Assign members to LTS using a user-defined tolerance

Did you know that bar members can be included in load distribution even when slightly offset from the surface, by using a Load Transfer Surface with a user-defined tolerance?

A Load transfer surface (LTS) is a special type of surface that converts surface loads into line loads and distributes them to structural members. This is particularly useful when surface loads, such as floor loads, snow loads, or wind loads, need to be transferred to supporting members.

In order to use the meteorological load generator function or our fluid-dynamics-based universal wind load generation tool, FALCON, the load transfer surfaces (LTS) on the structure must intersect, they must meet along a common edge. Otherwise, the results will not be accurate.

This creates a problem when, for example, the purlins take over the meteorological loads from the sheets or panels, but their planes do not intersect. In this case, the LTS is applied to the plane of the main structure, while the members assigned to it may lie within a specified distance from that plane.

To define the tolerance for the load transfer surface, first go to the Options menu. There, you can set the maximum allowable distance between the bar members and the load transfer surface. In this example, all members that are less than 1000 mm from the surface can be assigned to the load transfer surface.

In order to be able to manually select the members attached to the load transfer surface, when defining it, make sure that in the Select members section you choose the Distribute load to the selected members option. If this option was not selected initially, you can set it later by selecting the surface and defining the member selection in the Object Properties window.

In the example model below, observe how the load distribution changes from the main beams (left side) to the tops of the purlins (right side) by introducing a user-defined tolerance and assigning the appropriate members to receive the load from the roof.

Download the example model and try it!

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