【作者】 蔡东升；

【导师】 刘荣桂；

【作者基本信息】 江苏大学 ， 固体力学， 2013， 博士

【摘要】 在桥梁工程中,传统钢拉索的锈蚀、承载效率问题随着结构跨度增加显得日益突出,新型缆索替代材料的研究成为研究热点之一。具有高强、轻质、抗疲劳、耐腐蚀等优良性能的碳纤维增强复合材料(CFRP)作为长大跨径斜拉桥的拉索,既可以充分利用其高强性能,又能基本解决传统斜拉索的上述问题,还可以有效的降低斜拉桥上部结构自重,有效提升拉索承载效率和斜拉桥跨越能力。目前,国内外CFRP索长大跨斜拉桥结构非线性动力学方面的系统研究相对较少。本文结合国家自然科学基金资助项目‘CFRP索预应力大跨结构(桥梁与房屋)非线性分析与控制(50678074)”和“基于高性能材料CFRP索的超大跨桥梁原型设计与相关问题研究(51078170)”的研究,通过国内首座CFRP索斜拉试验桥试验分析与非线性动力学理论研究,探索CFRP索长大跨斜拉桥结构非线性动力学性能,以期为CFRP索长大跨结构的开发应用研究提供科学依据。本文主要完成了以下工作：(1) CFRP索非线性静动力特性及参数分析拉索是斜拉桥的主要受力构件,相比于塔梁结构具有轻、柔和低阻尼等特点。由于斜拉索自重垂度的影响,拉索呈现出强非线性的特征。根据斜拉索计算分析理论,详细探讨了基于悬链线单元的CFRP拉索静动力学分析的方法体系,将其用于分析不同长度、不同应力水平的CFRP索静动力特性及参数分析,并与传统钢拉索进行了静动力特性对比分析,得到了一些有意义的结论。(2) CFRP索试验桥静载试验研究及有限元对比分析对国内首座CFRP索斜拉人行试验桥进行了静载试验研究,详细介绍了静载试验的主要内容和方法,进行CFRP索斜拉桥有限元分析,并将有限元分析的理论计算结果与该桥的试验实测结果进行了对比分析,为长大跨CFRP索有限元模型的建立提供基础数据和参考依据。(3) CFRP索斜拉试验桥动态性能试验及其动力学特性分析在已有静载试验数据的基础上,进行了试验桥动态性能试验研究,详细介绍了试验桥模态试验的激励方式、信号采集系统和测试方法及主要测试内容和数据处理等内容,并将有限元动态性能分析结果与试验实测结果进行了对比分析,明确CFRP索斜拉桥的动态特性；在实测动态特性数据基础上,对CFRP索斜拉试验桥与同跨度的钢索斜拉桥的动力学特性和地震响应情况进行了对比分析。(4) CFRP索长大跨斜拉桥非线性动力特性及地震响应分析建立主跨千米级的CFRP索斜拉桥和钢索斜拉桥有限元动力学分析模型,对比分析了CFRP索及钢索长大跨斜拉桥的动力学特性,利用时程分析法分析了CFRP索长大跨斜拉桥竖向位移、主跨跨中弯矩、塔顶位移等内容的地震响应时程及响应峰值；并与传统钢索长大跨斜拉桥响应结果进行对比分析,探讨了CFRP索长大跨斜拉桥的抗震性能。(5) CFRP索长大跨斜拉桥地震响应控制研究选取目标函数(梁端纵向位移、主梁跨中竖向位移、桥塔顶纵桥向位移、桥塔底弯矩以及减震装置的内力和变形),分析了设置弹性和非线性粘滞阻尼器装置的CFRP索长大跨斜拉桥的响应特点,通过参数灵敏度分析,在对目标函数值灵敏度分析的基础上,确定了CFRP索长大跨斜拉桥结构合理的弹性连接刚度k、阻尼系数C和速度指数a,并对比分析了两种减震措施对CFRP索及钢索长大跨斜拉桥的减震效果。研究结果表明：CFRP索及其长大跨斜拉桥结构的非线性动力学性能相比传统钢索及其长大跨斜拉桥结构在基本动力学特性上存在较大差异,尤其是扭转基频与规范中的计算结果差异较大；斜拉桥采用塔梁固结体系时,扭转振型出现的可能性更小；CFRP索斜拉桥的自振频率较钢索斜拉桥高,CFRP索试验桥的地震响应曲线峰值小于钢索斜拉桥,抗震性能优于传统钢索斜拉桥结构,在满足同样的减震要求时,CFRP索长大跨斜拉桥对减震装置设计参数的要求较低,在相同的阻尼器参数下,CFRP索长大跨斜拉桥减震效果优于传统钢索斜拉桥结构。本文主要研究内容可为CFRP材料更好更快地应用于长大跨(桥梁、房屋)结构提供理论依据与技术支撑。更多还原

【Abstract】 With the trend that the span of cable-stayed bridge becomes longer and longer, not only the cable corrosion and bearing efficiency but also the structural weight become increasingly prominent for the project of cable-stayed bridge. To replace traditional steel used in the cable, new material found as Carbon fiber reinforced composite (CFRP), which has the excellent characteristic of high strength, lightweight, anti-fatigue, corrosion resistance, etc, becomes a research hotspot. Using CFRP as cables of the long span cable-stayed bridge can not only take advantage of its high strength properties and solve the corrosion problems of the traditional steel cable, but also efficiently reduce the superstructure weight of cable-stayed bridge, improve the bearing efficiency of cable and get longer spanning capacity, so CFRP used as cable has a obviously competitive advantage. However, nonlinear dynamics system study of long-span CFRP cable-stayed bridge is hardly found at present. Analyzing the experiment study of the nation’s first CFRP cable-stayed bridge and the study of nonlinear dynamics theory, the paper explores the nonlinear dynamics performance and expects to provide scientific basis for the development and application of CFRP long span structure, which is based on the support of the National Natural Science Fund Project "CFRP prestress span structures (bridges and buildings) Nonlinear Analysis and Control (50678074)"and "Prototype design and related problems research of super long span bridge with high performance CFRP cables(51078170)". This paper completes the following tasks:(1)Nonlinear static and dynamic characteristics and parameter analysis of CFRP cableCompared with beam structure, cable considered as the main load-bearing component of cable-stayed bridges has the characteristics of light, soft and low damping, showing strongly nonlinear characteristics under the influence of cable droops. Based on catenaries element, the methods of analyzing dynamics and static characteristics are discussed according to the calculation theory of cable. What’s more, the methods are also applied to the dynamics and static characteristics and the parameter analysis of CFRP cable under different length and stress level and compared with the result of traditional steel cable. The results illustrate a series of meaningful conclusions.(2) Static experiment of CFRP cable-stayed testing bridge and finite element analysisTo analyze the static characteristics of the CFRP cable-stayed bridge, the paper studies static experiment on the CFRP cable-stayed footbridge, introducing both the main contents, methods of the experiment and establishing finite element model. Comparing related analysis results with the results obtained from experiment, basic data and the reference are provided for establishing the finite element model of long span CFRP cable-stayed bridge.(3) Mode experiment and dynamic characteristics analysis of CFRP cable-stayed testing bridgeBased on the static experimental data, mode experiment research is made in detail concerning the excitation mode, signal acquisition system, test methods, and test content and data processing etc. Then the mode experimental results are compared with those obtained from finite element dynamic analysis to confirm the dynamic characteristics of the CFRP cable-stayed bridge. Lastly, with regard to the dynamic characteristics and seismic response, the comparison between CFRP cable-stayed bridge and steel cable-stayed bridge with the same span is conducted.(4) Nonlinear dynamic characteristics and seismic response analysis of long span CFRP cable-stayed bridgeTwo finite element dynamic analysis models of cable-stayed bridges with the lkm main span are established. One cable is steel, the other is CFRP. The dynamic characteristics between them are compared. Based on time history analysis method, differences of seismic response time history and response peak are analyzed between long span CFRP cable-stayed bridge and steel cable-stayed bridge. The exploration to the seismic performance of long span CFRP cable-stayed bridge is discussed.(5) Seismic response control research of long span CFRP cable-stayed bridgeThe paper focuses on elastic connection and viscous damper selecting several objective functions such as longitudinal displacement at the end of the main beam, vertical displacement at the middle of the main span, longitudinal displacement on the top of towers, bending moment and axial force at the bottom of towers and internal force and deformation of seismic reduction devices. Based on the sensitivity analysis in both the parameters and the objective functions’values, the flexible connection stiffness k, damping coefficient C and speed index a are selected reasonably. At the same time, the effects of two measures for seismic response control applied in the two kinds of cable-stayed bridges are analyzed and compared.It is shown that the dynamic characteristics of CFRP cable and long span CFRP cable-stayed bridge differs from the steel cable and long span steel cable-stayed bridge. The natural torsion frequency of long span CFRP cable-stayed bridge has an obvious difference with the result calculated from specification. The Cable-stayed bridge with tower beam consolidation system, the possibility of torsion vibration mode is less likely to appear. Natural frequency of CFRP cable-stayed bridge is relatively higher than steel cable-stayed bridge under the same span condition. Seismic response peak value of CFRP cable-stayed bridge is relatively less than that of steel cable-stayed bridge. Seismic performance of CFRP cable-stayed bridge is superior to that of steel cable-stayed bridge. Meeting the same requirements of seismic response control, CFRP cable-stayed bridge has a lower requirement for design mechanic parameters than steel cable-stayed bridge. Under the same damper parameters, damping effect of the CFRP cable-stayed bridge is superior to that of steel cable-stayed bridge. The main research contents in this paper could offer theoretical basis and technical support to better and faster application of CFRP material in long span bridges or buildings.更多还原