How can I implement Semi-Rigid Connection in SACS?

Please, can somebody help me? I want to implement Semi-Rigid Connection on my structure. I try to use spring joint on the node that I want to analyze but I don't know it is a proper way or not since I don't know the affect of spring joint to matrix calculation on SACS. Can anyone give me advice, please? Where can I get the manual calculation of spring joint analysis on SACS? Thanks.

  • Springs in SACS are boundary conditions with a linear stiffness as opposed to infinite stiffness of a typical fixity. I'm not quite sure what you are asking here. You can verify the behavior fairly easily by running a simple model with spring elements and checking the forces and deflections in the listing report or Postvue.

    Regards,

    Geoff

  • Thank's for your answer, Sir. I want to know that is SACS can model semi-rigid connection or not. As I know, If we implement the semi-rigid connection the moment diagram will be shown like the picture below.

    Figure Source: https://femci.gsfc.nasa.gov/semirigid/

    So, I made a little experiment (see below figure). I used 10000kN for the point load in the middle of the span and I assumed the support is fixed (111111).

    I tried some cases for this little experiment as in the following table.

    Case                                              Joint Fixity     Member Release
                            A                           B       1        2
    1 - - - -
    2 Spring Rotational (100, 100, 100) Spring Rotational (100, 100, 100) - -
    3 - - 000011 000011
    4 Spring Rotational (100, 100, 100) Spring Rotational (100, 100, 100) 000011 000011

    Note: all spring rotational in kN-m/rad.

    For the results (Moment Diagram Y-direction) are shown in this following figures.

    Case 1

    Case 2

    Case 3

    Case 4

    From this little experiment, I got conclusion that if I added spring joint in the fixed member connection (joint A and B), the spring joint will make the connection stiffer and it will resisted more moment (see picture in case 1 and 2).

    In another case (case 3 and 4), I thought the matrix displacement has zero value on the y and z rotation. So, the spring joint has no influence into the calculation. 

    But I am not quite sure about that. Please, correct me if I'm wrong, Sir.