Analysis On Compactness And Shear Lag In Prestressed Concrete I-Beams

The durability of concrete has become a study hotspot in civil engineering in recent years. Since the foundation of PRC, with the rapid development of bridges, the concrete bridges of various forms and various structures have been built. However, the service life of existing bridges has not been up to the design service life. In recent years, during the detection of the established reinforced concrete or the prestressed concrete box girder bridges etc. the large structures, we can find that the concrete in particular structural positions such as the anchorage zones of prestressed reinforcement with dense reinforcement, the prestressed pipe in which the space of reinforcement or the thickness of concrete cover is small, the top and bottom flange of box girder and so on has brought great difficulty to concrete construction because of the small size and densely-packed reinforcement. Therefore, it inevitably leads to the incompactness in these positions, accordingly causes the crack or the peeling off of the concrete etc. early diseases. The early diseases not only are related to the appearance quality, but also influence the whole performance of the members, decrease the service life, seriously can also jeopardy the safety of bridge structure.The paper relies on the project of"the disease diagnose and maintenance method aiming at early deterioration in small size member of bridge"belonging to the Communications Department of Jilin province. The project is completed in the collaboration of the Transportation College of Jilin University and Transportation Science institute in Jilin province. The paper mainly studies the characteristics and mechanical performance of small size member of bridge, the problems of concrete dense degree and shear lag effect of wide flange. The static load test and supersonic nondestructive test of four pieces of prestressed I-girder with varying section are carried out in bridge structure laboratory of Jilin University. The width of web plate of two pieces beam is 14cm and another two is 16cm. The paper consists of five chapters. Of these chapters, chapters two, three and four are kernels.