Cable Force Research And Dynamic Analysis Of Partial Cable-Stayed Bridge

Partial cable-stayed bridge occupies a middle position between continuous girder bridges,which are of rigid bridge type and cable-stayed bridges, which are of flexible type. And thus it is said to be a half rigid and half flexible type bridge. It integrates such characteristics as "low towers, rigid girder and concerntrated cables".Due to its excellent structural performance and good economic features, the partial cable-stayed bridge has a huge potential for development. The difficulty lies in the determination of the reasonable finished cable force and cable forces during construction in cable-stayed bridge design. This article is based on Liantai bridge,which is located in Nan'an,Fujian,uses the existing general FEA program, had determined rational completion status cable force of this bridge with the smallest bending energy method and stress balancing method, and educed reasonable construction initial tension with the difference method. Earthquake resistance computation in the high intensity area is a very important work, analyzes dynamic property and the earthquake response property of Liantai partial cable-stayed bridge situated at eight-degree seismic intensity regions. This paper mainly deals with the following four parts:(1) The development process and research present situation of partial cable-stayed bridge are reviewed briefly and elaborated, domestic and foreign design and construction cases of partial cable-stayed bridges are utilized, general arrangement, structural characteristics, mechanical characteristic and application prospect of partial cable-stayed bridges in the bridge engineering are analyzed.(2) Genaral methods of determining reasonable finished cable force for cable-stayed bridge are introduced, various methods characteristic and the application scope are compared and explained. Comprehensive method of soluting rational completion cable force with the smallest bendingg energy method combined with stress balancing method is put up, this method establishes statically indeterminate equation of the solution to reasonable finished cable force with influencing matrix of cable force for bending moment ,displacement and cable force, solutes reasonable finished cable force with principle of method of least square. Reasonable finished cable force of Liantai partial cable-stayed bridge is obtained,which is located in Nan'an with comprehensive method, and confirm rationality of cable force through computation of rational completion status.(3) In the foundation of analysis and compares for several methods of determining initial tension of cable in the construction, put up the idea calculating initial construction tension with the difference value and iterative method. The difference value and iterative method is simpler and more convenient.We can obtain initial construction tension based on the general finite element analysis software through iteration. The initial tensile force of Liantai bridge is calculated,which is located in Nan'an with the differential value and iterative computation. And then the simulation computation of construction process is carried on, a computation and the analysis was given in the completion status and completion operating status. The computational results satisfy the code requirement. Confirmed the feasibility calculating reasonable initial tensile force with differential value and iterative method.(4) Natural vibration characteristics and earthquake response of Liantai partial cable-stayed bridge are analyzed,which is located in Nan'an. Tridimensional earthquake response analysis with response spectrum method is carried on, loading from three directions which are longitudinal, horizontal and vertical respectively.Longitudinal and horizontal bending moment of brake pillar were both very large,whose longitudinal bending moment would become the controlling factor of aseismic design of bridges,and reflect architectural characteristics of this bridge; According to local earthquake fortification intensity ,the bridge is at eight-degree seismic regions which lie in minor earthquake probability scope, the structure is in the elastic working condition, therefore, the design of this bridge can satisfy earthquake resistance fortification request for "no collapse under minor earthquake".