Due to the overwhelming popularity of the 'Did You Know' snippets featured in various
issues of News.St7, we have placed them all here so you can easily access them
from one centralised location.
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0001: Dynamic Scaling
0002: Ctrl-Click the Entity Show/Hide Toggle
0003: Shear Centres of Beams
0004: Transparent User Stress Limits
0005: Shortcut to Selection Arrow
0006: Applying Attributes
0007: Ctrl-Click Edit Nodes
0008: Right-Click Attributes
0009: Verification Manual
0010: Subdivide only Normal Beams
0011: Brick Cutting Plane Animations
0012: Auto-Assign Restraints
0013: Ctrl-Click Retrieve
0014: Run Time Improvements
0015: Strand7 Viewer
0016: Edit-Delete-Attributes
0017: Animations in Powerpoint
0018: Summary-Information
0019: Length-Area-Volume Loads
0020: Draw Ply Axes
0021: Hide Zeros
0022: Whiteboard
0023: Nonlinear Convergence Graph
0024: View Load Factors
0025: Anchoring Node Coordinates
0026: Background Image
0027: Numbered Backups
0028: Select Brick or Plate Faces
0029: Plate and Brick User Contour
0030: Skip Transitioning
0031: Browse...
0032: Middle Button for Dynamic Rotate
0033: User Contour of Principal Stress with Largest Magnitude
0034: Perspective in 3D Drawing
0035: Beam Local and Principal Results
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0001: Dynamic Scaling
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With results open press F4 to enter the dynamic view environment.
You can dynamically increase or decrease the Displacement Scale of deformed
models by clicking Scale in the Dynamic Rotation toolbar (shown) and
holding the left mouse button while moving the mouse: up to increase
and down to decrease the displacement scale. When an appropriate
scaling factor is obtained, click OK. This will automatically set
the displacement scale to the desired value.
Shortcut
The Scale option can be quickly accessed (while performing any of
the other dynamic functions - ie Auto, rXY, rX, rY, rZ, Zoom and Pan),
simply by pressing and holding down both the Ctrl key and the
left mouse button and following the procedures explained above.
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0002: Ctrl-Click the Entity Show/Hide Toggle
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Normally, by clicking the show/hide toggles, the model window automatically
updates and redraws to effect the changes. Often we need to turn on/off
more than one entity and for large models this can take time when redrawing
after each selection. Instead, hold the Ctrl key while clicking
the entity toggles to prevent Strand7 from redrawing after each click.
When finished select redraw to refresh the screen. (F3 or F5)
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0003: Shear Centres of Beams
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By default, Strand7 beam elements are positioned such that the element's nodes
coincide with the section's centroid. In sections such as C-sections, where
the shear centre is not located at the centroid, significant twisting
displacements will be generated due to lateral (shear) loads. If your
structure is constructed in such a way that this twist is restrained,
due to the load passing through the shear centre, you can offset your
section such that the nodes are located at the shear centre of the section.
You can do this automatically with the Auto Assign Beam Offsets tool.
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0004: Transparent User Stress Limits
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If you're interested in the sections of your model that exceed the design limit,
you can contour your results such that anything outside the defined limits is transparent.
This makes it easier to check complex internal components without having to manually
hide outer elements.
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In Results/Settings under the Style tab clear the < Min and
> Max options. Now, under the Limits tab, set the user defined
limits to a minimum value of say the design limit and the maximum to the maximum calculated.
Only those elements with stress over the allowable limit will be contoured with the
rest of the model being transparent.
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0005: Shortcut to Selection Arrow
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Have you ever tried to select an element only to discover that the entity
selection arrow is not active?
Well, there is no need to use the mouse to toggle the arrow. Simply
press the space bar.
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With Release 2.3 single key shortcuts are
also available to toggle the entity selection buttons:
node, beam, plate, brick, link, vertex, geometry.
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0006: Applying Attributes
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When applying attributes to an element, for example Beam Rotational End Releases,
selecting the beam before opening the attribute dialog box will apply the
release to both ends.
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But, what if you only want the release at one end?
There is a simple solution. Before selecting the beam, bring up the required
dialog box. Now select the end of the beam you want to apply the release to and
you will find that only half the beam is selected. Only this end will be assigned the attribute.
Strand7 uses this approach for the other attributes, such as brick face and plate edge attributes.
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0007: Ctrl-Click Edit Nodes
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Moving nodes can be done with 2 simple clicks in Strand7 just like drag and drop.
- Bring up the Edit/Nodes dialog box.
- Holding down the CTRL key, click the node you wish to move with the left mouse button.
- Now release the CTRL key and click the node you wish to move it to.
All Done! But don't forget to clean the mesh after you're finished.
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0008: Right-Click Attributes
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Once you have applied an attribute to a particular element, you can easily
apply a different type of attribute by right clicking over the existing
attribute dialog box.
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For example, you have just assigned restraints to a node and now you want to assign a
force.
In the Node Restraints dialog box, right-click to bring up a list of attributes
to choose from.
Select Force and you will find that the Node Force attribute is now the
active dialog box. It's that easy.
This works for all attribute types in Strand7.
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0009: Verification Manual
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Confused about how to set up your nonlinear model?
Example models can be found in the Strand7 Verification Manual.
You can find the "Verification Manual" folder within the main Strand7
program folder on your computer. Here you will find around 350 Strand7
models set up and ready to run.
The Verification Manual PDF contains the documentation that describes
each model and compares Strand7 results with target values. There are
examples for all of the solver options available in Strand7, divided into
separate sections for easy identification. It's a great first reference
for how to set up your model.
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0010: Subdivide only Normal Beams
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When a model contains both normal beams and other line elements, e.g.
trusses and springs, you may not want to subdivide the truss/spring elements
when the beams are subdivided as it could lead to singularities.
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Preferences within Strand7 can be changed so that when all beams in a model
are selected, only those that are normal beams are subdivided.
Choose Tools/Options. Under Subdivide set Subdivide only Normal Beams.
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0011: Brick Cutting Plane Animations
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Viewing internal stresses in a brick can often be difficult and so the cutting
plane option is used to view the stresses through a slice. You can then create
an animation in the usual manner, (Results/Create Animation), which will create
an animation of results for this slice.
But what about if you want to see this slice progress through the brick
structure for a single load step?
Choose to create an animation and set Move Cutting Plane. When animated the
slice will progress through the structure for that load step, between the
extremities of the model.
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0012: Auto-Assign Restraints
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When creating a rigid link array there is no need to go through the
process of creating rigid links one at a time. Instead you can make
use of the auto-assign tool in Strand7.
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Select all the nodes you wish to be connected via rigid links then
choose Tools/Auto Assign/Restraints. Select Rigid
Connections as the Type and click Apply.
This will connect all the nodes via rigid links to an automatically
generated master node, which will lie at the average of the selected
nodes. Alternatively you can select your own master node for the rigid
links to radiate from.
This tool is particularly useful for models that have bolted
connections or areas where a point load is to be applied over an area.
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0013: Ctrl-Click Retrieve
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Have you ever found yourself wanting to assign a restraint to a node
similar to an adjacent node, or perhaps assign a common value of
normal pressure to a brick face?
Within Strand7 is a simple procedure that can retrieve this information,
ready for it to be assigned elsewhere. Open the required attribute dialog
and then ctrl-click the node or element. The dialog will be
automatically filled out with all the attribute values of the clicked
entity, which can then be applied to other elements.
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For example, open the node restraint dialog and ctrl-click a node with
restraints. The node restraint dialog box will be updated to match the
applied restraints. This procedure can be used for all element attributes.
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0014: Run Time Improvements
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There are a few tips that you should keep in mind when trying to improve
the run time of your Strand7 solve.
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Firstly store your temporary files locally, not across a network.
Choose File/Preferences, to change the location of your temp
directory. Also if it is a very large model try saving the results files
to your local drive while solving, reducing the time taken to write across
the network.
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However while all this will show some small performance improvements in solve
time, for large improvements, the Sparse Solver should be top of the agenda.
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0015: Strand7 Viewer
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If you have clients that don't have a copy of Strand7 and you want to
be able to display your Strand7 model and results to them in their
office the Strand7 Viewer can be used. You can download a free copy
of the Strand7 Viewer from here.
This allows you to interrogate a model file and results in the same
way as you would in the full version of Strand7.
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0016: Edit-Delete-Attributes
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If you find the need to delete all attributes in a model without
deleting the elements themselves there is a simple tool to do this.
Choose Edit/Delete and select Attributes Only. You can then
choose whether to do so for all cases or simply a single case.
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0017: Animations in Powerpoint
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When presenting your Strand7 analysis to your client a PowerPoint presentation
can be very effective. To give depth to the content a Strand7 Animation of
results can be included.
There are two common methods that can be used:
- Save the animation as an exe file. Then in PowerPoint choose to Insert
a Hyperlink and browse to the correct location.
- In the Strand7 Animation Window choose to save the animation as a series
of images. Then create a gif animation of these in an appropriate software package
This can then be inserted in the PowerPoint presentation with the animation
permanently running.
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0018: Summary-Information
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At the top of every print from Strand7 a title block is presented where
information on Project Title, Company Name, etc. can be given.
To fill this in simply choose Summary/Information and complete
the required fields. The information here will then be displayed on
all Print jobs from Strand7 (unless turned off).
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0019: Length-Area-Volume Loads
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The ability to assign element attributes based on their geometry is a
particularly useful one. In Strand7 attributes can be assigned based
on the length of a beam or plate edge (L), the area of a plate or brick
face (A) and the volume of a brick (V). For example, a beam pre-tension
that is proportional to the beam's length can be applied by entering an
equation such as 2.5*L, where L represents the length of each beam
element.
Furthermore, each of these variables can be prefixed with the letter T,
signifying Total, e.g. if five plate elements are selected, to assign
a force of 1500N, enter 1500/TA which will divide the force by the total
summed area of the five plates to give the correct pressure.
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0020: Draw Ply Axes
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If your model contains laminate properties you may wish to investigate the
local axis orientation of a specific ply.
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Choose View/Entity Display and when you set Draw Axes for
plate elements also enter the ply number you wish to view them for in
the box on the right. Plate axes for that ply will be displayed on the
element.
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0021: Hide Zeros
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Have you ever found yourself with so many linear or nonlinear load case
combinations that you lose track of which columns have load and which are
set to zero?
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In Strand7 there is a quick and easy way to hide all those zeros; to make
viewing loads a breeze. In the Linear load case combinations (or nonlinear
load increment) window, right-click and select Hide Zeros. All zeros
are hidden making it a simple matter to see where all the load has been
applied.
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0022: Whiteboard
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Determining the distances between two nodes is an easy process in Strand7.
Choose Summary/WHiteboard and click the two nodes you wish to determine
the distance between. Information on the node numbers and attributes will be
displayed. Along with this will be a straight line distance between the
two nodes and relative distances, DX, DY and DZ.
If three nodes are selected then along with the distance between the nodes,
an angle between the nodes will be given. Information on other elements can
also be shown in the whiteboard, for example, plate area, brick volume etc.
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0023: Nonlinear Convergence Graph
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Convergence of the nonlinear solvers is based on the displacement and
force norms for the model for each iteration. Within R2.4 you can now
click 
in the solver panel to display a graph of the displacement and
force norms for each iteration.This means that it is easier to track
the path of convergence of the model.
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0024: View Load Factors
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With the release of Strand7 R2.4 comes the ability to view the applied
loads for a specific load case combination, nonlinear load increment,
quasi-static or transient dynamic time step. Results/View Load Factors
will show the load factors applied for each load case for the displayed
result case.
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0025: Anchoring Node Coordinates
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If you wish to create nodes in a specific plane or line, you can anchor
one or more nodal coordinates and then enter the remaining values.
In the Create/Node dialog enter the coordinates that are to stay the
same, e.g Z = 250. Then clear the Z checkbox. Now every node that is
created when an X and or Y coordinate is entered will be at Z = 250.
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0026: Background Image
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A background image can be added to your Strand7 model window to allow
you to include your company logo or perhaps a theme that matches your
structure to “jazz up” the presentation of your model to your client.
Choose View/Options and select the jpeg or bmp image you wish to
use as the background. This will be displayed in the model window.
The model can still be manipulated within Strand7 as per usual.
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0027: Numbered Backups
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You can set the file preferences to allow Strand7 to save
your model with a different numbered backup every time you click save.
This should give users peace of mind, knowing that model changes
can be retraced and, more importantly, recovered. This Option is accessed via File/Preferences.
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0028: Select Brick or Plate Faces
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You can select brick or plate elements based upon
the relative angles between free faces. This is useful for
situations where a surface pressure needs to be applied,
but the shape does not lend itself to easy selection using
Select by Region or any other convenient method.
Command accessed via Select/Brick(or Plate) Faces.
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0029: Plate and Brick User Contour
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For plate and brick elements a User Contour based on stress and strain result quantities can be defined in Results/Results Settings. This is useful in plotting the contours of derived quantities based on the elemental stress and/or strain, for example a material failure criterion. This quantity is also available for the Peek tool and in the Results Listings.
In this example, we derive and contour a concrete cracking index according to  , where ft(t) is the tensile strength at age t obtained from concrete design codes and s1(t) is the maximum principal stress calculated by Strand7.
Since only the tensile stress is required, the function IFPOS can be used in this case, for example "IFPOS(x)" returns "x" when "x" is positive otherwise it returns "zero"). The user contour by the equation "0.35*SQRT(32)/IFPOS([S11])" indicates that some cracking can be expected in the concrete beam due to the creep and shrinkage where no pretensioning has been applied.
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0030: Skip Transitioning
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Skip Transitioning is an automeshing option that aims to produce a mesh as regular as possible by ignoring small features in the geometry. This option can be used in conjunction with the Vertex/Mesh Size attributes to create a mesh with specific boundaries such that it can be directly “stitched” onto the existing mesh.
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Initial Mesh:
A modification is required to include an additional hole to the existing mesh.
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Using geometry tools such as Face from Beam Polygon and Graft Edges to Faces, a geometry face with a cavity can be created.
Additional vertices with matching Mesh Size attributes are created.
Geometry tools are accessed via Tools/Geometry Tools.
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Final Mesh:
The geometry face is surface meshed with the Skip Transitioning option and the mesh will be modified with the required feature.
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Skip Transitioning can also be useful for skipping over small features, such as small mismatched edges producing small element edge lengths.
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0031: Browse...
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If you are trying to find a model and cannot remember its name you can try using File/Browse in Strand7.
Navigate to a likely model location in the Browse window and click Browse. This will display an image of the last saved model view with the file name of all Strand7 files located in this folder. A little contour bar is displayed in the bottom left hand corner of the image if the model has results.
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Also, if you right-click a model image you can open, rename, delete or see information about the file.
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0032: Middle Button for Dynamic Rotate
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As of R242 you can now quickly switch to dynamic rotate mode by simply clicking the middle mouse button.
The Equivalent keyboard shortcut is the F4 key.
Refer to the Online Help for other shortcuts.
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0033: User Contour of Principal Stress with Largest Magnitude
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For plate and brick elements a User Contour based on stress and strain result quantities can be defined in Results Settings. This is useful for plotting contours of derived quantities based on the elemental stress and/or strain, such as a contour of principal stress with largest magnitude according to:
smax = MAX( s11, s22)
This allows you to display both maximum principal stresses in the same contour. Enter the following formula into the user defined contour for plates:
IFPOSB(ABS([S11])-ABS([S22]))*[S11]
+ IFNEGB([S11]-ABS([S22]))*[S22]
This produces the signed principal stress with largest magnitude.
IFPOSB(X) evaluates to +1.0 if X is positive and 0.0 if X is negative or zero.
IFNEGB(X) evaluates to +1.0 if X is negative and 0.0 if X is positive or zero.
To plot the absolute value of the principal stress with largest magnitude enter:
IFPOSB(ABS([S11])-ABS([S22]))*ABS([S11])
+ IFNEGB([S11]-ABS([S22]))*ABS([S22])
Substitute [S33] for [S22] when contouring for bricks.
The signed principal stress with largest magnitude for bricks is shown below.
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0034: Perspective in 3D Drawing
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Strand7 allows you to change the perspective setting in a 3D model (View/Options/Drawing) so that you can see the 3D model on a plane view (say YZ plane view) more clearly. The setting is simply a number that ranges from 0 (no perspective) to 200 (very high perspective, like a fish-eye lens). It can be very useful when viewing/editing a complex 3D model.
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Isometric view with Perspective set to 25 (default)
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YZ plane view with Perspective set to 25 (default)
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YZ plane view with Perspective set to 0 (parallel view)
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0035: Beam Local and Principal Results
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Cross sections in beam elements contain both local and principal axes and they do not necessarily coincide (e.g. in the case of unsymmetrical or user defined sections).
For example, the principal axes of an equal angle section are oriented at a 45 degree angle from its local axes.
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To help make the extraction of beam results more versatile,
Strand7 reports beam forces and moments in both the local (x,y) and principal (1,2) axes.
For example, the highest bending moment at the root of the cantilever beam shown is
reported in plane y if the load is applied in the Global Z direction.
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