Shear Behaviour Experimental Study for Full-scale PC Box Girder Strengthened by Composite Strengthening Method

Concrete bridges take a great percentage of existing bridges in highway transportation infrastructures in China, especially in medium or short span range bridges. A large number of concrete bridges have been constructed since 1980s in China. Under couple action of factors, like increasing vehicle volume and vehicle load, environmental corrosion and so on, many in-service concrete bridges are enduring structural behaviour degradation and other durability damages. Bridge investigation report has shown that a certain number of existing concrete bridges are unable to meet the demands of the modern transportation development. Therefore, it is necessary to explore effective strengthening method and conduct bridge performance evaluation after reinforcement, to ensure bridge safety and extend their service life. The steel plate and concrete composite strengthening (SPCCS) method was proposed, which included the process of welding studs on the reinforcing steel plates, planting steel bars in the original concrete, and casting concrete between the original structure and the steel plates. This paper is focus on shear behaviour test study of full-scale concrete box bridge strengthened by SPCCS method. The full-scale box girder tested in this paper was demolished from an in-situ bridge, which had durability problem. Based on the inspection results of this concrete box girder, the detailed strengthening measures were determined. To check reinforcement effectiveness, shear resistance test were conducted before and after reinforcement. From the comparative analysis of test results, it was showed that SPCCS method could effectively improve shear capacity for more than 67%. Besides, the concrete box girder after reinforcement showed very well overall load carrying behaviour. Learn from study results in this paper, SPCCS method is an effective method to strengthen the in-service concrete bridge with durability problem, which can help realize the sustainable management and maintenance of concrete bridges.