Analysis Of Cable Force And Pre-camer During Arch Rib Installation Of Daninghe Bridge

The non-bracket cable-stayed suspension supporting construction method is used in most of large span arch bridge since it is successful use in Yongning Yongjiang bridge.On the background of the scientific research items'Daninghe Bridge in Wushan', a series of analysis for non-bracket cable-stayed suspension supporting methods are presented in this paper. The main subjects are summarized as follow:1,The current popular cable force calculation method has been summed up, and divide them into analytics method and numerical method.2,Zero moment method, zero movement method and optimization analysis methods are adopt to calculation the force of Daninghe Bridge, then both the advantage and disadvantageand have been comparison, then the applicability of the methods is discussed.3,In consider of the nonlinear impact of the cable stress, employed the method of calculation cable outside the membrane in tension structures based on the existing methods. In which, the cable will be divided into sections of participation. This method reduces the number of iterations in the process of calculating effectively.4,The paper concludes that the effect is more express in low-stress state of cable sag by increase of the length of the cable when analysis the sag effect of the 150 m, 300m and 500m cable deduction under 100 MPa stress level. On the basis of this conclusion the paper presents a reasonable number of subparagraphs in the different length of the cables, which ensures the accuracy of the calculation, and reduces the number of iterations.5,In consider of that its hard to ensure tangent the installation when birth and death element technology is adopt to simulation the model of restraint at both ends of the segmental construction, employed half-span structure to simulate the construction phase, solve the problem by impose symmetrical constraints to simulation cut cable to arch after half of the closure installation. In which, avoid the construction stage in the computation of the coordinates that dual-element method cumbersome and complex pre-treatment.6,A second-degree parabola is employed to matching the segment pre-camer, and the coefficient is adopt as design variables to fitting the segment pre-camer, in which the number of design variables is reduced and easy to finite element model of iterative convergence.7,The impact of the elevation of the main arch caused by the fluctuation of the temperature in the construction period is analysis, and the factors of the impact are disscused. The impact on the elevation caused by temperature is quantitative analysis by finite element analysis; it shows that the bridge linear movements caused by the flections of temperature are significant.8,The height formula based on the height of the former arch is deduced according to the relationship of the arch ribs, and the relationship between the linear and the cable force is also involved.9,The concept of Reasonable Angle is proposed, and the scope of the Lever Pitch is deduced by the analysis of the impact on the arch stress caused by the cable.