Study Of Bridge Weigh-in-motion Method Based On The Support Reaction Force

As one of the most potential tools for controlling bridge overloading,bridge weigh-in-motion system has the characteristics of good durability and high identification accuracy.Most of the current commercial bridge weigh-in-motion(BWIM)systems still adopt traditional Moses algorithm.However,the strain-based traditional BWIM systems have limitations on the scope of types and spans of bridge,and it also needs auxiliary sensors for axle information identification.The development of a new BWIM system that further enhances the recognition accuracy of vehicle weight and has a wider range of application is of great significance for bridge overloading.In view of the above situation,a bridge weigh-in-motion method based on the support reaction force(SRF)is proposed considering the sensitivity to the axle load.The method uses the support reaction force of bridge when the vehicle is driving over the bridge as the object of measurement to identify the axle weight and the total weight of the vehicle.The method can directly identify the speed and spacing of vehicle with high accuracy and applies to bridge type and bridge span faultlessl y.This article first analyzes the feasibility of the SRF method theoretically.Then,a simple supported T-beam bridge with a span of 20 meters is taken as an example.The model test is used to further verify the correctness of the theoretical analysis results.Finally,numerical simulation is carried out based on the coupled vibration theory of the vehicle and bridge.The results from this study show that:the results from both model tests and numerical simulations both show that the proposed method can accurately identify vehicle speed,axle spacing,axle weight and gross vehicle weight;the accuracy of the proposed method is better than the commonly used BWIM techniques that are based on bending strains,and this advantage becomes more obvious as the vehicle speed increases;the proposed method has good stability under the interference of road surface roughness,noise,etc.The main research contents are as follows:(1)Combining the current status of the bridge overload,this article puts forwards the significance of this topic and briefly introduces the composition and characteristics of the BWIM system.Introducing the research status and deficiency of domestic and foreign BWIM systems.Describing the principle of SRF method to identify vehicle speed and spacing.(2)The development of the bridge weigh-in-motion algorithm is introduced.The principle of identification for axle weight based on the traditional strain-based Moses algorithm is derived,and the calculation principle of the the extracted infl uence lines based on bridge dynamic response is introduced.Theoretical analysis of the advantages of the SRF method compared to the traditional Moses algorithm.Using n umerical simulation to show the potential of the BWIM based on the support reaction force in the identification of the axle information.(3)For verifying the feasibility of the SRF method,scaled model test of BWIM based on support reaction force method is designed.The preparations mainly include:the design of a model test platform,the determination of materials and dimensions of bridge models based on similar principles and similar propor tions,and the production of test platforms.The SRF method is studied under different vehicle speeds(1m/s-5m/s,corresponding to the actual vehicle speed range 10.4km/h-52.2km/h)and lateral loading positions by model test.The experimental results show that the SRF method has high accuracy in the identification of vehicle speed,spacing and axle weight.(4)In order to further analyze the stability of the SRF method,combined with the vehicle-bridge coupled vibration theory,the parameters of the BWIM based on support reaction force method are studied.The influences of vehicle speed,road surface roughness level,noise level,bridgehead jump,multi-vehicel traffic on the identification accuracy of axle load and total weight are studied.Comparing the accuracy of the axial weight and the total weight of the traditional strain-based Moses algorithm under the same conditions.