| With the rapid development in transportation of China, bridges have encountered increasing new dynamic problems due to heavy traffic load, including vehicle-bridge coupling vibration (VBCV) of bridges with complex configurations, vibration of cable-stayed bridges and stay cables due traffic load, and low-frequency noise induced by vehicle-bridge vibrations, etc. The traditional methodologies are not always applicable for these new problems, for which great endeavor should be made to establish new models and methodologies.In this thesis, a finite element (FE) model of spatial cable-arch-beam system including the effects of local vibration of cables is developed for concrete-filled steel tube arch bridges having complex profiles. For each hanger cable, the multiple degrees of freedom (MDOF) are reduced to two end nodes by replacing all of inner nodes using the eigen-functions of the whole cable, thus avoiding heavy computational costs in the traditional FE simulations with direct use of cable elements. Based on the theory of VBCV with a vehicle model of MDOF, the newly proposed model is then applied to simulate the Changfeng Bridge in Ningbo. Intensive investigations are performed to the effects of road surface roughness, vehicle velocity, and structural damping on wheel load and impact factors of arch ribs, main girder, and cable tension.The VBCV of cable-stayed bridges (CSB) are also studied using the proposed FE model considering the effects of local vibration of stay cables. As a case of medium-span CSB, the subpart of Hangzhou Bay Bridge over the north channel is analyzed with emphasis on the impact effects on its dynamic responses. For super long-span CSB, attentions are focused on the vibration of stay cables. The equations of motion in incremental forms are established for the nonlinear vibration of long and flexible stay cables based on the theory of VBCV. A long span CSB with span of 1400 m is investigated as an example. Both nonlinear vibrations of steel and CFRP cables are analyzed comparatively, and the potential applicability of CFRP cables in long-span CSB is evaluated.A major part of the thesis is devoted to the low-frequency noise induced by the vibration of bridges. Firstly, numerical results based on the analytical solutions for acoustic radiation of point source are presented for a simply supported steel girder bridge. Here, the bridge deck is modeled as a beam-plate system considering merely the shear deformation of the plates fully supported by beams. Secondly, the boundary integral equations are derived for three-dimensional sound field, which is solved using the boundary element method (BEM). Thus, a combined method of FEM-BEM is developed for the problem of VBCV-induced low-frequency noise for steel girder bridges. Finally, the image method is adopted to incorporate the effects of reflection of acoustic waves by the ground on the sound field near the bridge deck.The proposed hybrid FEM-BEM is employed to analyze to the steady-state and transient acoustic radiation by the VBCV of simply supported or continuous steel girder bridges. By comparing numerical results to the on-site tested data, the correctness of the present formulations and BEM code, as well as the effectiveness and efficiency of the proposed method, is firmly validated. Numerical results are given both for the noise level around the bridge deck and for the distribution of sound pressure in spatial and time domains. Comprehensive analyses are carried out against the effects of road surface roughness, velocity of vehicles, and distance of bridge deck away from the ground on the noise level and distributions of sound field. Finally, the hybrid FEM-BEM is applied to evaluate and verify effective strategies for noise reduction for continuous steel girder bridges.
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