| The single inclined pylon cable-stayed bridge has been constructed in recent decades because of its novel structure and beautiful shape.However,there are few study on the single inclined pylon cable-stayed bridge with hinged pylon bottom,and it is the first time that the universal hinge support is used to support the bridge pylon.The internal force of this new structural system is complex,and there are many technical difficulties different from the conventional bridge system.At present,there are few study on this type of bridge.Therefore,the research on this new structure system is of great significance to enrich the bridge structure form and promote the popularization and application of this new bridge structure system.Based on a single inclined pylon cable-stayed bridge with universal hinge support at the bottom of the pylon,the analysis of structural mechanical characteristics and study of structural parameters are carried out.Firstly,based on MIDAS / civil finite element model,the reasonable cable force and the reasonable state of the completed bridge were determined by using the multi-step and multi constraint objective method.Based on the reasonable finished cable force,the unstressed cable length was calculated,and the reasonable construction cable force at each construction stage of stay cable was obtained by using the forward analysis of unstressed length.Secondly,the solid finite element model of the universal hinge support was established by ABAQUS software,and the theoretical formula of the rotation torque of the arc contact surface was used to verify the finite element model.According to the finite element simulation,the torsional stiffness of the universal hinge support was calculated,and then the influence of whether the torsional stiffness of the universal hinge support is considered on the structural stress was compared and analyzed.Finally,based on the consideration of the torsional stiffness of the universal hinge support,the finite element method was used to study the influence of the pylon bottom boundary constraints,auxiliary pier,pylon stiffness and girder stiffness on the static and dynamic characteristics of the structure.The results show that: the step-by-step,multi constraint objective method can quickly and better calculate the reasonable cable force,and the unstressed state method can quickly calculate the reasonable construction cable force.These two methods have good applicability in the single inclined pylon cable-stayed bridge with universal hinge support at the bottom of the pylon.Whether the torsional stiffness of universal hinge support is considered or not has a great influence on the cable force,internal force of bridge pylon and torsional deformation of bridge pylon in the state of completion and construction,and also has a great influence on the main beam alignment in the state of construction,but has a small influence on the main beam alignment in the state of completion.In design and construction,the torsional stiffness of universal hinge support should be considered.This kind of special-shaped bridge pylon bottom using universal hinge restraint is more beneficial to the overall stress of the structure.The mechanical characteristics of bridge structure are very sensitive to whether the main span is equipped with auxiliary piers.With auxiliary piers,the internal force and displacement of the structure can be reduced to a large extent 60%-70%.The pylon stiffness has little influence on the static characteristics of the structure,but has significant influence on the torsion effect of the structure.The main beam stiffness has a great influence on the static characteristics of the structure,while the main beam stiffness has a little influence on the dynamic characteristics of the structure.The vertical vibration frequency of the bridge mainly depends on the overall stiffness of the bridge structure.The conclusion of this paper provides a theoretical support for the design and construction of the actual project,and has a certain reference significance for the application and development of the universal hinge support in the special-shaped bridge in the future. |
