索辅体系桥梁设计理论研究

发布时间：2018-10-25 20:08

【摘要】：在城市桥梁中单孔跨径100m左右的小跨径斜拉桥较为常见，然而一般的斜拉桥设计理论都是基于处于经济跨径范围的常规斜拉桥而得出的，，虽然其在力学计算上具有普遍性，但从结构利用效率的角度分析，一般性理论并不能很好地适用于小跨径斜拉桥。索辅体系桥梁的出现使人们在设计小跨径斜拉桥时有了新的选择。通过充分利用小跨径斜拉桥的主梁刚度，考虑主梁和拉索的组合受力，从而发挥其各自材料性能的设计理念，索辅体系桥梁能达到使用性和经济性的统一。鉴于目前鲜有专门针对索辅体系桥梁设计理论的系统性研究，本文对该体系的特征参数、设计关键问题、长期性能进行了详细分析和评价。首先，本文基于白山市向江大桥，对按常规斜拉桥理念设计的小跨径斜拉桥的结构和受力特性进行了详细分析；针对分析结果，从提高主梁刚度利用率和拉索强度利用率的角度，提出了小跨径斜拉桥优化设计方案，得到了索辅体系桥梁的体系特点；通过对该体系拉索恒载分担率和疲劳强度容许应力的分析，提出以拉索恒载分担率作为界定索辅体系桥梁的特征参数，并指出其取值范围为35%~65%，同时拉索安全系数可取1.67~2.5。然后，本文基于沈阳市三好桥对索辅体系桥梁设计过程中的关键问题进行了研究：推导了索辅体系桥梁主梁、拉索、桥塔等主要构件的刚度表达式，为定性掌握该体系整体刚度提供了依据；基于已得到的主梁和拉索刚度的计算式，采用比拟梁法推导了拉索活载分担率表达式，分析了拉索活载分担率与结构参数的关系，评价了该公式的计算精度，为掌握活载在结构中的分配提供了参考；阐述了主梁纵向预应力的设计方法，指出了采用弯起束提供竖向预应力的优势，分析了腹板束和顶底板束预应力效应的特点，为合理布束提供了借鉴；比较了简支梁模型、梁格模型和实体模型计算拉索锚固横隔梁的结果，评价了三种模型的适用性；分析了索辅体系桥梁内力和位移对不同结构参数的敏感性。最后，本文简要阐述了混凝土收缩和徐变的相关概念；通过建立按施工阶段的有限元模型，分析了收缩徐变对索辅体系桥梁内力和位移的影响，评价了其长期性能；研究了混凝土加载龄期对该体系长期性能的影响，并指出了改善其长期性能的措施。
[Abstract]:Small span cable-stayed bridges with single span of 100 m or so are common in urban bridges. However, the general design theory of cable-stayed bridges is based on conventional cable-stayed bridges in the economic span range, although it is universal in mechanical calculation. However, from the point of view of structural utilization efficiency, the general theory is not suitable for small span cable-stayed bridges. The emergence of cable-assisted bridge makes people have a new choice in the design of small span cable-stayed bridge. By making full use of the stiffness of the main beam of the small span cable-stayed bridge and considering the combined force of the main beam and the cable, the design idea of their respective material performance can be brought into play. The cable-auxiliary system bridge can achieve the unity of usability and economy. In view of the lack of systematic research on bridge design theory of cable-auxiliary system at present, the characteristic parameters, key design problems and long-term performance of the system are analyzed and evaluated in detail in this paper. Firstly, based on Xiangjiang Bridge in Baishan City, the structure and mechanical characteristics of small span cable-stayed bridge designed according to the concept of conventional cable-stayed bridge are analyzed in detail. According to the analysis results, the optimum design scheme of small span cable-stayed bridge is put forward from the point of view of improving the utilization ratio of main girder stiffness and cable strength, and the system characteristics of cable-auxiliary system bridge are obtained. Based on the analysis of the tensile load sharing rate and the fatigue strength allowable stress of the system, the paper puts forward that the tension constant load sharing rate is used as the characteristic parameter to define the bridge of the cable auxiliary system, and points out that its value range is 35 / 65. At the same time, the cable safety factor may be 1.67 or 2.5. Then, based on the research of the key problems in the design process of the cable-auxiliary system bridge in Shenyang Sanhaoqiao, the stiffness expressions of the main girder, cable, tower and other main components of the cable-auxiliary system bridge are derived. It provides the basis for qualitatively mastering the overall stiffness of the system. Based on the calculated formula of stiffness of main beam and cable, the formula of live load sharing rate of cable is derived by analogy beam method, the relationship between live load sharing rate of cable and structural parameters is analyzed, and the calculation accuracy of the formula is evaluated. It provides a reference for mastering the distribution of live load in the structure. This paper expounds the design method of longitudinal prestress of main girder, points out the advantages of vertical prestressing force provided by bending beam, analyzes the characteristics of prestressing force effect of web beam and top and bottom slab, and provides a reference for rational distribution of beam. The results of simply supported beam model, girder lattice model and solid model are compared to evaluate the applicability of the three models, and the sensitivity of internal forces and displacements of cable-auxiliary system bridges to different structural parameters are analyzed. Finally, this paper briefly describes the concepts of shrinkage and creep of concrete, analyzes the influence of shrinkage and creep on the internal force and displacement of cable-auxiliary system bridge by establishing the finite element model of construction stage, and evaluates its long-term performance. The influence of concrete loading age on the long-term performance of the system is studied, and the measures to improve the long-term performance of the system are pointed out.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.27

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