【作者】 张伟；

【导师】 张亮亮； 钟宁；

【作者基本信息】 重庆大学 ， 土木工程， 2015， 博士

【摘要】 大跨度悬索桥主缆为桥梁的主要承重结构,其性能决定了悬索桥的跨越能力和承载能力,但温度的变化对其内力和线形有着显著影响。由于悬索桥主缆为组合结构,其导热机理较复杂,当外部环境温度变化较大时,主缆与外部环境以对流与辐射等多种形式进行热交换,主缆表面温度变化迅速,但由于主缆内部温度变换滞后,且随着主缆直径变大,滞后现象越显突出,进而形成明显的温度梯度,导致内外温差很大。这种温差会产生温度变形,会引起悬索桥主缆结构受力和线形的变化,甚至会产生及大的温度应力。这种温度应力和变形影响到悬索桥的安全施工和后期健康运营,但相关温度研究工作开展较少,也没有相关的计算规范。且在大跨度悬索桥施工监控中普遍采用主缆实测表面温度或环境温度代替主缆的实际温度,影响悬索桥施工安全和精度。鉴于以上现状,在国家西部交通建设科技项目管理中心、重庆市交通委员会的资助下,本文以重庆市最大跨度悬索桥(修建时)为工程背景,对大跨度悬索桥主缆的温度场计算、温度应力推导及其效应进行了较为系统的研究,本文所做的工作如下:1.主缆热物性参数试验及温度场测量研究。本文进行了多工况的主缆模型热物性参数测试,对主缆模型的一系列热物性参数(表观热传导系数、表观热扩散率、自然对流下的表面换热系数)进行了稳态测试和非稳态测试,并进行了依托工程现场环境下即桥址处(晴天、雨天)温度场测试研究,得到了复杂环境下主缆温度场分布规律;并通过模型实验的有限元仿真对试验测试方法的合理性进行了验证,结果证明主缆横截面温度场实测值与计算值基本相符,误差不大。2.悬索桥主缆温度场的普适计算方法研究。通过对主缆温度场分布规律的分析,以传热学、普通天文学以及太阳物理学为理论基础,研究了对日照温度效应有所影响的各种因素,如:材料参数、太阳辐射强度、经纬度位置、天气状况和桥梁方位等,系统地建立悬索桥主缆结构日照温度场分析的边界条件,探讨了主缆表面与外部环境和主缆表面与内部之间热量传递的机理,提出了一套悬索桥主缆温度场的普适计算方法,建立了悬索桥主缆温度响应的计算模型,进行能够满足对任意复杂条件的数值分析。3.悬索桥主缆三维温度应力计算方法研究。温度场及温度应力现有分析基本是采用有限差分法与有限单元法等数值方法,计算较复杂且工作量较大,不便于实际应用。基于此,本文对悬索桥主缆结构三维温度应力的更为简便、实用的计算方法进行了探讨,基于热弹性力学理论,推导出了悬索桥主缆结构三维温度应力的一般计算方法,研究了影响悬索桥主缆温度应力的参数,并对悬索桥主缆温度应力进行了计算分析,在考虑了泊松效应引起的各应力分量间的藕合作用的同时,能够实现采用二维问题代替三维问题分析的三维温度应力空间分析方法,且只需运用结构力学方法即可实现。4.主缆温度效应分析。基于对悬索桥主缆的温度场分布及温度应力的探讨,系统的研究了悬索桥各结构应力、内力和变形等主缆温度变化所带来的温度效应,更进一步对悬索桥安全性和耐久性等方面进行了探讨。以依托工程为例,系统计算了依托工程主缆索股架设过程索股温度场及对主缆内力、线形及张力差的影响,为减少内力和线型的偏差提供依据;评估温度变化对成桥后主缆的内力、线形以及索塔内力的影响。5.温度场与温度效应计算实例。研究项目直接服务于西南最大悬索桥(修建时)的架设施工,通过对依托工程基准索股架设阶段、主缆索股架设阶段、大桥索夹定位阶段以及加劲梁架设阶段等不同季节主缆温度场测试研究工作,以试验结论为依据,对依托工程主缆温度场和温度效应进行了计算,研究成果将实测温度数据和计算数据进行比较分析,及时调整参数取值、修正计算模型,保证用于依托在主缆架设控制的主缆温度场的准确性及可靠性,顺利完成了依托工程的施工监控工作,主缆上下游高差和桥梁线形达到了目前其他同类桥梁施工尚未达到的目标,确保了施工安全和精度。更多还原

【Abstract】 The main cable of long-span suspension bridge is the major bearing structure in bridge, and its performance determines the spanning capacity and bearing capacity of suspension bridge. However, the temperature change has an obvious effect on its internal force and linear. Because the main cable of suspension bridge is composite structure and the thermal mechanism is complicated, when the external environmental temperature changes greatly, the main cable and external environment will make thermal exchange in the form of convection and radiation. The surface temperature of main cable changes rapidly while the internal temperature of main cable changes slowly and with the increasing of diameter of main cable, the lagging phenomenon will be clearer, thus forming clear temperature gradient and leading to great difference between internal and external temperature. This kind of temperature will cause temperature deformation and lead to the change in force and linear of main cable of suspension bridge and even cause extremely great temperature stress. This kind of temperature stress and deformation will have an effect on the safe construction of suspension bridge and later healthy operation. However, the relevant temperature research is less, nor is the relevant computing regulations. Besides, in monitoring the long-span suspension bridge construction, it universally uses measured surface temperature or environment temperature of main cable in replace of the actual temperature of main cable, which will affect the construction security and accuracy of suspension bridge. According to the current situation aforesaid and funded by State Western Traffic Construction Scientific Project Management Center and Traffic Committee of Chongqing City, this thesis makes a systematic research on the temperature field computing, temperature stress deduction and temperature effect of long-span suspension bridge on the basis of the longest-span suspension bridge in Chongqing. The steps are shown as follows:1. Research on thermophysical parameter test and temperature field measurement of main cableIn this thesis, it makes the thermophysical parameter test(apparent thermal conductivity, apparent thermal diffusivity and coefficient of surface heat exchange in natural convection) for main cable model in multiple operating modes. It also makes the steady-state and unsteady-state tests for a series of thermophysical parameters of main cable model, and studies the temperature field test in bridge location(in fine or rainy days) by relying on engineering field environment, thus getting the distribution rules of temperature field of main cable in complicated environments. Besides, it verifies the rationality of test method by way of finite element simulation of model test, which proves that the measured value of the temperature field in the cross section of main cable basically conforms to the computed value and the error is small.2. Research on pervasive computing method of temperature field of main cable of suspension bridgeBy way of analysis of distribution law of main cable and on the theoretical basis of heat transfer theory, general astronomy and solar physics, it studies various factors affecting the solar temperature effect, such as material parameter, solar radiation strength, location in longitude and latitude, weather condition and bridge direction, etc., systematically establishes the boundary conditions for solar temperature field analysis of main cable of suspension bridge and discusses the mechanism of heat transfer between the surface of main cable and external environment and the surface of main cable and interior. Thus, it proposes a set of pervasive computing method of temperature field of main cable of suspension bridge and establishes the computing model of temperature response of main cable in suspension bridge, which can satisfy the value analysis in any complicated conditions.3. Research on computing method of three-dimensional temperature stress of main cable in suspension bridgeThe current analysis for temperature field and temperature stress basically adopts such value methods as finite difference approach and finite element method, which is complicated and needs more efforts, not convenient for actual application. Based on it, it discusses the more simple and actual computing method for the three-dimensional temperature stress of main cable structure in suspension bridge, thus deducing a general computing method for the three-dimensional temperature stress of main cable structure in suspension bridge on the basis of thermoelasticity theory. Besides, it studies the parameters affecting the temperature stress of main cable in suspension bridge and makes computing analysis for the temperature stress of main cable in suspension bridge, and therefore, it can realize the spatial analysis of three-dimensional temperature stress, which replace the three-dimensional problems with two-dimensional problems, only by using structural mechanics method while considering the coupling action between each component of stress caused by Poisson effect.4. Analysis for temperature analysis of main cableBased on the discussion about the temperature field distribution and temperature stress of main cable in suspension bridge, it systematically studies the temperature effect brought by temperature change of main cable, such as structural stress, internal force and deformation, etc., and further discusses the safety and durability of suspension bridge. In the case of project, it systematically computes the temperature field of strand and its effect on internal force, linear and tension difference in the process of erecting strand of main cable in the project, thus providing basis for reducing the deviation of internal force and linear; it also evaluates the effect of temperature change on the internal force and linear of main cable and internal force of bridge tower after the completion of bridge.5. Compute example of temperature field and effectThis research project directly serves the erection and construction of the largest suspension bridge(under construction) in the Southwest. It studies and tests the temperature field of main cable in different seasons of stages of standard strand erection, strand erection of main cable, positioning of cable clamp of bridge and erection of stiff girder, and then computes the temperature field and effect of main cable in the project based on the test conclusions. In the research result, it makes a comparative analysis for the measured temperature data and computed data, adjusts the parameter choice and modifies computing model timely, so as to guarantee the accuracy and reliability of the temperature field of main cable controlled in erection of main cable. In this way, the project-based construction monitoring is successfully made and the height difference between the upper course and lower course and the bridge linear has reached the goal that other similar bridge construction has not reached yet, thus ensuring the construction safety and accuracy.更多还原