大跨PC矮塔斜拉桥箱梁应力及索梁锚固局部应力分析

发布时间：2019-03-11 16:50

【摘要】：矮塔斜拉桥因其外形美观、主梁刚度大、跨越能力强可用于铁路桥梁的建设。本文是以即将建设的成昆铁路扩能改造工程三堆子金沙江预应力混凝土矮塔斜拉桥为背景，对预应力混凝土矮塔斜拉桥的若干关键问题进行了数值模拟分析，主要工作和结论如下： 1.基于APDL语言对矮塔斜拉桥的索力优化进行参数化分析。斜拉索是矮塔斜拉桥的重要组成部分，斜拉索与主梁的锚固使主梁类似多点弹性支撑的连续梁。当荷载确定时，通过调整斜拉索的索力，可以改变结构的受力分配，使反映结构的各种性能指标达到最优。矮塔斜拉桥为三维空间结构，要进行索力优化计算需要建立空间有限元分析模型，本文选用弯曲能量最小的原理，通过ANSYS参数化设计语言APDL编制索力优化程序段，对索力优化进行了分析计算，得到成桥状态恒载作用下的一组索力值。本文建立的索力优化模型精确模拟了主梁截面在高度和宽度方向的变化，弥补了以往应用ANSYS建模时模拟主梁的不足。计算实践表明，所编制程序计算精度较高，应用方便，并且收敛速度快，具有很高的应用价值。 2.采用ANSYS12.1建立预应力混凝土矮塔斜拉桥上部结构三维空间有限元模型。计算分析表明，结构在自重、二期恒载和预应力共同作用下主梁的线型平顺，主梁受力均匀，各截面处于受压状态，出现的最大压应力远小于混凝土的抗压强度限值。结构在自重、二期恒载、预应力和最不利活载共同作用下主梁各控制截面的竖向位移和纵向应力均在合理范围内。在活载（偏载）作用下，得到了主梁各控制截面左、中、右腹板的纵向应力分布特征。结果表明在主梁向下挠曲变化最剧烈的部位，偏载下方边腹板的纵向应力小于远离活载的另一边腹板，可知该部位是主梁受力最不利的区域，如中跨跨中截面和边跨跨中截面，而主梁其他部位偏载下方边腹板的纵向应力大于远离活载的另一边腹板，由于主梁全截面受压，出现这样的应力分配使结构具有一定的安全储备。本文首次探索了预应力混凝土矮塔斜拉桥单箱双室主梁左、中、右三个腹板的纵向应力分布特征，得到了较好的结果，可为同类型的桥梁设计提供参考。 3.运用ANSYS12.1对多种新型的索梁锚固方式进行了数值分析。结果表明：在单钢板锚拉的情况下，虽然锚固段主梁混凝土绝大部分区域的应力值在允许的范围内，但是钢板局部应力过大，通过分析不宜采取该锚拉方式。采用双钢板锚拉时，锚固段主梁混凝土和钢锚拉板结构绝大部分区域应力在允许的范围内，局部应力较大的部位可以采取适当的加固措施，可以满足结构受力要求。总体来说采用钢锚拉板锚固，结构新颖，样式优美，但是锚拉结构传力复杂，钢板和混凝土之间的连接不好处理，要消耗大量钢材，费用较高。当采用混凝土锚拉块锚固时，必须适当加入预应力才能满足结构受力要求。通过圆导角锚块锚固和楔形导角锚固的数值计算，可知采用楔形导角锚块锚固时，，锚固段梁体和锚拉块大部分处于受压状态，个别区域出现拉应力，与圆导角锚块锚固时的最大拉应力值相比，出现的最大拉应力要小的多，并且应力集中的面积很小。楔形导角大部分处于受压状态，其中出现最大拉应力的位置属于构造发生突变的截面，出现局部应力集中现象，集中应力数值小，范围小，如果采用圆角过渡，可以满足结构受力要求。索梁锚固的方式不同，锚固区梁段的受力比较复杂，影响因素较多，通过对四种不同锚固型式的分析计算，可为矮塔斜拉桥的索梁锚固设计提供参考。
[Abstract]:The short tower cable-stayed bridge can be used for the construction of the railway bridge because of its beautiful appearance, large rigidity of the main beam and strong crossing ability. In this paper, a numerical simulation analysis of several key problems of the pre-stressed concrete short tower cable-stayed bridge is carried out based on the construction of the pre-stressed concrete low-tower cable-stayed bridge of the Sanhe Jinshajiang pre-stressed concrete cable-stayed bridge. The main work and conclusion are as follows: 1. The optimization of the cable force of the short tower cable-stayed bridge based on the APDL language Analysis. The stay cable is an important part of the short tower cable-stayed bridge. The anchor of the stay cable and the main beam causes the main girder to be similar to the multi-point elastic support. When the load is determined, the stress distribution of the structure can be changed by adjusting the cable force of the stay cable, so that the various performance indexes of the reflecting structure can reach the most For the three-dimensional space structure, the low-tower cable-stayed bridge is a three-dimensional space structure. It is necessary to establish a space finite element analysis model for the optimization of the cable force. In this paper, the principle of the minimum bending energy is selected, and the cable force optimization program segment is prepared by the ANSYS parametric design language APDL, and the optimization of the cable force is analyzed. calculation to obtain a set of cable force under the constant load of the bridge state The cable force optimization model established in this paper accurately simulates the variation of the cross section of the main beam in the height and width direction, and makes up the problem that the main girder is not simulated when the ANSYS is used for modeling. The calculation practice shows that the program has high calculation accuracy, convenient application and high convergence rate, and has a very high application price. Value.2. Use ANSYS2.1 to set up the three-dimensional space of the upper structure of the prestressed concrete short tower cable-stayed bridge The calculation results show that the structure is smooth and the main beam is smooth and the main beam is uniform under the common action of the dead weight, the second phase and the pre-stress, and the stress of the main beam is uniform. The maximum compressive stress of the main beam is much smaller than that of the concrete. The vertical displacement and longitudinal stress of each control section of the main beam under the common action of the dead weight, the second phase, the prestress and the most unfavorable live load are both reasonable and reasonable. The longitudinal stress of the left, middle and right webs of each control section of the main beam is obtained under the action of live load (partial load). The results show that the longitudinal stress of the web under the partial load is less than that of the other side of the live load on the most severe part of the downward deflection of the main beam. It can be seen that this part is the most unfavorable area of the main beam, as shown in the cross-section and the cross-span of the cross-span. The longitudinal stress of the web under the partial load of the other parts of the main beam is greater than the other side of the web which is far from the live load, and due to the compression of the whole section of the main beam, such stress distribution will make the structure have a certain safety. The longitudinal stress distribution in the left, middle and right three webs of the single-box, double-chamber, double-chamber, double-chamber main girder of the prestressed concrete short-tower cable-stayed bridge is studied for the first time in this paper, and the better results can be obtained, which can be provided for the same type of bridge design. For information.3. Use the ANSYS2.1 to anchor a variety of new cable-beam anchoring methods The numerical analysis is carried out. The results show that, in the case of single steel plate anchor drawing, although the stress value of most area of the main beam of the anchor section is within the allowable range, the local stress of the steel plate is too large, and it is not appropriate to adopt the analysis. In the anchor pulling mode, when the double-steel plate anchor is adopted, most of the area stress of the main beam concrete and the steel-anchor pulling plate structure of the anchor section is within the allowable range, and the part with the larger local stress can adopt appropriate reinforcement measures, so that the knot can be met. The structure is required. In general, the steel anchor pulling plate is adopted for anchoring, the structure is novel and the style is beautiful, but the force transmission of the anchor pulling structure is complex, the connection between the steel plate and the concrete is not good, and a large amount of steel is to be consumed. The cost is high. When the concrete anchor block is used for anchoring, the pre-stress must be properly added to meet the knot. According to the numerical calculation of the anchorage of the anchor block and the wedge-shaped guide angle of the round guide angle anchor block, it can be seen that when the wedge-shaped guide angle anchor block is used for anchoring, most of the anchor section beam body and the anchor block are in the pressed state, the tensile stress in the individual area, and the maximum pull when the anchor block is anchored by the round guide angle anchor block. the maximum tensile stress that occurs when compared to the stress value is small and the stress concentration The area of the wedge-shaped guide angle is very small. The wedge-shaped guide angle is mostly in the pressed state, the position where the maximum tensile stress occurs belongs to the section with the abrupt change of the structure, the local stress concentration phenomenon occurs, the concentrated stress value is small, the range is small, and if the fillet transition is adopted, the junction can be met. The structure and force requirements are different. The anchorage mode of the cable beam is different, the stress of the beam section of the anchorage zone is more complex and the influence factor is more. Through the analysis and calculation of the four different anchoring types, the cable beam anchorage for the short tower cable-stayed bridge can be provided.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.27;U441

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