Abstract
The present study attempts to determine the optimum cable-stay forces for the design of prestressed concrete (PC) cable-stayed bridges. Unlike the steel cable-stayed bridges, PC cable-stayed bridges have two stress adjustment systems, which are systems for cable-stay forces themselves and internal prestress in the main girders. A formulation combining these systems has been presented as a problem of optimization of cable-stay forces. Also formulated is the mechanism of changes in forces due to creep of the concrete and treated is the creep in the optimization process. As a result, determination of the optimum stay forces for PC cable-stayed bridges requires solving two simultaneous systems of the stay forces and the internal prestress. Another result shows that the stay forces tend to approach the characteristic stay forces which are inherent in the individual structure.
