Application Of Two Time Domain Methods In Modal Parameter Identification Of Bridge Health Monitoring

A large number of bridges have been built in China since 1949,but most of the bridges have not been properly maintained and maintained.By the end of 2006,there were more than 100 thousand disease bridges in our country.Therefore,it is of great significance to study how to effectively evaluate the health of the bridge structures.As an important step,modal parameter identification is also one of the hot research topics.In this paper,combined with the development of the health monitoring system of bridge structure,the application of two time domain modal parameter identification methods of ERA and SSI in the steel truss bridge is discussed.Through the related research work,we hope to provide an example for the application of the two time domain methods in the modal identification module of the health monitoring of steel truss bridges.This article will show you in such aspects:(1)Multidirectional comparison and analysis of structural modal parameter identification under environment excitation are carried out.Finally,ERA method and SSI method are selected as the main methods of research and analysis.(2)The bridge structure health monitoring system is explained in detail,and some structural health assessment methods are explained with the relevant mature system.At the same time,we also find that modal parameter identification of bridge structure is an important part of the system.(3)The MIDAS CIVIL is used to establish model of he Songhuajiang River dual-purpose bridge for modal analysis.The first ten modes of the structure are obtained,and some characteristics of the first ten order modes are analyzed and explained.(4)Considering the result of the finite element modal analysis,the vibration test of the structure of the Songhuajiang River dual-purpose bridge under the environmental excitation is tested to get the vibration response data of the key parts of the structure.(5)the modal parameters of the structure are obtained by calculating and analyzing the obtained response data through the ERA method and SSI method based on the state space model.Because of the large and complex structure of the structure,the main analysis is the self vibration frequency of the structure.The data obtained from modeling modal analysis are compared with those obtained from two kinds of time domain methods.We can find that the results of the two method are both accuracy,and the feasibility of the two methods applied in the steel truss bridge structural health monitoring system is verified.