Mechanical Properties And Key Construction Techniques For Self-anchored Suspension And Cable-stayed Combination System Bridge

As a new type of bridge, the self-anchored suspension and cable-stayed combination system bridge embodies aesthetic effect and social benefit. But its mechanical properties are more complicated and there are few relevant papers on this kind of bridge at present. Under the background of first self-anchored suspension and cable-stayed combination system bridge in the world, this paper analyzes design and construction data, studies the mechanical properties and parameter sensitivity by use of theoretical analysis, numerical calculation, model test and safety monitoring. In detail, the following aspects are investigated:1. According to the coordination of strain and displacement, the incomplete potential energy functional of self-anchored suspension and cable-stayed combination system bridge is established based on the pressure-bending of girder and tower. The equations of this kind of bridge are approximately derived, and the analysis theory is also obtained. The example shows that the results of analytic method agree with those of numerical calculation.2. Based on the structure mechanics theory, initial equilibrium conditions on structure of self-anchored suspension is analyzed based on spatial cross suspender cable. And the calculation method of spatial line shape and suspender force on self-anchored suspension and cable-stayed combination system bridge is also proposed. Finished bridge state on structure of cable-stayed is determined according to the principle of minimum bending energy. The calculation method of reasonable finished bridge state on self-anchored suspension and cable-stayed combination system bridge is then established. Furthermore, the reliability of the method is verified by the model test.3. By using finite displacement theory and the accurate calculation formula for cable, the spatial cable element tangent stiffness matrix is deduced. The three dimensional beam element tangent stiffness matrix is also developed. Furthermore, the finite element calculation method of self-anchored suspension and cable-stayed combination system bridge is established. Mechanical responses are obtained from the load of vehicle, temperature, temperature difference, shrinkage and creep.4. Under the guidance of sensitivity analysis theory, the structure parameters of self-anchored suspension and cable-stayed combination system bridge are analyzed including the ratio between side span and main span, length of overhang span, rise-span ratio, camber of girder, beam rigidity, cable rigidity and tower rigidity. Regularities of internal force and deformation are summarized. Similarities and differences'between the self-anchored suspension and cable-stayed combination system bridge and other types of bridges are discussed.5. In view of the geometric nonlinearity on self-anchored suspension and cable-stayed combination system bridge, the analysis method of reasonable construction state is proposed according to mechanical properties and construction condition. The method involves in spatial cable, inclined tower, spatial effect of cable and cross suspender cable. Then the new tensioning technique about self-anchored suspension and cable-stayed combination system bridge is put forward.6. Mechanical properties of self-anchored suspension and cable-stayed combination system bridge in construction control are studied on the basis of difference construction method. Weak interference principle on main cable displacement and near influence principle on suspender cable force are proposed. The influence of tension of cable is studied. And the opportunity of tension of cable is also investigated to the control principle of tower displacement. These principles are proved correctly through the model test.7. For the first self-anchored suspension and cable-stayed combination system bridge, the analysis method for the finished bridge state and reasonable construction state in this paper is used. The new tensioning technique(a single tension technique) is adopted. And construction monitoring techniques for this kind of bridge are set up. By compared with calculation results and measured results, the reliability of caculation method and rationality of tensioning technique are verified.