超重貨物運輸之載重通常會大於橋梁結構之設計承載力，因此為了防止橋梁損壞以及維護公共安全必須在超重貨物運送之前擬定出一套和運輸路線、交通管制與橋梁結構安全相關之措施。本文旨在探討超重車輛通過橋梁時所面臨之橋梁結構安全問題並提供相關解決之道。 本研究論文之橋梁案例主要針對國內桃園國光電廠、嘉義嘉惠電廠以及台南豐德電廠之發電機轉子重件運輸，受陸海運輸公司委託進行橋梁承載力分析與加固補強設計。選擇之加固補強方式採用全橋跨越方法與支撐縮短垮距法兩種；所使用之承載力評估方法採用工作應力法與極限強度法兩種，文中依照每個電廠，行經橋梁順序一一進行承載力評估及加固補強設計。 文末提出現有橋梁重車通行承載能力評估表，針對國內常見之公路橋梁結構型式建議一完整承載力評估流程，希望能提供工程界參考使用。 The Load of heavy-cargo transportation is usually larger then the design loading capacity of bridges structures. Therefore, for the purpose of avoiding bridge damage and maintaining public security, a measure concerning about transportation routes, traffic control, and bridge safety must be drawn up before transporting heavy-duty Vehicles. The substance of this thesis is to explore the issue of bridge structure safety while overloaded vehicles are delivered through bridges and then propose solutions to correlative problems. All vehicle-delivering cases in this thesis including Taoyuan Kuo-Kuang Power Plant, Jiayi Chia-Hui Power Plant, and Tainan Feng-Der Power Plant are commissioned by the Sea & land Integrated Corporation to conduct bridge loading capacity analysis and strengthening design. Two ways of strengthening are Full-Bridge-Span Crossing Method and Support-Shortened-Span Crossing Method. As for loading capacity evaluation, both Working Stress Design Method and Ultimate Strength Design Method are adopted. The bridge loading capacity evaluation and strengthening methods of each bridge are processed in accordance with sequences of vehicles conveyed to power plants. At the end of this thesis, a bridge loading evaluation table and a suggestion of bridge loading capacity evaluation flow chart are proposed for reference in practical bridge construction projects.