Seismic Damage Identification Of Bridge Structures On Time Domain

Earthquake is a kind of sudden and destructive natural disasters. It will not only make the people's lives and property losen, but also give a variety of buildings and bridges the great damages. As the hub for transportation, bridges are able to bear heavy transport in the normal time, and they can also become the artery to transport the relief supplies, and more importantly, the evaluation and repair for them are also very significant after the earthquake. Therefore, it is meaningful to establish health monitoring system in the bridges to monitor the health status after the earthquake.As the core technology in both health monitoring system and engineering structural test, damage identification becomes a hot research focus in recent years. Its main task is to use actual measurement data to identify whether there is damage, damage type and damage location in the structure. The results of damage identification can provide damage detection with general location, and can make the early warning when the damage exceeds regular value, and can also serve as the base for the structural reliability evaluation. Consequently, it is significant to research on the structural damage identification theories and methods.The method of ARMA model(Auto-Regressive and Moving Average model) is an important method to analyze time series. It consists of autoregressive model (AR model), moving average models (MA model) and their "mixed" form. In this paper, ARMA model is used as a main damage identification method. By using ARMA model's time-domain analysis function, especially the high precision prediction in the short-term, the acceleration time history data is used to form DSF to detect the seismic damage in bridge structure. A numerical test of a large span continuous rigid frame bridge under earthquake is carried out, and the method of this paper is used to detect the seismic damage in the brdige. The results show that the method can accurately identify whether there is damage, damage location and damage ponderance. The following aspects are included in the study:1, Significance and development of the damage identification for bridge structures are briefly described, and problems and difficulties of the study in the present are briefly introduced; 2, Seismic vulnerability of the bridge structure is analyzed and the general vulnerable sites on the bridge are found for the guidance of location of data exporting points;3, Damage detection theory under dynamic fingerprint and time-domain-ARMA model and its moder construction methods are systematically described;4, A large span concrete continuous rigid frame bridge-Jiujiapeng Bridge is used as the study project, and the seismic numerical test is carried out to varify the structural damage indentification method of this paper. Finite element analysis software ANSYS is used to establish Jiujiapeng Bridge's finite element model for structural dynamic analysis, and the acceleration time history of some nodes are collected. The ARMA model is established by MATLAB program, and regression coefficient from the model is used to form structural damage sensitive factor-DSF. The DSF value is used to show whether there is structural damage, damage location and damage ponderance, and the results are analyzed and summarized.Finally, all the work and research results in this paper are summarized, and problems that need further study are briefly indicated.