The Application Of Curvature Mode Analysis Method In Bridge Damage Identification

With the rapid development of society,science and technology are changing for the better day by day.The civil engineering field has also been developed unprecedentedly.Large and complex bridges are constantly emerging.While achieving amazing achievements,the damage accumulation of bridge structure also is one of the problems that must pay attention to.The safety of the bridge structure relates to the safety of people's lives and property,and relates to the harmony and stability of the country and society.And it's designed to last a couple of decades,it is not possible to serve people all the time.The unknown is always terrible,if cannot grasp the damage condition of bridge,which will be very passive.If grasp effective information,it will effectively prevent the danger and ensure the safe operation of the bridge.Curvature modal analysis is used as the research direction,the curvature mode analysis method is applied to a three span continuous beam bridge,and by using the mobile vehicles,the traditional curvature mode parameters are improved.Through real bridge analysis,the identification effect of the curvature mode analysis method and the improved curvature mode parameter are verified.The main research contents are as follows:1.The theoretical basis of bridge damage identification method based on curvature mode theory is expounded,and to put forward to some damage identification parameters which are derived from the mode curvature:curvature mode difference,curvature mode change rate,mean curvature mode damage factor and instant curvature mode damage factor.These damage identification parameters are able to identify the damage location and damage level of the bridge structure.2.A three span continuous beam is taken as the research background.The vibration characteristics of continuous beam under different damage locations and damage degress are caculated by the finite element software Midas.The curvature mode of each node is calculated by the central differernce method.Observe the curve diagrams which are drawn by the five damage identification indicators.The results show that the damage location can be found based on the point where the curve changes abruptly.3.The mobile vehicle in the power test can simplified as a mobile quality model.Five kinds of curvature recognition parameters under the action of mobile vehicle are put forward.Through the numerical simulation,the vibration characteristics under the action of the moving mass can be obtained.With that,calculate the damage parameter identification curve with the changing of the position of moving mass.An automatic screening program is developed to analyze when the moving vehicle travels on the bridge,when the damage identification parameter curve changes most violently.At the same time,the damage identification parameter curve is combined with the damage identification information.With this result,bridge damage information can be obtained by the combinstion of damage identification parameter.4.Simulate natural excitation and vehicle excitation under different damage conditions of beam bridges,systematically analyze the five mode damage identification indicators,compare the characteristics of each parameter and the conditions encountered in the research.