轻量化FRP拉索超大跨桥梁研究

发布时间：2018-08-02 07:54

【摘要】：随着桥梁跨径的不断增长,传统钢拉索由于自重大、垂度效应明显、承载效率低等缺点,限制了超大跨桥梁跨径的提升。同时传统钢拉索的疲劳强度不高、耐腐蚀性能差,钢拉索的寿命在疲劳与腐蚀的耦合作用下大大缩短,影响了钢拉索的长期服役性能。纤维增强复合材料(Fiber-Reinforced Polymer,简称FRP)由于具有轻质高强、抗疲劳、耐腐蚀等优异的力学性能与化学性能,近三十年来广泛的应用于土木工程结构加固和增强领域,FRP拉索作为FRP材料最有效的应用方式之一,能够充分发挥其质量轻、抗拉强度高、抗疲劳、耐腐蚀的优势,规避FRP材料各向异性的劣势。当FRP拉索应用于超大跨桥梁结构,不仅能够有效减轻拉索的自重、增大超大跨桥梁的跨径,而且还能有效的提高拉索的长期服役性能,FRP拉索为改善超大跨桥梁的短期、长期性能提供了一个有效的途径。FRP拉索应用于超大跨桥梁,能够实现超大跨桥梁的轻量化,然而目前对FRP轻量化超大跨桥梁力学性能研究不足,特别是由FRP轻量化引起的振动问题还有待深入探讨。由于作用机理较为复杂,拉索振动特性与阻尼性能的研究需要在试验的基础上进行,但是由于目前缺少超大跨桥梁FRP拉索的应用实例,目前FRP拉索振动特性与阻尼性能的研究分析主要采用半经验半理论的方法,缺乏试验的支持与验证。同时如何兼顾整桥的力学性能与经济性能,优化FRP轻量化超大跨桥梁的结构设计,建造跨径更大材料利用效率更高的桥梁的问题也亟需解决。本文围绕超大跨桥梁FRP轻量化的上述问题,采用理论分析与实验研究相结合的方式,从整体结构性能、经济性能评价以及拉索振动特性三个方面开展研究,具体的研究内容与成果包括：(1)基于相似准则,选取苏通大桥中两根最具代表性的斜拉索为原型,设计并按照自由衰减振动法进行了钢拉索、CFRP拉索与BFRP拉索的模型振动试验,拉索振动试验的结果证明,设计的拉索模型振动试验,能够有效的模拟实际拉索的振动特性。而且拉索面内振动试验的阻尼分析结果表明,FRP拉索面内振动的模态阻尼比大于钢拉索,证明拉索的轻量化有利于提高其面内的减振耗能性能。此外拉索面外振动试验的阻尼分析结果证明,拉索的面外振动阻尼比与自振频率成反比。基于能量耗散理论以及模态振型曲率法,修正了拉索模态阻尼比的计算公式,然后根据修正公式计算了FRP拉索的动态应变阻尼能系数,结合拉索振动的试验结果,证明了以动态应变阻尼能系数为指标,评价不同材料拉索阻尼特性的可行性。(2)通过模型振动实验研究了一种新型FRP自减振拉索的振动特性与阻尼性能,振动试验结果的对比表明,FRP自减振拉索能够根据拉索振幅的大小调整自身的阻尼特性,实现FRP拉索的自减振性能。同时基于阻尼耗能理论与粘弹性阻尼理论提出了FRP自减振拉索的模态阻尼比的计算方法,通过理论计算结果与实验结果的对比证明,本文提出的计算方法,能够有效的预测FRP自减振拉索的模态阻尼比。(3)通过不同材料FRP拉索关键的力学性能参数与经济性能参数的分析,确定了不同材料FRP拉索的合理适用跨度区间,提出了一种将不同材料FRP拉索在同一桥梁不同跨度区域混合布置的斜拉桥设计方案。并以主跨为2038m的某跨海大桥为例,对FRP混布拉索斜拉桥的静、动力性能,以及经济性能进行研究,分析结果表明,FRP混布拉索斜拉桥方案能够满足超大跨斜拉桥的静力结构设计的要求；而且能够有效的提高整桥的自振频率,减小桥梁地震位移响应,并提升整桥的抗风稳定性；同时拉索的全寿命周期成本分析结果表明,在满足超大跨桥梁结构要求的设计方案中,FRP混布拉索斜拉桥的经济性能最优。(4)基于FRP混合布置拉索的斜拉桥设计方案,以苏通大桥为原型,按照相似准则,提出了FRP混合布置拉索模型桥的设计方案,按照刚度相似、质量相似的要求,对加劲梁、索塔、拉索、桥墩等模型桥的主要构件进行了详细的设计,并根据倒拆法对FRP混布拉索模型桥进行了施工分析,为FRP混合布置拉索斜拉桥的实际施工分析提供了参考。(5)以主跨为3300m的超大跨悬索桥为例,通过有限元分析,研究了不同材料FRP拉索(尤其是混杂FRP拉索)超大跨悬索桥的静、动力性能：与传统钢拉索悬索桥相比,FRP拉索能够增大悬索桥的极限跨径,提高拉索的承载效率,提高拉索的材料利用率,进而优化整桥的静力学性能；而且拉索的轻量化能够提高了超大跨桥梁的自振频率,提升整桥的抗风稳定性；同时自重小、阻尼性能良好的FRP拉索还能够有效的减小整桥的地震响应,提高桥梁的抗震安全性。超大跨悬索桥不同材料拉索的全寿命周期成本评估,基于第一座进行主缆全面维护的福斯公路桥的维护成本分析进行,分析结果表明FRP拉索由于具有良好的抗疲劳、耐腐蚀性能,应用于超大跨悬索桥能够有效的提升超大跨悬索桥的经济效益。最后对本文的研究成果进行了概括总结,梳理了论文的主要创新点,提出了研究中存在的问题以及进一步的研究内容。
[Abstract]:With the increasing span of the bridge span, the traditional Graso, because of its great self importance, obvious droop effect and low bearing efficiency, restricts the improvement of the span of the super large span bridge. At the same time, the fatigue strength of the traditional Graso is not high, the corrosion resistance is poor, and the life of the steel cable is greatly shortened by the coupling of fatigue and corrosion, which affects the steel cable. For a long time, Fiber-Reinforced Polymer (FRP) has been widely used in the field of reinforcement and reinforcement in civil engineering for thirty years because of its excellent mechanical and chemical properties, such as light weight, high strength, fatigue resistance and corrosion resistance. FRP cable is one of the most effective application ways of FRP materials. Taking full advantage of the advantages of light weight, high tensile strength, fatigue resistance and corrosion resistance, avoiding the anisotropy of FRP material, when FRP cable is applied to the super large span bridge structure, it can not only effectively reduce the weight of the cable, increase the span of the super large span bridge, but also effectively improve the long service performance of the cable, and the FRP cable is the improvement over the superstructure. The short term and long term performance of large span bridges provides an effective way for the.FRP cable to be applied to the super large span bridge, which can realize the lightweight of the super large span bridge. However, the research on the mechanical performance of the FRP lightweight and super large span bridge is not enough, especially the vibration problem caused by the light quantization of FRP. The research on the vibration characteristics and damping properties of the cable needs to be carried out on the basis of the test. But because of the lack of application examples of the FRP cables of the super long span bridge, the research and analysis of the vibration characteristics and damping properties of the FRP cable are mainly used in the semi empirical and semi theoretical method, the support and verification of the lack of test. At the same time, how to take the whole bridge into consideration In order to optimize the structural design of FRP lightweight and super large span bridge, the problem of building a bridge with greater material utilization efficiency is also urgently needed to be solved. This paper, focusing on the above problems of FRP lightweight, combines theoretical analysis and experimental research, from the overall structural performance and economic performance. The evaluation and the vibration characteristics of the cable are studied in three aspects. The specific research contents and results include: (1) based on the similarity criterion, the two most representative cable-stayed cables in the Sutong Bridge are selected as the prototype, and the model vibration test of steel cable, CFRP pull cable and BFRP cable, and the cable vibration test are carried out according to the free attenuation vibration method. The results show that the designed cable model vibration test can effectively simulate the vibration characteristics of the actual cable, and the damping analysis results of the vibration test in the cable plane show that the modal damping ratio of the vibration in the FRP cable is greater than that of the steel cable. It is proved that the lightening of the cable is beneficial to the improvement of the vibration damping and energy dissipation in the plane. In addition, the cable surface is also improved. The damping analysis of the external vibration test shows that the damping ratio of the cable is inversely proportional to the frequency of the vibration. Based on the energy dissipation theory and the modal shape curvature method, the formula of the modal damping ratio of the cable is corrected, and the damping energy coefficient of the dynamic strain of the FRP cable is calculated according to the modified formula, and the test knot of the cable vibration is combined. The feasibility of evaluating the damping characteristics of different materials is proved by the dynamic strain damping energy coefficient. (2) the vibration characteristics and damping properties of a new FRP self damping cable are studied by the model vibration experiment. The comparison of the vibration test results shows that the FRP self reducing Jinraso can adjust itself according to the amplitude of the cable. The damping characteristic is used to realize the self damping property of the FRP cable. At the same time, based on the damping energy theory and the viscoelastic damping theory, the calculation method of the modal damping ratio of the FRP self damping cable is proposed. By comparing the theoretical calculation results with the experimental results, it is proved that the proposed method can effectively predict the modal damping of the FRP self damping cable. (3) through the analysis of the key mechanical properties parameters and economic performance parameters of different material FRP cables, the reasonable span interval of different material FRP cables is determined, and a design scheme of a cable-stayed bridge with different material FRP cables mixed in the different span of the same bridge is proposed. A cross sea bridge with the main span of 2038m is taken as a cross sea bridge. For example, the static, dynamic performance and economic performance of the FRP mixed cable-stayed bridge are studied. The analysis results show that the FRP mixed cable-stayed bridge scheme can meet the requirements of the static structural design of the super span cable-stayed bridge, and can effectively improve the vibration frequency of the whole bridge, reduce the response of the bridge seismic displacement, and improve the resistance of the whole bridge. At the same time, the whole life cycle cost analysis of the cable shows that the FRP mixed cable-stayed bridge has the best economic performance in the design scheme satisfying the requirements of the super long span bridge structure. (4) the design scheme of the cable-stayed bridge based on the FRP mixed cable-stayed cable is based on the Suzhou bridge as the prototype, and the FRP mixed layout is put forward according to the similarity criterion. The design scheme of cable model bridge is designed in detail according to the requirements of similar stiffness and similar quality. The main components of the stiffened beam, cable tower, cable, pier and other model bridges are detailed, and the construction analysis of the FRP mixed cable model bridge is carried out according to the reverse method, which provides a reference for the actual construction analysis of the FRP mixed cable stayed cable-stayed bridge. (5) A super span suspension bridge with a main span of 3300m is taken as an example. Through the finite element analysis, the static and dynamic performance of the super span suspension bridge with different material FRP cables (especially the hybrid FRP cables) is studied. Compared with the traditional steel cable suspension bridge, the FRP cable can increase the limit span of the suspension bridge, improve the carrying efficiency of the cable and improve the material utilization of the cable. Furthermore, the static performance of the whole bridge is optimized, and the lightening of the cable can improve the vibration frequency of the super large span bridge and improve the wind stability of the whole bridge. At the same time, the FRP cable with small weight and good damping performance can effectively reduce the seismic response of the whole bridge and improve the seismic safety of the bridge. The life cycle cost assessment of the cable is based on the analysis of the maintenance cost analysis of the first FOS highway bridge which is fully maintained by the main cable. The results show that the FRP cable can effectively improve the economic benefit of the oversuspension bridge because of its good anti fatigue and corrosion resistance. The results are summarized, the main innovation points of the paper are sorted out, and the existing problems and further research contents are put forward.
【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U443.38

【参考文献】