Abstract
In recent years, many cable-stayed girder bridges with a long span length more than 400m have been planned and these projects are mostly planned as structures with multipie cables. Nevertheless, the materials for basic planning of them have not been prepared sufficiently so far.
In this paper, the materials for basic planning of them are presented. That is to say, the determining method of prestress quantity of the cables which is most important on designing the cable-stayed bridges is discussed and presented relating to the anchoring points of the cables to the girder. Furthermore, the materials for selecting the ratio a side span length to a center span length are presented.
