Scaling Down Design Values of Combined Response Spectrum

[lesgiu]

Good morning guys,

I have done a response spectrum analysis to a 16-story building and I got that my dynamic base shear is bigger than my static base shear. Since i don't need to scale up my dynamic base shear as per asce7 12.9.4, can i instead scale it down?? not to an 85% but to a 100% (dynamic base shear = static base shear)?

I would like to hear your thoughts on this,

Thanks

 

[shin25]

Not sure why your RSA is showing larger base shear than the base shear calculated by equivalent lateral force method. When you calculated the static base shear did you limit the structure's period to maximum allowable by the code?

 

[Agent666]

It should always be lower if your equivalent static actions are based on the first fundamental period, I can't think of any reason why it would be higher.

But if it actually is higher I believe all codes state something along the lines of scale up to a minimum of 100%, otherwise if over 100% you use that value as you are not required to scale it up.