topic Re: Cannot generate SLS combinations in Robot Structural Analysis Forum

Cannot generate SLS combinations

Anonymous — Mon, 22 Jan 2018 13:27:06 GMT

I have an issue when trying to generate SLS load combinations. I can generate ULS combinations no problem, but for some reason when I am in the window to choose combinations from ULS, SLS, ACC, SPEC, I can only choose ULS. I am unable to check the SLS box at all.

I am working in ASD code and I scoured the forums for a similar issue, but with no luck. Is there something I'm missing?

Re: Cannot generate SLS combinations

mustafahesenow — Mon, 22 Jan 2018 13:45:21 GMT

Hi @Anonymous

The ASD code regulation on Robot has defined only ULS load combinations for Sls you need to define them manually .

Re: Cannot generate SLS combinations

Artur.Kosakowski — Mon, 22 Jan 2018 13:49:00 GMT

Hi @Anonymous

@mustafahesenow is absolutely correct. On the other hand I'd like to learn more about the provisions of ASD code for SLS combination generation. Shall they be the same as for ULS but when the load factor for ULS is above 1 it should be replaced with 1 for SLS and when below 1 kept as for ULS?

Re: Cannot generate SLS combinations

Anonymous — Mon, 22 Jan 2018 15:11:18 GMT

@mustafahesenow thank you for the quick response!

Artur, the SLS load combinations would in fact be the same for as ULS. In ASD the servicibility is restrained by factors of L/360; L/600; etc.

Correct me if I'm wrong with the method I was approaching, but the trouble I had was when I wanted to verify members in steel design, I would have blank results for deformation, but I would get results from strength. This I assumed was because ULS was in fact checking for strength, but not deflection. So This is where I was having confusion with generating SLS combinations to check for deflections.

I know I can set service limits in the members properties, but that doesn't help since I keep getting blank results for deformation.

I know I can change the combination state manually to SLS (which would then give me deformation results), but would I have to do that to all of them one at a time? Or is there a more efficient way to have a whole second set of the ULS combinations copied and simply relabel them as SLS, and also change its state to SLS? This way I can check for strength AND deflection simultaneously.

Re: Cannot generate SLS combinations

Artur.Kosakowski — Mon, 22 Jan 2018 15:38:28 GMT

Hi @Anonymous

What you can do is to generate automatically manual combinations rather than code combinations. Then having ULS combinations defined you can copy and paste them in the combination table and then change their type to SLS:

If one or more of these posts answered your question, please click Accept as Solution on the posts that helped you so others in the community can find them easily.

Re: Cannot generate SLS combinations

Anonymous — Mon, 22 Jan 2018 15:50:46 GMT

Artur, this is exactly what I needed. Thank you!