Why IS Code 800-2007 LSD fails Ratio INFINITY, while AISC 360-10 ASD passed Beam with Ratio 0.44? Taper beam

RE: Why IS Code 800-2007 LSD fails Ratio INFINITY, while AISC 360-10 ASD passed Beam with Ratio 0.44? Taper beam

Arun Chugh — Wed, 10 Aug 2022 20:08:29 GMT

Also please recheck compactness criterion for IS:800., for mine std file above.

Mine section size calculates to b/ tf ratio is 350/2 / 12= 14.58 fails, and if flange thickness 13 mm, b/tf = 175/13=13.46 pass,

and Semi-Compact ratio under table 2 IS:800 is 13.6e = 13.6 x 0.845 =11.49, Or for Rolled type 15.7e = 13.32. while e= sqrt(250/fy 350) =0.845.

To me , increase from 12 mm to 13 mm fits nowhere! i.e 13.46 pass is still < 11.49 or even rolled section 13.32.

How not slender for 13 mm flange thickness too?

Thanks

RE: Why IS Code 800-2007 LSD fails Ratio INFINITY, while AISC 360-10 ASD passed Beam with Ratio 0.44? Taper beam

Arun Chugh — Wed, 10 Aug 2022 18:28:32 GMT

Noted, thanks for your prompt response.

Just curious whether inclusion of bending ratio(s) possible by showing ratio for major, minor axis, in last tabular data of member output? apart from a warning- "INFINITY" value - a failed member?

RE: Why IS Code 800-2007 LSD fails Ratio INFINITY, while AISC 360-10 ASD passed Beam with Ratio 0.44? Taper beam

Abhisek M — Wed, 10 Aug 2022 18:14:53 GMT

The reason is that the flange is becoming slender in section classification check with 12mm and non slender with 13mm. For slender flange STAAD does not check bending criteria for a section as per IS800 2007 code and hence infinity is printed to aware the user about it. Previously is showed a warning also but that is not showing now. We are fixing this to show the warning again in next immediate release. More information regarding this issue can be found in below wiki (question number 5)

https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/30240/warnings-in-is800-2007