Study On The Theory And Its Methods Of Prestressed Concrete Bridge Dynamic Load Test

The two important methods of bridge assessment and detection are static loading test and dynamic loading test. At present, although the two test methods theory has already quite mature , bridge detection at static load test upcast of human material resources ratio dynamic load test multiple, furthermore dynamic load test can react bridge using status because no bridge is static load designing.In a few year nearly, dynamic loading test is emphasized by more and more experts and the trending is abolish static loading test by perfecting dynamic loading test the evaluation indexs of which look simple, only using in anterior a few order vibration frequency and the maximum dynamic deflection .These indexs are no relation each other, in other words, when one of them meets needs but cannot reflect others' eligibility. Single vehicle road does not increase except vehicle speeding and moving road, so we should pay much attention to research vibration characteristics of structures.Based on many literature datas at home and abroad, the article researches mechanical characteristics and dynamic characteristics of Prestressed Concrete Bridges firstly, then discusses limitation and developmental characteristic of domestic bridge dynamic testing at present and proposed the idea of abolishing static loading test by dynamic loading test.On aspects of theory analysis, deduced finite-element analysis calculated formulae using energy method , then establish prestressed concrete bridge dynamic calculation model and deduced theory calculation expression formula of test parametric of prestressed concrete bridges.The article makes appropriate three-dimensional model using Midas, analysis natural frequency and of vibration mode of YiLi River Bridge, further analysis speed,acceleration,displacement and stress responding of special sections such as middle span and edge span in different vehicle speeding and compares damping ratio in all kinds of situation.I deduce kinds of such as kinetic energy,potential energy and doing work by external force of continuous bridge in vibration state and count all kinds of energy at specific tiime in moving loads as simply supported bridge for example , proving the feasibility and value of energy method as a comprehensive index of dynamic loading test.At last, the article refers to the constraining conditions of bridge model andcannot express practical carrying model exactly. And it is necessary to predigestenergy formulas of multi-span variable section bridge.