The Research On Nonlinear Static-Dynamic Mechanics Performance Of Long-span Cable-Stayed Arch System

Along with the appearance of lightness, flexibility and inherently low damping cables, the cable-stayed arch system are applied widely on civil engineering, the system first was applied in construction structure and so on the stadium, and it mainly is taken the temporary stress structure system in the erection stage of long span arch bridges in bridge engineering, but the application as the permanent stress structure system in the bridge engineering still is at the exploration stage, This paper take the cable-stayed system as the project background, mainly has conducted the research in two aspects: one is that the forth bridge of Xian tan in which the system is taken the temporary stress structure for the first time in china was taken as the research object, based on theory of nonlinear finite element analysis method, Considered the effects of geometric non-linearity as well as material non-linearity, The mechanics performance of the cable-stayed bridge was conducted the thorough research; the other is that the temporary cable-stayed arch system which widely exists in the erection stage of the long-span arch bridges was taken as the research object, using the non-linear dynamics theory, the parametric and sub-harmonic resonances of cables are analyzed, and the internal resonance, bifurcation as well as chaos of the cable and the arch has been thoroughly studied. The studies have more profound theoretical significances and important engineering application values. The main content in this paper is as follows:Chapter one carries on the summary to the cable-stayed arch in civil engineering application, specially carries on the detailed outline to the cable-stayed arch in bridge engineering. From the temporary cable-stayed arch and the permanent cable-stayed arch, the chapter outlines study methods, research situation and recent advances on the system first, and introduces the aim, contents and innovations of the study in this paper.Chapter two in detail introduces the finite displacement theory. Using the total Lagrangian formulations and the updated Lagrangian formulations, the non-linear FEM equation are derived from the virtual work principle, Based on the summary to the nonlinear cable element, the spatial catenary cable element which suits in the long-span bridge was derived. A user nonlinear cable element was defined in FEM software ANSYS using User Programmable Features. The stiffness matrix of spatial element was derived, and the shearing deformation of beam was considered. Thus the beam element has the widespread serviceability. With the help of the cable element and the beam element, the nonlinear analysis theory which suitably applies in the long-span cable-stayed arch bridge is formed through the large displacement theory.In chapter three, based on the forth bridge of XIANGTAN, the mechanics characteristic of the cable-stayed arch bridge are introduced in detail. On the basis of chapter two, the nonlinear analysis program (NSGCB) was developed, by which the analysis can be performed to the cable-stayed arch bridge with geometrical non-linearity. Using the program, the mechanics characteristic of the cable-stayed arch bridge in detail were analyzed, the effects of the initial tension of cables and the tilt angle of cables on the mechanics characteristics of cable-stayed arch bridge are discussed with emphasis, the difference of the two kinds of arch bridges are contrasted with under designing load, and the difference of the two kinds of arch bridges are contrasted with under ultimate load. The effects of the non-linear factors on the cable-stayed arch bridge are analyzed by the quota.Chapter four describes the concept of the ultimate bearing capacity of bridges, and outlines main study methods by which the ultimate bearing capacity of bridges was studied. The research present situation of the ultimate bearing capacity of CFST arch bridge was summarized from fundamental research and experimental study. The computational method and formula by which the cable-stayed arch bridge was analyzed was given. On the basis of above-mentioned work, considered nonlinear characteristics of concrete filled steel tube arch in both material and geometry in deformation and instability, based on the constitutive relations of combinatorial material of concrete filled steel tube and the finite element method of high accuracy beam, the ultimate bearing capacity of the cable-stayed arch bridge was analyzed under many kinds of static loads, and traced the distortion process during increasing load until losing bearing capacity.In chapter five, we present the nonlinear mechanical model for parametric vibration problem of cable-stayed arch structure. The nonlinear equations of motion of the cable-stayed arch structure were derived, and the static sag of the cable as well as the geometric nonlinearity is considered. Appling the multi-scale perturbation method, the parametric and sub-harmonic resonances of cables were analyzed. We obtained the influence factor and the condition of the parametric and sub-harmonic resonances of cables in the cable-stayed arch structure.In chapter six, a nonlinear dynamical modal of cable-stayed the cable-stayed arch structure is built by application of the cable-arch connecting condition. The nonlinear dynamical equation of the cable-arch connecting condition was solved by the multi-scale perturbation method. The internal resonance of the cable-stayed arch system subjected to the external excitation is investigated; the nonlinear dynamical characteristic of the cable-stayed arch system subjected to the external excitation is discussed in detail. The internal resonance and the non-internal resonance of the cable-arch were studied qualitatively with primary resonance of the cable-stayed arch structure.In chapter seven, taking the first construction stage of the forth bridge of XIANGTAN as research object,, the internal-resonant modal, the bifurcation and chaos of the cable-stayed arch structure were thoroughly and systematically studied with the appearance of primary resonance of the cable-stayed arch structure under internal resonance and non- internal resonance respectively. The region of dynamic instability, the region of bifurcation, the region of chaos and the region of excitation amplitude are obtained, the effects of structural parameter on the nonlinear dynamic performance of the cable-stayed arch structure are analyzed in detail, and then we have determined the sensitivity of structural parameters. Based on the above work, the dynamic parameters of the cable-stayed arch structure are considered with emphasis during designing the temporary structure system in the erection stage of long span arch bridges.Chapter eight have carried on the summary to main contents of the study in this paper, and have pointed out the diligently direction in the cable-stayed arch system.