【作者】 王高宁；

【导师】 郭彦林；

【作者基本信息】 清华大学 ， 土木工程， 2005， 硕士

【摘要】 车辐拱是一种由索和拱杂交而成的新型结构形式,它造型美观,受力合理,近年来在国外有所应用。本文首先介绍了车辐拱的发展历史,包括车辐结构和索—拱结构及一些车辐拱的工程实例,阐明了车辐拱的结构特点和受力机理,提出了本文的研究内容和研究方法。其次,介绍了车辐拱稳定性研究的有限元基础,提出了特征值屈曲分析和非线性屈曲分析的主要内容和方法,并以一个车辐拱和相应的纯拱为例,对计算结果进行了分析和比较。本文主要是针对车辐拱不同的参数,研究了全跨和半跨均布荷载作用下的稳定承载力和变形性能,内容主要包括它的弹性和弹塑性稳定极限承载力、变形过程和失稳模式、全跨荷载下的缺陷敏感性,以及弹塑性失稳时拱和拉索的应力分布等。在假设材料为完全弹性的基础上,对影响圆弧形车辐拱稳定性能的各项参数进行了详细的比较分析,主要是拱的矢跨比、索盘位置、拉索数量和拉索截面,对车辐拱适用的矢跨比、最优索盘位置进行了分析总结,并阐述了增加拉索用量对改善车辐拱稳定性的规律。此外,对拉索预应力、拱截面、结构跨度和荷载分布形式也进行了一些变化,考察了这些参数对车辐拱加载路径的影响。然后将拱的轴线形式从圆弧形扩展到椭圆弧形(包括不同形状)、抛物线形和悬链线形,仍在弹性范围内,固定其它参数,只改变拱的矢跨比和索盘位置,研究不同轴线形式下车辐拱适用的矢跨比和索盘位置,并对不同轴线形式车辐拱的稳定性进行了比较。抛物线形和很扁的椭圆弧形车辐拱的稳定承载力较低,失稳时的变形较大;圆弧形、接近圆弧的椭圆弧形以及悬链线形的车辐拱承载力较高,失稳时的变形却较小。最后,假设拱为理想弹塑性材料,同时控制拉索的应力使之也处于弹性范围内,研究上述四种轴线形式车辐拱的弹塑性稳定性。车辐拱的弹性失稳是由其几何非线性引起的,而弹塑性失稳主要是因为材料塑性区的形成和发展,因此承载力大大降低,失稳时刻结构的变形也非常小。更多还原

【Abstract】 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.更多还原