3-D Behavior and Strut-and-Tie Model Analysis of Diaphragm in PSC Train Bridge

PSC철도교량 격벽부의 3차원 거동 및 스트럿-타이 모델 해석

The function of diaphragms at abutments and piers of prestressed concrete (PSC) box girder train bridge is to transfer forces from the superstructure onto bearings or column and to stiffen the superstructure cross-section against in-plane deformation. Due to large stress disturbance at diaphragm, the design for the diaphragm using conventional design method is relatively irrational than designs for other structual members. And, due to contribution to boundary condition of deck slab by the diaphragm, the behavior of deck slab near the diaphragm is different from behavior of the deck slab obtained from two dimensional analysis of the bridge, which is basis far the design of deck slab. In this paper, three dimensional behavior of deck slab near diaphragm of PSC box girder train bridge constructed by the precast span method are analyzed by using three dimensional finite element modeling. Then, strut-and-tie model is applied to design the diaphragm of PSC box girder train bridge. The modeling techniques in this paper can be applied effectively to examine the causes of cracks at deck slab near diaphragm and to design diaphragm rationally.