Long-term deflection control in cantilever prestressed concrete bridges .1. Control method

Creep and shrinkage of concrete may lead to excess long-term deflection in concrete members, especially in prestressed concrete structures. The long-term vertical deflection of a segmentally constructed prestressed concrete bridge due to prestress loss is a typical example. This excessive deflection not only reduces service life of bridge structures but also leads to poor riding quality for the passengers. This paper proposes a method that employs control tendons to adjust the prestress of a bridge system in a timely basis. The result of this study shows that deflection control in a prestressed concrete bridge can be achieved through the application ; of small tendon forces at proper timings. The proposed deflection control method is also verified by experimental studies. This paper describes the concept of the proposed method and control algorithm. Experimental verifications and numerical simulations are shown in a companion paper.