车流密集程度对重载随机车流与桥梁耦合振动影响分析

Analysis of the Impact of Traffic Density on Coupled Vibration of Overloaded Random Traffic Flow and Bridge

目的 将元胞自动机建立的重载随机车流模型引入车桥耦合振动系统,探究重载随机车流密集程度激发桥梁振动响应规律。方法 基于元胞自动机和NaSch模型,模拟道路交通周期边界条件下单向双车道重载随机车流,真实还原桥梁上车流演变规律,建立考虑车型、车速、车道、车重和驾驶员行为特性的重载随机车流-桥梁耦合振动模型;采用MATLAB软件编程求解重载随机车流与桥梁耦合振动特性。结果 重载车流从自由流向阻塞流转变,桥梁竖向挠曲变形逐渐增大,振动加速度先增大后减小;阻塞流时桥梁产生最大竖向变形,密集流时桥梁竖向振动速度和加速度响应最剧烈。桥梁振动响应的能量峰值主要集中在桥梁主频4 Hz和9 Hz附近,且随着车流密度增大、车速降低,随机车流激发的桥梁振动响应能量峰值先增大后减小。结论 车辆占有率为18%的密集流出现最大振动响应能量峰值,车辆占有率为31%的拥挤流最易激发桥梁高阶频率振动。

The study establishes a model of heavy random traffic flow based on cellular automata and introduces a vehicle-bridge coupled vibration system to explore the law of bridge vibration response induced by the density of heavy random traffic flow.By simulating one-way two-lane heavy random traffic flow under periodic boundary conditions using cellular automaton and NaSch model,the study aims to accurately reproduce the evolution of traffic flow on the bridge,and establish a coupled vibration model of heavy random traffic flow and bridge which vehicle type,speed,lane,weight,and driver behavior characteristics are taken into consideration.MATLAB software is used for programming to solve the coupled vibration characteristics of heavy random traffic flow and bridge.The results show that the overloaded traffic flow transitions from free flow to blocking flow,and the vertical deformation of the bridge gradually increases.The vibration acceleration initially increases and then decreases.The maximum vertical deformation of the bridge occurs during blocking flow,and the vertical vibration velocity and acceleration response of the bridge are most intense during dense flow.The energy peak of the bridge′s vibration response is mainly concentrated around the bridge′s main frequencies of 4 Hz and 9 Hz.With the increase in traffic density and the decrease in vehicle speed,the energy peak of the bridge′s vibration response excited by random traffic flow first increases and then decreases.The maximum vibration response energy peak occurs during dense flow when the vehicle occupancy rate is 18%,and the congested flow with a vehicle occupancy rate of 31% is most likely to excite higher-order frequency vibrations in the bridge.