Load combinations to use for SAFE 14 non-linear analysis

[rabi24]

Hey guys,

I am just wondering what load combinations am I supposed to be using when conducting a non-linear cracked analysis for determination of immediate and long term deflections on SAFE 14?

I added 6 load cases, Dead-Immediate (Cracked), SDL-Immediate (Cracked), Live-Immediate (Cracked), Dead-Long (Long term cracked), SDL-Long (Long term cracked), Live-Long (Long term cracked) with appropriate sequencing of the loads for each of the cases.

Are the load combinations to be used G+0.7Q for immediate cases and G+0.4Q for long term cases as per AS3600? Also what do you guys usually use for the creep coefficient? The default is 2.0 in SAFE but I seem to think it should be higher. Is that the same factor as the final creep coefficient in Table 3.1.8.3 AS3600?

Appreciate any input.

Regards

 

[li0ngalahad]

For the long term deflection analysis load cases are
A) IMMEDIATE ALL LOAD CRACKED G+0.7Q
B) IMMEDIATE SUSTAINED CRACKED G+0.4Q
C) LONG TERM SUSTAINED CRACKED WITH CREEP AND SHRINKAGE G+0.4Q
Then as a combination :
A+C-B

For the creep coefficients and shrinkage strain I assume one should calculate them from AS3600 tables, but I'm not 100% sure as SAFE is based on ACI. The most important thing I think it's the modulus of rupture (Run-cracked analysis) by default it's 0.33sqrt(f'c)but AS3600 indicates it as 0.6sqrt(f'c),but again I'm not sure if we can use this (I asked the question on another topic yesterday). This value will greatly change the long term deflection, if someone has any indication about it would be very appreciated.

 

[rabi24]

Thank you lion!

 

[rabi24]

Hmmm, I fiddled around with it today at work. I am not sure we add immediate+long term sustained cracked. Maybe long term cracked in SAFE is the total long term deflection accounting for creep and shrinkage.

Hopefully someone has some insights on this.

 

[li0ngalahad]

rabi, have a look at this video from CSi

https://www.youtube.com/watch?v=7ngJT8f2vPM

and this page from CSi knowledge base

https://wiki.csiamerica.com/display/safe/Cracked-section+analysis