Evaluation Of Bearing Capacity Of Highway Prestressed Beam Bridge Based On Static And Dynamic Testing

With the extension of the service time,the bearing capacity of the bridge decreased year by year,causing a huge security risk.Therefore,Using the existing assessment technology to evaluate the bearing capacity and ensure the safe operation of bridges has become the key issue.Bridge load test is an important method to evaluate the bearing capacity of the bridge structure.Considering the engineering characteristics of the prestressed concrete beam bridge,this dissertation proposed a method of assessing the bearing capacity of highway prestressed concrete beam bridge based on the check-calculation method and the load test,the problem of defective evaluation index and imperfect evaluation system has been solved.The main research contents and conclusions are as follows:1?This dissertation summarized the commonly used theories and methods of assessing the bearing capacity of highway bridges,classified the limitations and advantages of each method,compared the similarities and differences of bridge evaluation norms between China and the United States,and proposed the improvement suggestions of bridge evaluation norms in China:the bridge evaluation formula should be expressed in the form of equation,which shows the abundance or deficiency of the bearing capacity by the ratio of resistance to effect;the calculation coefficient Z₂ determined by the calibration factor should be adjusted to be determined by multi-factor synthesis;the evaluation formula should also take into account the system reliability and structural redundancy.2?Based on the basic theory and method of static and dynamic load test,this dissertation discussed the evaluation index of load test in existing assessment rules,analyzed the influencing factors of calibration factor in detail,and pointed out the deficiency of the calibration factor,that is,the evaluation result is inaccurate.3?In order to solve the problem of defective single evaluation index and imperfect evaluation system,a new method of assessing the bearing capacity of highway prestressed concrete beam bridge was proposed,and the parameters of bearing coefficient index were discussed in detail.Furthermore,the flexural bearing coefficient,tensile stress bearing coefficient,compressive stress bearing coefficient and deflection bearing coefficient were established.This method can quantify the bearing capacity of bridge structure,reflect the live load safety reserve and the utilization rate of carrying capacity.4?Based on each bearing coefficient and reliability index,the comprehensive bearing coefficient evaluation index was established by using the itemized weight coefficient,the evaluation interval of the comprehensive bearing coefficient was divided preliminarily by the maintenance criterion of highway bridge,the bearing capacity and safety of the bridge were evaluaed quantitatively.This evaluation interval can guide bridge maintenance management.5?The operation flow and comprehensive evaluation method was recommended in this dissertation.The feasibility and maneuverability of the evaluation method proposed in this dissertation were verified by a simple bridge and a continuous beam bridge.