基于热力学和结构健康监测的混凝土箱梁温度时空分布研究
发布时间：2018-07-28 09:58
【摘要】：桥梁在服役期间承受复杂多因素荷载的耦合作用,包括运营荷载、环境因素、性能退化甚至自然灾害。其中温度荷载是环境因素中最为重要的一部分,钢筋混凝土箱梁在太阳辐射、环境温度和风等随机因素共同作用下产生的瞬态不确定性温度场,引起截面不均匀的温度分布,引起温度应力的集中和挠曲变形,甚至引起严重的温致裂缝,造成桥梁承载能力严重退化,不符合工作服役期间的安全性、耐久性的要求。此外,基于振动的损伤识别方法中环境因素尤其是温度对损伤识别的准确性有较大影响,因此将结构监测系统真正应用到桥梁状态的评估及损伤识别前,必须首先剔除温度等环境因素对损伤识别的影响,如何从多因素耦合的结构响应中分离温度效应等单因素效应成为研究的热点与难点,研究温度时空分布十分必要。基于有限元的传统桥梁温度场分析方法难以考虑太阳辐射、环境温度和风等不确定性的随机因素对瞬态温度场的影响,往往与实际不符,研究基于监测数据的全桥真实温度荷载模型的建立将更有实际意义。本论文的研究内容分为下面几个部分:首先,建立起确定性晴空太阳辐射,根据空间几何关系,得到太阳高度角、方位角与太阳时角、太阳赤纬、所在地纬度之间的解析关系式,考虑桥梁不同表面方位角与倾角,得到一天之内任意时刻太阳辐射入射角以及桥梁的太阳辐射热流的边界条件。研究箱梁悬挑翼缘对腹板的遮挡形成的阴影,得到了一天之内箱梁表面阴影随时间的演化。然后,建立混凝土箱梁桥三维热力学有限元模型,研究在环境温度、太阳辐射和对流换热等因素共同作用下温度时空分布规律,考虑了时变阴影不均匀受热对箱梁温度分布的影响。最后,在确定性热物理模型的基础上,提出了一种基于卡尔曼滤波重构混凝土箱梁全桥温度时空分布的方法,该方法可考虑量测噪声和不确定性边界热流的影响。利用少量温度传感器量测值,得到太阳辐射强度等不确定性参数的最优估计和全桥其他任意位置的温度分布。通过某桥数值算例验证该方法的可行性和有效性,并且研究了不同信噪比和初始温度值对滤波准确性和鲁棒性的影响。该方法为基于监测数据的全桥真实温度荷载模型的建立提供了可能性。
[Abstract]:Bridges are subjected to complex multi-factor loads during service, including operational loads, environmental factors, performance degradation and even natural disasters. The temperature load is the most important part of the environmental factors. The transient uncertain temperature field of the reinforced concrete box girder under the action of the random factors such as solar radiation, ambient temperature and wind causes the uneven temperature distribution of the section. It causes the concentration of temperature stress and flexural deformation, and even causes serious temperature induced cracks, resulting in serious degradation of the bearing capacity of bridges, which does not meet the requirements of safety and durability during service. In addition, the environmental factors, especially temperature, have a great influence on the accuracy of damage identification in Vibration-based damage identification method. Therefore, the structural monitoring system is really applied to the bridge state evaluation and damage identification. Firstly, the influence of environmental factors such as temperature on damage identification must be eliminated. How to separate the single factor effect such as temperature effect from the multi-factor coupling structure response has become a hot and difficult point, and it is very necessary to study the temperature space-time distribution. The traditional bridge temperature field analysis method based on finite element method is difficult to consider the influence of random factors such as solar radiation, ambient temperature and wind on the transient temperature field, which is often inconsistent with the actual situation. It will be more meaningful to study the real temperature load model of the whole bridge based on the monitoring data. The research content of this paper is divided into the following parts: firstly, the deterministic solar radiation from clear sky is established. According to the spatial geometric relationship, the sun altitude angle, azimuth angle and sun time angle, solar red latitude, solar azimuth angle and solar azimuth angle are obtained. Considering the azimuth and inclination of different surface of the bridge, the analytical relation between the local latitudes is used to obtain the boundary conditions of the solar radiation incident angle and the solar radiation heat flux of the bridge at any time of the day. In this paper, the influence of the overhanging flange on the web of box girder is studied, and the evolution of the surface shadow over time in one day is obtained. Then, the three-dimensional thermodynamics finite element model of concrete box girder bridge is established to study the temporal and spatial distribution of temperature under the combined action of environmental temperature, solar radiation and convection heat transfer. The influence of uneven heating of time-varying shadow on the temperature distribution of box girder is considered. Finally, on the basis of deterministic thermophysical model, a method based on Kalman filter is proposed to reconstruct the temperature space-time distribution of concrete box girder. This method can take into account the influence of measurement noise and uncertain boundary heat flow. The optimal estimation of the uncertain parameters such as solar radiation intensity and the temperature distribution at other arbitrary locations of the bridge are obtained by using a small amount of temperature sensor measurements. The feasibility and effectiveness of the method are verified by a bridge numerical example. The effects of different signal-to-noise ratio (SNR) and initial temperature on the accuracy and robustness of the filter are studied. This method provides the possibility for the establishment of the real temperature load model of the whole bridge based on the monitoring data.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446;U448.33
本文编号：2149724
[Abstract]:Bridges are subjected to complex multi-factor loads during service, including operational loads, environmental factors, performance degradation and even natural disasters. The temperature load is the most important part of the environmental factors. The transient uncertain temperature field of the reinforced concrete box girder under the action of the random factors such as solar radiation, ambient temperature and wind causes the uneven temperature distribution of the section. It causes the concentration of temperature stress and flexural deformation, and even causes serious temperature induced cracks, resulting in serious degradation of the bearing capacity of bridges, which does not meet the requirements of safety and durability during service. In addition, the environmental factors, especially temperature, have a great influence on the accuracy of damage identification in Vibration-based damage identification method. Therefore, the structural monitoring system is really applied to the bridge state evaluation and damage identification. Firstly, the influence of environmental factors such as temperature on damage identification must be eliminated. How to separate the single factor effect such as temperature effect from the multi-factor coupling structure response has become a hot and difficult point, and it is very necessary to study the temperature space-time distribution. The traditional bridge temperature field analysis method based on finite element method is difficult to consider the influence of random factors such as solar radiation, ambient temperature and wind on the transient temperature field, which is often inconsistent with the actual situation. It will be more meaningful to study the real temperature load model of the whole bridge based on the monitoring data. The research content of this paper is divided into the following parts: firstly, the deterministic solar radiation from clear sky is established. According to the spatial geometric relationship, the sun altitude angle, azimuth angle and sun time angle, solar red latitude, solar azimuth angle and solar azimuth angle are obtained. Considering the azimuth and inclination of different surface of the bridge, the analytical relation between the local latitudes is used to obtain the boundary conditions of the solar radiation incident angle and the solar radiation heat flux of the bridge at any time of the day. In this paper, the influence of the overhanging flange on the web of box girder is studied, and the evolution of the surface shadow over time in one day is obtained. Then, the three-dimensional thermodynamics finite element model of concrete box girder bridge is established to study the temporal and spatial distribution of temperature under the combined action of environmental temperature, solar radiation and convection heat transfer. The influence of uneven heating of time-varying shadow on the temperature distribution of box girder is considered. Finally, on the basis of deterministic thermophysical model, a method based on Kalman filter is proposed to reconstruct the temperature space-time distribution of concrete box girder. This method can take into account the influence of measurement noise and uncertain boundary heat flow. The optimal estimation of the uncertain parameters such as solar radiation intensity and the temperature distribution at other arbitrary locations of the bridge are obtained by using a small amount of temperature sensor measurements. The feasibility and effectiveness of the method are verified by a bridge numerical example. The effects of different signal-to-noise ratio (SNR) and initial temperature on the accuracy and robustness of the filter are studied. This method provides the possibility for the establishment of the real temperature load model of the whole bridge based on the monitoring data.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446;U448.33
【参考文献】
相关期刊论文 前1条
1 丁幼亮;王高新;;Estimating extreme temperature differences in steel box girder using long-term measurement data[J];Journal of Central South University;2013年09期
相关博士学位论文 前2条
1 彭友松;混凝土桥梁结构日照温度效应理论及应用研究[D];西南交通大学;2007年
2 张福俭;大跨度斜拉桥拉索索力与车辆荷载识别及建模研究[D];哈尔滨工业大学;2013年
，本文编号：2149724
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