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## Robot Structural Analysis

Distinguished Contributor
Posts: 195
Registered: ‎04-10-2012

# Canadian steel code design - values changing after clicking *Auto' button

342 Views, 7 Replies
05-24-2012 05:12 PM

See the scree capture: http://screencast.com/t/oxs2Esv9Xbs1

After clicking *Auto* button, the values change. I think this has something to do with that this member consists of two members with different section, but I want to make sure what is going on here.

BTW, the first equation below *RESULTS* is missing U1 variables.

Product Support
Posts: 4,048
Registered: ‎12-17-2010

# Re: Canadian steel code design - values changing after clicking *Auto' button

05-28-2012 12:45 AM in reply to: PatrickEC

1. The Auto as well as manual check (Forces button) are intended for a quick check of the capacity of the cross section and some limitation comparing to the 'standard' verification done by the program especially for accessing the data from other locations along a verified bar when checking the capacity in the specified location of this bar.

2. The check of the cross section strength (13.8.2.(a)) is done with no influence of stability control (no buckling). As it is assumed Ce= infinity (13.8.4) then U1 is assumed as 1.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

Artur Kosakowski
Distinguished Contributor
Posts: 195
Registered: ‎04-10-2012

# Re: Canadian steel code design - values changing after clicking *Auto' button

05-29-2012 12:28 PM in reply to: Artur.Kosakowski

2. The check of the cross section strength (13.8.2.(a)) is done with no influence of stability control (no buckling). As it is assumed Ce= infinity (13.8.4) then U1 is assumed as 1.

I reviewed the steel  code again and it is somewhat unclear, but I tend to agree with your explanation.

However, if that is the case then the calculated value in Robot in incorrect.

See the attached example:

Cf = 628.70

Cr0 = 2030.40

Mfy = 2.92

Mry = 286.76

Mfz = 48.45

Mrz = 71.69

Cf/Cr0 + 0.85*Mfy/Mry + 0.60*Mfz/Mrz = 628.70/2030.40 + 0.85* 2.92/286.76 + 0.60*48.45/71.69 = 0.72

Product Support
Posts: 4,048
Registered: ‎12-17-2010

# Re: Canadian steel code design - values changing after clicking *Auto' button

05-29-2012 11:10 PM in reply to: PatrickEC

Could you attach the rtd file please? I assume that you check the 13.8.2(a) line?

Artur Kosakowski
Distinguished Contributor
Posts: 195
Registered: ‎04-10-2012

# Re: Canadian steel code design - values changing after clicking *Auto' button

05-30-2012 10:50 PM in reply to: Artur.Kosakowski

I will create a sample file and attach it here when I have a minute, but just take a very slender column 200<KL/r<300, apply force Cf  > Ce so that U is 1000 and you will see similar results.

Yes, I am reffing to 13.8.2(a).

Distinguished Contributor
Posts: 195
Registered: ‎04-10-2012

# Re: Canadian steel code design - values changing after clicking *Auto' button

05-31-2012 03:38 PM in reply to: PatrickEC

Artur: I sent you a private message with the model.

Product Support
Posts: 4,242
Registered: ‎04-26-2010

# Re: Canadian steel code design - values changing after clicking *Auto' button

06-01-2012 01:48 AM in reply to: PatrickEC

Patrick : send me or to Pawel this file. Artur is out of office.

Rafal Gaweda
Product Support
Posts: 4,048
Registered: ‎12-17-2010

# Re: Canadian steel code design - values changing after clicking *Auto' button

08-06-2012 02:10 AM in reply to: Rafal.Gaweda

After installation of SP2 for v.2013 in  the 13.8.2(a) formula U1y and U1z will be displayed. In case they are equal to 1.0 this value will be shown instead of U1y or U1z.