BCF-Shear force at column face - Seismic provision

Dear Admin,

I am designing extended end plate connection for IMF-frame (AISC-LRFD) with seismic provisions (AISC-DG4 & AISC 358-05). 

Regarding to the provisions given in the aforementioned standards and report calculated by the RAM, I have several questions:

- plastic modulus of UB 406x178x67 beam should be Z=1346cm3 (as per BS section table), Z=15000cm3 (RAM)

- why gravity load component of shear force is equal to zero (Vg=0kN)

- distance between plastic hinges is obtained how?

Please refer to attached document.

Best Regards,

  • I confirmed that in our section database in Ram Connection the UB406x178x67 is listed with Ze = 1,350,000 mm^3. At some point out data must have been rounded or reduced in precision. It is possible to export the shape data to a spreadsheet, then generate a new table of custom shapes with edited properties if the 0.3% deviation is critical for you. (I do see the correct 1,346,000 value in some tables e.g. RAM Structural System).

    Regarding Vg, this value comes from the host application typically. 

    In the STAAD.pro interface if you have seismic provisions enabled under Connection Design - Assign Ram Connection Settings, then, when you go to assign the connection to the BCF Joint be sure to select an acting load case for calculating Vg.

    Vg would default to zero if seismic provisions were not pre-enabled, or if the selected loading yielded zero beam end shear. 

    There is no place in STAAD.pro currently to define the plastic hinge locations (distance Sh) so the program is using the beam end shear for the selected load. I'll log an enhancement for the STAAD.pro interface to locate the plastic hinge given user input (which we do in the the other interfaces).



    Answer Verified By: Ivan Hadži Bošković