Research On Damage Identification Of Mid-arch Bridge Based On Curvature Mode

The rapid development of the economy has promoted the rapid development and expansion of the bridge system.The mid-supported arch bridge is widely used in practical engineering because of its shape and force.The medium-sized arch bridge will be used in various operations.The causes,such as external force,environmental influence and fatigue effect,are damages,and the damage is also a cumulative process.When the damage accumulation changes from quantitative change to qualitative change,the structural members of the bridge are damaged or the overall structure of the bridge is unstable,causing serious damage.Accidents that damage people's lives and the safety of public property.In order to avoid the occurrence of such accidents,this paper promotes the development of bridge health monitoring system,and conducts damage analysis on the main force-transmitting component of the mid-support arch bridge.In this paper,a finite element model of a mid-supported arch bridge with a span of 142.5m and a calculated center height of 35.64 m is used.The finite element model is established by using the finite element software Midas/civil.The object of the test is to test and analyze the damage of the mid-support arch bridge boom.In order to study the positioning problem of damaged hangers,this paper firstly uses the curvature mode method to locate the damage of the suspension rods,and set up the damage of single boom,double boom,triple boom and different damages caused by small damage.In this case,the position recognition ability of the traditional curvature mode based on dynamic characteristics is studied under different damage conditions.The first four orders of mode vector data are extracted,and the curvature difference is calculated by the central difference method.The traditional curvature mode method has certain recognition ability.Fractal theory is one of the important branches of modern mathematics nonlinear disciplines.Its ability to describe local irregularities such as graphics is widely used in various fields.In this paper,the development history,definition and characteristics of fractal theory are briefly summarized,and the different fractal dimensions in fractal theory are introduced.The Katz dimension and its calculation method are described in detail.Due to the selection of the Katz dimension and the number of sample distances in the sliding window and the distance of the measuring point,in the case of aconstant distance of the measuring point,the structural damage positioning ability and description ability when the number of sample distances in the window are 2 and 4respectively The comparison is made,and n=2 is selected as the number of sample distances contained in the Katz dimension sliding window of this paper.In this paper,the Katz dimension is used in the field of bridge structure damage identification,and the local irregularity of the vibration mode of the bridge structure caused by the suspension damage is described based on the dynamic characteristics.The different damage conditions of the mid-supported arch bridge boom in actual engineering are set.The fractal dimension is used to describe the local irregularity of the vibration mode under different working conditions.The description tool is Katz dimension difference and Katz dimension curvature difference.And the results are compared with the set conditions,verifying the ability of the Katz dimension difference to locate the damage position of the boom and the different feedback information for different damage levels.In addition,the curvature based on the dynamic characteristics from multiple angles The modal method and the Katz dimension method are compared and analyzed,and their advantages and disadvantages are pointed out.