RISA Member Detail Report

[nuche1973]

Using RISA-3D, I analyzed a steel frame. This is an existing frame, which I am checking the adequacy of its members. My analysis showed the columns to be overstressed (at 1.18), in combined loading. I used the Member Detail
Report in RISA to clarify the output and begin considering options on reinforcing the columns. (I plan on adding plate or channels to the columns where the overstress occurs.) The MDR shows where the overstress occurs,
but the information regarding AISC unity equation H1-1 given does not match the variables noted in my 9th edition manual. Has anyone come across this? If so, where do I look for clarification on how RISA calculates these variables? As always, any comments would be greatly appreciated.

 

[JoshPlumSE]

What variables don't match? There are a couple of things that I would look at if I were you:

1) Confirm that the program is really calling out equation H1-1 as the controlling equation.

2) When using eqn H1-1, the Cb must be taken as 1.0 for non-sway frame members.

3) Cm will be based on the moments and on whethr the sway flags have been checked:

4) For WT's and Double Angles, the KL/r reported may actually be an "effective" KL/r for flexural torsional buckling per equation C-E2-2 on page 5-142.

I hope that helps!