Experimental investigations on the structural behaviour of prestressed concrete box girders using innovative construction technology

摘要

The increasing use of prestressed concrete for medium and long span bridges led to the development of box girder bridges. Apart from good aesthetic appearance and slender form, the box section is structurally superior in resisting eccentric loads because of its rigidity against torsion1. Optimum design of box girders is possible only by studying the behaviour of box girders upto the ultimate load range. The load deformation relationships can be used to realistically predict the behavior of structures. The post-cracking load deformation behavior and ultifffate strength are influenced by parameters such as the stress-strain characteristics of materials and geometry of cross-section. Hence, detailed experimental investigations are required to study the strength and behaviour of prestressed concrete box girders. Aravindan and Rajeeva2 tested in the elastic range, two single cell reinforced concrete box girder models of skew angles 0 deg and 30° with three intermediate diaphragms and compared the results with the finite element analysis to study the effect of skew angle and intermediate diaphragms. Babu Kurian3 carried out analytical and experimental investigations to develop simplified equations to predict the collapse load of concrete box girders. He suggested a set of correction factors for transverse moments obtained from the simplified frame analysis4. From the literature study, it was found that very limited number of experimental investigations was carried out on prestressed concrete box girders in India. This could possibly be because of the difficulties faced in casting the specimens. The problems encountered commonly in the casting of prestressed concrete box girder models in the laboratory are as follows.