Static And Dynamic Research Of Self-Anchored Suspension Bridge Based On Deflectin Theory

The research of the earth-anchored suspension bridge has been already very comprehensive and thorough, As a recognizable bridge type, the self-anchored suspension bridge should be payed more attention on it and the key point of research should be lied in the differences between the both types.The thesis firstly introduced mechanics character about the self-anchored suspension bridge briefly. Then the literatures were reviewed on the static and dynamic theory of the self-anchored suspension bridge. Based on those theories, we put forward the key method of this thesis that is by applying the deflection theory to discuss the static and dynamic character of the self-anchored suspension bridge.The thesis deduced the basic differential equation of the deflection theory of the self-anchored suspension bridge. Then the thesis gave the influence line formula to solve the horizontal tension of main cable produced by the live load, deflection of the main girder, internal force respectively in four types as three span suspended structure, three span suspended structure adding outside span, two span suspended structure, two span suspended structure adding outside span. Respectively, According to the deduced formula as above, by using the dynamic program to add loads, we wrote the calculation program of the deflection theory of self-anchored suspension bridge. This program can compute internal force and deformation by live load of the structure such as three span suspended, three span suspended structure adding outside span, two span suspended structure, two span suspended structure adding outside span, etc. The program has been verified by the practical bridge. Based on this program, we analyzed the rise-span ratio, ratio of side span to center span, stiffness of the stiffening girder, whether there exists the constitution of outside stretching span and the length of it will effects the internal force, deformation and horizontal tension of main cable produced by the live load. According to the theory analysis and comparison of the computation cases, the thesis gave the formular explanation to the influence of changeable rise-span ratio to the suspension bridge mechanics performance.Based on energy principles, the thesis deduced the computation formula of symmetry and antisymmetry natural vertical frequency of self-anchored suspension bridge with flexible tower by the Rayleigh's method. Then, we discussed the effect of the stiffness of tower to the symmetry vertical frequency. The torsional computing formula of symmetry and antisymmetry were deduced. A case was studied, and the precise of the approximate formula was validated. The thesis also discussed the related parameters which will influence the fundamentalfrequency.The research of the thesis gives some contributions for the conception design and primary design of the self-anchored suspension bridge.