| Masonry Bridge is very common in our China.Before 70 s,bridges in China are mostly Masonry Bridge.Now with the development of economy,the increasing load of the operating bridge,the influence of natural environment,earthquake and other natural disasters,the existing masonry bridge face the problems of insufficient bearing capacity,and even the extent of the damage of the bridge is too large which can finally lead to the collapsing.So it is very important to study the bearing capacity and seismic resistance of the masonry bridge.The researches about optimization of reinforcement provide valuable reference for the reinforcement design of the damaged bridge.In the static force analysis of the masonry bridge,this paper mainly studies the influence of defects,the influence of the impact of the floods and the ultimate bearing capacity of the bridge.The study found that the defects can cause the greatest effect when they are located in the inside foot of the arch,the stress concentrated around the defects,and it increases about 40%,therefore we must resolutely avoid these defects,the designer can consider to design arch into the variable cross section form which is thick in the middle but thin on both sides of it.The stress of one side of the masonry bridge accepting the impact of the food reduces about 50%,the other side stress increases about 6%,so the designer should strengthen the structural strength of the flood-impacting side.This paper do some research about the geometric nonlinearity and geometric material double nonlinearity of the masonry bridge,and it discovers that the live load limit coefficient under the double nonlinearity is 1/3 of the geometric nonlinearity.The result got under double linearity is closer to the actual conditions and more accurate.The research found that when the transversal arrangement of the load of the bridge is unbalanced loading,the live load limit coefficient of the bridge will be less than 4% comparing with the medium loading.It means that the bridge’s construction has more disadvantages under the unbalanced loading circumstances.After different methods of reinforcement,the structure of the bridge has been significantly improved.The maximum displacement under normal circumstances decreases about 20%,the maximum displacement under limit circumstances decreases about 30%.In the different strengthening methods,ribbed reinforcement method can not only save material but also produce effective reinforcement.It is the most ideal method of reinforcement.In the study of stability of Masonry Bridge,this paper mainly studies the difference response of the masonry bridge before and after reinforcement under different seismic waves of earthquakes.The study found that,under different earthquake affections,the horizontal bridge of the masonry bridge is relatively stable before and after the reinforcement.The change of displacement is only about 8%;But the displacement of along the bridge and the vertical ranges furiously from 10%~30%.In the seismic strengthening design,it is essential to strengthen the longitudinal and the vertical anti-seismic design.All stress decreases little under the action of earthquake,and the decrease is about 13%.This shows that the reinforcement of the masonry bridge can well resist the seismic stress,can play an important role during the earthquake. |
