry)  Perpendicular to plane (Geometry)
Column corbel			Horizontal axis position: Angle between the horizontal axis of the corbel and the local y’ axis of the column	Alpha[°]
Point support			Rotation direction	Predefined direction (Geometry)
			Motion component direction	Parallel with line (Geometry)
			Component direction	Perpendicular to plane (Geometry)
Point support group			Component direction	- (Predefined direction)
			Component direction (reference system)	Predefined direction (Geometry)  Local system (Geometry)
Line support			Rotation direction	Predefined direction (Geometry)
			Motion component direction	Parallel with line (Geometry)
			Component direction	Perpendicular to plane (Geometry)
Line support group			Component direction	- (Predefined direction)
			Component direction (reference system)	Predefined direction (Geometry)  Parallel with line (Geometry)  Perpendicular to plane (Geometry)
Point-point connection			Component direction	Predefined direction (Geometry)  Local system (Geometry)
Line-line connection			Component direction	Predefined direction (Geometry)  Local system (Geometry)

Table: Structural Objects and their direction settings

Change Direction

Any previously set direction can be modified by the editing commands (Edit menu): Change direction and Rotate.

Change direction uses the Predefined direction, Parallel with line and Perpendicular to plane direction definition tools.

Figure: Beam position (local y’ axis) is modified with Change direction

Rotate edits a selected direction or the main direction of a selected system with giving new direction points or the rotation angle. Rotation works around a given point or an axis.

Figure: Rotate modifies the main direction (x’) of the Point support group

Supports and Connections

This chapter summarizes the possibilities and properties of the available supports and connections.

The connection with the ground (model space) can be modeled with Supports, while the link among structural elements can be defined with Connections. All support/connection components can be set to:

• “infinite” rigid: blocked motion/rotation,
• “free”: released motion/rotation, or
• semi-rigid: given stiffness value (spring) against motion/rotation.

Non-linear behaviors, independent compression and tension, elastic and plastic behaviour settings are also available for all motion and rotation components.

Edge connection is a special tool of structural object definitions. Although it was described at planar objects (like Plate), the following connection settings and functions are also valid for Edge connections.

Support motion loads have to be assigned to supports, so supports are requested input parameters for motion-type loads. Always try to create stable structural model by defining correct support and connection conditions. From unstable (kinematically indeterminate) structure equilibrium error can be resulted. In that case the program sends a warning message at the end of the calculations, and you can determine the location of the problems by checking the equilibrium (Analysis > Equilibrium), the displacement/buckling and/vibration shape results of the structure. It may also happen that the model is so incorrect that calculations stops with error messages and without results.

“Infinite” Rigidity

The value of “infinite” rigidity can be defined and set as project default by support/connection types and components at Settings > All > FEM. Go through the Motion and Rotation components by support and connections types and set the requested stiffness value that model blocked absolute/relative displacement.

The “rigid” values can be set to default for further projects, if select “Rigid” values in the Settings tree and click Save as default. Figure: “Rigid” values

The “rigid” value can be set by support/connection/fictitious bar element inside its settings dialog (Setup “Rigid”) independently of the project default. Figure: “Rigid” value set by support objects

Properties (Non-linear behaviours)

Compression, tension, elastic and plastic behavior of supports and connections can be set separately and by components.

Figure: The parts of typical support/connection settings dialogs

• Stiffness fields by compression and tension
  “Rigid” or Free can be chosen from the pop-ups, or stiffness value (spring support/connection) can be typed in the fields.

  Active   icon assigns the stiffness value typed in the Compression field to the Tension field. Inactive icon   lets to define the stiffness values separately.

• Predefined types
  Click   to set all motion and rotation components to “rigid”. The result will be a totally rigid support/connection.
  Click   to set all rotation components to “free” (allow rotation around all directions). The result will be a hinged support/connection.
  Click   to set all components to free. This tool gives the possibility to virtually connect independently moving elements.

  “Uplift” can be modeled both in 2D and 3D design modules by defining compression-only support / connection (tension = 0 (free)) and by checking the Consider non-linear behavior of supports, trusses and connections box at Calculate> Analysis. Figure: Allow uplift in Plate and 3D Structure modules

• Using “Detach” option
  The nonlinear behavior of supports and connections (Point support, Point support group, Line support, Line support group, Surface support, 3D Plates and Walls Edge connection, border and panel connection of Timber panels and Profiled panels) can be controlled by one signed component. It means, if the force in the connection / support happen to act in this selected direction, all spring constants will be set to 0, so called it is detached. This option can be set in the dialog, where the spring coefficients are set. If in the Detach list anything is selected (e.g. z’ tension) the corresponding spring constant will be automatically set to 0.
  
  

If in Calculations dialog the ”Consider non-linear behavior of supports, trusses and connections” option is checked the calculation method is the following: If in the connection where the detach behavior is defined (e.g. z’ tension) the connection force is tension in the given direction (z’) in an iteration step all of the other spring constant will be set to 0. If in any later iteration step the connection force will be compression, the spring constants will be set to the previously defined values.

There is a big difference between setting any of the components to zero or selecting a detach behavior. If the user sets manually a component to zero, in the analysis the connection or support will not have rigidity in that direction.

Supports

Support types

The following table summarizes the available support types and their main features in the different FEM-Design Modules.

Column and Plane wall are developed to model single point and line support in  Plate module. These types of support are not mentioned in the Support chapter.

Icon	Name
	Point support
	Point support group
	Line support
	Line support group
	Surface support group

Single Support versus Support group

Single Support defines only one component in one step, whilst Support group places a group of more components in one step. Although single Supports can be combined and work as a group support, it is recommended to define multi-support conditions with Support group, because all support components can be set or modified later (with the  Properties tool) inside one settings dialog.

Figure: A fully rigid support modeled by six single Support components or one Support group

Special color-system differentiates single Supports from the Support group components. Whilst a single Support uses the color of the “Supports” Object layer, the components of a Support group are displayed in the colors equivalent with the support’s Local system (Settings > All > Display > Support and Local systems).

Figure: Color settings of support types

Connection Objects

Connection types

Icon	Function
	Point-point connection
	Line-line connection

Edge connection is not a “connection object”. It is a definition tool for boundary connection conditions, which is available for Plate/Wall, Profiled panel and Timber Panel elements. But, the non-linear behavior and component settings are valid for edge connections introduced for the supports and below mentioned connection elements. See the definition modes and possibilities of an Edge connection at Plate. The end connection property of the bar elements are also not “connection objects”. You can read more about them at the Beam, Column and Fictitious bar connection settings.

For the end points of the edge connections two options are available:

• Separate end points from environment,
• Connect end point to environment.

In all Shell Toolwindows this setting is available by choosing ‘Edge connection’ then clicking  on ‘End point behaviour’   button. The end point can be chosen in three steps by selecting the Plate or Wall, then the edge and finally the end point.

Using this function can solve problems like the one on the picture below: On the right side structure all edge connection end points are connected to the environment which cases difference between the shear force on the wall and the sum of shear forces on the plate panels, which should be in balance according to common sense and this is exactly the case on the left side structure where edge connection end points are separated from the environment.

Plastic calculation

The plastic data can be set in the Default settings/Data tab of each above mentioned options. The figure shows where the feature is placed in the dialog.

Rigidity type

This option is used by Point support group, Line support group, Surface support group, Edge connection in Plane Plate and Wall structural objects, Point-point connection, Line-line connection, border and panel connection of Timber and Profiled panels. With rigidity type the user can define and load specific predefined spring constants.

If the rigidity type is Custom the user can define the spring constants as in previous versions. To define a type the user has to choose the Edit library… option.

After defining rigidity types, the defined spring constants will be registered in the Library and it can be loaded in the future.

There are some objects that use the same rigidity type library: Line – line connection, Edge connection (3D Plate, Wall), border and panel connection of Timber panels and Profiled panels

Construction stages

Construction stages are explained on this page: Construction stages