# Horizontal distribution of Seismic Load



## vhmehta (Oct 7, 2009)

I wanted to know that if in a problem the Center of rigidity and center of mass are provided and we need to calculate the force in each lateral elements, would you add 5% minimum eccentricity to actual eccentricity?

In my Masters degree Seismic course they added 5% on top of the actual eccentricity.

Six minute solution problem number 12 is similar. They have not added 5% accidental eccentricity to the actual eccentricity.

Thanks,


----------



## kevo_55 (Oct 7, 2009)

vhmehta,

Of course when looking at a particular level you would do this.

I don't happen to have the 6 min solutions with me, but you might need to check the wording of the question. My guess is that is the reason why they did not add this.

Don't worry, you've got this.


----------



## vhmehta (Oct 7, 2009)

kevo_55 said:


> vhmehta,
> Of course when looking at a particular level you would do this.
> 
> I don't happen to have the 6 min solutions with me, but you might need to check the wording of the question. My guess is that is the reason why they did not add this.
> ...



Thanks Kevo. I the problem deals with wind load and not seismic load. May be thats the reason they did not add 5%.


----------



## kevo_55 (Oct 7, 2009)

^^If that is true I think you just answered your own question. :bananalama:


----------



## TGordon (Oct 8, 2009)

vhmehta said:


> I wanted to know that if in a problem the Center of rigidity and center of mass are provided and we need to calculate the force in each lateral elements, would you add 5% minimum eccentricity to actual eccentricity?
> In my Masters degree Seismic course they added 5% on top of the actual eccentricity.
> 
> Six minute solution problem number 12 is similar. They have not added 5% accidental eccentricity to the actual eccentricity.
> ...



No!!!

If in a problem the Center of rigidity and center of mass are provided and we need to calculate the force in each lateral elements, No 5% accidental eccentricity need be added (See PCI hand book example 3.7.1, both 5th and 6th edition has this example for 5th, see page 3-27 to 3-29).

Only in real world problem when you were given a building layout and calculate its lateral shear on each shear wall you need add 5% accidental eccentricity to the value calculated from the building geometry.


----------

