Bridge Weigh-in-motion Based On The Virtual Simply-supported Beam Method

The Moses algorithm is one of the most reliable bridge weigh-in-motion(BWIM)technologies,and is the basis of the commercial BWIM systems.However,restricted by the calibration of the influence line,the current commercial BWIM systems can only be applied to short-span bridges.Exploring new ways to further expand the bridge span scope of BWIM application has become an important and urgent problem.In order to solve this problem,the virtual simply-supported beam method(VSSB)was proposed,in which the strain of an isolated section of a bridge was used to calculate the axle load and the vehicle weight.The proposed method can be applied to large span bridges and is not restricted by the bridge span length.The finite element models of two simply-supported T-beam bridges with span lengths of 20m and 40m were built.Based on the developed vehicle-bridge coupled system,the bridge responses were obtained and used for identifying the axle load and the vehicle weight with the proposed new method.The influence of the road surface roughness,vehicle speed,etc.,on the simulated results was analyzed.The identification precision of VSSB was compared with the traditional Moses algorithm.Finally,the new method was verified by the scaled model experiment.The simulation results show that:(1)for the T-beam bridge with a short span length of 20m,the average identification errors of vehicle weight for the three-axle vehicle and the five-axle vehicle are around 2%and less than 1%,respectively;(2)for the T-beam bridge with a span length of 40m to which the traditional Moses algorithm is not applicable,the average identification errors of vehicle weight for the 3-axle vehicle and the 5-axle vehicle can be controlled within 3%by using the new method.The results indicate that the proposed new method is not restricted by the bridge span length and has the potential to be applied widely.The main works are summarized as follows:(1)The research background and its meaning were introduced.The dynamic weighing technology classification for the moving vehicle load was introduced,and advantages and disadvantages of the WIM system and the BWIM system were presented.Research status of BWIM at home and abroad were reviewed,and the main research content was summarized.(2)The dynamic equations of the vehicle-bridge coupled vibration were introduced.Bridge models were established in ANSYS software.And vehicle models were also established.The road roughness hierarchy and its numerical simulation method were introduced,and it provided a theoretical basis and the conditions for the numerical simulation of BWIM,which was based on the traditional Moses algorithm and VSSB.(3)The bridge weigh-in-motion,which was based on the traditional Moses algorithm,was studied.The traditional Moses algorithm was derived in detail.Axle load recognition theory development of BWIM system and its engineering application were introduced.ANSYS software was used to establish a 20 m span simply-supported T beam bridge,which was simulated based on the traditional Moses algorithm,and the influence of different factors,such as road roughness,speed and vehicle model,on the recognition accuracy of axle load and vehicle load was investigated.(4)The bridge weigh-in-motion,which was based on VSSB method,was studied.First,the theory of VSSB method was introduced,and the equations of VSSB method were derived.It was showed that the influence of different factors,such as road roughness,vehicle speed and vehicle model,on the recognition accuracy of axle load and vehicle load was investigated based on the numerical simulation of VSSB method.The recognition results were compared with the traditional Moses algorithms.(5)The experiment of the bridge weigh-in-motion,which was based on VSSB method,was conducted.And the new method was verified by the scaled model experiment.