Prestress Tendons Layout Considering Spatial Stress Characteristics of Prestressed Concrete Box-Girder Bridges

Prestressed concrete box-girder bridge is a typical spatial structure. Prestresses in three directions are often used to control the stresses of the slabs to meet the demands of serviceability-limited state. Because Finite Element Method (FEM) for plane beam is used by most bridge design software in practice, prestresses in different directions have to be designed separately. Researches about interaction of prestresses in three directions are rare and prestress-tendon layout arranged by spatial stress distribution of the box-girder is seldom. In this paper, a long span prestressed concrete box-girder bridge is analyzed by FEM for solid elements with reinforcement. Normal stresses of flange of the box-girder bridge in different prestress conditions are compared to explain interaction mechanism of the prestresses. Suggestions about vertical prestress arrangement are also provided by normal stress distribution of the bridge web in vertical direction.