Mechanical Property Analysis Of Large-span Prestressed Concrete Box Girder

Prestressed concrete simply-supported box girder has many advantages, the sectionof the form is beautiful, the static and dynamic performance is good, light weight, shortperiod of construction and erection, It is widely used in high-speed railway bridges. Themechanical property of box section is very complex, showed significant spatialmechanical effects, the traditional calculation method of box girder mostly adopts theplane state analysis, if instead of the spatial mechanical characteristics may producelarge error.This paper takes a prestressed concrete simply supported box girder which length32m as the research object, this box girder is located on the Shijiazhuang-WuhanPassenger Dedicated Line. Based on the monitoring data of the construction site, usingMidas/Civil, a nonlinear finite element software, to establish spatial model of the boxgirder, analyze of the mechanical properties of its construction and service stages, putforward reasonable suggestions for design and construction of box girder. The mainresearch contents are as follows:1. Summarize and analyze the relevant theory of mechanical properties ofprestressed concrete box girder.2. Present the monitoring technology and method of the prestressed concretesimply-supported box girder during the construction, analyzes the monitoring data andcollate it.3. Using the finite element software MIDAS/Civil to simulate and analyze thestress of box girder, build the basic model of finite element, realized the simulation ofprestress in the entity unit, gained the maximum stress and displacement at the controlsection in each construction conditions. Comparative analysis of the simulation resultswith the monitoring data which gained at the construction site, the results of both aresubstantially the same, the measured values of stress and deformation are less than andclose to the theoretical values, stress and deformation of the beam meet the design andspecification requirements.4. Analysis of the natural vibration characteristics of prestressed concrete box girderby MIDAS/Civil, evaluate the dynamic performance, and obtained the influencingfactors, such as elastic modulus, damping ratio and the speed of the train, of dynamiccharacteristics by time history analysis method.