# How is response spectrum result used for earthquake analysis

For simpler buildings we can use response spectrum analysis. How is this used? The maximum acceleration we get from this , is simply multiplied by the mass of the building to get F=ma , total earthquake force on the building? Simple as that?

Yes, Right. After you verify that your building structure geometry and utility make it qualify for using design spectra charts:

it gives you the acceleration Sa and speed of ground motion, Sv and the amount of motion, Sd which are all related by factors of $$\omega$$.

Then you can apply F=ma. Ther are inherent errors in this method that a designer must be aware of and use good judgment. Search for - (Nigam and Jennings, 1969), to see the article on the errors.

here is the chart. • and after we obtain that F from F=ma, we distribute it as a triangle alnog the height of the building right? the most force on the top and least at the bottom? (which is what I saw but should it not be the opposite, i mean all structure is hanging on fromthe foundation so most lateral force should not be at foundation level?) Apr 16 '20 at 18:17
• what we talk about here is called a linear elastic analysis right now? or it is called response spectrum analysis? Apr 16 '20 at 18:18
• if we made more complicated analysis such as dynamic analysis we would use displacement and velocity right? but not for static analysis? Apr 16 '20 at 18:19
• Yes exactly, except there is an additional whiplash force of Ft applied on top. Apr 16 '20 at 18:31
• @user3600630, regardless of triangular assigning the lateral loads and Ft when we sum them the greatest shear is applied at the foundation. Let's say you have a total of 500 kips to distribute, regardless of how you do that the shear at the foundation is 500 lips. the shear on the higher floors is more than equal distribution. Apr 17 '20 at 14:26