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Valued Mentor
AJA14
Posts: 491
Registered: ‎11-01-2011

service load combinations

366 Views, 4 Replies
12-06-2011 04:43 AM

Hi. After generating automatic code combinations as per LRFD, i can't find the seismic loads in any of the SLS combinations. They can only be found in ULS combinations. I transfered to ACI and used ACC loads, but still i don't get any service combinations including seismic loads. I even tried BS 5950, but in that case, I received nothing in both the ULS and SLS cases. Any ideas. Thanks.

Ali Al-Hammoud
Structural Design Engineer
MZ & Partners Engineering Consultancy
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Product Support
Rafal.Gaweda
Posts: 5,315
Registered: ‎04-26-2010

Re: service load combinations

12-06-2011 05:06 AM in reply to: AJA14

Seismic cases in SLS combinations ?

Please provide us code paragraph saying that.



Rafal Gaweda
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Artur.Kosakowski
Posts: 4,965
Registered: ‎12-17-2010

Re: service load combinations

12-06-2011 05:32 AM in reply to: AJA14

 I even tried BS 5950, but in that case, I received nothing in both the ULS and SLS cases. Any ideas. Thanks.

Most likely after changing the code the default relations among load cases have been lost. You need to restore them in the way shown on the attached picture.



Artur Kosakowski
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Valued Mentor
AJA14
Posts: 491
Registered: ‎11-01-2011

Re: service load combinations

12-06-2011 06:04 AM in reply to: Rafal.Gaweda

I think I did not explain myself clearly. In UBC, the code provides ASD load combinations that include the original load combinations but with 1.0 factors except for seismic loads which are divided by 1.4 becuase the code is based on an ultimate seismic force. That is why, in lrfd code combinations, seismic loads are multiplied by 1.0. We are trying to see if we can automatically generate the ASD load cominations that include the seismic load divided by 1.4. Sorry for the misunderstanding. Would appreciate any input on the matter.

Ali Al-Hammoud
Structural Design Engineer
MZ & Partners Engineering Consultancy
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Product Support
Rafal.Gaweda
Posts: 5,315
Registered: ‎04-26-2010

Re: service load combinations

12-06-2011 06:19 AM in reply to: AJA14

I think you mean this:

 

coeff.jpg



Rafal Gaweda
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