Research On Static And Dynamic Detection Method Of ShuangYang Double-Curved Arch Bridge In ChangChun City

The bridge type of double arch bridges is invented by bridge workers of our nation in 1964.This bridge type has many adavantages,such as saving steel,low cost,simple structure,easy construction and strong across ability.Therefore,during the period 60s to 70s of the twentieth century,the bridges of this type have been widely used in china.By 1979,the number of double arch bridges is4085,and the total length is 350 thousand linear meters.The proportion is 25.7% in large and medium bridges of ours.So far,the service period of the bridges of this type is about 40 years.With the extension of the service period,Damages with varying degrees appear in bridges of this type.Analysis of the reasons are:on the one hand,with the development of transportation of our country,traffic growth is rapid,vehicle load is increasing year by year.This imposes increased load standard bridges,and the carrying capacity of bridges of this type can not meet the requirements of modern traffic.On the other hand,the bridges fell into disrepair, lack of rational management and conservation measures. The survey data of bridges of this type shows that,main disease form of the bridge of this type is poor overall of the main ring structure,inadequate cross-section of main arch,the building on the arch mishandled,and foundation deflection and so on.Given that the universality of the bridge disease of this type,it's basically impossible to demolite and reconstruct the bridges.The data indicates that the cost of reinforcement of a bridge is only about 15% of that of demolition and reconstruction.Therefore,it's feasible to demolite and reconstructe the bridges economically.The reasonable measure of this bridge is to carry current capacity of the bridgfe tap,and take reasonable measures of reinforcement to improve the traffic capacity of the birdge.Before the reinforcement of the bridges,firstly current state of the bridge has to been obtained,in order to do "the right medicine".Only by testing of the bridge,the current state of the bridge can be fully grasped.The current testing methods of bridges can be devided into three categories:appearance of investigators,static load test and dynamic test.Appearance survey mainly depends on the experience of investigators.This method is subjective,with more human factors.Static load tests and dynamic tests are to evaluate the stress state of the bridge by using mechanical parameters of the bridges, and then the carrying capacity of the bridge is assessed overall.Both of the two methods are objective.Because of the difference of sructure and force performance between double arch bridges and the bridges of other types,therefore,detection methods are different.Currently,researchers carry out some research on tesing methods of the bridge of this type.And some meaningful results are made.These results can be drew on,but the theoretical system has not been formed yet.Therefore,Shuangyang curved arch bridge in Changchun city is taken as example in this paper,static load tests of this bridge of this type is studied.Firstly,the basic principles and processes of calculation of structure static response by using finite element method are introduced.Spatial finite element analysis model of the double arch bridge is established based on the beam grid method.Acorrding to the characteristics of double arch bridges, the double arch bridge static load test prgram is designed,and the Changchun Shuangyang double arch bridge is tested by static method acorrding to the test program.The dynamic characteristics of the arch bridge are theoretically analyzed.Based on theoretical analysis,dynamic load test is done to Shuangyang double arch bridge,and the dynamic characteristics of this bridge is analyzed.Main research work of this paper are as follows:1.Started with the basic principle of structure static response by using finite element method,acorrding to the mechanical characteristics of double arhc bridges,the general process and method of establishing theoretical model of double arch bridges by using beam grid method is proposed,and the theoretical analysis model of double arch bridges is established.2.Acorrding to the force characteristics of double arch bridges,static load test program of Changchun Shuangyang double arch bridge is designed.Static load test is done to this bridge acorrding to the test program.Based on the testing data,the distribution of transverse load,stiffness and strength of this bridge is analyzed.3.The vibration characteristics of the arch bridge is theoretically analyzed,and the dynamic characteristics of double arch bridge are theoretically analyzed by using the established finite element analysis model.Based on theoretical analysis,dynamic load test is done to Changchun Shuangyang double arch bridge.Dynamic characteristics of this bridge is analyzed from dynamic response.Based on theoretical analysis of dynamic parameters and measured values,the state of this bridge is evaluated.