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2020-02-06

Using Facade Surfaces in RFEM for Transmission of Wind Loads to Main Structure

Are there any facade surfaces in RFEM to transmit wind loads to the main structure?


Answer:
In RFEM, there are no special facade surfaces for distributing wind loads. However, you can create such a load distribution element without any influence on the resistance of the main structure using standard RFEM tools. To do this, proceed as follows:

  1. Define the isotropic linear elastic "facade material" with the average stiffness of the adjacent elements of the main structure without the weight, thermal expansion property, or stiffness modification.



  2. In the facade areas, describe the surfaces made of the facade material with the "Orthotropic" stiffness type. To ensure that no opposing load is transferred to the main structure at the surface corners, the thickness and torsional stiffness must be defined near zero. We recommend applying the average thickness of the adjacent elements of the main structure / 1,000 as the thickness, and dividing the related torsional stiffness k33 by the factor of 1,000 as well.



  3. Define a line release between the facade surfaces and the main structure elements so that only forces perpendicular to the main structure elements can be transferred. All other directions must be specified without any force.

     

  4. To prevent the surfaces that have been detached with the line releases from slipping in the wall plane, a surface support in the planar degrees of freedom x and y must be placed on the facade surfaces.


This option allows for the distribution of compression loads acting perpendicular to the facade surfaces, as well as of wind pressures from the RWIND Simulation calculation to the main structure. In this case, it is necessary to use this modeling of the facade surface in connection with the linear method of analysis.


Author

Mr. Niemeier is responsible for the development of RFEM, RSTAB, RWIND Simulation, and in the area of membrane structures. He is also responsible for quality assurance and customer support.

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