Experimental Research On Mechanical Performance Of Stone Arch Bridge Strengthened By The Enclosed Reinforced Concrete

Masonry structure is widely used in bridge engineering, especially a large number of stone arch high way bridges build in mountain areas in our country. The old masonry structures counld not meet the demand of modern traffic because of low bearing capacity, ageing of material and various damage caused by kinds of load. Too much money would be spent if the old structures will be rebuilt. The method to strengthen old structures by enclosed reinforced concrete is widely used in stone arch bridge because of advantages of improving significantly bearing capacity and easy construction, short construction period and economic benefits, but the research works are very less on strengthened masonry bridge. To the above situation, the specialized theorecal and experimental research works have been carried out on the strengthened structure. Conclusions are as follows:1. The mechanical behavior of strengthened compressed composite members is researched by failure experiments of eccentric compression strengthened composite columns. The influence of different design parameters on the behavior and load bearing capacity are given by changing the thickness of enclosed-reinforced-concrete, ratio of the longitudinal and hoop reinforcement, eccentricity, and existed stress level.2. Based on experimental analysis of strengthened compressed members, three failure modes and concept of bound existed strain are given by analyzing the limit state of bearing capacity, a simplified calculation method to normal section bearing capacity of strengthened compressed members accounting for existed stress level is given by nonlinear analysis of composite section.3. The nonlinear finite element analysis have been done for composite specimens strengthened by the finite element analysis software ANSYS. The simulated results are agreed with the test result very well. Influence of other parameters is analyzed by the finite element simulation method to obotain influence coefficient of enclosed function and existed stress on the bearing capacity of strengthened compressed members. Based on this, the simplified calculating method to ultimate bearing capacity is given.4. The shearing behavior and the change rule with the bar length rate is got by experiment research on the interface of new concrete to old masonry. The calculating formula of shearing strenghth is got by the theorical anysis of bearing behavior and failure model of the interface to give.5. The research on the mechanical behavior and the bearing capacity of stone arch bridge structure strengthened is done by the model experiment. It is got that the mechanics characteristic and failure model of arch strengthened is similar to the Reinforced concrete arch by the experiment. the calculation method is verified reliability.6. The research of engineering application of stone arch strengthened by reinforced concrete is done by the analysis of Duanqu Bridge strengthened. The result shows that the calculated results are more accurate, more close to the actual bearing capacity by the calculation method of this paper. The computational procedure for bearing capacity of stone arch strengthened is given.