Acquisition And Analysis Of Bridge Dynamic Characteristics Data Based On Hilbert-huang Transform

In this paper,the goal is to design a data acquisition and analysis system for dynamic characteristics of bridges.It is started with the theoretical knowledge of time-frequency analysis technology.Based on transforming time domain responses to frequency domain responses of bridges,a kind of damage index is constructed.The efficiency of damage indicators will be proved by experiments.Finally,a software system will be developed to achieving dynamic characteristics data acquisition and analysis for bridges.First of all,the basic theory of damage identification of bridge structures and Hilbert-Huang Transform(HHT)are introduced,then HHT package is programmed in C#,which is a programme language on windows platform.By comparing the characteristics of structural damage identification methods based on static and dynamic characteristics tests,the advantages of damage bridge structural identification methods based on HHT are analyzed.Then the theory of HHT is discussed in detail,the realization of which is explored in depth and the programme is realized by C#.Finally,the programme is proved effective and complete through simple harmonic vibration signal.Secondly,this paper constructes the damage indicators based on the characteristics of HHT marginal spectrum,and these indicators have proved to be effective and feasible by processing the measured data.It is introduced the concept of marginal spectrum,and its pratical significance is demonstrated by classical signals.Then,it constructs the damage indicators by comparing the marginal spectrum of the reference data and the undetermined data.After that,the dynamic responses of experimental model,a simplified simply supported beam,are measured under different working conditions,which the damage indicators can be calculated from the responses.The change laws between the structural state and the load force,and the damage location and the distance to measurement point reflected by the indicators is consistent with the actual situation.This phenomenon illustrates the effectiveness of the indicators.By measuring the dynamic respose of highway bridges,the feasibility of the proposed indicators for structural damage identification of bridges was proved.Finally,a data acquisition and analysis system for dynamic characteristics of bridges is designed,and the PC software have been development.According to the actual demand,the overall design principles are proposed for the development of the proposed system,and the system function and structure are sorted out.The sensor and hardware acquisition system used in the experiment are introduced.The data can be transmission reliably between hardware and software data by using TCP/IP protocol to network.The software system development and interface design were finished by C# on the Microsoft.NET Framework 4.0 framework,which achieve functions of real-time monitoring and data analysis.In addition,data management was realized by using MySQL 5.7 database.