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Thread: Direct Stiffness Method works for Simple Unbraced Frame, but does not for Braced Fram

  1. #1
    Associate Engineer
    Join Date
    Aug 2014
    Posts
    1

    Direct Stiffness Method works for Simple Unbraced Frame, but does not for Braced Fram

    Hi everyone!

    I am trying to develop a spreadsheet that calculates reaction forces for a simple braced frame using direct stiffness method. I did the regular process of

    Calculation of stiffness matrix in local coordinate
    Calculation of stiffness matrix in global coordinate
    Calculation of global stiffness matrix
    Calculation of reaction forced from known values

    My problem is that my spreadsheet calculated right reaction forces for unbraced frames. It does not calculate right reaction forces for braced frame though. Is Direct Stiffness Method limited to unbraced frames only? I didn't think so but I feel like I have reached a road block can't find out why. :( Please help.I can upload the spreadsheet if you all want me to.

  2. #2
    Principle Engineer Cragyon's Avatar
    Join Date
    Feb 2013
    Location
    Newark, NJ
    Posts
    283
    Yes, upload your calculations. The "Direct Stiffness Method" is not simple as I believe it require calculus.

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