Hi All,
I have noticed that STAAD incorrectly calculates the shear capacity for a member.Specifically, it uses a VERY large shear area (overstated by a factor of 2!).Here is the output for an Australian 250UC72.9:INTERMEDIATE: Aw: Cv: Kv: h/tw: Vn:MAJOR(VZ): 7.454 1.000 1.200 8.944 194.597The depth of a 250UC72.9 is 254 mm and the web thickness is 8.6 mm which yields an area of 2184 mm^2 (3.385 inch^2). STAAD uses 7.454 inch^2 which is 2.2 times larger, causing the final capacity to be similarly overstated.Is this intended? Has anyone else experienced this problem?
Hello Edward,
You might have been using an older version of STAAD.Pro , I guess.
Look at the MEMBER Properties below reported by STAAD.Pro 20.07.10.66 (newest as of date).
Note that these properties are being used for analysis and design as well.
MEMBER PROPERTIES. UNIT - CM
MEMB PROFILE AX/ IZ/ IY/ IX/ AY AZ SZ SY
1 ST UC250X72.9 93.20 11400.00 3880.00 58.60 21.84 48.09 897.64 305.51
May I know your version of STAAD.Pro please? This information could be found at Help->About STAAD.Pro
Best regards,
BM
Thank you for your reply. I have those same figures in the member properties as well and... seem to have just found the crux of the issue - in the output and evidently, STAAD's calculations, major and minor axes are switched: SHEAR: FORCE: CAPACITY: RATIO: CRITERIA: LOAD CASE: LOCATION(ft): MAJOR(VZ): -2.135 175.137 0.012 Eq. G2-1 62 16.797 MINOR(VY): -2.040 88.393 0.023 Eq. G2-1 63 0.000 INTERMEDIATE: Aw: Cv: Kv: h/tw: Vn: MAJOR(VZ): 7.454 1.000 1.200 8.944 194.597 MINOR(VY): 3.386 1.000 0.000 26.233 88.393 My version of STAAD is 20.07.10.41. So even though the values are correct in the member properties, they are used or presented incorrectly in the calculations.
EDIT: Aside, in 10.66 have they fixed it so the output can be presented in metric units for AISC 360-10?
I don't think it's true. Look at the Design output where AY (shear area along local Y) was reported correctly. The same applies for AISC Unified 2010 as well.
You're right. I was mistaking the values. Thank you again.
EDIT: It doesn't help that they label VZ as Major and VY as Minor...