A performance evaluation of the arch bridge members using the strain index based on the parameters obtained from linear buckling theory

To develop a seismic performance evaluation method based on the strain demand control of some critical parts when the arch bridges are subjected to the strong ground motions, it is necessary to establish the method to determine the ultimate strain of each segment (defined as the limit of the strain) which has reached the corresponding critical stress. In this study, the empirical formulas of the ultimate strain corresponding to the failure criterions by in-plane buckling and out-of-plane buckling are investigated and proposed emphasized on the stiffened box-section with longitudinal stiffeners. The applicability of box-cross sections with the longitudinal stiffeners and concrete filled is also been brought into one of the ideas to strengthen the arch bridge where the plasticization are formed in some segments due to the strong ground motion. To perform the analyses, the aspect ratio of the arch member which the lowest maximum strength may be expected was determined beforehand by considering the parameters obtained from linear buckling theory. Then the bending analyses under various axial load ratio parameters were examined to clarify the effect of failure segments in both stiffened sections with and without concrete filled models by the FEM analyses. The post buckling behaviors of concrete filled sections were also observed and compared to the stiffened box-cross sections for each width-to-thickness ratio parameter. Based on the numerical results of the stiffened sections with and without concrete filled models, empirical formulas of the ultimate strain were proposed in functions of width-to-thickness ratio parameter and axial load ratio parameter.