下承式拱桥结构安全性分析

发布时间：2018-03-23 13:35

  本文选题：钢管混凝土拱桥　切入点：吊杆损伤　出处：《华北水利水电大学》2017年硕士论文

【摘要】：钢管混凝土拱桥以其独特的力学性能,优越的施工工艺在桥梁建设领域得到越来越多的青睐,随着结构的创新和跨径的增大,还有各种偶然因素的出现,钢管混凝土拱桥等一类桥梁工程建设正面临着巨大风险,必须引起高度的重视,否则极易引起坍塌事故,给人们交通出行带来不便。基于ANSYS建立一单跨30米的混凝土梁,研究了其材料、几何参数、边界条件、物理参数等对模态频率的影响。结果显示材料特性、几何尺寸、边界条件对模态频率影响比较明显,因此在利用模态频率进行损伤判断时应特别注意这几个参数变化。以下承式拱桥习营东南跨渠生产桥为例,利用有限元分析软件ANSYS建立三维有限元模型,分析了习营东南跨渠生产桥在不同温度和不同预应力时,拱桥的动力特性。在-35℃~35℃的环境变温时,拱桥的振型变化不明显。当环境温度升高时,振动频率随温度的升高而增大,随温度的降低而减小,但变化幅度较小。以习营东南跨渠生产桥为实例展开对纵梁施加不同大小预应力的情况下,对桥梁动力特征的影响,发现随着预应力增加振动频率会增大,说明预应力会改变拱桥的性能,进而影响振动特征,但与温度相比影响更小。并分析了吊杆损伤时拱桥力学性质和位移情况,得出吊杆损伤程度一般大于吊杆张力的变化率,且吊杆损伤会引起相邻几根吊杆张力变大,单侧吊杆损伤对拱桥对侧吊杆的力学性能影响较小,可以不计。通过对不同工况下拱桥振动特征的分析,最后发现桥梁横向振动、竖向振动和扭转振动阵型依次出现,因此得出拱桥的竖向和扭转刚度明显大于横向刚度。对下承式钢管拱桥结构体系中的重要构件进行可靠度分析,结果显示吊杆可靠度最高,因此设计时应加强薄弱部位的强度。但是近几年随着下承式钢管拱桥的发展,大多数事故都是因为吊杆损伤所引起的,因而进一步开展对吊杆的安全评估研究是必要的。在实际工程实践当中应采取一定措施加强安全监测,以保证桥梁安全运营。在以上分析的基础上给出了一套下承式钢管混凝土拱桥的安全预警方案,为现代钢管拱桥技术的改进及同类型拱桥安全监测提供参考。
[Abstract]:Concrete-filled steel tubular arch bridge is more and more popular in the field of bridge construction with its unique mechanical properties and superior construction technology. With the innovation of structure and the increase of span, there are also a variety of accidental factors. The construction of concrete filled steel tube arch bridge and other bridge projects is facing great risks, which must be attached great importance to, otherwise, it is easy to cause collapse accident and bring inconvenience to people's transportation. Based on ANSYS, a concrete beam with a single span of 30 meters is established. The effects of materials, geometric parameters, boundary conditions and physical parameters on modal frequencies are studied. The results show that the effects of material properties, geometric dimensions and boundary conditions on modal frequencies are obvious. Therefore, special attention should be paid to the variation of these parameters when using modal frequency to judge damage. Taking the through arch bridge as an example, the three-dimensional finite element model is established by using the finite element analysis software ANSYS. The dynamic characteristics of the arch bridge under different temperature and different prestress are analyzed. When the ambient temperature changes from -35 鈩，

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