I also emailed RISA tech support earlier, but I expected I'd get a quicker answer here.
Good to know about (Mx + Mxy) being an approximation, not directly a mechanical behavior. Is Mxy more like rolling shear in plywood? It seems like Fxy shears would shear along the yz-plane but Mxy shears...
"I believe the Txy value should be based on a combination of Fxy and Mxy." Bingo, thanks! So the warping moment Mxy gets added to Mx and My for concrete reinforcement design, but it gets added to τxy for finding Principal Stresses in steel. That's odd.
The equations below caused my results to...
JoshPlumSE,
Correct, I did that for the moments (copying from above):
fbx = 6*Mx / tpl2 = 17.399 ksi (+ at top)
fby = 6*My / tpl2 = 30.229 ksi (+ at top)
fbxy (warp) = 6*Mxy / tpl2 = -4.077 ksi
But shouldn't σx and σy, for use in the equations below, also include axial stress and warping...
Can someone explain how RISA-3D calculates Plate Principal Stresses? Specifically, how does it derive σx, σy, and τxy for use in the Mohr's Circle calculations that lead to σ1, σ2, τmax, and σVon-Mises? The methodology is described here. The Plate Forces and Plate Principal Stresses for a 2.25"...
