The Design on a Prestressed Concrete Precast Segmental Continuous
Frame Box Girder Bridge with Internal and External Cables
By T.Matsuda, T.Okada, N.Nakamura and K.Idani
Concrete Journal, Vol.34, No.6, June 1996
- Synopsis
- In recent years, the internationalization of domestic construction market and purchasing materials from abroad are distinguished, and so reducing bridge construction fee and labor saving seem to be very important. In order to solve those problems precast segmental box girder with both external and internal prestressing-tendons and continuous rigid frame system are adopted for Shigenobu viaduct in Matsuyama Expressway. The characteristics of this viaduct are listed as follows ; (1) Using rigid frame system, sesmic energy is transmitted not only to substructure but also to superstructure. Therefor it is possible to reduce dimension of piers and foundation, and to get free maintenanse of shoes. (2) Precast segmental construction method realizes not only use of machines for bar arrangement, formwork, and casting concrete but improvement of quality control. (3) External prestressing tendon makesnot only decreasing required sectional area of box girder but also reducing segment weight in erecting. (4) Span-by-span erection method accomplishes continuous and rapid construction, and saving labor for prestressing work with large sixe tendons such as 19T15.2 which are consisted of single span cables and 2-span continuous cables. However, this type of bridge is adopted for thefirst time in Japan. So a stress increase in the external tendon at ultimate was considered reasonable and used in the detail design in order to reduce construction cost,and a two span reduced-scale segmental box girder model was constructed, tested, and demonstrated the adequacy of the design. Then prestressed concrete column members with U-shaped tendonwhich were reduced-scale model of connecting part between girder and pier were carried out during semi-dynamic horizontal loading simulated earthquake under axial load in order to certify its design method. This report presents the outline of the design concrete of Shigenobu-viaduct and these test results.
- Keywords:
- precast segmental box girder, external tendons, rigid frame system, span-by-span erection method, Shigenobu viaduct, U-shaped tendon, a stress increase in the external tendon
