Extracting Moments, Shear etc from Plate model of Beam

[cm8000]

Hello all,

I have modelled a long span beam in STAAD using plate elements to recreate the beam web and flanges. This might seem an unusual approach but is due to the need to account for notching in the beam flanges which could not be accurately represented with STAAD beams alone (at least as far as I could tell). Having created my model and checked deflections, reactions, stresses against hand calculations and satisfied myself, I am now looking to extract moments and shear at points through my plate elements so I can run design checks.

Using the Results along a line function, and drawing a plane perpendicular to my beam through the point where greatest moment is expected, I get results which I am struggling to interpret. Would anyone be able to offer me assistance?

For example, for bending moment:
I have only vertical loads applied to my beam across it's top flange, whereby the maximum hand calculated moment should be ~160kNm. The loads reported by the STAAD "cut through a line" give me a ~40kNm Mz(line) moment (and nominal Mx, My values) developed in the beam web. I also observe a Fy (line) force of ~180kN (equal and opposite) in each flange. When I multiply both Fy forces by the lever arm to centroid of the beam and add to the Mz (line) moment, this appears to give me the moment as calculated in hand calculation. Is this a reasonable method?

I look forward to any resources you might have that could help me with this.

Many Thanks,

cm8000

 

[CarlosAguera]

Without seeing your model it is hard to determine exactly what you are trying to model. What I would suggest if you need to have a finite element model, then create a suitable mesh to get node points at or close to the points where you want to extract the forces. Alternatively you can work with a simpler beam model simply introduce node points at the locations where the shape changes and change the property of the beam for those segments. Either way, if you are struggling to achieve that the Bentley support guys are great and should be able to assist you.