Performance Evaluation Method Study Of Existing PC Beam Bridge Based On The Short-term Deflection

PC girder bridge is one of the most widely used type of bridge structure, but influenced by its structure performance, this kind of bridge in be used actually tend to have a large number of structural damage. Origin and development of bridge structure disease and damage not only affect the bridge structure performance and function, and endanger the structure of the bridge. Scientific detection and safety assessment of the bridge, to understand the status of the real bridge structure, is the rational use and maintenance in the premise and foundation of existing Bridges, bridge bearing capacity is the maximum mining, obtain the best economic benefits.The current safety assessment of the bridge method are many, in this paper, on the basis of existing research results, through the static load test, based on the short-term load deflection increment, on the basis of the relationship between deflection and bending stiffness, the PC girder bridge deflection limit research in different security levels, and the application and verification through engineering examples. The main research results are as follows:(1) Through the analysis of the deformation of reinforced concrete material performance, put forward the PC beam deflection calculation, to the bending moment of inertia measure the simplified method of flexural rigidity change. PC beam crack before and after the deflection calculation methods at home and abroad on the basis of research results, analysis of the specification and the deflection calculation methods of the standard in China, the analysis shows that crack before the standard calculation deflection is consistent with the measured values, the two countries but after cracking to steel yield stage, China specification more close to the measured values. Accordingly put forward the deflection calculation methods of the Chinese specification, reflex Bridges in service to the actual structure stiffness, and evaluation of bridge bearing capacity method.(2) Based on the bridge deflection theory and system identification theory, analyzed the deflection of the static load test of calibration coefficient rating method basic principle, its essence is through the ratio of the measured deflection and deflection theory, reflect the detection section stiffness and the ratio of stiffness theory actually, in essence reflects the actual stiffness of the structure. Three line constitutive relation based on bending curvature, PC structure is deduced in the cracking status, the yield of prestressed state, the state of concrete crush stiffness calculation. And based on the actual bending moment of inertia and the ratio of the bending moment of inertia theory of bridge bearing capacity evaluation method.(3) In the static load test of a real bridge as the engineering background, according to the transverse distribution theory, by using beam system, is deduced on the basis of static load test actual calculated by the measured deflection testing beam section flexural rigidity calculation process. And based on the presumption of the upper limit value of the deflection of the static load test, presents the deflection of bridge static test calibration coefficient to evaluate the theoretical scope of application of four level bridge carrying capacity classification standard is established.The bearing capacity of accurate analysis of PC beam bridge is a comprehensive study of the subject, according to the PC beam from the use of the destruction of a moment of inertia method of deflection limit value system is still in the theoretical stage, how to improve the parameters based on model test and theory still need to be further studied.