GussetBP Column Weld Yield Line Pattern

RAM Connection module in STAAD.Pro 22.11.00.156

Assigning GussetBP to column web/brace joint. When calculating the beff parameter used in the column welds check, RAM is using the beff parameter calculated based on the length "L" from bolt to the tension interface yield line at 0.85*bf. beff=2*L


  Base plate

    Flexural yielding (bearing interface)               [kip*ft/ft]          25.31     0.30      LC-2013-1                       0.01                                                                          DG1 Eq. 3.3.13, DG1 Sec 3.1.2

      fMn = f*Fy*tp2/4 = 0.9*50000 [lb/in2] *1.5 [in] 2/4 = 25.313 [kip*ft/ft]                              DG1 Eq. 3.3.13

      m = m = 5 [in]                                                                                                          DG1 Sec 3.1.2

      n = n = 4.25 [in]                                                                                                       DG1 Sec 3.1.2

      Mpl = max(MpM, MpN) = max(0.304 [kip*ft/ft] , 0 [kip*ft/ft] ) = 0.304 [kip*ft/ft]                   

    Flexural yielding (tension interface)               [kip*ft/ft]          25.31     8.30      LC-2046-3                       0.33                                                                          DG1 Eq. 3.3.13

      fMn = f*Fy*tp2/4 = 0.9*50000 [lb/in2] *1.5 [in] 2/4 = 25.313 [kip*ft/ft]                              DG1 Eq. 3.3.13

      MpT = Mstrip/Beff = 1.079 [kip*ft] /1.56 [in]  = 8.296 [kip*ft/ft]                                           

   

  Column

    Weld capacity                                             [kip/in] 12.53     10.64     LC-2046-3             0.85             p. 8-9, Sec. J2.5, Sec. J2.4, DG1 p. 35

      LoadAngleFactor = 1 + 0.5*(sin(q))1.5 = 1 + 0.5*(sin(1.571))1.5 = 1.5                               p. 8-9

      Fw = 0.6*FEXX*LoadAngleFactor = 0.6*70000 [lb/in2] *1.5 = 63000 [lb/in2]                     Sec. J2.5

      Aw = (2)1/2/2*D/16  [in] *L = (2)1/2/2*6/16  [in] *1 [in]  = 0.265 [in2]                                   Sec. J2.4

      fRw = f*Fw*Aw/L = 0.75*63000 [lb/in2] *0.265 [in2] /1 [in]  = 12.529 [kip/in]                  

      beff = 2*L = 2*0.78 [in]  = 1.56 [in]                                                                               DG1 p. 35

      Maximum weld load = T/beff = 16.593 [kip] /1.56 [in]  = 10.636 [kip/in]



This beff is also used to determine ultimate bending moment MpT for flexural yielding of the base plate which is correct, but is it really appropriate for calculating maximum weld load T/beff?

I would think the maximum weld load should be calculated based on beff = (y-tw/2)*2 where y is the distance from anchor to CL column and tw is web thickness. This would match the AISC DG 1 calculation on page 35.

  • Note:
    • When selecting "weld outer flanges only" the demand decreases significantly. It seems like the program is allowing a yield line pattern out to the flanges but when the weld is on the web it ignores the yield line pattern back to the web.
    • The standard CB joint appears to use the beff = (y-tw/2)*2
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