The Running Imposed Load Command in SOFiPLUS

The “Running Imposed Load” command enables you to distribute a single freeload or a group of free loads along a curve (straight line, arc, spline and polyline).

Either a fixed number or a specific step length are available options to create the load positions and load cases.

The Reference Load and Path

Before you run the command “Running Imposed Load” it’s necessary to do following preparations to get smoothly through the entire workflow.

Create a Reference Load Case Number

This can be done in the Load Case manager within the load tab in the SOFiPLUS Sidebar.

Keep in mind, this reference load case will be used as base load case number for all duplicated ones. I’ll come back to this later in the workflow. For now, just keep plenty of spare numbers after the reference load case number.

Create a Reference Free Load

The “Running Imposed Load” command basically creates duplicates of free loads along a path. Which means you need to create the original beforehand. This can be a single free load or a group of several ones.

Distribution Path

It’s not mandatory to define a path as you’ll get the option to create one straight in the “Running Imposed Load” command. However, this capability is limited to polygonal lines. I recommend creating a path – if it’s more complicated – beforehand.

Running Imposed Load – The Workflow

As you have a reference load and reference load case number as well as the path available – let’s focus on the “Running Imposed Load” command.

Creating loads along a path is done by the following 4 steps.

1 Type of Distribution
2 Increment of Target Load Case
3 Select or Create the Path
4 Select the Reference Load

To get started, open the command “Running Imposed Load” in the SOFiPLUS sidebar tab “Loads”.

The “Moving Load” dialogue box comes with a few options only in the first few – but will allow further inputs by the right-click context menu.

1 Type of Distribution

The uppermost section of the dialogue box allows settings of the specific number or step size to generate the loads along the selected path.

The path can be a straight line, arc, spline or polyline. Completing all settings in the “Moving Load” dialogue box first before selecting the path.

2 Increment of Target Load Case

As a new set of load cases will be generated it’s required to create a new load case number for every single load position – what is done by the software automatically. However, you get the option to choose the increment between the generate load case numbers. With that said it’s also essential to understand what’s the reference load case to count from. Well, it’s the load case number which was applied to the load or load group to distribute along the path.

Bear in mind, to keep sufficient spare numbers after the reference load case number to avoid clashes with other already occupied ones.

3 Select or Create the Path

You can either create a new path as polyline by clicking the single points or by converting already created elements. Geometries allowed are lines, arcs, splines or polylines.

Use the right-click to open the context-menu for further options to select the elements. Actually, there is only one command applicable “Pick lines or curves”.

You’ll find “Pick lines or curves” in the AutoCAD command line too.

Confirm the selection with “Enter”

4 Select the Reference Loads

In the last step, you select the reference loads. Combining the different types such as “Point Load”, “Line Load” and “Area Load” is possible. All loads of a group have to be assigned to the same load case number.

Select all loads to include and confirm with “Enter”.

The command generates the new loads immediately. Checking the new loads is quite easy, and changes can be done straight away. To close the “Running Imposed Load” Command hit the “Esc” or “Enter” key.

Check the new generated load case numbers – which were generated automatically – in the “Loadcase Manager”. You’ll recognise, every single load position got a separate load case number.

Modify Generated Loads

All new loads are grouped and linked to the reference load or loads. If necessary to modify the loads, double-click on the created load group (all single load positions). An almost similar dialogue box as during creating the loads in the first place opens. Make the changes and apply them.

Reference Point of The Load Group

Let’s have a look into how the new loads are actually positioned. The graphic below shows the path (red line), a load group (blue geometries) as well as the tangent in the reference point on the spline (cyan dashed line).

The reference point for the load group lies exactly at the start of the path. I placed the single load precisely to that location. It’s not mandatory to place a load to that position, it’s just for representation purpose. When the load gets distributed along the path the tangent information is used to align the entire load group. The load group works like a rigid body which rotates dependent on a tangent on the spline of the reference point.

Watch the Video

Check-out the video to see the command in action.

Wrap-Up

The “Running Imposed Load” features is definitely a time-saver to distribute loads along a path. If you aren’t familiar with the text input CADiNP you might prefer this option too. Benefits such as the flexibility to change the reference load group and adding or removing load positions afterwards easily are worth to have a look into that tool.

Download the “Running Imposed Load” example file.

Software version: SOFiSTiK FEA v2018-09.