This study attempted to enhance conventional lattice model that can express the shear resisting mechanism of RC members to the 3D analytical method. Analytical studies of the biaxial and torsional response of RC members based on the 3D lattice model are presented. Results obtained by using the 3D lattice model are compared with several sets of experimental results for RC columns subjected to pure torsion or combined loads of torsion and bending. Based on these comparisons, the applicability of 3D lattice model to the prediction of the behavior of RC columns is demonstrated. In addition, the influence of characteristics of the earthquake ground motion on the seismic performance of RC columns is estimated from the simulation using several kinds of 3D ground motions.