Abstract
The interaction between a stiffening girder and a floor system always make some problems in the design of through-type arch bridges. The purpose of this paper is to investigate the relation between rigidity of floor system and additional stress, and to propose a design method for floor system. In order to study the interaction behavior in actual structure, a typical through-type arch bridge was analyzed using 3-D frame model. And, in order to explain the interaction behavior qualitatively, a new approximate formula was proposed by improving Bleich's formula. As the result, this study indicates the rigid design method using a box-type girder as an end floor beam excels what is called as the flexible design method.
