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Therefore, response spectrum scale factor shall be g*I/R where g is acceleration due to gravity (use 386.4 in/sec2 for models in kips-inch units and 9.81 m/sec2 for models in kN-m units). After analysis is performed, review the Response Spectrum Base Reaction Table and refer to the Base base shear due to all modes. If reported dynamic base shear is more than 85% of the static Base base shear then no further action is required. However, when dynamic base shear is less than 85% of static base shear then readjust the scale factor to match the response spectrum base shear equal to 85% of static base shear (i.e., new scale factor = (g*I/R) * 0.85*Static static base Shear shear /Response Spectrum response spectrum base shear). Use this readjusted scale factor in Response Spectrum and response spectrum case and rerun the 2nd analysis.