Analysis Of The Mechanical Properties Of The Continuous Rigid Frame Bridges Of The Composite Piers

With the rapid development of highway construction in recent years,in many complex terrain,high pier and long-span continuous rigid frame bridge is widely used because of its advantages.At present,the research on mechanical performance of single column pier continuous rigid frame bridge and double limb thin-walled pier continuous rigid frame bridge has been relatively in-depth.However,the research on combined pier continuous rigid frame bridge is relatively few,and no mature theory has yet been formed.So in this paper,based on the background of merun viaduct in Hunan Yongji expressway,the finite element software is used to simulate and analyze the mechanical performance and stability of the combined pier continuous rigid frame bridge.The main contents are as follows:(1)The development situation of combined pier continuous rigid frame bridge at home and abroad is introduced,and the current research status of bridge stability theory at home and abroad is summarized.The structural characteristics of combined pier continuous rigid frame bridge and the commonly used structural form of combined pier are summarized.(2)Taking the high-speed runway bridge in Yongji expressway as the background,the finite element analysis model is established by Midas Civil bridge software.The whole process of the bridge is analyzed during the construction stage,and the internal force results of three typical construction stages are compared.It is found that the internal force of the maximum cantilever to the side span is little changed,and the bridge state,the positive bending moment of the middle span and the side span are increased,and the negative bending moment of the pier top is reduced.(3)The influence factors of mechanical performance of combined pier continuous rigid frame bridge are analyzed.The influence of the location of the boundary points,the height of the pier,the radius of curvature,and the thickness of the hollow pier wall on the main girder and pier are considered respectively.The results show that the influence of the increase of the location of the cut-off point on the horizontal displacement of the main girder is greater than that of the main girder,and at the same time,the stress of the pier boundary and the adjacent pier is improved.With the increase of pier height,has great influence on beam and bridge pier's horizontal displacement and vertical displacement.When the radius of curvature is reduced,the vertical displacement of the main beam increases,while the horizontal displacement of the pier decreases gradually.The change of the wall thickness of the hollow pier has little influence on the internal force of the main beam.When the wall thickness increases,the stiffness of the pier increases and the vertical displacement value of the pier top is reduced.(4)The stability of the continuous rigid frame bridge is analyzed,and the parameters of its stability are studied.The analysis shows that the pier height and wall thickness changes have a greater impact on the stability and boundary point,The number of middle beam in the double pier thin wall pier has little influence on the stability of the continuous rigid frame bridge of the combined pier.