Application of GEBT to overhanging simply supported beam

  1. Shiva Harsh Pothula

    Dear all,

    I'm trying to implement GEBT for an over hanging simply supported beam. When I'm trying to apply I'm getting below error as shown
    Failure of MA28AD with iflag=-1
    I'm expecting the error can be from the boundary conditions. Still I' unable to figure out the error. I'm attaching the input please go through the code and help me in solving the problem.
    The problem has
    point 1 as the free end
    point 2 as the hinged support
    point 3 as the load
    point 4 as the roller support
    point 5 as the free end
    Applying boundary conditions is still not clear, it would be great help if you could share some examples for overhanging beam.

    Thank you in advance.

    Shiva Harsh
    IISc, Bangalore

  2. Qi Wang

    Hi Shiva,

    I agree with you that the problem could be in the boundary conditions. To be specific, I think your definition of the "roller support" at Point 4 is not correct. I checked the GEBT manual, it is said that the dof_i in the ncond_pt block should be "integers with values ranging from 1 to 12". However, in your input file, these are "2 3 4 0 0 0".


  3. Shiva Harsh Pothula

    Dear sir,

    Thank you for the reply. I tried with finite boundary condition values. Still the error persists. As mentioned in the manual, 1 and 5 are boundary points six boundary conditions has to be prescribed. So for

    point 1 and 5, I had given Forces and moments has zero. (free ends-over hanging)

    Point 2 is hinged, so u1=u2=u3=M1=M2=M3=0

    point 3 is Load F3=1000N

    point 4 is Roller so u2=u3=M1=M2=M3=0 and F1=0

    With this also the error persists. I'm attaching the modified input file. Please find the attachment and clear my query.

    Thank you in advance

    Thanks & Regards

    Shiva Harsh

  4. Ning Liu

    Hi Shiva,

    I checked you file, and it seems at point 3, you put value 100 to bc#9 but control parameters 1s to bc#10.

    Hope that helps.


  5. Shiva Harsh Pothula

    Hi sir,

    Thank for your response. I think the value 100 for bc#10 corresponds to the moment M1. I had given bc#9 because I want to give F3.

    Also I tried running by changing the value but the error still persists.

    Thanks & Regards

    Shiva Harsh


  6. Shiva Harsh Pothula

    Dear all,

    I took the help of the examples for (GEBT) and tried to implement to the overhanging beam,

    The boundary conditions I used are

    #1 and #5

    Free end So F1=F2=F3=M1=M2=M3=0 which implies 7 8 9 10 11 12 are zeros

    #2 is roller support

    u2=u3=M1=M2=M3=theta1=0 which implies 2 3 4 10 11 12 are zeros

    #3 is loading condition

    F1=F2=M1=M2=M3=0 and F3=-100 which implies 7 8 10 11 12 are zeros and 9=-100

    #4 is Hinge support

    u1=u2=u3=M1=M2=M3=0 which implies 1 2 3 10 11 12 are zeros

    Note: Theta1=0 is zero i imposed externally as there is load only in 3 direction & there wont be any twist. Correct me if I'm wrong.

    The input file is running but the I'm unable to capture the reaction forces at the roller and hinge support. I'm attaching the input file for your reference. I need this problem because I'm using this model for validation in my ME thesis.

    In the results I'm getting the value of reactions as the zero's but the value is nonzero just right to the roller support and left to the hinged support. The value is 500N as the load applied for this input is 1000 in 3 direction. The values are right but at the supports the value is zero,What could be the reason.

    Thank you in advance.

    Thanks & Regards

    Shiva Harsh 

  7. Ning Liu


    Natural bc and essential bc cannot exist for same dof at one point