A numerical procedure for linear-elastic analysis and nonlinear material analysis of curved prestressed concrete box girder bridges is demonstrated through two examples. A curved nonprismatic thin-walled box beam element is used to model the bridges. The cross sectionof the element is a rectangular single-cell box with side cantilevers. Eight displacement degrees of freedom, including transverse distortion and longitudinal warping of the cross section, are consideredat each of the three element nodes. Prestressing, consisting of posttensioned bonded tendons in the longitudinal direction, is considered. For nonlinear material analysis, the uniaxial stress-strain curves of concrete, reinforcing steel, and prestressing steel are modeled. The shear and the transverse flexural responses of the box beam cross section are modeled using trilinear constitutive relationships based on cracking, yielding, and ultimate stages. The first example demonstrates the versatility of the numerical method in determining the linear-elastic distribution of forces in a three-span prestressed box girder bridge of curved plan geometry and variable cross section. Dead load, live load, and prestressing load cases are analyzed. In the second example, overload behavior and ultimate strength of a three-span curved prestressed concrete box girder bridge under increasing vehicular load are investigated. The different response characteristics of the bridge induced by different transverse locations ofthe overload vehicle are presented. This paper appears in transportation research record no. 1180, bridge design and testing.
Abstract