Analysis And Calculation Of Expansion Amount For Bridge Expansion Joint By MIDSA

The bridge expansion joint is an important component of the bridge structure. Its main function is to ensure that meet the normal expansion deformation of bridge structure under the influence of various factors. Once the expansion joint failed to meet the free stretching deformation of the main beam, it will lead to stress concentration of the main beam, decrease the service levels and service life of the expansion joint, aggravate the pavement damage, affecting the traffic safety and comfort. Therefore, a reasonable and accurate design of the expansion amount directly affects the service life of the bridge structure and the traffic safety, and also plays a decisive role in the service levels and service life of the expansion joint.This paper summarizes the characteristic and the scope of application of the current several commonly used expansion joint in our country, and analysis and master the effecting on the expansion amount and its calculation method by the main factors, such as the change of temperature, shrinkage and creep of concrete etc. And then the paper takes the expansion joint of Jinma Bridge which is on the No. 13 pier of the approach bridge as an example, according to the relevant provisions of the " Code for Design of Highway Rein forced Concrete and Prestressed Concrete Bridges and Culverts "(JTG D62-2004), calculated the design of the expansion amount. Through establishing the finite element model of the bridge to simulate the calculation of bridge, the paper also discussed from the following aspects:(1) It respectively simulates and calculates the displacement deformation of beam end under the different temperature and shrinkage and creep of concrete, and then compared with the results of design calculation. Conclusions show that simulation results are consistent with the results of design calculations, and the design calculation results can accurately express the deformation of beam end by the different temperature and shrinkage and creep of concrete effecting.(2) It simulates and calculates the displacement deformation of beam end under the effect of automobile brake force standard value, and then compared with the results of design calculation.it founds that the design calculation results lack of the displacement of beam end caused by bending deformation of bridge pier.(3) Analysis of the vehicle load effecting on the beam end displacement deformation, It founds that vehicle load does not have a significant impact to the displacement of beam end. The reason is mainly due to the bridge for the simply supported continuous beam of variable, but small long span beam.(4) Analysis of the influence to the displacement deformation of beam end by the different longitudinal slope, the results show that the longitudinal slope does not have a significant impact to the along bright displacement of beam end, but it mainly will make the beam end have a vertical displacement, that can lead to the jumping phenomenon, affecting the traffic safety.(5) Through the comprehensive simulation calculation and contrast analysis, the results show that the design of expansion amount can be obtained by the sum of beam end displacements deformation caused by system of temperature, shrinkage and creep of concrete and automotive braking force and multiplied by the corresponding coefficient increases. and then base on the conclusion obtained the design of expansion amount which is on the No. 13 pier of the approach bridge.