A pseudo-structure with a layer and two spans containing center pillars is often used at and between subways stations. Open cut tunnels are normally designed based on the two-dimensional frame analysis of the cross section that contains a center pillar. Three-dimensional effects of the change in the interval between center pillars are considered by decreasing the rigidity of center pillar alone. However, the change in the interval effects not only the force of the lateral cross section that does not contain a center pillar but also that of the longitudinal cross section. Therefore, we performed three-dimensional analysis of a model that precisely simulates the tunnel structure. Based on the results of analysis, we studied a method to appropriately reflect the three-dimensional effects in the two-dimensional frame analysis.