Setting global factors

[Ginny]

I have a question about the mechanical and ultimate limit factors. On the Setup Form I set the factors globally for mechanical limit, ultimate limit and panel local knockdown. However, when I go to the design to loads for each of the components, the Mechanical limit is different from the value I had set globally. Strangely, the \"mechanical ultimate\" and \"local knockdown\" in the design to loads and buckling tabs changed to match what I had set globally. Should I also change the mechanical limits in the design to load tabs to match what I had set globally or does global override anything written in that tab? Does setting factors on both the setup form and sizing form have a multiplicative effect?

[jjainswo]

If you set a Mechanical Ultimate/Limit factor for a load set on the setup form this is multiplied by the valued entered on the design-to-loads tab. 

By using the setup form you can apply a Mechanical Ultimate or Limit factor to each load set separately, which you can not do if you simply apply the factor on the design-to-loads tab.

Using the design-to-loads tab you can apply the same factor to all projects.  I have seen this trip people up in the past so make sure you don't double up on the mechanical ultimate factors and size to much heavier loads than necessary.

[Ginny]

Thanks for the answer, but I believe there was a misunderstanding. The answer involved setting the factors on the load sets tab in the setup form, but my concern is about the factors you input on the setup tab in analysis defaults on the setup form. Thank you for the quick response.

[jjainswo]

Applying the defaults globally should not overwrite anything in the tab, it simply sets these values in the design-to-loads tab when a new project is created in the database after the defaults have been set.  This should not affect any projects/workspaces that were in the database already.

These settings will also only apply to the ultimate, limit and knockdown factors on the design-to-loads tab, so there should be no multiplication effect there.  I would say it is safe to go ahead and change them to match in the design-to-loads tab.

Did you apply the global before you created your project or after?

[hunterqiu]

what does it mean "multiply" is like the followed example:

in setup form,  limit factor = 1.0, ultimate =1.5; and in design-to-loads in sizing form, limit factor=1, ultimate=1.5.

then the real load factor, limit=1.0*1.0=1.0, ultimate=1.5*1.5=2.25.

is it clear?

[jjainswo]

This is exacly what will happen if you have an ultimate load factor defined for the load set on the load sets tab and have an ultimate load factor defined on the design-to-loads tab, they will be multiplied together so you will be sizing to ultimate loads that are 1.5 (Ultimate load factor) higher than what they need to be.

Try it and see