The Research Between Temperature And Structure Modal Frequency

In recent years, health monitoring in bridge structure have already become a hot point problem in civil engineering research. Based on identifying the modal parameters, inspecting damages for bridge structures is developed which can help to eliminate hidden troubles and avoid the occurrences of catastrophic accidents. This circumstance will cover up the modal parameter variety that caused by the structure small injury. Temperature variety is the main factor that influences the modal parameter variety among environment factors. So, it is very important to study the relationship between temperature and frequency.In order to establish the model between temperature and frequency, definite the effect degree, improve damage identification precision, so in this paper, one concrete beam which distributes the two acceleration sensor on cross-section is considered, the temperatures of every measure points are gathered, then the effective temperature and the temperature gradient are decomposed, two parts are considered respectively. Through laying two acceleration on the beam top, through making use of dynamic state structure test and modal parameter identify to carry on modal analysis; The usage of supports vector machine technique(Support Vector Machines) building up relation between temperature and modal parameter. This text's main research results are as follows:1. The effective temperature and temperature gradient on concrete cross-section are obtained through a temperature experiment in a simply beam. The changes regulation not only between effective temperature and time but also between temperature gradient and time are developed. Then, the temperature changes on cross-section can be validated by finite element thermal analysis. The experiment result is closed with the finite element analysis result.2. The dynamic characteristics are studied and one mode frequency is gained by Peak Picking Method through the concrete beam dynamic test system. Based on this, variety regulation of the instantaneous frequency in structure can be get during the test period.3. By the usage of Support Vector Machines technique, the models that effective temperature and temperature gradient with frequency respectively are built up. Then the relationship between temperature and frequency is studied. The result is that frequency changes mainly because of the effective temperature, and they show non- linear behavior.