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# Response Spectrum in RAM Structural

## Response Spectrum in RAM Structural

(OP)
I have couple of questions related to Response spectrum, i will really appreciate everyone input.
I have a building in which the lateral frame members are not parallel to global X and Y axes.
Some engineer suggested me to run the response spectrum cases and input the angle which make the forces parallel to lateral members. If i do that, then RAM gives me component in X and Y. How should i scale this as per ASCE7? should i scale the value in X with respect to Static earth quake which will be in global X?
Also even if i don't put an angle in the response spectrum case, then still RAM reports force as X and Y components for both cases of X and Y, how this should be scaled?
If we run the response spectrum case with eccentricity then RAM reports 2 values, one for +ve ecc and other one for -ve ecc, any suggestion on scaling this case? if I pick up the lower value of those two cases then base shear for other case becomes higher than static base shear.

Thanks everybody.

### RE: Response Spectrum in RAM Structural

Let's start with the basic X and Y cases with X and Y frames.
If you are not considering sign in the analysis, then the perpendicular dynamic base shear value is not really relevant to the X direction scale factor (it could be a result of torsion on the structure only), so I usually recommend scaling the Dynamic load based on the base shear parallel to the load angle.
Our wiki says as much here:
http://communities.bentley.com/products/structural...
but for a skewed frame, where global X and Y shear forces are bound to occur it does seem more reasonable to scale the load based on forces in the plane of the frame. If the global base shear values are not sufficient, then frame shear, member forces or reactions might be another way to establish the total shear on an angle.
Rotating the model is always an option, but a painful one.

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