Research On Driving Comfort Of The Elevated Bridge

The urban elevated bridge has become the preferred scheme of large and medium-sized city’s main traffic distribution, the efficiency and capacity of urban elevated bridge’s traffic organization directly affects the overall traffic of the city. Vehicles will change the dynamic characteristics of the structure when it’s passing the elevated bridge. In addition to ensure the safety of the bridge, the bridge vibration will also influence the comfort of driving. This is a process of vehicle-bridge interaction(VBI), especially when one side pass, the other side in a traffic jam, the vehicle the driver and passenger feel more intense discomfort in the vehicle which in the traffic jam side.previous research on VBI rarely involves the bridge as a board, and ignores the torsion effect of the board, so it can’t accurately simulate a side by passing vehicle influence on the passengers to the traffic jam side. So the research of driving comfort problems on the elevated bridge is very necessary.Now Various countries mainly research the vibration problem aimed at the subway, highway,light rail traffic system, they rarely involves the vibration problem research on urban elevated bridge. The vehicle problem on highway Bridges based on the theoretical analysis, and lack of the measured data based on calculation and analysis.It pay no attention before because of the elevated bridge’s short span compared with other bridges, but the width-span ratio across the elevated bridge is very big, sometimes even reached1:1. So the space effect of elevated bridge should not be ignored, when one side pass of the bridge, the traffic can produce larger response to the other side of the bridge, and the traffic on the bridge vibration response inside the passenger vehicle and driver, which in turn could cause the passenger discomfort.The paper aims at large bridge structure with background of the South LuoShi Road elevated bridge, the system of VBI is divided into two substructures, which are moving vehicle-bridge substructure and upper static vehicle. Vehicle-induced dynamic responses of the large steel box bridge structures and the people’s comfort problems on the static vehicle is researched systematically. The following research works are carried out:(1) As to the moving vehicle-bridge substructures, moving load-bridge calculation model is established, and according to the model, the paper established a seven degree of freedom vehicle model with quality-spring-damper general distribution.(2) The paper consider bridge deck roughness as a smooth random process.Based on frequency domain power spectrum equivalent, it simulated bridge deck roughness.(3) The paper established the space coupling equations of vehicle-bridge,which separately solve the equation of vehicle and bridge equations with iterative method.(4) The paper created VBI analysis program based on MATLAB and ANSYS APDL language,which can be suitable for VBI simulation analysis under different working conditions.(5) The paper researches vibration response of the South LuoShi Road elevated bridge. Modality tests based on environment motivation and elevated bridge vibration response tests based on vehicle loads are made, and correctness of the elevated bridge model and effectivity vehicle-induced method are checked.(6)Calculation model of the upper vehicle in traffic is built. Obtaining vibration acceleration reaction of bridge from calculation results of upper moving vehicle’s vibratory response, and use the vibration acceleration reaction as input load of vehicle in traffic, dynamic response of vehicle in traffic is calculated.(7) On the basis of the above analysis works, the paper calculated the vibration acceleration reaction of vehicle in traffic under the most unfavorable conditions, and evaluated vibration comfort level of the people in vehicle under traffic jam.