Studies On The Dynamic Characteristics As Well As The Evaluation Of Wide Bridge In Service Based On The Degradation Of Its Lateral Stiffness

Bridge is an important part of the highway transportation. Its performance will have a direct impact on the quality of the traffic condition. Even more, it will impact the life of the users. So, it's extremely important to detect and evaluate the property of the bridge. Because of the large wide-span ratio of the wide bridge, it has to study of the lateral stiffness of it when the property of the wide bridge is detected. However, we hardly pay enough attention to the lateral stiffness of the wide bridge when we detect the property of it.In this paper, it mainly studies of the wide bridge. The wide bridge has large wide-span ratio. And its lateral stiffness is different from its longitudinal stiffness. Due to the above specialties, this paper adopts the model of orthotropic rectangular plate to simulate the upper structure of the bridge and analyze the dynamic characteristics of it. From relationship between the dynamic characteristics and the lateral stiffness, the paper establishes the equation between the vibration frequency and the lateral stiffness of the structure. Through the data of the vibration frequency from the bridge detection, the lateral stiffness of the structure is quantitative studied, and the degradation of the lateral stiffness can be evaluated.The paper firstly researches the vibration theory of the isotropic rectangular plate. It introduces the transverse vibration small deformation theory of the elastic thin plate. And it establishes the basic differential equation and the variational equation of the plate under the system of rectangular coordinates. Using differential basic principle, it researches vibration problems, and gives corresponding frequency equations and vibration modes of the thin isotropic rectangular plate in several common boundary conditions. Using variational principle, it gives several common methods to solve the frequency approximate solution of the thin isotropic rectangular plate in the general boundary condition.Based on the research of the transverse vibration of the thin isotropic rectangular plate, the paper further researches the dynamic characteristics of the orthotropic rectangular plate. And it carefully analyzes the vibration frequencies and vibration modes of the orthotropic rectangular plate in several boundary conditions. Then, it gives vibration fi-equency approximate solution of the orthotropic rectangular plate in general boundary condition.Take for example the wide hollow slab bridge, the paper uses the principle of orthotropic rectangular plate to analyze its dynamic characteristics, when the structural orthotropic rectangular plate is equivalent to the material orthotropic rectangular plate in equal stiffness method. According to the actual support condition of the bridge, the paper gives the equation between the vibration frequency and the lateral stiffness of the structure with the boundary condition of opposite edges simply supported and the others free. Using the data of the vibration frequency from the bridge detection, the lateral stiffness of the structure is quantitative studied, and the degradation of the lateral stiffness can be evaluated.In order to further confirm the research method in this paper, the lateral stiffness assessment results of the bridge are compared between static load test of the bridge and the analyzed result of the paper. According to the compare, the assessment results are basically the same. Meanwhile, the paper also solves the vibration frequencies in different lateral stiffness and dimensions by the help of the finite element software. And it also compares the results with the calculated results by the approximate formulas. From the compare, the results are consistent with both.