Nonlinear Dynamics Analysis Of Rope Way Bridge And Engineering Software Design

Rope way bridges have many virtues, such as low cost, fast speed of erection, convenient maintenance, etc. Therefore they are widely used in such fields as military field, temporary engineering, canyon area and so on. But rope way bridges are not the prevailing bridges due to their disadvantages such as the shorter span, vertical alignment which is unfavorable for driving, so study on rope way bridge is also less. Special design code for rope way bridges are not layed out presently, the design is mainly based on experience and design code of other flexible bridges. Only the static caculation is considered in the actual designing calculation, while the nonlinear dynamic behavior is still not under concern.The main contents about of this theise are as follows:(1)With the single span rope way bridge as the research background, suspension curve methods are introduced. From the perspective of practical engineering, tension in different states, elements of rope, length of rope and internal force of beam are caculated.(2) Difference form of gravity curves equation is obtained from the suspended cable, and the unified form of difference equation is established by the analysis of the infinitesimal section under concentrated load. General computer program for the lineshape and tension of suspended cable is designed with the unified difference equation. Calculation steps of the program in different initial case are set up, and the example is caculated.(3)Through deducing from chord momentum equation, the 3D nonlinear dynamic equation of suspension cable is set up, as well as the plane nonlinear dynamic equation based on the static line of deflection of suspension cables,which provide essential basis for nonlinear analysis of suspension cables. As to unloading rope way bridges, linear frequency calculation equation for all ranks suspension cable system under no-load is obtained by Galerkin method, meanwhile, Torsional vibrationo of rope way bridge is preliminary analyzed, and torsional vibration frequency calculation equation for all ranks is obtained.(4) Nonlinear dynamical equation under moving load is established. It is discovered that the moving velocity of load is consistent when primary resonance takes place. by analysis of Galerking method, and the vehicle speed possibly leading to primary resonance is obtained. The primary resonance of the first-order mode of suspension cable under velocity excitation is calculated by adopting the method of multiple scales, and the bifurcation control equation is obtained. At the same time, the stability of its solution is analyzed. Then, the bifurcation graph of the first-order mode is obtained through numerical calculation. (5) The possible hypo-resonance of the rope way bridge under moving load and the condition of hypo-resonance are analyzed. The general expression of hypo-resonance solution to suspension cable is obtained, Then, order-2 superharmonic resonance, order-3 superharmonic resonance,1/2-subharmonic resonance and 1/3-subharmonic resonance of the first-order mode are analyzed through examples, and the bifurcation graph is also acquired.