Load cases unavailable for results review

Question:

Dear Technical Support:


I defined 4 load cases:

  • PIER_SW: self-weight from the pier column, Element load group: LD1P_SW

  • Girder_SW: girder self-weight, including frame element loads, and wet-concrete which is removed once the segmental component is added as a structural entity with its own element dead load.

    + Element load:         Load groups LD1G_SW0 - 12

    + Wet concrete load: Load groups SW1G_0 - 11

  • PS: prestress loads. Will be added gradually according to the advance of the segment erection, Load groups: PS_P1_0 - 11

  • FT: load from the form traveler, Load groups FT_P1_0 - 11

I defined one construction sequence that erects one half of the bridge: one half structure associated with one pier.


After I ran the data file, I could not find any of the above load cases for result review.


How I can review the results (reactions, deflections and member forces) for the above load case? 


Or I have to define a few load combinations for the loads involved in the above construction sequence? The structure is analyzed with nonlinear analysis even if I configured the construction sequence is performed with linear analysis as mentioned in yesterday's reply to my question; as such superposition could not be applied and the results could not be identified for individual load cases because of the compression-only point spring support.


When I defined one load combination ConstructStage, I can find this load combination, but the construction stage/step are lost. I only have the final results. What is wrong with my data file.


I attached my data file.


Regards,




 


Answer:

Hello,

I'll try to segregate the overall query into smaller questions and try answering them.

1)  After CS analysis, the results of individual load cases are not available.  How to check different results for these loads?
A:  All the loads (except prestress) that are activated in construction stage get clubbed into Dead Load (CS) case.  To view the result of each case individually, these loads need to be separated from the Dead Load (CS) case.  This can be done using the construction stage analysis control.

Once this is done, the result of each individual case could be checked in the construction stage.  Kindly note that though the springs are compression only, there could be a downward reaction for any particular load case.  This is stored, since this will cause a relieving effect.  In the summation case though, all the supports would behave as compression only.  If the load acting is such that the negative component is more, then the support is not considered.

2)  Or I have to define a few load combinations for the loads involved in the above construction sequence? The structure is analyzed with nonlinear analysis even if I configured the construction sequence is performed with linear analysis as mentioned in yesterday's reply to my question; as such superposition could not be applied and the results could not be identified for individual load cases because of the compression-only point spring support.
A:  Load combinations are not required to be done as these loads act in defined sequence in construction stage.  However, it isn't advised to go for superposition in PostCS, if the support in inactive in any specific load case that acts only in PostCS, like temperature.

3)  When I defined one load combination ConstructStage, I can find this load combination, but the construction stage/step are lost. I only have the final results. What is wrong with my data file?
A:  When forming load combination in Post CS for loads activated in construction stage, only the last stage results are available.  As such the loads activated in construction stage are always combined in CS:Summation.

Hope this resolves most of the concerns.  Kindly let us know if further assistance would be required.

Regards,
Nandeep
Technical Manager, MIDAS
Creation date: 10/17/2018 10:48 PM (dklee@midasit.com)      Updated: 10/18/2018 8:19 AM (dklee@midasit.com)
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Staging Construction - Half-structure.mcb