Driving Comfort Study On Wind-induced Vibration And Vehicle-bridge Coupling Vibration Of Cable-stayed Bridges

With the development of design theory and the advancement of building materials and construction techniques, modern long-span cable-stayed bridge is approaching towards the extra long-span and extremely flexible structure. The research on coupled vehicle-bridge system caused by wind has been increasingly urgent. Such vibration may cause the fatigue failure of some local components on the bridge and reduce the service life of the bridge. What is more, some large vibration displacement can even have a influence on the comfort and safety of the drivers and passengers.Therefore, It is very indispensable to investigate on the vibration of coupled vehicle-bridge system caused by wind and the comfort during driving. Based on this,the following aspects are studied in this research:1. Based on the force features on the cable-stayed bridge, the FEA model of a large span cable-stayed bridge is established with the software ANSYS. Analysis on self vibration of the proposed model is conducted to study the dynamic characteristics of the bridge and the accuracy of bridge modelling is verified as well.2. According to the features of the wind field on the proposed bridge, WAWS method is utilized to simulate the fluctuating wind velocity time history. Based on the quasi-steady aerodynamic forces theory, the expressions of the aerodynamic forces acted on per length of the whole bridge deck are introduced. Finally, the time history of lifting force, dragging force and lifting moment of the cable-stayed bridge are calculated.3. With the representative seven degree vehicle model, numerical methods are applied to simulate the roughness of ground, the sample function of excitation is obtained. Assuming the vehicle and bridge as a system, the roughness of ground as self excitation, the analysis model and governing equation of the coupled vehicle-bridge system under wind force are obtained.4. The influence of speed, weight, road level, wind-speed on the dynamicalresponse is studied with or without the consideration of wind. The vertical responses of bridge and vehicles are obtained.5. Systematically conclude the criterion and evaluation method of the driving comfort both in domestic and overseas, summery the latest ISO criterion which may be applied in the presented research, and list some assisted frequency analysis methods to evaluate the horizontal driving comfort for comparison. In accordance with the ISO2631 1/3 octave analysis, the vertical acceleration in different operation condition are transferred to the Sperling smooth index and the acceleration mean square which are applied in the evaluation of driving comfort.6. As indicated in the research results, the reduce of road level, increase of vehicle speed, increase of weight will result in the increase of the dynamical response without wind force. Among which, the road level has the largest influence on the dynamical response and the driving comfort requirements can be satisfied in this situation. However, with the consideration of wind force, the dynamical force of the bridge may significantly increase. For some extreme condition, the neither the comfort requirement or the safety can be satisfied.