Shearwall Modeling Technique

[mshani]

I have a 26 story building in seismic zone 3. The main lateral system consist of 46'x46' interior concrete core with additional perimeter frame for 25% EQ loads. When I am modeling my shear walls with 4 corner supports, I am getting huge lateral forces even in DL or LL cases. Overall lateral force is zero as the forces are equal and opposite in direction at each corner. But when u have load combinations, this forces add up and give me huge base reactions.

I was wondering if any of u know any better technique to get rid of this reactions due to DL or LL? (note: there are no errors in the model)

 

[plopez]

Hi mshani:

You have to use the sequential load case to eliminate those reactions in the base.

The problem is you load at one time the hole building when run the analysis and that is not the real way of loading the structure.

Using Seq. Load Case the reactions in the base changes depending the type of building you are doing,but is more real than your results.

Try with Etabs v8.2.7