Duplication of self weight in all load defined load cases - Cable structure

[Anonymous]

Hi @Artur.Kosakowski

I have some questions regarding the following screenshots..

I have defined cable elements at the rear of the structure for lateral support however from a graphical display of the load cases I see that the self weight load case is duplicated in every other defined load case. Please explain why this is occurring?

Does this mean that the self weight is overestimated when I create combinations - I have checked the reactions for the dead load case and another vertical load case and I can confirm that the self weight is being duplicated?

Regards

Dane

[mustafahesenow]

Hi @Anonymous

Can you send us the model please?

[Artur.Kosakowski]

HI @Anonymous

I have defined cable elements at the rear of the structure for lateral support however from a graphical display of the load cases I see that the self weight load case is duplicated in every other defined load case. Please explain why this is occurring?

This is as intended for these types of structures. In fact you first assemble it under self-weight and then you apply other loads. This is exactly what happens in Robot, the other loads are applied on an already deformed (under self-weight) model so the self-weight is applied only one time.

Does this mean that the self weight is overestimated when I create combinations - I have checked the reactions for the dead load case and another vertical load case and I can confirm that the self weight is being duplicated?

No, it isn't unless you define it again in any other than 1st (assembly) load case.

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[Anonymous]

Hi @mustafahesenow @Artur.Kosakowski

I have attached the model as reference.

Regards,

Dane

[Artur.Kosakowski]

Hi @Anonymous

Perhaps it would be enough if you use tension only bars instead of cables?

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous]

Hi @Artur.Kosakowski

Thank you for the assistance.

So my understanding is that the 1st load case is used to assemble the model and the state of the cable. How does this work within the load combinations where various load cases are defined?

I have been thinking of using tension only bars yes, I think I will change this.

In any case. has the definition of the cable model been done correctly regarding the load cases and combinations.

Regards

Dane

[Artur.Kosakowski · Accepted solution]

Hi @Anonymous

1/ Assembling load case is always added to all consecutive simple load cases.
2/ Load combinations: assembling load case is added by default (even when it is not specified in the definition of combination) to the combination with the factor of 1. It is added only once rather than  from all simple load cases composing the combination (see point 1/).
If any factor different than 1 is specified for assembling load case in the definition of combination, this value overwrites the default value of 1.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Artur.Kosakowski]

Hi @Anonymous

I just wanted to ask if i managed to explain the difference in handling the 1st (assembly) load case for cable models. Thank you.

[Anonymous]

Hi @Artur.Kosakowski

Apologies for the delay. I only got to your response this morning.

Yes, I believe I understand the approach taken now. Thank you for spot on explanation.

Appreciate the help 

Regards

Dane