Analysis Of Crawling Of Curved Girder Bridge Under The Action Of Random Traffic Flow

Curved girder bridges with beautiful curves can span complex terrain and fulfill the demand of vehicle traffic,which is an indispensable part of today’s transportation construction,but some of the concrete curved girder bridges have developed various diseases during the long-term operation and use,and the crawl problem is more prominent.Main beam to crawl will cause bridge bearing to shear damage,pier column and seismic block cracking,etc.,and even trigger bridge overturning,which seriously threatens the structural stability of the bridge.The combined impact on a number of loads causes curved bridge crawl.One of the key factors of curved beam crawl is the time-varying radial force produced by the vehicle for the bridge and the braking force produced by the fluctuating speed.This thesis establishes the solid model of curved girder bridge and considers the time-varying and random nature of vehicle load in order to study the influence of vehicle load on the crawl of curved girder bridge and effectively control the crawl disease.We expect to get the crawl law of curved bridge by analyzing the response to curved bridge under the action of three kinds of traffic flow based on CA’s micro traffic flow,heavy vehicle flow,and bulky transportation vehicle.The major research and relevant conclusions of this thesis are as follows.(1)The shear-slip characteristics of the bearing are investigated using the solid finite element model of the circular plate rubber bearing and the spring model of the basin rubber bearing.Under various operating conditions,the single girder model and the girder lattice models were developed and compared to the solid model of the curved bridge.The findings demonstrate that the proposed solid model of the plate rubber bearing has an error of only 0.024% between the tangential rigidity and the theoretical rigidity,that the hysteresis curve of the spring model of the basin rubber bearing complies with the bilinear spring mechanics model,that the vertical displacement error of the bent bridge model section is less than 0.1mm,and that the error of the bearing reaction force is all within5%.These studies indicate the solid model’s validity.(2)Through the traffic load survey data,the random traffic flow parameters such as vehicle class,vehicle type proportion and vehicle mass were determined.The front and rear suspension lengths of vehicles were comprehensively considered to determine the cell size.Take into account the length of the vehicle’s front and rear overhangs as well as the metacell size.Vehicle speed characteristics are analyzed to determine the vehicle overthe-curve bridge speed change rules,as well as the formulation of vehicle curve travel rules and lane change rules.MATLAB is used to produce random traffic flow,which simulates actual traffic flow better.(3)To investigate the influence of varying traffic densities on the crawl of the curved bridge,the microscopic traffic load is equivalently applied to the curved girder bridge.The results of the traffic flow calculation are then contrasted for various sections.The results reveal that as traffic density increases,so do the maximum and average values of the transverse displacement of the curved girder bridge section and the difference in the reaction force of the external support within the same section.The frequency of peak cross-sectional transverse displacement rises as traffic density increases.The average value of lateral displacement produced by steady section traffic on the curved bridge are less than 55% of that produced by deceleration section traffic,and the maximum value is less than 65% of that produced by deceleration section traffic,and traffic in the deceleration section has a greater influence on the crawling of the curved bridge.To guarantee that the curved beam bridge operates normally,the vehicle should be brought down to a reduced driving speed before entering it.(4)The influence of heavy vehicles on the crawling of curving bridges was studied using three parameters: vehicle weight,vehicle speed,and fleet vehicle spacing.The heavier the vehicle,the faster it travels,the closer the spacing between fleet vehicles,the greater the maximum value of transverse displacement and residual value of the curved bridge section,and the greater the difference in reaction force between the outer and inner supports of the same section.To control the curving bridge crawl,the heavy truck’s weight and speed should be closely restricted,and the vehicle should maintain a suitable workshop distance when traveling.(5)The influence of large transporter on the crawling of curved bridge is analyzed.The results demonstrate that the bulky transport truck has little impact on the crawling of the curved girder bridge,and little residual displacement is created on the cross section,but due of its considerable weight,the vertical damage of the support must be considered.