scholarly journals Temperature Field Online Reconstruction for In-Service Concrete Arch Dam Based on Limited Temperature Observation Data Using AdaBoost-ANN Algorithm

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhuoyan Chen ◽  
Dongjian Zheng ◽  
Jiqiong Li ◽  
Xin Wu ◽  
Jianchun Qiu
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Temperature Data ◽  
Arch Dam ◽  
Observation Data ◽  
Measured Temperature ◽  
Concrete Arch Dam ◽  
Temperature Observation ◽  
Limited Temperature ◽  
Online Reconstruction

Temperature is one of the factors affecting the safety operation of concrete arch dams. To accurately reconstruct the temperature field of the concrete arch dam online based on the temperature data of several typical dam sections, this paper proposes the AdaBoost-ANN algorithm. The algorithm uses artificial neural network (ANN) to establish a training set of the measured temperature data and the temperature field of the concrete arch dam obtained by the three-dimensional finite element model; these trained artificial neural networks are used as weak classifiers of the AdaBoost algorithm. Then, the AdaBoost-ANN algorithm is used to establish the mapping relationship between the measured temperature data and the temperature field, and the online reconstruction of the temperature field of the concrete arch dam is realized. The case study shows that the temperature field of the concrete arch dam can be accurately established by AdaBoost-ANN algorithm based on limited temperature observation data. The algorithm is more time-saving and labor-saving than the finite element method and is convenient for online reconstruction of the temperature field and assessment of the safety status of the concrete arch dam.

3D Thermal Mechanical Coupled Elasto-Plastic Finite Element Analysis in the Whole Rolling Process of H-Beam

2008 ◽  
Vol 575-578 ◽  
pp. 532-538 ◽  
Author(s):  
Guo Ming Zhu ◽  
Yong Lin Kang ◽  
Wei Chen ◽  
Guang Ting Ma
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Rolling Process ◽  
Temperature Data ◽  
Measured Temperature ◽  
Element Analysis ◽  
Whole Process ◽  
Microstructure Prediction ◽  
H Beam ◽  
Good Agreement

In the H-beam rolling process, the deformations and temperature field of workpiece significantly influence the mechanical properties due to the change of product microstructure. Prediction of them is important for the groove design and passes sequences. To get the deformation behavior and the temperature field of workpiece, commercial FEM program LS-DYNA has been used to analyze the whole process of H-beam rolling. The approach is based on 3D thermal mechanical coupled finite element method. The rolling process is divided into several units for calculation. The mesh of workpiece is rebuilt in the simulation for reducing the influence of element distortion. The result shows that, the temperature at the wed to flange position maintains the highest during the whole rolling process, while area of the web the lowest. After the rolling, temperature difference is above 150K between the web’s surface and flange’s inside surface, approximate 130K on the flange’s outside surface and 200K in the cross section. The simulation results show good agreement with the measured temperature data.

scholarly journals Numerical Analysis on Temperature Rise of a Concrete Arch Dam after Sealing Based on Measured Data

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Qingbin Li ◽  
Guohe Liang ◽  
Yu Hu ◽  
Zheng Zuo
Keyword(s):  
Boundary Conditions ◽  
Temperature Rise ◽  
Internal Heat ◽  
Arch Dam ◽  
External Boundary ◽  
Measured Temperature ◽  
External Temperature ◽  
Concrete Arch Dam ◽  
Thermal Boundary Conditions ◽  
Environment Temperature

The thermal boundary conditions in the construction and operation phases of a concrete arch dam are always complex. After sealing, differences between the arch dam temperature and its sealing temperature can cause compressive or tensile stresses. Based on measured temperature of an arch dam located in China, a temperature rise phenomenon (TRP) is found in the after-sealed regions of the arch dam. By mining and analyzing the temperature data of various monitoring apparatus embedded in the arch dam, higher environment temperature is considered to be the main cause for the occurrence of the TRP. Mathematical methods for complex thermal boundary conditions, including external boundary conditions and internal heat source conditions, are proposed in this paper. A finite element model is implemented with the concern of the construction phase and operation phase of the arch dam. Results confirm good agreement with the measured temperature and verify the conjecture that the TRP occurs mainly because the external temperature of the arch dam is higher than its sealing temperature.

scholarly journals FEA of Effects Induced by Diurnal Temperature Variation on Downstream Surface of Xiaowan Arch Dam

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Huanhuan Li ◽  
Shaojun Fu ◽  
Gang Li ◽  
Guofei Hu
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Temperature Stress ◽  
Air Temperature ◽  
Mesh Size ◽  
Element Model ◽  
Arch Dam ◽  
Mass Concrete ◽  
Finite Element Program ◽  
Field Simulation

In order to make clear the cracking reasons in arch dam of Xiaowan Hydropower Station during operation period, the approach to combine ANSYS with finite element program COCE-3D is adopted. Firstly, the influence by element type and mesh size for the temperature field simulation result is analyzed. Subsequently, the three typical dam segments cut from Xiaowan arch dam are selected and the relevant finite element model is established; the effect of the measured diurnal air temperature on temperature field and temperature stress of arch dam is analyzed thoroughly. The results indicate that the temperature gradient in mass concrete becomes lower, whereas the affecting depth becomes deeper when the mesh size is too large. Therefore, it is advisable to use smaller size mesh to study the influence of the measured diurnal air temperature on the surface temperature distribution in mass concrete. The temperature of downstream zone in arch dam is significantly affected by air temperature; the changing laws of temperature field and temperature stress with the air temperature are basically consistent, which is sensitive to lower temperature. When the temperature sharply decreased, the temperature stress in the downstream zone is mainly in tensile stress state. The calculated results are basically consistent with the measured results, and the temperature stress induced by the day-night temperature difference is the important reason for the horizontal cracks on the downstream surface. The submodel analysis method is an important alternative approach to study the changing laws of temperature field of arch dam. The research results not only provide an evidence for temperature control and crack prevention of Xiaowan arch dam but also provide a reference for temperature field simulation of similar projects.

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