Q: How can I get a vehicle to move across the bridge?

Question

I have set up my bridge, and have a single vehicle loading. How can I get the load to move across the bridge to find the most critical loading position?

Solution

There are two methods of doing this in LimitState:RING:

Method 1 - Using multiple load cases

A vehicle can be moved incrementally across a bridge by setting up a series of load cases. In this way the user can quickly identify the critical load position:

1. Open the loading dialog.
2. Select the vehicle you wish to move across the bridge.
3. Click the Add new load case button.
4. Select Copy an existing load case.
5. Select the target load case (usually load case 1).
6. Specify the number of loads that will be needed to adequately cover the whole bridge with a reasonable spacing. For example, for a bridge with loading required from -1000mm to 6000mm, 40 additional load cases would be sufficient to have a spacing of 175mm, which will find the critical loading position.
7. Click OK, and complete the Wizard by clicking Finish.
8. Now when the problem is solved, all loading cases will be considered. For the example above, there will now be 41 load cases. Note that If you need to model different vehicles, you should setup different models, since the axle spacing will differ between vehicles.

Method 2 - Using "Drag and Solve"

An alternative method is to enable automatic recalculation whenever the load is moved.

To enable this feature, go to the Tools > Preferences dialog. Select the option Solve automatically after dragging a vehicle, and close the dialog.

Now when you click on the wheel and drag it in the interface, the new problem you have defined will solve automatically.

The use of multiple load cases as well as drag and solve are covered in the LimitState:RING User Manual.