Mechanical Properties Analysis And Research On Cable-stayed And Self-anchored Suspension Bridge

A cable-stayed and self-anchored suspension bridge is one kind of new composition, which is few at home and abroad. Without large anchor, it is appreciated by people for its elegant shape and high adaptability. No matter construction or mechanical properties, cable-stayed and self-anchored suspension bridge is different from other kinds of bridges and has its own particularity. Combined with the engineering practice, this paper gives the study and discussion about its static properties, dynamical behaviors, seismic resistance and wind resistance. The main research work covers the following aspects:(l)Based on the finite displacement theory and considering the nonlinear factors of cable-stayed and self-anchored suspension bridge, a cable-stayed and self-anchored suspension bridge with span of 133m is detailed analysis .It is found that a cable-stayed and self-anchored suspension bridge with span of 100m meets the elasticity theory approximately and the nonlinear behavior can be ignored. Compared with the cable-stayed and self-anchored suspension bridge of plane cable, the one with space cable can decrease the structural rigidity and increase its deflection. The lean suspension cable can increase the structural rigidity more than the vertical suspension cable. Owning to the initial force of main girder, the structural rigidity becomes weaker. The concrete shrinkage and creep of stiffening girder has great influence on the internal force and deformation of the structure. Temperature load also has great influence on the internal force and deformation of the structure.(2) Based on the finite displacement principle, the dynamic computation of the No.l bridge of Xinghaiwan is set up. By means of the alteration of dead load, rigidity of stiffening girder, stiffness of tower, rigidity of main cable and suspension cable, and also camber of stiffening girder, the natural vibration character of cable-stayed and self-anchored suspension bridge is studied in the paper. The results shows that the alteration of the rigidity of stiffening girder has an obscure influence on the structural rigidity, on the contrary , the alteration of the rigidity of main cable and suspension cable has a significant influence on the structural rigidity. Thus we draw a conclusion that the stiffening girder of cable-stayed and self-anchored suspension bridge, especially the long span cable-stayed and self-anchored suspension bridge, has an obscure influence on the structural rigidity, and its main function is translating the dead load and its own gravity to the cable.(3) Based on the analysis of natural vibration character, this paper studies the seismic response of cable-stayed and self-anchored suspension bridge is analyzed by the response spectrum method and time-history method. The result shows that the structural response of cable-stayed and self-anchored suspension bridge under earthquake probability PI is approximately twice as much as that under earthquake probability P2. Longitudinal vibration is not couple against the horizontal vibration, so is vertical vibration and horizontal vibration. For the randomness of the ground shock, three orientations seismic wave may act at the same time. So not only the level vibration but also the vertical vibration should be considered in the earthquake resistance design. From the structural response result of the composition ofdifferent seismic loads, we can draw a conclusion that vertical vibration play an important role in the composition, and can not be ignored. The result of time-history method is much bigger than that of the response spectrum method, and in some case it is twice as much as the last one. So the response spectrum method and time-history method should be consider at the same time in the earthquake resistance design of cable-stayed and self-anchored suspension bridge.(4)According to the guide on the wind resistance design of the highway bridge, some questions about the wind resistance design is discussed in the paper. And on the basis of it ,by means of a group of...