The online structural analyser STRIAN is a unique free online software intended for students and teachers. STRIAN 2015 was created by Miroslav Stibor and Petr Frantík. Its core employs Matrix Stiffness Method for analysis and was ported from existing Java application MaFoDeM (another free software for structural analysis). Note that you will be able to export model from STRIAN towards MaFoDeM by pressing Shift + Solve button from the menu.

Our tool doesn't have ambitions to compete with professional suits. The programs as Autodesk Robot, ANSYS or SAP 2000 are too complex and complicated for a student just having to learn structural analysis. Our program is focused on a simple user interface and instant availability: all it requires is a web browser with javascript and SVG capabilities. Since all major browsers among all computer platforms fulfill such requirements, users can create and solve models out of the browser, with no downloading and installing any software. No data are sent to our server: once the web page is opened all actions are processed locally by javascript within the browser then. That says you will be able to open and use the website regardless your platform:

  1. What the program can and can not do
  2. Creating spans
  3. Creating supports and hinges, inclined roller support
  4. Applying loading
  5. Obtaining reactions and internal forces
  6. Load and save

What the program can and can not do:

Can do

Can not do

Basic tutorial

You may want to start with clicking the  Settings to switch to imperial units (if you are not familiar with the metric system). Note that you can drag any dialog around by its handle and there is a contextual help available if you click the blue icon with a question mark.

Creating spans

The bars start and end at nodes. Nodes are by-products of creating the structure. Your supports or hinges can be placed only at nodes. A load can be placed anywhere.

You will likely start the structure by creating bars (spans). Let you use pointer at the beam's start and let you be guided by the network of grid lines to enter the bar's end. It is almost as simple as drawing. Or type relative coordinates of the endpoint explicitly into the dialog shown meanwhile.

The bottom grayed dashed line bellow the beam shows where the bottom of the beam is. It is only a matter of convention, which is useful when reading shear force diagrams later. You can change the bottom surface for vertical bars by drawing them from the other ends.

If bars cross each other then they do not interact unless the junction is managed to be their node.

If you are finished or need to start at another place, either

You can modify created geometry by

  1. Selecting the bars and
  2. dragging a node then.

Note: the bars can be selected also by clicking on them.

Drag the node to change the geometry. Note that the functionality is limited and you will likely lose forces (loading) if already applied there.

Finally, press ESC or  Abort icon to unselect the beams.

Creating supports and hinges

Let's assume that both ends are to be fixed and the middle node is to be loose, i.e. designed as a hinge. First, let you call the  Supports icon from the menu, select Fixed support (as required by design) and press Run it button to enter the chosen support type at nodes which you point further.

Escape the Supports dialog since we have to enter the hinge then.

If the dialogs are closed, press  Hinges button. Entering a hinge is an analogy to entering a support. But instead of pointing a node you have to point a beam and watch whether the hinge(s) are placed at the required end. If not, point the same beam again until the hinges are placed to your satisfaction. Note: in some cases (structure with braces) you may want to apply hinges to more braces at once rather than pointing brace after brace. That is a case when the bulk mode is handy: apply the function to a selected set of bars or braces. The bulk mode is useful for solving a truss.

Inclined roller support

Such feature is not implemented and the below structure depicts a workaround. Although you can't enter inclined roller, there's a way to substitute it by means of a bar:

Inclined roller support substituted by bar with hinge

Applying loads

Press  Loads button from the toolbar menu. A load can be entered, modified and deleted. A continuous load can be entered only within one span. If you intend to have a continuous load through more spans, you have to repeat the process for each span.

The simplest way to modify or delete a load is to click on the load itself and follow the instructions then.

Obtaining reactions and internal forces

If your model is valid, let you press  Solve button from the menu. After a while the reactions will appear.

Let you use  Diagrams button to control whether and how the internal forces and deflections are drawn.

In the above screenshot the deflections are drawn and reactions are disabled. You can also read horizontal and vertical deflection in predetermined points of the structure if you point cursor there (that's usually not possible on touchscreens, so you have to click instead then). In our above model the deflections would not provide meaningful values as no section was defined.

Load and save

You have two positions for saving your project. The first one is Autosave and you can't save into this position freely since the program maintains it itself. It's handy to use this one to recover in case of an emergency: let you open the Autosave position in such case. It can save you from creating your model again.

The second position can be used to save your project on your request.

Credit

This software uses several libraries


Click on the below image to enter the structural analyser.


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