Study Of The Bridges Carrying Capacity Evaluation Method Based On The Quasi-static Influence Line

In recent20years, our country’s traffic undertakings have developed rapidly, the number ofbridge is the first in the world.Many old bridge’s bearing capacity declined with the extension oftime, that will be a serious threat to people’s life and property safety. Evaluation of the bearingcapacity of the old bridges and determine their safety carrying capacity becomes more and morenecessary.Now the commonly used methods of the bearing capacity evaluation of bridge are themethod based on visual examination, the method based on design code, loading test, and themethod based on expertise，etc. But these methods have their limitations, for example, slow andlaborious, costly, the result is conservative, and long time interrupt traffic, etc.In regard of the problems above, as viewed from practicality, this dissertation put forward“the bridges carrying capacity evaluation method based on the quasi-static influence line”, it isvery applicable for the medium and small span reinforced concrete bridges.Application of this method, first of all to solve the problem of the finite element modelupdating. The influence line is acquired through the movement of load position. Compared withother static data, the influence line contains more structure information; Compraed with thedynamic data, the accuracy is greatly increased. So the influence line is called “quasi-dynamicquantity”, use the influence line in finite element model updating has its unique advantages. Thispaper applied strain influence line correct the finite element model. The strain influence line isacquired through the bridge moving load arrangement and the BDI bridge diagnosis system..After the finite element model updating completed, we got the accurate model which canreflect the actual working state of the structure, based on the model calculation and analysis,respectively obtain the bridge carrying capacity and the load effect under the required load, thancan calculate the bearing capacity factor of the bridge structure, and complete the bridge carryingcapacity evaluation.This paper first expounds on the evaluation theory, and then applied to the actual bridge inthe evaluation work. Proves that this method is correct in practice.