Analysis Of Dynamic Response Of The PC Bridge By Prestress Loss

PC Bridge has been used in China years of history, with the continuousdevelopment of the socio-economic, vehicle load increasing more and more, many PCbridges have been close to the design life span, many different damages are appeared.The times of bridge of our country are also gradually transferred from the constructionperiod to the maintenance period. And the prestress Loss make a very importantinfluence on the bridge’s damage, so the study of the valied prestress value of builtbridge become extremely necessary.The strained condition and the bearing capacity canreflect from the Dynamic characteristics of the bridge structure out. Frequency andvibration model of structure reflect the strained condition. The prestress loss would leadto change in stiffness of the whole structure, frequency and vibration model of structurewill also be changed. If we can sought out the relationship between prestress andDynamic characteristics from the Dynamic Response after load impact, it will be veryimportant for Assessment and strengthening of bridges.In this article, from the damage of the concrete and stiffness strengthen ofprestressed reinforced analyzed the relationship between the stiffness and the prestresswhich is the most important factor affecting the beam frequency, proposed a method ofcalculating effective prestress from deflection and frequency of bridge, establish thecalculation formula of effective prestress based on deflection and frequency, andcontrast with the test data, got the fairly consistent result.In this article, from the damageof the concrete and stiffness strengthen of prestressed reinforced analyzed therelationship between the stiffness and the prestress which is the most important factoraffecting the beam frequency, proposed a method of calculating effective prestress fromdeflection and frequency of bridge, establish the calculation formula of effectiveprestress based on deflection and frequency, and contrast with the test data, got thefairly consistent result.The vibration of the bridge is a kind of spatial vibration, in thisarticle, through the analysis of the Beam Grillage System, established the Bridge spatialvibration model based on Beam Grillage System, transforming the Equation fromMulti-beam vibration to Single beam vibration, simplify the model and calculation ofthe bridge spatial vibration.Imitate the built bridge model after vehicle load affect through finite element, analysis the variation regularity of response of fundamental frequency and inter-spanDynamic deflection which cause by PC Bridge prestress loss. Explore the impact of theloss of prestress on the dynamic characteristics of the bridge, provide a reference forrich the bridge power detection range and improve the bridge health assessment system.