The Application Research On The Modification Method To The Bridge Structure With The Combination Of The Data Of Static And Dynamic Loading Test

Model updating is a scientific and effective method to evaluate the securityand reliability of bridge structures,which is based on the correction of the FiniteElement Models.By using the data of dynamic and static load test,ModelUpdating Method make the calculation value of finite element models consistentwith the results of the test.The study progess of the Model Updating Method canmake a great engineering and practical value in the assessment of bridgestructures’ operational safety performance,and also in the area of the damageidentification and the prediction under different loading cases of the structures.In this paper,a lot of research of the Model Updating Method was done forengineering applications. Dynamic and static load test was taken to a40mprestressed concrete T-beam and a30m prestressed concrete box girder.Data ofmid-span deflection and strain in the static load test and the data of verticalnatural frequency in dynamic load test was obtained. These data provide reliableexperimental basis for the discussion of the engineering application structuremodel updating methods.On the basis of the dynamic and static load test,two kind of the Modelupdating Method were carried out in the structural modeling analysis andexperimental verification.The study shows that,the Model updating has aPractical engineering value.These two methods are:1) Direct correction to the finite element model Setting up the finite element models of prestressed concrete T beam and boxgrider.The models was modified with the integrated use of dynamic weightingcoefficients and the combination of dynamic and static loading test data.Becauseof dynamic weighting coefficients were used in the construction of the objectivefunction,so this method overcomes the disadvantages of weighting coefficientscan’t being updated with the change of dynamic or static functions’magnitude.This method also avoid the drawbacks of the objective functionwould converged in the great part of the residuals.So,this method can easily findthe overall optimal solution but not the local minimum.The results showedthat,after being modified,the error between the calculation value and the testresults of the model was converged into a reasonable error range.In addition,thedata of the modified model could coincide to the static loading test.The reseachrevealed that the modified model could be used in the assessment of bridgestructure performance,and it shows the practical application value.2) Correction method based on the response surface model.On the basis of the finite element model updating,27groups of sampleswas preduced by orthogonal experimental design method.The ANOVA showsthe results was consistent with the analysis results of sensitivity,which is basedon the finite element model. Parameters with high sensitivity were selected,andthen the response model was set up by using Quadratic polynomial. Thecorrelation coefficient,R,was up to0.99, it revealed That the response surfacemodel can be used to replace the finite element model for model updatingresponse calculation.The error between the results of test and the correctedmodel by Response Surface Method was in a range of8%,and the error satisfedthe requirements of precision engineering. The study of the RSM showedthat,the calculating speed of the RSM is more faster than FEM,and the RSMalso has advantages of efficiently and it can easily converged.At last,take30m prestressed concrete box girder as an example,two damage cases were assumed and calculated in ANSYS.The rsm was used to identify theextent and location of the damage.The results shows that:the response surfacemodel can identify the extent and location of the damage accurately.The RSMcan be used in damage identification of bridge structure,and it has significantengineering value after being improved.