Serviceability as a significant factor of the bridge life-cycle

Prestressed concrete bridges are very sensitive to long-term increase of deflections. The cost of reduced service life of such bridges is tremendous for society, the owners and users. Reliable prediction of bridge deflections during their construction as well as during their service life is of crucial importance for achieving good durability and long-term serviceability. The excessive and with time increasing deflections of long-span prestressed bridges are caused by a combination of several simultaneously acting factors. Two of them are discussed in detail. Special attention is directed to effects of the differential shrinkage and to arrangement of prestressing-a procedure to find the optimal arrangement of tendons layout is presented, allowing to avoid the tendons contributing to deflection increases. Developed computer programs are freely available; repair examples, as well as recommendations for the design practice are also presented. Results of the presented solutions and the developed analytical and design methods can help creating suitable theoretical tools for reliable and economic structural design of prestressed concrete box girder bridges without deflection impairments.