In the steel bridge, corrosion often occurred severely at the girder end rather than the other part, therefore this work will mainly focus on the corrosion at the girder end, but also consider the corrosion at the mid-span. Due to corrosion, the load-carrying capacity of the bridge is reduced. By using ABAQUS, the capacity of the corroded bridges can be evaluated. Eigenvalue analysis and initial deflection are taken into account, but not for residual stress analysis. After the preliminary verification has been done, some parametric studies were conducted with two bridges (Design Example 1 and Keelung Bridge) by changing the thickness reduction, damage height, damage width, corrosion shape, and corrosion location. At the mid-span, both the height and width of the corroded region are insignificant in terms of the reduction of the load-carrying capacity. However, the height of the corroded region at the girder end is a decisive factor for the load-carrying capacity reduction, but not for the width aspect. The corrosion on the free-boundary part significantly reduces the capacity, but not for the corrosion on the interior part. When normal corrosion occurs, the capacity reduction of the multi-area corrosion with the corrosion at both sides of the stiffener is found to be the highest. However, when the thickness reduction is extreme, the multi-area corrosion with the corrosion at only one side of the stiffener is the case that reduces the capacity greatest. Then, suggested graphs are presented and the engineer may use them to predict the capacity of the corroded bridge. Based on some introduced estimation equations for the corroded girder end, the equations proposed by Usukura et al. (2017) is proved as the best one. By some modification, those equations produce the conservative and the more accurate results. Additionally, the equations for the corrosion case at the mid-span are also introduced.

panels. Marine Structures, 17(5), 385-402.
European Convention for Constructional Steelwork. Committee on Stability, & Sfintesco, D. (1976). Manual on stability of steel structures. European Convention for Constructional Steelwork.
Guidelines of the buckling design. (2005). Japanese Society of Civil Engineering (JSCE), 55–66 (in Japanese).
Hung, V. T., Nagasawa, H., Sasaki, E., Ichikawa, A., & Natori, T. (2002). An experimental and analytical study on bearing capacity of supporting point in corroded steel bridges. Doboku Gakkai Ronbunshu, 2002(710), 141-151 (in Japanese).
JBA (2005). Design example and commentary of composite girder. Japan Bridge Association (in Japanese).
JRA (2012). Specifications for Highway Bridges, Part 2: Steel Bridges. Japan Road Association (in Japanese).
JSSC (2006). Maintenance of Weathering Steel Bridges. In W.F. Chen & L. Duan (Eds.), Bridge engineering second edition: Fundamentals (pp. 421-424). CRC Press.
Kayser, J. R., & Nowak, A. S. (1989). Reliability of corroded steel girder bridges. Structural safety, 6(1), 53-63.
Khurram, N., Sasaki, E., Katsuchi, H., & Yamada, H. (2013). Finite element investigation of shear capacity of locally corroded end panel of steel plate girder.
86
International Journal of Steel Structures, 13(4), 623-633.
Khurram, N., Sasaki, E., Katsuchi, H., & Yamada, H. (2014). Experimental and numerical evaluation of bearing capacity of steel plate girder affected by end panel corrosion. International Journal of Steel Structures, 14(3), 659-676.
Khurram, N., Sasaki, E., Kihira, H., Katsuchi, H., & Yamada, H. (2014). Analytical demonstrations to assess residual bearing capacities of steel plate girder ends with stiffeners damaged by corrosion. Structure and Infrastructure Engineering, 10(1), 69-79.
Li, J.S., Yan, Y.Z., Meng, B.J. (2013). 鋼橋塗裝常見缺失及後續改善對策-以102年考評縣府鋼橋為例 (Report Vol. 39 No. 12). Taiwan Highway Engineering (in Chinese).
Mateus, A. F., & Witz, J. A. (2001). A parametric study of the post-buckling behaviour of steel plates. Engineering structures, 23(2), 172-185.
Miyashita, T. (2017). 橋梁定期点検を活用した劣化鋼橋の構造性能評価に関する事業. Nagaoka University of Technology.
Sharifi, Y., & Rahgozar, R. (2010). Remaining moment capacity of corroded steel beams. International Journal of Steel Structures, 10(2), 165-176.
Ship Structure Committee. (1997). Strength and stability of stiffened plate components. SSC-399. Washington, DC: Ship Structure Committee.
Smith, C. S., Davidson, P. C., & Chapman, J. C. (1988). Strength and stiffness of ships’plating under in-plane compression and tension. Royal Institution of Naval Architects Transactions, 130.
Tamakoshi, T., Nakasu, K., Ishio, M., Takeda, T., & Suizu, N. (2006). Research on local corrosion of highway steel bridges. Technical note of National Institute for land and Infrastructure management, (294).
U.S. Department of Transportation. (2012). Design example 1: Three-span continuous straight composite steel I-girder bridge (Publication No. FHWA-IF-12-052 - Vol. 20.
Usami, T. (2005). Guidelines for stability design of steel structures, 2nd ed., JSCE (in Japanese).
Usukura, M., Miyashita, T., Sasaki, E., Mitsugi, Y., Yamazaki, T., & Sugiyama, T. (2017). 腐食損傷を有する鋼 I 桁端部の耐力推定方法に関する一検討; 腐食損傷を有する鋼 I 桁端部の耐力推定方法に関する一検討; a Study on Estimation Method of Ultimate Strength of Corroded Steel Girder Ends. JSCSE, 73(3), 560-
87
578.Wakabayashi, D., Miyashita, T., Okuyama, Y., Kobayashi, A., Hidekuma, Y., Horimoto, W., ... & Nagai, M. (2013, December). Repair method using CFRP for corroded steel girder ends. In Fourth Asia-Pacific Conference on FRP in Structures (APFIS 2013) (pp. 1-6).
Yamaguchi, E., Akagi, T. (2013). A study on load-carrying capacity of corroded steel I-section girder end. 構造工学論文集A, 59, 80-90 (in Japanese).
Yamaguchi, E., Akagi, T., & Tsuji, H. (2014). Influence of corrosion on load-carrying capacities of steel I-section main-girder end and steel end cross-girder. International Journal of Steel Structures, 14(4), 831-841.