SAFE v12 Deflections with Creep
SAFE v12 Deflections with Creep
(OP)
What is the best way to determine deflections in Version 12?
In Version 8 my firms procedure was to create a load combination called LONG and scale load cases to match the time period being investigated. For example the combo would have 2.0xDL, 2.0xSDL, and 0.5xLL for final deflection (5years+) Also part of the procedure involved setting the long term deflection multiplier to 1.0 for all load cases and selecting Normal and cracked deflections under analysis options.
The new version is quite different in setup. You now have to specify if a load case is linear or nonlinear, what type of nonlinear, starting conditions of the nonlinear, you can create load cases that include other load cases at scaled factors, Load combinations can include linear and nonlinear load cases, you can select Service initial, normal or longterm for load combinations. I have tried to match our old method but there are too many variables with the new version. I have not been able to duplicate the results from the old version 8.
I have an inquiry in to CSI if they respond with some valuable insight i will share it.
Any help is appreciated.
In Version 8 my firms procedure was to create a load combination called LONG and scale load cases to match the time period being investigated. For example the combo would have 2.0xDL, 2.0xSDL, and 0.5xLL for final deflection (5years+) Also part of the procedure involved setting the long term deflection multiplier to 1.0 for all load cases and selecting Normal and cracked deflections under analysis options.
The new version is quite different in setup. You now have to specify if a load case is linear or nonlinear, what type of nonlinear, starting conditions of the nonlinear, you can create load cases that include other load cases at scaled factors, Load combinations can include linear and nonlinear load cases, you can select Service initial, normal or longterm for load combinations. I have tried to match our old method but there are too many variables with the new version. I have not been able to duplicate the results from the old version 8.
I have an inquiry in to CSI if they respond with some valuable insight i will share it.
Any help is appreciated.





RE: SAFE v12 Deflections with Creep
The cracked deflection analysis as implemented in SAFE v12 is documented in Example 16 of Analysis Verification problem along with hand calculations to verify SAFE v12 results. We also provided the S16.FDB file in the Verification folder so you can run this model and look at the details documented in Example 16 verification document.
There are two common situation for investigating cracked deflection i.e., immediate cracked deflection and long-term cracked deflection. This can be set up as follows:
1) Immediate Cracked Deflection:
a. Add Dead Load case using Nonlinear (Cracked) started from Zero Initial Condition.
b. Add SDL Load case using Nonlinear (Cracked) started from using Continue from State at End of Nonlinear case "Dead".
c. Add LL Load case using Nonlinear (Cracked) started from using Continue from State at End of Nonlinear case "SDL".
2) Long Term Cracked Deflection:
a. Add Dead Load case using Nonlinear (Long Term Cracked) started from Zero Initial Condition.
b. Add SDL Load case using Nonlinear (Long Term) started from using Continue from State at End of Nonlinear case "Dead".
c. Add LL Load case using Nonlinear (Cracked) started from using Continue from State at End of Nonlinear case "SDL".
The reason to start from a previous case ensures that the change in stiffness due to cracking developed in previous load case is considered when additional loading is applied.
I hope this clarifies this issue.
After looking at the file they mention i am not sure how the creep coefficient and shrinkage strain are determined. For 5years or more the time-dependent factor is 2.0 in ACI 318-05. If anyone has comments on these factors i would like to hear them.
Thanks
RE: SAFE v12 Deflections with Creep
in addition - you do not need to use modifiers as per 10.11, when load assigned as nonlinear cracked cracking conditions internally calculated by safe on element by element base w/ determination of Ie. when load assigned as nonlinear cracked long term, safe calculates long term deflection as 3 times immediate, no compressed reinforcing is taken into consideration.
RE: SAFE v12 Deflections with Creep
RE: SAFE v12 Deflections with Creep
for safe 8 it was very simply immediate x 3 (default, branson recomende 1+3 ) = long term.
in safe 12 it seems more accurate.
i did by hand comparison for different kind of assigning for load case - linear, non-, non- long term.
it seems more accurate than i said before - it seems they implemented 435r procedure.
RE: SAFE v12 Deflections with Creep
RE: SAFE v12 Deflections with Creep