【作者】 邓瑞基；

【导师】 陈自力；

【作者基本信息】 中南林业科技大学 ， 结构工程， 2010， 硕士

【摘要】 索道桥由于造价低、架设快、维护方便等优点成为军事、临时性工程、峡谷地形等的常用桥梁,但是受其跨度不大、桥面线形不利于行车等缺点影响,索道桥并不是当今主流桥梁之一,对于索道桥的研究也相对较少。目前索道桥设计施工并无相关专门规范可依,主要根据经验或借鉴其它柔性桥梁规范来进行,设计中大多是从静力学角度考虑,对于索道桥动力学特性考虑较少。主要从以下几个方面进行研究：(1)以单跨索道桥为背景,介绍了悬索的曲线理论,从工程实用角度出发,对索道桥设计过程中悬索在不同状态下的张力、索的根数、悬索长度、横梁内力等进行了计算。(2)从悬索重力曲线方程出发,得到了重力曲线方程的差分形式,通过对集中力作用点的微段进行分析,得到了悬索在各种荷载作用下的统一形式的差分方程,并根据该差分方程建立了悬索线型和张力的通用计算程序,并给出了在不同初始条件下程序的计算步骤,通过算例进行了计算。(3)从弦的动量方程出发,建立了悬索的三维非线性动力学方程和基于悬索静态挠曲线的悬索平面非线性动力学方程,为悬索的非线性分析提供了必要的基础。对于在空载时的索道桥,通过伽辽金方法得到了索道桥的各阶线性频率计算公式,并对索道桥的扭振进行了初步分析,得到了各阶扭振频率计算公式。(4)建立了移动荷载作用下悬索的非线性动力学方程,通过伽辽金方法分析发现：在移动荷载作用下,索道桥各阶模态产生主共振时荷载移动的速度是一致的,并得到了可能产生主共振的车速。通过模态截断和多尺度法对移动荷载激励下的索道桥的一阶模态进行了计算,得到了分叉控制方程,并对可能的解的稳定性进行了分析,通过数值计算得到了一阶模态分叉图。(5)分析了索道桥在移动荷载作用下可能产生的次共振,以及产生次共振的条件,得到了可能产生的次共振解的通式,并对2次超谐波共振、3次超谐波共振、1/2次亚谐波共振、1/3次亚谐波共振进行了分析,得到了分叉图。更多还原

【Abstract】 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.更多还原