Simple Steel Lifting Frame Analysis. Please Help!

Hi there,

I am trying to model what would appear to be a simple steel lifting frame with 1 bracing member. I have so far created a model but I am getting quite a few warnings when attempting to analyse about zero stiffness in members etc. (I think this is due to using tension only members for the cables). I have attached the Staad file and the CAD drawing of what I am trying to model. All I am trying to do is model a frame with all pinned connections held in place by tension cables to determine all forces and moments acting on the structure to make sure that it matches my hand calculations. The lifting frame is meant to hold up a force of 240kN from the crane hook (the node at the top) or a force of 60kN at each of the corner frame nodes. I applied 60kN to the corner nodes and just put a pinned support at the crane hook. I would love to be able to get this model working.

Any assistance would be greatly appreciated. Steel Lifting Frame_edited.std

Parents Reply
  • The following changes were made to the file

    *MEMBER TRUSS

    *1 3 12

    was changed to

    MEMBER TRUSS

    12

    *SUPPORTS

    *5 FIXED BUT FX FZ MX MY MZ

    was changed to

    SUPPORTS

    5 FIXED BUT MX MY MZ

    *PERFORM CABLE ANALYSIS BASIC SAGMINIMUM 0.7 STABILITY 5 145

    was changed to

    PERFORM CABLE ANALYSIS BASIC STABILITY 6 145

    The cable analysis runs fine with the basic analysis engine and results match pretty nicely with those coming from advanced cable analysis. If you are required to carry out nonlinear cable analysis frequently, I would suggest that you get the license for the advanced analysis engine. It has a far superior and advanced cable analysis algorithm and does not require tweaking the stiffness parameters.

    A modified file is attached for your reference.

    Basic.std 



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