| Newly-built bridges gradually become unsound bridges with time. As they age, deterioration caused by heavy traffic and aggressive environmental conditions have a great effect on their serviceability and load carrying capacity. How to accurately evaluate the load carrying capacity of existing bridges under the existing conditions is a hot research topic. Combining with the Liaoning Province Transportation Department's key subject "Study on Quality Classification Index and Assessment methods", this subject is mainly concerned with the experimental study on shear deteriorated RC beams. The research works and conclusions of this paper are as following:1. Spot field investigation and load carrying test on highway RC bridges in Liaoning Province were carried out. Analyses and summaries of the types of deterioration and the causes were made.2. The on-the-spot survey shows that the environmental conditions have a great effect on RC bridges. The more severe deterioration parts of bridges are the side beams of bridges. The main cause of this is that the drainages of bridges is not good . That causes freeze-thaw damages and other bridge diseases.3. Concrete carbonization is not sufficient condition of steel corrosion. The depth of carbonization exceeds the position of reinforcement in concrete beams, nevertheless, the steel reinforcement is still good.4. The reinforcement strain, development of inclined cracks and mechanisms for the shear strength of RC beam are analyzed. The failure types at the ultimate load are also discussed.5. The formula of reduced shear strength coefficient of RC beams with inclined cracks is put forward to according to the test data. On the basis of the current design specification of highway reinforced and prestressed concrete bridge and culvert (JTJ023-85), the shear capacity assessment methods of existing reinforced concrete bridge considering the main influence factors of reduced shear capacity of reinforced concrete beam-bridue . |
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