The Study On Stability Behavior Of Spoke Arch Structure

Spoke arch, hybridized by arch and cables, is a new type of structure, which ischaracteristic of beautiful appearance and appropriate mechanical property. In recentyears spoke arches have been adopted in several overseas projects.This thesis firstly introduces the history of spoke arch, including spoke structure,cable-arch and the practical projects, and then clarifies the mechanical principle ofspoke arch, and presents the main content and the research method. Secondly, thefinite element method, eigenvalue buckling analysis and nonlinear buckling analysisto study the stability of spoke arch are put forward with numerical results of a spokearch and a pure arch. This thesis mainly studies the ultimate load-carrying capacityand relations between load and displacement of spoke arch with varied parametersunder full and half span uniformly distributed load respectively. The main contentincludes its elastic and elastic-plastic stable ultimate load capacity, deformationprocess, buckling mode, sensitivity to initial geometric imperfection under full spanload, stress distribution of arch and cables in the elastic-plastic buckling mode, etc.Based on the assumption that the material is completely elastic, the parametersinfluencing the stability of the arc spoke arch is analyzed in detail, such as the ratio ofrise to span, the cable hub position, the number and the section of cables. The properratio of rise to span and the optimized cable hub position are obtained, and the rulethat the stability of spoke arch is improved when the number or section of cablesincreases is also found. In addition, the cable prestress, the section of arch, thestructure span and load distribution are all changed to investigate their influences onloading path.Furthermore, the arch axis is changed into ellipse arc, parabola arc and catenaryarc, which are still in elastic state. The ratio of rise to span and the cable hub positionchange while other parameters are constant to find the proper ratio of rise to span andproper cable hub position. Stabilities of different arch axis are compared. Ultimateload capacities of parabola arc spoke arch and flat ellipse arc spoke arch are lower,and the buckling deformations are large;while ultimate load capacities of arc spokearch, ellipse arc near arc spoke arch and catenary arc spoke arch are higher, and thebuckling deformations are small.Finally, assuming the arch material to be ideally elastic-plastic and meanwhilecontrolling the cable stress in elastic state, the elastic-plastic stabilities of the abovefour types of axis spoke arches are studied. The elastic buckling of spoke arch iscaused by geometric nonlinearity, while the elastic-plastic buckling is mainly due tothe formation and development of material plastic area, which results in low loadcapacity and small deformation at the moment of buckling.