The Research Based On The Measurement Of Dynamic Deflection Of Bridge

The Static deflection of the bridge structure and the vibration performance of itunder dynamic load are both the important indicators of bridge inspection. Thisdirectly reflects the bridges’ stiffness, stability, carrying capacity, seismic behaviorand so on. We can derive the deformation of individual point from the wholedeflection curve and estimate whether they are safe. The Traditional methods ofmeasurement are easily affected by the environment, sensitivity and accuracysurrounded. When the vehicles drive the bridges quickly, those methods cannot beused. The curve that vibrates up and down along the zero can be measured but largepart of the deflection may be lost.So a new method should be found to measure the dynamic deflection of bridges.The static deflection and strain can be easily measured. So first a assumption shouldbe made that a relationship existed between the static deflection and strain which canbe defined as Calibration Value. Then the calibration value is applied to the dynamicdeflection. That is the relationship that also exists between the dynamic deflectionand strain and we can obtain the dynamic deflection by this relationship.This paper discards the traditional method to measure bridge static deflectionand dynamic deflection and use a new method to survey them. The concrete methodis as follows: Take uniform section of the simply supported beam as an example. Themain content of the research in this article is as follows:(1)Summarize the research at home and abroad on the bridge static anddynamic characteristics. This summary includes two parts: Theory and practicemeasurement methods. We list some experiment methods and instructions tomeasure above characteristics of bridge in engineering, and analyze their advantagesand disadvantages. Then choose a batter deflection mode to express deflection of thesimply supported beam.(2)Obtain the relationship between the static deflection and strain of mid-span.Then get the dynamic deflection though the Calibration Value and dynamic strainand verify the accuracy of it.(3) Analysis the impact factor of the bridge and find a new breakthrough pointof fatigue analysis.