The Research Of Long-span PC Girder Bridge Degradation Prediction Model And The Maintenance Strategy Optimization

In recent years, with the rapid development of national infrastructureconstruction, as the long-span prestressed concrete bridges possess advantages ofpowerful spanning capacity, excellent integrity and continuity of bridge, smooth andcomfortable for driving, concise, graceful, economical and practical, that make itbecomes one popular type of the bridge in road construction in our country. However,bridges usually deteriorate and get damaged because of natural environment andlong-term usage which will affect the safety and suitability of the structures.Therefore, it is very important to get awareness of the performance status well andpredict the trend of deterioration of bridges for maintenance. This paper, basing on thereliability index of bridges, using reliability analysis method of numerical simulations,established the degradation prediction model of long-span prestressed concretebridges, and put forward that the genetic algorithm is the optimal managementstrategy for bridge maintenance. The main research in this thesis including:(1) It introduces the basic principle, characteristics and algorithm steps oftraditional First Order Reliability Method (FORM) and two numerical simulations,Monte Carlo Simulation (MCS) and Response Surface Method (RSM) respectively.Based on ANSYS Parametric Design Language (APDL), programs are compiled toanalyze reliabilities of am plane structure. The results from two numerical simulationsincluding their characteristics of calculation are compared and analyzed.(2) As the background of engineering of long-span prestressed concrete girderbridges-Beijiang. Using ANSYS Parametric Design Language (APDL) to write thecommand stream file, realize the automation of structure modeling and analysisprocess. The response surface method (RSM) based on numerical simulationtechnology is applied to analyze the reliability of serviceability limit states forbridges based on crack and deflection of concrete member.(3) The time-varying model of the corroded steel bars’section area and strength,and the time-varying model of the concrete strength are built on the basis of currentresearch about the law of reinforcement corrosion and the law of concrete strengthdegradation. The time-varying reliability computational procedure is programmed byfielding the time varying models of resistance random variable into the procedure ofthe response surface method based on numerical simulation technology. Analyze the time-varying reliability on the Beijiang bridge about cracks and midspan deflection.(4) For the beijiang bridge, on the basis of this cracks and mid-span deflectionreliability index deterioration curve and by using Genetic Algorithms compile theoptimal maintenance strategy program which make the long-span prestressed concretebridges maintenance strategy optimization, as well as work out the optimalmaintenance management plan in the life cycle and calculate the correspondingmaintenance costs.