Study On Modal Parameter Identification Methods Of Bridge Structure Under Seismic Excitation

The safety and durability of the Bridge directly with people's lives and property are closely related, through the bridge structure detection, early detection can be a bridge diseases and greatly cut down a bridge repairs, maintenance costs and avoid the ultimate frequent overhaul, caused by the closure of traffic The major economic loss, or even to prevent the collapse of bridges and other major security incidents. In the detection of the bridge, identify the modal parameters of the bridge structure, there may be detected the injury, and establish a mechanism for early warning and timely maintenance, and help to fundamentally eliminate hidden dangers and prevent catastrophic accidents. Modal traditional test methods require a structural exciting, and sometimes makes it difficult to complete testing, and the environment based on the vibration mode can be a good test method to solve this problem, it is only measured in response to signals in the circumstances modal analysis A new mode test method, they are widely used in engineering. The incentive based on the environmental vibration mode test is not expensive equipment, the structure does not interrupt the normal use, they have the convenient and time-saving, and other notable advantages, the bridge structure more in line with the actual use features. Only because of environmental vibration test measuring the vibration of output data, modal parameter identification is only based on the export of data to identify, it is different from the traditional input and output based on the modal analysis, structural engineering systems become very active in identifying research topics.This paper study for the bridge structure and the structure of incentives for the unknown, it focus on the combination (referred to as NExT / ERA) of natural environment inspire technology (NExT) and characteristics of systems algorithm (ERA) in the environmental vibration mode analysis the application.First, this paper discussed topics on the background and significance of research on the current situation at home and abroad and introduced several typical environment inspired by the modal parameter identification methods, and that the relevant method of the status quo.Second, from the basic principles of finite element from the basic concept, it introduced a finite element method and the advantages of finite element analysis of the major steps, and then introduced the incentive in the earthquake, the finite element analysis of time-law principle, the final brief with functional A powerful pre-treatment and post-processing procedures ANSYS software.Third, a study of the environmental vibration mode analysis of the Algorithm: NExT / ERA law. it introduce the NExT / ERA recognition of the theory, and the preparation of the modal parameter identification procedure to achieve the MATLAB. Finally, through the simple cantilever beams and the numerical model, a simulation of the incentive structure in the environment similar to the smooth white noise were inspired by the response, taking into account the purpose of measuring changes in points, different levels of white noise outside interference. Application NExT / ERA identified by the beam modal parameters, the natural environment that encourage technology (NExT) and characteristics of systems algorithm (ERA) of the effectiveness and verify the NExT / ERA and the accuracy of anti-noise capability.Finally, finite element software ANSYS structural concrete continuous bridge structure of the finite element model of space, inspired by the earthquake response signal that simulation, and NExT / ERA response of the simulation data processing and analysis, identify the structure of modal parameters, And ANSYS analysis of the results, compared to verify NExT / ERA in the practical application of engineering feasibility.