Add Rectangular Load

A rectangular or square load can be defined with the Add Rectangular Load option. The load magnitude can be uniform or variable, and the load application can be staged.

To add a rectangular load:

  1. Select Add Rectangular Load from the toolbar or the Loads menu.

  2. You will see the Define Load dialog for rectangular loads. Enter the following information:

See below for details about the input parameters. When you are finished entering the load information, select OK.

  1. You will now be prompted to define the location of the rectangular load in the Plan View. The location of a rectangular load is defined by entering the x,y coordinates of the center of the rectangle. This can be entered graphically with the mouse, by clicking at the desired location in the Plan View. Or you can use the keyboard to type in the x,y coordinates in the prompt line.

  2. As soon as the load location has been entered, the load will be added to the model, and displayed in both the Plan View and 3D View.

Rectangular load in 3D view

The parameters which define a rectangular load are described below.

Rectangle Properties

Length and Width

The size of a rectangular load is defined by entering Length and Width.

Angle

The orientation of a rectangular load is defined by entering the Angle with respect to the X-axis of the Plan View. The Angle is defined as the counter-clockwise angle between the X-axis and the Length dimension of the rectangle.

NOTE: a rectangular load cannot be converted into a general polygon using the load editing options. If you require a more complex load shape, then use the Add Polygonal Load option to define the load.

Load Magnitude

Load magnitude is defined in terms of force / area (i.e. distributed load). You can define a uniform or variable load magnitude.

Uniform Magnitude

To define a uniform load magnitude, enter the magnitude (force per unit area) in the Magnitude edit box. This will define a load with a uniform magnitude over the area of the rectangle.

Variable Magnitude

To define a load magnitude which varies over the area of the rectangle, select the Variable checkbox and select the Define button. You will see a dialog which allows you to define the load magnitude at each corner of the rectangle.

NOTE: the load magnitude at each corner is defined as a distributed load (i.e. force / area). You are NOT defining point loads, you are defining the magnitude of the distributed load, at each corner. It is up to the user to determine the appropriate magnitude at each point, which correctly models the desired load distribution.

The load distribution over the area of the rectangle is obtained by interpolation using the load magnitudes at the four corners. For example, a load which varies from zero along one edge of the rectangle, to a maximum value at the opposite edge, might appear as follows in the 3D View.

Variable load magnitude over a rectangular area

If your model uses multiple stages, the load can be applied at any stage, or applied in increments at different stages, as described in the Load Staging section below.

Load Depth

A load can be applied on the ground surface or at any depth below the ground surface.

If your model uses multiple stages, the depth of the load can be staged, as described below.

NOTE: if you apply a load at some depth below the ground surface, the soil above the load depth is NOT assumed to be excavated, it is assumed that the soil layers remain in place. If you wish to define loading within an excavation, then you must use the Add Excavation option to define an excavation, and then define the loading. See the Add Excavation topic for details.

Load Staging

If your model uses multiple stages, the load can be applied at any stage, or applied in increments at different stages using the Advanced Staging option.

Installation Stage

If you wish to apply a load at a particular stage of a multi-stage model, then use the Installation Stage option to select the desired Installation Stage.

Advanced Staging

For more complex load staging, the Advanced Staging option allows you to stage the magnitude and depth of the loading. To use the Advanced Staging option:

  1. Select the Advanced Staging checkbox. The dialog will expand, allowing you to enter a Load Factor and Depth for each stage.

  2. The Load Factor is a multiplying factor for the Load Magnitude. For example:

  1. The Depth can be staged by entering the Depth of the load application at each stage. The actual depth from ground surface is entered, NOT a factor. The depth is entered as a positive number. If you are modeling an excavation, see the note above regarding Load Depth and the Add Excavation option.

If your load is staged, it is a good idea to select the Stage Tabs, after adding the load, to check that the load is applied at the correct stage(s), and that the magnitudes and depths are correct. If not, then use the Edit Load Properties option, and make sure that the correct values have been applied at the correct stages.

Display Properties

The appearance of a load can be customized by selecting the Display Properties button in the Define Load dialog. You will see the Load Display Properties dialog, in which you can define:

NOTE: Load Display Properties can be customized for each individual load. Load Display Properties can also be accessed by right-clicking on a load, and selecting Display Properties from the popup menu.