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2.3 Moving Loads
This module window manages the load parameters of the movable loads. You can combine different loads in one Load Model moving as a "load block" over the surface.
A set of moving loads includes one or several loads describing the moving load by forces and moments. The number of the first set of moving loads is preset. You can overwrite the description Load model 1 manually.
If moving loads on surfaces are running parallel or with an offset, another set of moving loads should be created with the [New] button. Thus, an individual control of moving loads within one set of movements is possible (see chapter 2.4).
The buttons have the following functions:
Goes to next or previous set of moving loads
Creates a set of moving loads
Allows for renumbering a set of moving loads
Deletes current set of moving loads
Deletes all sets of moving loads without any warning
The column titles are synchronized to the selected load type and distribution.
A load can be defined as Force or Moment. You can access the list with the button or the function key [F7].
The list offers different options to represent the load's effect. The selected load is shown symbolically in the graphic below the table column.
|Load Distribution||Load Symbol||Description|
Single force, single moment
Uniformly distributed load, trapezoidal load
Areal block load
Areal round load
Axle - Concentrated Forces
Single load pair
Axle - Rectangular Areas
Block load pair
Axle - Circle Areas
Round load pair
Left - Endless
Uniformly distributed load
Right - Endless
Uniformly distributed load
Uniformly distributed load
The effect of loads can be defined Local in direction of the surface axes, or Global in direction of the axes X, Y and Z. You can access the list with the button or the function key [F7].
The location x describes the distance of the load to the load step's fixed point along the moving line. This point is symbolized by a red cross in the sketch.
A positive value moves the loads in the viewing direction of the set of lines. If x is negative, the load is placed before the center of the load step. This way, it is possible to model tandem axle loads entering the runway of surfaces.
This column allows you to place loads alongside the moving line. A positive y-value arranges the load in viewing direction to the right of the moving line, a negative value to the left.
Here, loads can be individually shifted at right angle to the moving line. By contrast, the Eccentricity in window 1.2 Sets of Lines shifts all loads.
If axle loads are set, table column E gets the title Gauge. Then, the value describes the load pair's centroidal distance according to the sketch.
In this column, you can enter the magnitudes of the force P or the moment M.
For a line load you have to enter the magnitude of the load P1 at the line start. The load value P2 at the line end can then be defined in the next column. If both values differ from each other, a trapezoidal load is applied.
For rectangular loads you have to define the load width according to the sketch. It represents the dimension of the load contact patch at right angle to the moving direction.
If an Endless load is applied, you have to specify the width of the lane on which the uniformly distributed load is acting.
In this column, you have to specify the length of the load contact patch in the direction of the moving direction, respectively the length of the line load.
The geometric conditions are taken into account when using offsets or bumpers (see chapter 2.2): The areas only get proportional loads from the contact patches.
This input field allows for a user-defined description of load parameters.
Combining movable loads usually involves a lot of effort. But many load models are stored in a database that you can access with the [Library] button.
Use the list in this window section to filter the load models by different criteria.
In the Load type list, you can find sets of moving loads described in bridge construction standards . When activating a row in the table, the data record of the respective load model is shown in the Load Parameters section below.
The list of load models contains axle and surface loads representing the effects from truck transport and car traffic. It is being constantly expanded and adjusted to the updated standards.
If a dispersal layer is applied, you can specify its thickness t in the input field. By taking into account the Angle of dispersal α, this layer produces a distribution of the contact patch loads. The Width and Length load parameters will be adjusted accordingly in the window section below.
The thickness of the RFEM surface won't be automatically used for the load distribution.
[OK] transfers the load model to the 1.3 Moving Loads window. If load data is already there, the new loads will be added.
In window 1.3, you can save the current set of moving loads so that it can be used in other projects. You can find the [Save] button below the Load Parameters table. It opens the New Model dialog box.
As soon as the Model and Description is entered, you can [Save] the new load model.
All user-defined load models are available for selection in the [Library]. There, they can be clearly displayed by using the Library filter.
Use the key combination [Ctrl]+[Y] to delete a table row in window 1.3. Alternatively, you can use the delete function available in the shortcut menu (for example, right-click into the input field of a selected load parameter).