Study On Dynamic Comprehensive Evaluation System Of Plate Bridge Based On Test Data Base Updating

The dynamic assessment method of bridge's bearing capacity is always the researchhotspot in the academic field.In the past,The dynamic assessment research was focused onbuilding the connection between single beam's stiffness and frequency by regressing theexperiment data obtained in lab.By far,there is no well-rounded theory that can be used inpractice because of the test data's discretization.Though the span of plate bridge is usuallysmall,the task of static test is complicated,it is economical and essential to look after a fastevaluation method for assessing structure's load bearing capacity.Based on this,189 bridgesin the actual projects as a sample were selected,the connection between static test result anddanymic test result was built in this paper in order to assess the structure's bearing capacity bydynamic characteristics of bridge.The main contents are as followings:(1)On the base of actual observation records of bridge samples,the mechanicalproperties of the assembly slab bridge is obtained,and the mechanical characteristic ofhinged joint and bridge deck,the distribution of the guard rail in transverse direction are alsodiscussed.Based on the above analysis,the rational theoretical model is built,which offerssome reference to assess the structure's bearing capacity.(2)The dynamic characteristic of assembly slab bridge is discussed,which is brought byanalyzing of different diseases location,disease patterns and structural parameters.Thetheoretical results are validated by the actual test data,which is as a foundation for assessingthe structure's bearing capacity.(3)After analyzing the relationship between the deflection,frequency and stiffness ofstructure,the concept of nominal frequency coefficient is put forward.Besides,therelationship between static deflection and strain coefficient and dynamic strain coefficient isobtained,furthermore,using static load test data for the analysis of sample return,therelationship between of deflection and strain coefficient and frequency coefficient is also builtup.Meantime the rational range of deflection coefficient,strain coefficient is obtained byverifying the structure's bearing capacity,and the rational range of frequency verificationcoefficient is obtained on the foundation.The lower acceptance value is confirmed as the reference to assess the structure's bearing capacity.(4)Carrying on the analysis from the damping diffusion energy angle,the influence ofstructure's disease to damping is studied,which is after deriving the relational expressionbetween damping and stiffness.In addition,the rational range of damping is confirmed basedon analyzing the actual observation records,which is a reliable reference for assessing thestructure's bearing capacity.(5)The vehicle-bridge coupled model is built on the base of three axis vehicle in orderto research the influence of the disease in the different location in single beam,the disease indifferent beams,and the disease of hinge and this regularity is validated by the actual testresult.(6)The relations between impact coefficient and frequency are regressed based on the testdata.The standard formula is updated after comparing the theory result and the regress result,which is a rational reference for designing and assessing the same type bridge.Furthermorethe relations between theory result and actual observation result are concluded,which can beused for assessing the structure's mechanical characteristic.(7)The general dynamical evaluation system of structure's bearing capacity is broughtforward,which is validated by different strengthened bridges on the base of comparingdead-load test result and live-load test result.The following innovations of this paper are summed up based on above labors:(1)Study on the mechanical characteristic of the assembly slab bridge based onthe test dataThe mechanical characteristic of hinged joint and bridge deck,and the distribution of theguard rail in transverse direction are derived after analyzing the actual test value.With thisconclusion,the rational theory model is built to provide references for assessing thestructure's bearing capacity.(2)Study on rational span of verification coefficientThe deflection and strain of structure is received on the respective model with the sameload as the experimentation load,and deflection and strain verification coefficient is built upafter comparing the actual measured value.The rational span of deflection/strain verificationcoefficient is discussed based the structure's load bearing capacity. (3)Frequency coefficient evaluation method of structure's bearing capacityFor the first time,evaluation method of frequency coefficient is built up to evaluated thebridge's bearing capacity.The method is implemented by the span of frequency coefficient,which is ascertained through the relation between frequency coefficient and deflection andstrain coefficient.(4)Study on damping evaluation method of structure's bearing capacityThe expression between damping and stiffness is established,and the damaged degree ofstructure is assessed by the stiffness changes which are reflected by damping.The rationalspan of damping is gained after analyzing the actual observation records,which is thereference for assessing the structure's bearing capacity.(5)Study on vehicle-bridge coupled vibration program of multi-beams bridgeThe vehicle-bridge coupled vibration equation is detruded on the base of three axisvehicle,and the vehicle-bridge coupled vibration program is established with iteration method,which is used for analyzing the dynamic response of the assembly slab bridge.(6)Dynamic evaluation system of structure's bearing capacityFor the first time,the dynamic evaluation system is built up to assess structure's bearingcapacity with structure's frequency,damping and compact coefficient.