铁路PC拱形腹板槽形梁受力分析及施工中预应力张拉控制研究

发布时间：2018-08-01 15:57

【摘要】：在交通基础设施建设中槽形梁作为一种新型的桥梁结构形式,以其竖向刚度大的结构优势,受到了工程人员的青睐,广泛使用在轨道交通线路中。目前对槽形梁的受力分析研究主要集中在等截面、无横梁的槽形梁结构形式上,但对变截面有横梁的槽形梁研究不多。本文以某在建铁路建设中的一座变截面预应力混凝土槽形梁为研究对象,对其不同阶段的整体受力进行了数值模拟分析,主要做了以下几个方面的工作:(1)通过查阅国内外的相关文献,对槽形梁的发展、工程应用、分析方法和研究现状进行了综述。文中采用MIDAS-FEA有限元专业应用软件建立了槽形梁的实体分析模型,探索了纵、横梁设置对主梁内力及其变形的影响,证明了纵、横梁设置可以有效的增强道板床的纵、横向抗弯刚度,进而减小道板床厚度和主梁自重,同时可以改善道板床的受力和主梁线形。分析表明主梁底板(道板床+横梁)的竖向变形大于腹板,因此桥下净空的确定应以横梁下缘的标高为基本依据。(2)对于设有纵、横梁体系的槽形梁结构,其主梁腹板与道板床、主梁与横梁、次纵梁与横梁交汇处也是预应力束交汇处,预应力束密集,应力集中现象明显,在设计、施工时要多关注这些位置的构造链接,保证梁体的安全性和可靠度。在恒载、活载作用下,槽形梁在支座布置有横向约束一侧的腹板横向变形大,因此在设计中应该以该侧腹板的内力作为腹板配筋设计的依据。(3)在单线列车运营时,槽形梁会出现偏载效应,主梁表现出明显的弯扭耦合效应;设有纵、横梁体系的槽形梁其道板床的“剪力滞”现象不明显。结合工程中支座发生沉降对主梁进行整体受力分析,结果表明在恒载、活载作用下支座发生沉降对主梁内力的影响不大。(4)在施工阶段的预应力束张拉过程中,按照顺序依次张拉及间隔张拉腹板束两种情况进行主梁内力和变形的分析比较,确定出后者为合理的张拉方案。(5)通过对槽形梁的主梁腹板、纵、横梁及道板床预应力束的超欠张拉分析,结果表明:超张拉对主梁的变形控制有利,但对于结构会产生附加的超压、拉应力;欠张拉对于主梁的线形控制不利。因此在结构设计中,通常要求对预应力束超张拉应该控制在10%以内,且避免欠张拉。随着横向预应力束张拉程度的降低,道板床和主梁腹板的横向压应力减小,由于次纵梁的存在,横向压应力在道板床横向呈齿状变化。
[Abstract]:As a new type of bridge structure in the construction of transportation infrastructure, slot beam is widely used in rail transit lines because of its advantages of large vertical stiffness. At present, the stress analysis of grooved beam is mainly focused on the equal section, the structure form of the groove beam without cross beam, but the research on the groove beam with variable cross section is not much. In this paper, a prestressed concrete slotted beam with variable section in the construction of a railway is studied, and the numerical simulation of the whole force at different stages is carried out. The main works are as follows: (1) the development, engineering application, analysis methods and research status of grooved beam are summarized by consulting the relevant literature at home and abroad. In this paper, the solid analysis model of grooved beam is established by using MIDAS-FEA finite element professional application software, and the influence of longitudinal and transverse beam setting on the internal force and deformation of main beam is explored. It is proved that longitudinal and transverse beam setting can effectively enhance the longitudinal of track slab bed. The transverse bending stiffness can reduce the thickness of the slab bed and the weight of the main beam, and at the same time, it can improve the force of the slab bed and the alignment of the main beam. The analysis shows that the vertical deformation of the bottom slab of the main beam is greater than that of the web plate, so the determination of the clearance under the bridge should be based on the elevation of the lower edge of the beam. (2) for the slotted beam structure with longitudinal and cross beam system, the main beam web plate and the track slab bed should be determined. The intersection of main beam and crossbeam, secondary longitudinal beam and crossbeam is also the intersection of prestressing beam, the prestressing beam is dense, and the phenomenon of stress concentration is obvious. In design and construction, more attention should be paid to the structural link of these positions to ensure the safety and reliability of beam body. Under the action of dead load and live load, the transverse deformation of the web with transverse constraint on the support is large, so the internal force of the side web should be taken as the basis for the design of web reinforcement. (3) in the operation of a single line train, the internal force of the side web should be taken as the basis for the design of web reinforcement. The beam-slabbed with longitudinal and transverse beams has a "shear lag" phenomenon which is not obvious. Combined with the settlement of the bearing in the project, the overall force of the main beam is analyzed. The results show that the settlement of the bearing has little effect on the internal force of the main beam under dead load and live load. (4) in the process of prestressing beam tensioning in the construction stage, The internal force and deformation of the main beam are analyzed and compared according to the sequence of tension and spacer web bundle, and the latter is determined to be a reasonable tensioning scheme. (5) through the analysis and comparison of the main beam web plate of the grooved beam, longitudinal, The results show that the overtensioning is beneficial to the deformation control of the main beam, but it will produce additional overpressure and tensile stress for the structure, and the undertensioning is unfavorable to the linear control of the main beam. Therefore, in the design of the structure, the overtension should be controlled within 10%, and the undertension should be avoided. With the decrease of the tension degree of the transverse prestressing beam, the transverse compressive stress of the track slab bed and the main beam web plate decreases. Due to the existence of the secondary longitudinal beam, the transverse compressive stress changes in the transverse tooth shape of the track slab bed.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441;U445.4

【参考文献】