Prevent Columns from taking lateral loads / Wind load question

[aboud47]

Good evening

I have two question and im really looking forward for your kind replays


1- How do i prevent columns in etabs analysis from shear caused by lateral loads ( eq,wind ) , the building i am modeling is meant to be shear-wall system only for lateral loads, so how do i prevent that from happening ?


2- In order to obtain proper results for earthquake analysis, a spectrum response function has to be defined and set up, so how about wind load is there any further action i need to consider after defining it and entering all the needed coefficients?


Thank you

 

[chekre]

Hi.
1- u can assign moment releases for all the columns or assign a stiffness modifiers to their bending moment in the 2 axes of the column equal to 0.01.
2- after defining the wind load cases, u should assign ur diaphragms and then u are ready to run the calculations.

 

[aboud47]

Thanks alot

 

[MrHershey]

While it's important to make sure the shear walls are sufficient to take everything, I would tap the breaks on releasing the columns for a couple reasons.

1. It's important to try and get your model to match real life as best you can. The actual building doesn't care what your modeling assumptions were. If the columns aren't built as pins in real life then they're not going to act as pins in real life regardless of what your model says. You can run them pinned to make sure shear walls can take the entire load, but you should consider the implications on the columns if they're not pinned as well.
2. If the columns do attract lateral loads and the magnitude is sufficient for the column to fail, that's not good. While what you've designated as your lateral system (the real building might disagree on what the lateral system is) may be sufficient, what you've designated as your gravity is going to run into some problems. ACI handles this for high seismic by forcing you to look at columns not part of the lateral resisting system. If they can handle the shears and moments due to the inelastic displacement, great. If they can't (or pin the ends and don't look), you have extra detailing to do to make sure you fail in a ductile manner.