Most building structures are 3D in nature and stiffness or mass asymmetries in conjunction with directivity of the earthquake signal with respect to the principal axes of the structure can result in very complex 3-dimentional responses that make the dynamic behavior largely unpredictable. It appears that there was no one ground motion scaling method properly incorporating the higher-mode effects ever developed for the bi-directional RHA of building structures. In this study, a multi-mode scaling(MMS) procedures incorporating the higher-mode effects for 3-D frames’ bi-directional RHA is developed. This study is to evaluate the effectiveness of the proposed MMS in reducing the scatter in estimated peak seismic demands for the 3-D building structures. The MMS analysis results are compared with those obtained from using other ground motion scaling methods.