Study On The Durability Of Concrete Bridges Of ShenHai Expressway In The Section Of Liaoning Province

Reinforced concrete and prestressed concrete structures are applied in bridge engineering widely with its good performance and low cost, especially mid-span and low-span bridges which are the main types of highway bridges at home. Performance of the bridges is dissatisfied in rigorous circumstances owing to irrationality of design and construction, lack of maintenance and concrete material. Therefore, finding the defect and their reasons is a key problem. Supported by the national fundamental project (973 project) task 3 "The fundamental research of extra long-span bridge safety design and evaluation" and the project of the ministry of science and technology (2013318223040,2014318494020), the main characteristic of defect of durability of concrete bridges in ShenYang-DaLian section of ShenHai expressway was studied, the main contents and conclusions are summarized as follow:(1) Detecting data of 453 concrete bridges in ShenYang-DaLian section of ShenHai expressway was analyzed, the main defect and influence factors were summarized. The results showed that cracks, leakage saltpetering and corrosion of the steel bar were the main defect of the upper and bottom load-carrying components in concrete bridges. This is relevant with concrete material, improper construction and maintenance, lack of concrete protecting thickness.(2) Carbonation probabilistic model was established based on detecting data of concrete compressive strength and carbonation depth of 453 concrete bridges in ShenYang-DaLian section of ShenHai expressway. Carbonation lifetime probabilistic analysis was conducted based on detecting data of bay bridges whose data was perfect. The results showed that discreteness of concrete carbonation depth was high because of variety of complicated reasons, whose whole tendency was that concrete carbonation depth decreased with concrete compressive strength increased. Carbonation failure probability of components of bay bridges below 10%, which accorded with the national durability standard.(3) Combining with the feature of durability defect of the bridges in ShenYang-DaLian section of ShenHai expressway, some methods of bridge maintainence was discussed.