Primary Exploration About The Bridge Condition Assessment Based On The Dynamic And Static Load Test

The article takes the engineering projects as the background, based on thedetection technology of the existing bridges, summarizes methods and means throughthe finite element theoretical calculation and actual detection. Herein the simplysupported girder bridge and the continuous rigid frame bridge are studied bydynamic and static load test and parameter identification, and the bearing capacity forthe hyperbolic arch bridge is calculated. The following are some conclusions:(1)、A summary of the bridge detection, the theory of dynamic and static loadtest review, all kinds of bridge dynamic, static load test project and test controlposition, as well as the problems that needs attention in the test;(2)、The modeling calculation of a simply supported beam with the finite elementsoftware of MIDAS/CIVIL bridge structure, and control of cross section loadefficiency by using influence line, bring out the most simple and convenient loadingplan. Load efficiency of the static load test of the bridge, cross the bridge deflectionand strain of calibration coefficient and residual values are within the normal range;the measured values are lower than the theoretical calculation value; and that provespractical rigidity is greater than the theoretical calculation of the bridge stiffness;(3)、Judging from the general finite element software ANSYS to XiaoGang leftpicture in the bridge and the bridge dynamic response study, tested values forXiaoGang bridge is different from value of the original model by certain degrees.With regard to this difference, to identify the dynamic and static characteristicparameter, through the correction of quality and stiffness of the model, finite elementmodel is revised and improved by the stiffness of the structure. And thus thefrequency of the structure, the deflection and stress of cross section in the theoreticalcalculation value is relatively lower than that before correction, and the measuredvalues remain unchanged, the calibration coefficient is relatively fixed. Such fixedcalibration coefficient is more accurate in evaluating carrying capacity of bridge.Byparameter analysis, studied the presence of damping and impact coefficient caused byvehicle load simulation form the XiaoGang bridge, the influence of the presence ofdamping effect on impact coefficient of bridge: as the speed grows, so does the impactof damping coefficient; when the speed is constant, the impact of damping coefficientthan the impact of the undamped coefficient; The impact coefficient is largest in the displacement of the first across, and the lowest in the displacement of the third spancross. As the change of speed, impact coefficient become bigger.when vehicle load isconsidered as constants and harmonic forces and the vehicle load is considered as aconstant force influence on impact coefficient of bridge: as the change of speedbasically coincides, when the speed is constant, only on the third cross crossdisplacement impact coefficient in effect. As the change of speed, impact coefficientlarger;(4)、Calculating the bearing capacity based on an old socket type hyperbolic archbridge, and the review of the old bridge bearing capacity, prove it meets therequirement of specification. Here are some experience in calculation, for example:for fracture to consider reduction factor is adopted to improve the correction; Fortransverse connection of should, according to the investigation of lateral contactstiffness;(5)、Static and dynamic load test is a kind of calculation for the whole bridgestatus by testing the local bridge. There must have been problems with the bridge if itfails the static and dynamic load test. But it doesn’t mean there’s no problem at alleven if it passes the test.