Base plate - Mstrip

Hello,

For the purpose of base plate design (LRFD), I don't get Mstrip and Beff values like I expext. I checked previous answers, but didn't get any clue. Please check attached pdf to see manuay calculated values and those from RAM.

Regards,

Parents
  • Here is a sample calculation from a prior question. The values don't match you case but it should explain how Ram Connection calculates Mstrip, Beff and Mpl. If it's not clear let me know.

    1. RAM Connection calculates the bending lines using a 45° distribution, from the centerline of the anchor rod to the face of the column flange or web (AISC DG1, 2nd edition, page 18).
    2. RAM Connection only reports the major critical bending line. Note that the plate will bend about the flange bending line and about the web bending line, independently of the Analysis Axis Option: Major, Minor or Both.

    In this sense we reproduce the calculations for the model:

    Data.-

    Pu = 39.4 kips (Uplift)

    bf = 14.6 in

    d = 14.2 in

    N = 21 in

    B = 21 in

     

    Calculation.-

    m = (N – 0.95*d) / 2 = 3.755 in

    n =  (B - 0.8*bf) / 2 =  4.66 in

     

    For bending about the flange

     

    Mpl = Mstrip / Beff

    Mstrip = T*Arm

                    T = Pu/4 = 9.85 kips           

                    Arm = m - Lev = 3.755 – 1.5 = 2.255 in

                    Mstrip = 1.85 kip-ft

                                    Beff = Arm + Leh = 3.755 in  (see the horizontal red line in the bellow figure)

                    Mpl = Mstrip / Beff = 5.91 kip-ft/ft

     

     

    For bending about the web

                    Arm = n – Leh = 4.66 – 1.5 = 3.16 in

                    Mstrip = 2.59 kip-ft

                    Beff = Arm + Lev = 4.66 in (see the vertical red line in the bellow figure)

     

    Mpl = Mstrip /  Beff = 6.67 kip-ft/ft

     

    So the most critical Mpl is for plate bending about the web line (the reported one) independently of the Analysis Axis Option.



  • Dear Seth,

    Please can you explain what are the bending and yield line that RAM takes into account for the case when the anchors are "INSIDE" the column section (not outside). Please refer to DG1 2nd edition; example 4.5; figure 4.5.2. Also please find query.pdf in attachment.

    This is very important to know, because RAM reports failure, and when I check it manual, I find it can pass (it differs a lot).

    Thanks in advance.

  • I am seeing some different results in Ram Connection Stand-alone version 11.00.01.208 (see attached file). Please confirm that I have the forces, sections, materials and dimensions right. If so, and if the results still differ from Ram Connection in STAAD.pro, send me your STAAD file and confirm the version of that you are using.

    Output:

    File: BP_lrfd_UK_db_units.cnx



  • Base plate properties and tension force are in attachment.

    Regards,

  • I get some warnings if I use M30 bolts in those positions (too close to the weld line), but the Beff is still 81mm.  It must be something about your version (or maybe the design code).

    revised file: BP_lrfd_UK_db_units_M30.cnx



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