Experimental Research On Mechanical Properties Of The Existing RC Girder Bridges

At present, concrete highway bridges are widely used in China. Almost all of these bridges have damages of fifferent degree because of design, construction, deterioration of material, environment and many other factors. There are some bridges which are designed according to lower designing grade. These bridges have more and more problems of safety along with the advancement of the highway development. The key problem to utilize those bridges properly is to research the degree of deterioration, the potential capacity of load-carrying, the degree of reliability and etc.Therefore, in this thesis, the experiments were carried out on a concrete simply supported girder bridge on province road 209 of Hunan province. Refined analysis includes researching the deterioration reasongs, simulating effects initiated by overload to mechanical performance, studying the destructive of bridge, analyzing the behaviors in the lifetime by nonlinear finite element method, and so on.(1) The deterioration and crack reasons of the girder bridge were analyzed. The behavior of the corrosion of the steel bar was also studied.(2) Loading was achieved to the bridge through a group of hydraulic jacks to simulate the heavy vehicle loads, the influence of truck overloads on highway bridge members mechanical performance is evaluated with the number of different loaded lane sand, different amplitude overload and the number of different overloading as the main parameters. Study shows that: When the beyond limit load was under some degree, the variance of structure reaction against load was linear; during the whole experiments, the transverse connection stiffness of bridge varied little.(3) This dissertation has done destructive experimental study of ultimate load-carrying capacity. This test combines engineering practice with be use of jack + bridge with heavy loading. The destructive character and theory and the whole destructive procedure of the bridge stales have been resignedly researched by full scale destructive tests on site. The results can help us to understand and master the structure rigidity, restoring force character, destructive state and load-carrying capacity of the concrete girder bridge under service load and ultimate load.(4) Make use of the large general finite-element procedure Marc, adopt 3-d elastic-plastic solid finite-element method to emulate analysis the whole process of the solid bridge experiment, obtain the structure respond and the development regulation of the bridge experiment's deformation, stress and crack in the whole process and carry on the contrast analysis to the spot experiment value. Analysis showed that the calculated values and experimental results coincide well.