基于日照辐射的悬索桥主缆热应力理论及结构温度效应研究

发布时间：2018-01-25 18:44

  本文关键词： 悬索桥主缆 温度效应 热物性参数 温度应力 施工监控　出处：《重庆大学》2015年博士论文　论文类型：学位论文

【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。
[Abstract]:The main load-bearing structure of the main cable of large span suspension bridge bridge, its performance determines the suspension bridge spanning capacity and bearing capacity, but the change of temperature has a significant effect on the internal force and alignment. The main cable of suspension bridge is a composite structure, the heat conduction mechanism is more complicated, when the external environment temperature changes greatly. The main cable and the external environment of the heat exchange by convection and radiation in various forms, the main cable surface temperature changes rapidly, but because of the internal temperature of the main cable transform lag, and with the main cable diameter becomes larger, the hysteresis phenomenon is more prominent, and the formation of the temperature gradient is obvious, resulting in significant difference in temperature inside and outside the temperature will produce temperature. Deformation will cause changes in the structure of the main cable suspension bridge stress and linear, and will even produce large temperature stress. The temperature stress and deformation affect the suspension bridge construction safety and healthy operation of late, but the temperature. The work carried out less, there is no calculation of related specifications. The actual temperature and in the construction control of long-span suspension bridge is widely used in the main cable measured surface temperature or ambient temperature instead of the main cable, affect the bridge construction safety and accuracy. In view of the above situation, in the Western Transportation construction technology project management center, the Chongqing Municipal Transportation Commission under the support of the Chongqing city is the biggest span suspension bridge (built) as the engineering background, the calculation of the temperature field of main cable of large span suspension bridge, the temperature stress is deduced and its effects were studied systematically. The work of this paper are as follows: the experiments and Research on temperature field measurement of thermophysical properties of 1. main cable in this paper the main cable parameters. The model of thermal parameters of multi operating tests on cable model of a series of thermal parameters (apparent thermal conductivity, apparent thermal diffusivity, surface under natural convection heat exchange system The number of steady state test) and non steady state test, and the on-site environment is at the bridge site (Qing Tian, rain) test of temperature field, the complex environment of the main cable temperature field distribution; and through the finite element model of the experimental simulation test method of rationality were verified. The results prove that the main cable cross section temperature field measured values are consistent with the calculated results, method of computing error is small.2. suspension bridge main cable temperature field in general. Based on the analysis of the main cable temperature field distribution, the heat transfer, general astronomy and solar physics as the theoretical basis of various factors, influence the temperature effects of the material parameters, such as the solar radiation intensity, the latitude and longitude location, weather conditions and Bridge orientation, systematically establish the boundary condition of the main cable suspension bridge structure temperature field, discusses the main cable 琛ㄩ潰涓庡�栭儴鐜�澧冨拰涓荤紗琛ㄩ潰涓庡唴閮ㄤ箣闂寸儹閲忎紶閫掔殑鏈虹悊,鎻愬嚭浜嗕竴濂楁偓绱㈡ˉ涓荤紗娓╁害鍦虹殑鏅�椋�

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