Serious/urgent question on Retaining walls in Etabs models 1

[The Designer]

I tried this several times and I'm confused now.
In Etabs models with retaining walls beside the columns .. the retaining wall carries a reaction greater than weights on the floor they are connected to.
For Example a 6 floors building with a retaining wall under the first slab/floor
the reaction of the retaining wall (i mean the summation of reactions of all retaining walls joints) is 1000 tons (working load combination)
while the total working load/weight of the building is 4500 ton ...
this seems illogical ..
i made a trial amd deleted all the floors except for the first one and the reaction of the retainig wall is not 1000 ton any more ... its like 400 ton (but i can't exactly recall the exact number)
i tried this on several Etabs models with retaining walls beside the columns ..
when i delete the upper floors the reaction of the retaining wall decreases...
so my question is .. does retaining walls really carry loads from the above floors or is this an error ... and if it is an error .. what can i do about it ..
i'll appreciate all your opinions
and thanks to you all in advance

 

[JLNJ]

It depends on how you have it modeled.

Stiffness attracts force. You have to know how to create the model so that it acts like your structure will. This includes the way you model the foundations.

 

[patswfc]

When doing hand calcs are you assuming that the upper column loads get transferred directly down though the bottom column which is adjacent to the retaining wall?

In your etabs model is the lower column connected to the retaining wall? If so load will be transferred from the column and in to the wall along the length of the connection, so you will get higher vertical loads in the wall and a reduction in the column load. Is the lower column load in etabs lower than you expect?

Even if the column is not connected to the wall in etabs, some of the column load may be transferred to the wall via the slab, depending on the elastic shortening of the columns vs the stiffness of the slab (which will be high right next to the support).
When analysing a structure in 3D in a software package, the load path in controlled by the stiffness of the various elements in the model. Generally hand calcs miss out the importance that stiffness of the elements has on the distribution of load and hence the design forces of the various elements.

Niether will be "correct", you need to decide which assumptions/set of forces you consider most realistic and design for them. You could even design for the envelope from both cases. There should be ways to change the model so that the results more closely match the assumption that the upper column loads are completely transferred to the column below, if you wish to analyse it like this.

 

[The Designer]

No matter how i change loacation of the wall .. it attracts force from the columns surrounding it. not just from the slab.
one way i can overcome this is by lowering its stiffness modifiers.. but that way i would also lower the load it will attract from the slab (which can also be wrong)
my question is will that happen in real life.. would the wall attract force from the column (not just from the slab)
I forgot to mention that i was referring to modelling of Reinforced concrete

 

[The Designer]

patswfc yea that is what i needed to know .. great info
I asked my professor will it be realistic for the wall ro carry load from the above column and he told me it is ...
he told me that in real.life the wall and the column are one unit not two ... so load would be transferred to the wall ..
and for the modelling he gave me similar explanation as you said