Research On Serviceability Design Of Long-span Floor And Footbridge Induced By Pedestrians Load

With the development of modern structure trending to be the light, large span, delicate and exquisite, the problem of vibration discomfort of structure is becoming more and more obvious, some buildings have to be reinforced, transformed even dismantled.It is easy to see that the solution of vibration discomfort of structure will be very difficult, so the analysis and research of the design on vibration discomfort of structure is great essential. The problem of floor and footbridge vibration due to human active was studied from the point of structural dynamics, ergonomics and theory of probability in this article.First of all, this article introduces Standards of Design and Evaluation Method about vibration comfort of floor and footbridge, through the method proposed by Ellingwood,30representative samples of time histories of human walking loads are simulated using Uniform Experiment design method. After a large amount of dynamic simulation on floor and footbridge by newmark method, the maximum acceleration response spectrum and the RMS cceleration response spectrum of vertical vibration of floor was achieved,the maximum acceleration response spectrum and the RMS aceleration response spectrum of lateral vibration of footbridge base on Interaction between man under the bridge was achieved. After researched the sensitivity of the span, boundary conditions, damping ratio and other factors of response spectrum, Reference response spectrum, Correction factor and envelope of Reference response spectrum were achieved. The a shortened form method that can calculate the maximum acceleration response spectrum and the RMS cceleration response spectrum of floor and footbridge was brought forward. The method can be used in the evaluation of the structure’s vibration discomfort.The research of structural vibration caused by single pedestrian load is relatively enough, vibration of the structure under the effect of crowd is becoming the focus of current researches. Monte-carlo simulation is adopted to research the vertical vibration response of floor and lateral vibration of footbridge in this article, included two major contents. (1) through20000times’ simulating of floor under different density of population, the Average value and Standard deviation of maximum acceleration and RMS cceleration of floor were achieved. Farther, the function relation of the response and the crowd can be achieved. changing the boundary conditions and the ratio of span, then20000times’simulating under the same density of population. The correction factor of boundary conditions under different ratio of span was achieved. Based on these factors, the acceleration response of floor was easy to obtained.(2) The footbridge lateral vibration under man-bridge interaction is considered. A dynamic model under man-bridge interaction was established base on additional lateral pedestrian force, through20000times’simulating of footbridge under different density of population, the function relation of the lateral vibration response and the crowd can be achieved. Further, compared dynamic response of footbridge between the influence of man-bridge interaction and without considering the interaction, the results showed that the influence of interaction can not be ignored when the number of people exceeds20. The method of structural vibration responses under different density is summarized, this method can be used to assess comfort of footbridge.This article studied the discomfort caused by structural vibration based on the method of response spectrum and Monte Carlo simulation, a general method for Assessment of two structures was obtained. This research will play a positive role in the application of engineering.This dissertation is part of the project sponsored by the Natural Science Foundation of China(Grant No.:51168021).