Vibration Serviceability Research With Human-included Load And Vehicle-included Load

Increasing strength of new structural materials and longer spans of new footbridges, accompanied with aesthetic requirements for greater slenderness, are resulting in more lively footbridges or some other structures. The static behaviors can meet design and operation requirements, such as the load-bearing or deformation. While the dynamic characters, especially the excessive vibration included by human, may lead to an increasing exposure and discomfort. Which may not lead to structure security, but could make the pedestrian feel nervous even panicky while pedestrian know less about the vibration.When the natural frequencies of some public structures such as the long span footbridges on the main trunk of the traffic or Landscape pedestrian bridges, are closed to normal walking frequencies of pedestrian, the resonance may be aroused. While as the magnitude of the vibration exceeds the vibration serviceability threshold that pedestrian could stand for, the serviceability performance of the structure is degraded seriously. The study of the vibration of footbridge is focused on the pedestrian-included vibration recently, while the vehicle-under-footbridge--included load is ignored the sight of the researchers. Therefore, focused on the footbridges in Wuhan, the vibration serviceability of footbridges is researched systematically in this paper. The following research works are carried out:1. On the basis of referential review of domestic and foreign bibliography, the recent national standards and guidelines on vibration serviceability of footbridge are summarized in a systematic way. The method to evaluate the vibration serviceability of footbridge in this paper are finally decided. As with the parameters in the evaluating method is discussed.2. Field test for the dynamic characteristics of9footbridges is taken in Wuhan, as a result that the natural frequencies and the dynamic response is analysed. After the vibration waves caused by the vehicle-under-footbridge are measured during different time in day and night, frequency spectrum characteristic of the vehicle-included vibration is acquired. The statistical data of the character of pedestrian walking on3footbridges is collected for determining the parameter distribution of walking pedestrian on footbridge in Wuhan, which is used in the method of evaluating vibration serviceability of footbridge.3. Li-gong footbridge is selected as a typical footbridge, and its finite element model is built using ANSYS soft, which is a large general soft on FEM(Finite Element Method). Vibration serviceability of Li-gong footbridge in different densities is preliminary assessed by using the method suggested in this paper. The vibration response of Li-gong footbridge combined with the load of pedestrian-included and vehicle-under-footbridge-included in different scenarios is simulated, and the response is compared with the evaluating result in this paper.Finally, based on the summaries and conclusions of all research works, some suggestions and prospect for further researches are put forward.