General Mechanical

General Mechanical

Effect of Reference surface

    • Aslinn

      Hi all, does anyone have experience with using reference surface to analysis a building structure?

      The problem I am trying to solve is as follows. I have a building frame (steel). I am asked to apply the wind load on its closed building envelope. Therefore, I created surfaces to represent the building envelope, bonded this surface to the steel frame, and apply the wind load on this surface. To avoid the self-weight of the reference surface, I reduced the density of the surface to a very small number. At the same time, I found I also need to reduce the Young's modulus of the surface to a very small number to eliminate the surface stiffness. I wonder if this is the correct way to do it? If not, what is the right way to do it? Normally, does the stiffness of the building envelope contributes to the stiffness of the primary building structure?

      Thank you!

    • jj77

      For the load what you need is what is called in some structural software a load patch (See Strand7) which is an element that will distribute the pressure on that face (tributary) on to the frame without adding stiffness. In Ansys I am not sure if there is such an element.


      Membrane elements (e.g., Shell181 with membrane option) would give similar to a load patch (tributary pressure distribution) when used in a large deflection analysis. So you can try those (small benchmark below shows that it works OK - right model with membrane and left one with load patch give the same bending moment). There is also an act extension for wind loads but I have never used it.


      The other question is industry specific and if you are a civil engineer you should know, or if not ask a professor at your Uni who has designed buildings.



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