High-speed Rail Cfst Arch Bridges Under Earthquake Axle Coupling Vibration Study

As the national economy development and social progress, China's railway construction has gradually entered the era of high-speed railway. The characters of high-speed railway are speed, as well as the high demand for the safety, comfort and smooth, and many dynamic problems to be solved. Because of good mechanical properties, conveniency for construction, pleasing shape and good seismic performance, pipe concrete arch bridge has well application in high-speed railway. At the same time, China is a earthquake country, with the bridges in the high-speed railway are longer and longer, the probability of the train on the bridge in the earthquake greatly increases. Therefore, this paper makes a study of the x-type concrete filled-in steel tube arch bridge of Zhengzhou Yellow River. The works completed in this paper are as the following:1. With the summary of the pipe concrete arch bridge Research, vehicle-bridge coupled vibration and vehicle-bridge coupled vibration under earthquake at home and abroad, it describes the necessity of the study on vehicle-bridge coupled vibration systems under earthquake.2. Based on the principle of total potential energy with stationary value in elastic system dynamics and the "set in right position" rule for formulating system matrixes, the corresponding analysis model is established. Aim at the wide main beam of the bridge, the grillage model accord with the actual condition is established and compared with the single beam and shell model. All the results show that the method is reasonable3. Based on the backbone, the shell and the grillage, it establishes three whole models of the x-type concrete filled-in steel tube arch bridge, and makes a comparative analysis for the dynamic characteristics of these models. The results show that the grillage model is reasonable and reliable to substitute for the shell model in the following calculations of vehicle-bridge coupled vibration system under earthquake, while the freedoms are more reduced compare to the shell models.4. According to the method of quadratic polynomial fitting and filtrating long-period fluctuations in the range of frequency domain, the earthquake acceleration time history is amended and used in the method of direct integration to obtain the rate time history and displacement time history. Aimed at the difficulty of filtering some stubborn long-period seismic waves, an amendment of filtering long period waves in the frequency domain before quadratic fitting is submitted and compared with the first two methods.5. Based on the above analysis models, it comparatively analyses the dynamic response of the bridge with the combination of single-line and double lines (ICE3 high-speed trains and domestic force C300) at different speeds. Finally come to the conclusion: the traffic safety of the bridge can be assured whether in the absence of earthquake or under small earthquake, and can't be assured under the moderate earthquake and intense earthquake function.6. In this paper, it also analyses the effect of some parameters on the dynamic response, which are the height of the pier, the ratio of height to span, the train speed, the intensity and the frequency of seismic waves, and so on.