Research On Unstressed Control Method Based On Plastic Deformation Analogy

With its advantages in engineering application,the unstressed control method has been applied in the construction control of modern long-span Bridges constructed in stages more and more widely.The theoretical basis of this method is the principle of minimum potential energy,and the general theoretical framework of mechanics of this method has not yet been eastablished;In addition,the research on the equilibrium equation of the unstressed control method based on space Euler beam element is not complete.There is still a gap in the application of the unstressed control method based on space Euler beam element in the curved beam bridge constructed in stages.So related studies have been done as follows:Taking plane link element,plane bending Euler beam element,plane Euler beam element,plane shear-bending Timoshenko beam element and space Euler beam element as research objects,the influence of plastic deformation on unstressed state amounts was discussed,and the plasticity theory significance of the equilibrium equation of the structure formed in stages was expounded;On this basis,the equilibrium equation of the space Euler beam element structure formed in stages was derived.The MATLAB program for space Euler beam element structure formed in stages was applied on space curved beam structure,the calculation results verifies the correctness of the equilibrium equation of space Euler beam element structure formed in stages.The principle of unstressed control method for space Euler beam element formed in stages is clarified,and the method of using the equilibrium equation is pointed out.Based on the engineering background of a curved cable-stayed bridge,according to the acquired principle,the finite element software MIDAS/Civil is used to realize the simulation analysis of the construction control of curved cable-stayed bridge by the unstressed control method based on space beam element,and the unstressed control method without considering the unstressed twist ratio is set up as the control group.Comparing the internal forces and displacements of the final bridged state and the target bridged state of the two control groups,the result figuers that the unstressed control method based on space Euler beam element in the curved beam bridge constructed in stages is available to the construction control analysis of the curved cable-stayed bridge,and it is necessary to consider the twist ratio of the curved cable-stayed bridge in the construction control by using the unstressed control method.