【作者】 涂永明；

【导师】 吕志涛；

【作者基本信息】 东南大学 ， 结构工程， 2005， 博士

【摘要】 我们预测,CFRP将是21世纪建造重大土木工程的新型高强高性能结构材料之一。采用CFRP索建造悬挂建筑结构,不仅可以减轻自重、提高有效承载能力,而且,可以从根本上解决拉索的腐蚀和疲劳问题,优化结构的受力性能,减少后期维护费用,使结构在综合性能和全寿命周期上受益。CFRP索悬挂建筑结构根据自然传力原理,蕴结构艺术于自然,具有深厚的建筑艺术内涵和结构美之表现力,达到了结构与建筑、功能与艺术、力与美的协调统一,是一种具有优良结构性能和发展、应用前景的高层建筑新型结构体系。CFRP索悬挂建筑结构兼有新材料和新结构体系之属性,本文对其力学性能和计算分析方法进行了较为深入的研究,如下所述。首先,分析了悬挂建筑结构的自然性和社会性,介绍了高层悬挂建筑结构的类型、国内外悬挂建筑结构及CFRP索(筋)的研究、应用与发展概况。阐述了CFRP索悬挂建筑结构的特点。建立了其结构形态与控制的概念;在回顾结构控制方法的基础上,阐述了悬挂建筑结构减振避震控制的思想。此外,展望了CFRP索悬挂建筑结构在我国的发展前景。其次,提出了CFRP索悬挂建筑结构的设计原则、计算模型及一些计算假设。CFRP索核筒悬挂建筑结构的核心筒既是竖向和水平向交通的枢纽,也是最重要的受力结构。根据正六边形六面开洞筒体的受力性能,采用连续化方法,分析了其在水平荷载、竖向荷载及扭矩作用下的力学性能,并与有限元方法计算的结果相比较,验证了文中提出的连续化分析方法的有效性,且该方法简便,节省计算时间和空间开销,可以用于实际设计分析中。再次,采用了悬挂质量控制体系(STMD)的概念,详细地分析了CFRP索悬挂建筑结构(即Super STMD,SSTMD)的能量传递及耗散规律。根据CFRP索单段悬挂结构的二自由度运动方程,推导出了地面谐振动作用下的加速度和位移响应频率传递函数以及悬挂建筑上部结构受到谐荷载激励的加速度响应频率传递函数。较为详尽地分析了调谐比、阻尼比及悬挂质量比对结构动力响应的影响。采用Den-Hartog方法推导出了绝对加速度及位移响应达到优化时的参数表达式。讨论了CFRP索悬挂建筑结构的参数优化方法,创新地提出了次结构阻尼比的极大值和合理值的概念,并由此较为全面地分析了在次结构合理阻尼比条件下的结构加速度和位移响应。引进了减振效率的概念,并分析了主、次结构的阻尼比、悬挂质量比等对减振效率的影响,表明悬挂建筑结构具有稳定的减振能力。对比分析了小质量比STMD和悬挂建筑结构的减振机理。讨论了CFRP索悬挂建筑结构减振能力的鲁棒性。然后,以随机振动为基础,将白噪声作为地面加速度激励,对二自由度CFRP索悬挂建筑结构的动力响应优化控制作了较为细致的分析。推导出了白噪声地震动激励下悬挂建筑结构的绝对加速度及位移的方差响应表达式。对CFRP索悬挂建筑结构进行了随机振动的无约束优化分析,推导出了主结构无阻尼条件下的优化参数解析表达式。对主结构有阻尼条件下的动力响应进行了优化分析,分别给出了主结构绝对加速度和位移响应的优化参数曲线。创新地对CFRP索悬挂建筑结构进行了单约束和双约束条件下的动力响应优化分析,并且证明了进行双约束优化,可以从根本上保证主结构相对位移响应的动力稳定性,避免迭代发散现象。分析了CFRP索悬挂建筑结构随机动力响应参数的优选问题,提出了四类优化目标函数和四类优化参数,并做了细致的对比,得到了有用的结果。其中,采用主结构加速度响应优化参数,可以兼顾主、次结构的绝对加速度响应及相对位移响应,减振避震的功效性与鲁棒性都很好;采用主结构相对位移响应参数,可以得到十分优良的主、次结构加速度响应以及主结构相对位移响应,然而,由其而得的次结构位移响应不太理想。接着,建立了CFRP索多段悬挂建筑结构减振体系计算模型及运动方程。确定了多段悬挂建筑结构地震动响应函数及多目标优化方法。创新地将主、次结构响应作为平等的优化目标,采用改进的理想点方法即“约束-评价函数法”对多目标优化问题进行求解。以三段悬挂建筑结构为例,阐述了CFRP索多段悬挂建筑结构减振体系参数优化方法。定义了多段悬挂建筑主结构减振效率系数。对悬挂建筑次结构位移响应进行了优化分析,表明次结构的位移响应与自身调谐比显著相关,而与其它次结构之调谐比相关性较低。分析表明,采用根据约束-评价函数优化方法得到的参数进行主、次结构响应计算,可以得到较全面的优化效果。经过参数优化后的CFRP索悬挂建筑结构的动力位移响应比普通巨型结构要优越,且采用约束-评价函数法进行参数优化具有高效、稳定的性质,比主结构位移响应优化方法合理。根据频域分析和时程计算结果,验证了经约束-评价函数法优化的悬挂建筑结构具有理想的减振效果,达到了多目标优化的根本目的。同时,对我校刘郁馨博士完成的单段核筒悬挂建筑结构模型试验作了简述,检验了悬挂建筑结构的动力性能,说明了该结构减振能力强,且验证了在一定条件下,随着主、次结构连接刚度的降低,体系减振效果增强的论点。另外,分别对CFRP索悬挂建筑主结构和主、次结构之间的抗震多道设防提出了建议。讨论了悬挂次结构振动刚度,得到了悬挂次结构精确的抗侧刚度表达式。研究了P-Δ效应下核筒侧移与箱基础倾角的静、动力耦合关系,得到了一系列有益的结果。分析了悬挂次结构刚体集合的摆动问题,建立了次结构刚体集合运动方程,并给出了计算次结构摆动位移幅值的计算公式。此外,根据现行规范,分别得到了正六边形核筒悬挂建筑主结构在不同抗震设防烈度时的名义高宽比限值。最后,介绍了配置CFRP索的悬挂转换大梁及吊杆的形式及特点。分析了转换大梁的设计原理,推导了设计公式。因为采用预应力技术和高强高性能的CFRP索,可以使得悬挂转换大梁承受荷载后处于微挠度水平,所以悬挂次结构相对于主结构的位移可以非常小,悬挂建筑的使用性能由此裨益良多。本文还简单介绍了以我校为主研究、设计并建成的国内第一座CFRP拉索斜拉桥。本文作者还与导师商量,提出了建造一座试验性的CFRP索悬挂建筑结构的建议。更多还原

【Abstract】 We forecast that CFRP is the structural material which plays a very important role in civil engineering in the 21st century. Suspended building structures, in which CFRP cable is used as main reinforcement, will not only reduce self-weight and increase effective load-carrying capacity of themselves, but also completely avoid corrosion and fatigue of the cables and optimize the structural capability and then reduce the maintenance expenditure, so the structures will benefit much from the general perfomance and whole-life-cycle economics.CFRP cable suspended building structures (CSBSs) conforming to the natural principle of transferring loads comprise structural art of nature and consist of profound architectural artistry and structural esthetics, which lead to harmonic unification of structure and architecture, function and art, and strength and esthetics.CFRP CSBSs possess the attributes of new material and new structural system. The mechanical performance and computational methods of this new structure have been studied, which are summarized as follows.Firstly, based upon the natural and social attributes, the general situation of types, application, development and distinguished merits of suspended structures and CFRP cables or tendons are introduced. The concepts of structural form and control of CFRP CSBSs have been established. After reviewing the structural control methods, the idea of suspended control system is brought forward. Additionally, the development foreground of CFRP CSBSs in China is forecast.Secondly, the design principles, mechanical model and some hypotheses are brought up. In CFRP cable core-tube suspended building structure, the core tube is the vertical and horizontal main stem, and also the most important load-carrying structure. The mechanical behaviors of the hexagonal core tube with holes in all the six sides are analyzed with the continuous method, and the analysis results are compared to that analyzed with finite element method, which proves that the continuous method is effective, and much simpler and more timesaving than finite element method, and capable of being used in practical design.Thirdly, the laws of energy transferring and dissipation in CFRP CSBSs (i.e. Super Suspended Tuned Mass Damper, SSTMD) are expatiated on based upon the concept of Suspended Tuned Mass Damper (STMD). According to the two-degree movement equation, the frequency transfer functions of absolute acceleration and displacement are derived under the action of harmonic ground excitation, as well as the transfer function of acceleration under the action of harmonic load on the superstructure of suspended building. The influences of frequency ratio, damping ratio and suspended mass ratio on the dynamic responses of the structures are analyzed detailedly. The optimal parameters of acceleration and displacement responses are derived with Den-Hartog method. The methods of parameter optimum of CSBSs are discussed, and then theconceptions of the maximum value and reasonable value of damping ratios of secondary structures are put forward, innovatorily. Moreover, the acceleration and displacement responses are analyzed in the round by using the reasonable values of damping ratios of secondary structures. The efficiency of shock absorption of CSBSs is analyzed with the combinations of different parameters, and indicates that the CSBSs are of very stable capability of shock absorption. Furthermore, the shock absorption mechanisms of both small suspended mass ratio STMD and SSTMD are studied. The robustness of the shock-absorption capacity of CSBSs is discussed.Fourthly, the dynamic response optimization of the two-degree SSTMD is analyzed, which is under the action of white noise ground excitation, and then the variance responses of acceleration and displacement are derived. When the SSTMD is in the case of non-constraints, the analytical expressions of optimal parameters are obtained without damp of main structure, while the numerical figures of optimal acceleration and displacement parameters are offered with damp of main structure. The dynamic responses of SSTMD in the cases of single or double constraints are discussed with numeric method. When the SSTMD is optimized in the case of double constraints, the stability of dynamic displacement response of main structure could be guaranteed radically and the iteration divergence could be avoided. And, withal, the double-constraint dynamic responses are of very nice robustness and efficiency. To choose the optimal dynamic parameters, four types of objective functions and four types of optimal parameters are summarized, innovatorily, and then some useful conclusions are drawn. Adopting the parameters of optimal acceleration response of main structure will lead to very good dynamic behaviors of main and secondary structures, including acceleration and displacement responses; adopting the parameters of optimal displacement response of main structure will lead to excellent acceleration behaviors of main and secondary structures and excellent displacement behavior of main structure, but the displacement behaviors of secondary structures are not so good.Fifthly, the mechanical model and movement equation of multi-section suspended building structure (MSBS) are constructed. Then the corresponding response functions and optimization method of the Multiple Objective Functions (MOFs) are determined. The method of parameter optimization of shock-absorption MSBS is innovatorily expatiated on with the instance of a three-section suspended building structure. The coefficient of shock-absorption efficiency of the main structure of MSBS is defined. The displacement responses of secondary structures are remarkably correlative with the frequency ratios of themselves, but not remarkable with the other frequency ratios. Based on the analysis, with the method of MOFs, all the responses of main structure and secondary structures are limited in a very low and even level. Moreover, the results are adequately accurate with the optimal parameters of some fixed mass ratio when calculating the responses of other ratios. According to the time-history analysis of MSBS, it is clear that the optimization method of MOFs is much superior to that of the SOF. After parameter optimization, the dynamic displacement responses of the MSBS are clearly better than that of ordinary structure. On the basis of analysis and computation in frequency domain and time domain, it is proved that the optimization method of MOFs is more effective and stable than that of SOF, and with the former, the ideal shock-absorption capability of MSBS could be acquired.Sixthly, the model experiment of a core-tube suspended building structure finished by Dr. Liu Yuxin is introduced. According to the experiment, the excellent dynamic capability of the suspended building structure is testified. And that in some given condition, the shock-absorption capability of the structure will increase with the adjacent stiffness between the main and thesecondary structures decreasing is proved.Seventhly, construction measures are offered to the main structure and the self-adjustment connections between main and secondary structures of CFRP CSBS, respectively. The vibration stiffness of secondary structures is discussed and the more accurate stiffness formula is derived. The couple relationship of P-? effect on core tube and inclined action of box basement is analyzed. The rigid-body movement function of secondary structures is constructed and solved analytically, and then the formula of the maximum displacement is obtained. Based on the current Chinese Code, the nominal height-to-width ratio of hexagonal core-tube suspended building structure under different seismic fortification intensities are listed in the table.Finally, the forms of the CFRP cable suspended transferring beams and hangers are introduced, as well as the elastic design method of the beams. Because the prestresssing technique and the high-strength and high-performance CFRP cable are used in the transferring beams, the deflection of the beam may be limited to a very low level, even to zero, and the relative displacement between suspended secondary structures and main structure is also very little, from which the performances of the suspended building structure will benefit very much. Additionally, with the guidance of Prof. Lu Zhitao, who is the author’s supervisor, the colleagues of the research team have developed and manufactured the CFRP cable anchorages. On the basis of our efforts, the 1st CFRP cable-stayed bridge in China has been designed and constructed. Furthermore, the author has proposed to design and build a CFRP cable suspended building structure, which is sustained by his supervisor.更多还原