Base shear from ETABS
Base shear from ETABS
(OP)
Hi all, I've got a question about the base shear. After you do the response spectrum analysis in Etabs, how do you find the total base shear of the structure(multi-storey building to be more specific)? This is to work out the scaling factor. I was told that you can look at the "Story force" section of the 1st storey of the structure in the output report. Is that correct?





RE: Base shear from ETABS
RE: Base shear from ETABS
You can get Story shears:
1) Display/ Show Story Response Plots.../ Story Shears
2) Display/ Show Tables.../ Building Output/ Story Shears
Drile007
RE: Base shear from ETABS
RE: Base shear from ETABS
I was able to do the show table thing, thanks for that. However, I could not find the "summation" function mentioned in your last post. I had to manually add all the reaction forces together under same direction to find out the base shear. Would you please give some instructions on this one?
RE: Base shear from ETABS
RE: Base shear from ETABS
Thanks for the replies. I have done a comparison using both the story shear method and the section cut forces summation method to calculate the base shear. In my case, the values are very close:
Vx (story force) : Vx (section cut) = 1 : 1.03
Vy (story force): Vy (section cut) = 1: 0.98
As you can see, the differences are within 5%. I tend to believe both methods are valid in terms of calculating the base shear using Etabs. Please give your comments.
RE: Base shear from ETABS
You should have a look at Display -> Show Tables -> Modal Information -> Table: Response Spectrum Base Reactions. They have had to introduce a special routine to determine base reactions since all results from Response Analysis are positive. Summing base reactions or column shears would be wrong.
GarthW