Hello All,
I am currently in the process of designing concrete shear walls in the RAM concrete module and noticed that I come upon varying results for the same wall design group! It appears that the only variable that is different between runs is the Beta factor which varies by 90 degrees:
Wall Design Group 6 Scenario 1:
Load Combo 277: Horiz bar = #6@6" oc / Vert bar = #9@12" oc / Controlling Interaction = .944 (LC 277) / Pu = -724.69 / Mu = 1803.49 / Beta = 0.1
Wall Design Group 6 Scenario 2:
Load Combo 277: Horiz bar = #6@6" oc / Vert bar = #10@6" oc / Controlling Interaction = 1.336 (LC 277) / Pu = -724.69 / Mu = 1803.49 / Beta = 90.1
Can someone please explain why sometimes the wall is passing with less rebar as shown in scenario 1) and why the wall is failing in other scenarios with additional rebar? Please note that the analysis data is consistent between the scenarios as the model has not been rerun.
Thank you!
As a follow up, it appears as if scenario 1 Mu = Mmajor, whereas in scenario 2, Mu = Mminor.
Right, 0 or 180 degrees is pure major axis bending, 90 or 270 is pure minor axis (out of plane bending) which have different capacities for rectangular cross section.
Seth, I understand the difference between the major and minor axis bending. The issue here is that the program is taking the major axis moment (in this example 1803.49 kip-ft) and for the same section cut of the same design wall group, happens to randomly apply this value as a major moment, or if I delete reinforcing and reapply, will apply this same moment as a minor moment.
There is a new version forthcoming where we addressed a number of issues in Concrete Wall design. I saw one case like this which was resolved simply by deleting and recreating the section cut. If that does not work in your version, send over your file and I can check the latest. Secure File Upload