Question: Why in different building codes (UBC 97 or ASCE 7) the results of Response Spectrum Analysis (RSA) should be scaled such that the design base shear should match with the (e.g. 80%, 90% or 100% of the) design base shear obtained from the Equivalent Static Analysis? Answer: The requirement of a base shear scaling for the Response Spectrum Analysis (RSA) procedure is included in the building codes as a means to ensure that the minimum strength of a structure designed using the RSA procedure is similar to the strength that would be required if the structure was designed using [...]