Effect of Cooling Pipe in Thin-Walled Hydraulic Structure during Construction

2012 ◽  
Vol 446-449 ◽  
pp. 1266-1269
Author(s):  
Zhen Hong Wang ◽  
Guo Xin Zhang ◽  
Zhao Gang Wang ◽  
Yi Liu
Keyword(s):  
Concrete Structure ◽  
Early Stage ◽  
Low Cost ◽  
Effect Of Temperature ◽  
Good Effect ◽  
Mass Concrete ◽  
Forming Mechanism ◽  
Cooling Pipe ◽  
Thin Walled ◽  
The Difference

In view of the problem of concrete crack in the period of construction, this paper introduces the cause and the forming mechanism of crack in thin-walled concrete structure and points out that the difference between the inside and outside temperature at early stage and the basic difference of the temperature at later stage are considered as the main factors influencing the phenomena. This paper puts forward the application of pipe cooling which is used in the mass concrete to the thin-walled concrete structure. In doing so, the difference of the internal and surface temperature is reduced and the appearance of cracking is avoided. Under the basic theories of temperature field and stress field of concrete, the 3-D FEM with the numerical algorithm of pipe cooling is adopted to simulate the thermal field and stresses field of concrete aqueduct during construction and the result shows that good effect of temperature control and crack prevention is achieved in thin-walled concrete structure. At the same time, water cooling pipe has many merits including simple operation, easy adjustment, high adaptability, and low cost

Study on the Application of Cooling Pipe in Thin-Walled Concrete Structure

2010 ◽  
Vol 163-167 ◽  
pp. 1107-1110 ◽  
Author(s):  
Zhen Hong Wang ◽  
Guo Xin Zhang ◽  
Yi Liu ◽  
You Zhi Liu
Keyword(s):  
Temperature Control ◽  
Concrete Structure ◽  
Thermal Field ◽  
Early Stage ◽  
Mass Concrete ◽  
Basic Difference ◽  
Cooling Pipe ◽  
Cooling Technology ◽  
Thin Walled ◽  
The Difference

Cracks of concrete structure easily appear in the period of construction and the difference between the inside and outside temperature at early stage and the basic difference of the temperature at later stage are considered as the main factors causing cracks, so the temperature control becomes the key of problem. In view of this problem, this paper puts forward the pipe cooling technology which is usually used in the mass concrete to the thin-walled concrete structure. Under the basic theories of concrete temperature field and numerical algorithm of pipe cooling, the 3-D FEM is adopted to simulate the thermal field of concrete sluice with and without cooling pipe during construction. The results of comparison show that cooling pipe in thin-walled concrete structure can achieve better effect on temperature control, so it should have great reference signification to similar concrete projects in the future.

scholarly journals Development of Simulation Program for Temperature Field of Mass Concrete Structures

2018 ◽  
Vol 38 ◽  
pp. 03020 ◽  
Author(s):  
Zheng Si ◽  
Qian Zhang ◽  
Ling Zhi Huang ◽  
Dan Yang
Keyword(s):  
Temperature Field ◽  
Concrete Structure ◽  
Relative Difference ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Field Calculation ◽  
Concrete Dam ◽  
Roller Compacted Concrete ◽  
Roller Compacted Concrete Dam ◽  
The Difference

Most existing temperature field calculation programs have relative defects. In the present paper, based on merits of ANSYS platform, a temperature field calculation program of mass concrete structure is developed and demonstrated. According to actual pouring progress and thermodynamic parameters, a roller-compacted concrete dam is simulated. The difference of maximum temperature between calculated and measured values of measuring points is less than 1.8°C. Furthermore, the relative difference is -5%–5%. This result shows that the calculation program developed based on ANSYS platform can simulate and calculate the temperature field of mass concrete structure.

The influence of temperature on the tension developed in an isometric twitch

1951 ◽  
Vol 138 (892) ◽  
pp. 349-354 ◽  
Keyword(s):  
Early Stage ◽  
Muscular Contraction ◽  
Effect Of Temperature ◽  
Maximum Tension ◽  
Velocity Of Shortening ◽  
Influence Of Temperature On ◽  
Higher Temperature ◽  
The Difference ◽  
Isometric Twitch ◽  
The One

In muscular contraction the development of tension requires that the contractile component should shorten and stretch the series elastic component. In an isometric twitch the maximum tension is reached as a balance between two opposing processes, internal shortening on the one hand and decay of the active state (relaxation) on the other. The fact that the maximum tension in a twitch is considerably less than in a tetanus has been attributed to oncoming relaxation allowing insufficient time for internal shortening to be completed. The maximum tension in a twitch is considerably reduced by a rise of temperature, while that in a tetanus is somewhat increased. This would require that the temperature coefficient of the velocity of shortening should be substantially less than that of the decay of activity. Evidence for this exists. On this view the effect of a quick stretch, applied during the early stage of a twitch, in increasing the tension ratio, stretch/isometric, should be much greater at a higher temperature. This expectation is confirmed on frogs’ muscles over the range 0 to 20°C. The effect of temperature, therefore, on the size of a twitch can be attributed to the difference between the temperature coefficients of velocity of shortening and rate of relaxation.

scholarly journals The Study on Cracking Strength of AIJs to Release the Early-Age Stress of Mass Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Xiaogang Zhang ◽  
Chengqiang Wang ◽  
Shuping Wang ◽  
Feng Xing ◽  
Ronghua Zhu
Keyword(s):  
Analytical Model ◽  
Concrete Structure ◽  
Present Model ◽  
Early Stage ◽  
Early Age ◽  
Mass Concrete ◽  
Element Analysis ◽  
Construction Period ◽  
Early Stress ◽  
Fracture Theory

This paper aims to theoretically and numerically assess the effect of setting artificial-induced joints (AIJs) during construction period of a mass concrete structure to release the early-stage thermal stress. With respect to the coupling influences of various factors such as size and boundary of AIJs, an analytical model for its cracking strength on the setting section of mass concrete is proposed based on double-parameter fracture theory. A kind of hyper-finite element analysis (FEA) for many array AIJs in simplified plane pate is also presented by using bilinear cohesive force distribution. The results from the present model and numerical simulation were compared to those of experimental data to prove the efficiency and accuracy of the analytical model and FEA. The model presented in this study for the cracking strength of AIJs provides a simple useful tool to accurately evaluate how many early stress AIJs reduced. The theoretical solution and FEA results could also be significantly contributed to find the “just” and “perfect” release of the temperature stress and to improve the design level of AIJs in mass concrete structure.

scholarly journals Adsorption Studies of Textile Dye (Chrysoidine) from Aqueous Solutions Using Activated Sawdust

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Muhammad Waqar Ashraf ◽  
Nidal Abulibdeh ◽  
Abdus Salam
Keyword(s):  
Aqueous Solutions ◽  
Low Cost ◽  
Cost Effective ◽  
Effect Of Temperature ◽  
Contamination Level ◽  
Textile Dye ◽  
Sorption Ability ◽  
Feather Grass ◽  
The Difference ◽  
Isotherm Equations

Chrysoidine is a type of industrial azo dye and a well-known toxicant. Due to its good dyeing characteristics, it is widely used for dyeing leather, paper, feather, grass, wood, bamboo, etc. Hence, it is very important to remove or reduce its concentration below the contamination level in the waste line by using low-cost technologies. Sawdust is a plentiful material available very cheaply from sawmills and woodworks. Therefore, the present work was conducted to study sorption ability of both raw sawdust and chemically activated sawdust carbon on the removal of chrysoidine from the aqueous solutions. Adsorption isotherms of the dye on sawdust were determined and correlated with usual isotherm equations like Freundlich and Langmuir. Experimental results have shown that sawdust has a high adsorption efficiency, and the adsorption of chrysoidine followed Freundlich’s isotherm. Although raw sawdust proved to be slightly less efficient in comparison to chemically treated sawdust but in economic terms, raw sawdust is more cost-effective as the difference in the percent dye removal is less than the difference in the manufacturing costs. The influence of several parameters such as effect of temperature, adsorbent dose, adsorption time, etc., on the adsorption process was studied along with thermodynamic parameters such as enthalpy (ΔH°) and entropy (ΔS°).

The Effect of Hydration Rate on Concrete Simulation with Cooling Pipe

2011 ◽  
Vol 71-78 ◽  
pp. 4907-4911
Author(s):  
You Ping Zhu ◽  
Tong Chun Li ◽  
Jing Chen
Keyword(s):  
Temperature Effect ◽  
Three Dimensional ◽  
Complex Problem ◽  
Effect Of Temperature ◽  
Mass Concrete ◽  
Computational Results ◽  
Hydration Rate ◽  
Cooling Pipe ◽  
Concrete Hydration ◽  
Temperature Interaction

Hydration rata and temperature interaction is a complex problem. This paper focuses on variation of concrete hydration and its effect on temperature and stress filed simulation of concrete with cooling pipe. Through three-dimensional specified project with two methods that include consider effect of temperature on hydration rate and no consider effect of temperature on hydration rate, the computational results have been compared and the differences have been analyzed. So we advised that the temperature effect on hydration rate should been considered in temperature stress filed simulation of concrete with cooling pipe. It provide basis to the construction of mass concrete.

The Impact of Cold Wave Strike on Thin-Walled Concrete Structure

2012 ◽  
Vol 446-449 ◽  
pp. 1115-1118
Author(s):  
Zhen Hong Wang ◽  
Zhao Gang Wang ◽  
Guo Xin Zhang ◽  
Yi Liu
Keyword(s):  
Concrete Structure ◽  
Thermal Field ◽  
Reference Value ◽  
Cold Wave ◽  
Shrinkage Stress ◽  
Mass Concrete ◽  
Removal Time ◽  
Thin Walled ◽  
Heat Preservation ◽  
The Impact

When the cold wave comes, there are worse effects on thin-walled concrete structure than its on mass concrete structure during construction. In the view of this problem, the 3-D FEM is adopted to simulate the thermal field and stresses field of thin-walled concrete launder during construction when it is struck by cold wave. The simulation results show that shrinkage stress in the surface and inner of thin-walled concrete structure will appear and bring a lot of difficulties for temperature control and crack prevention. In order to reduce the impact degree of cold wave strike, some effective measures should be taken, including enhancing the level of external heat preservation and prolonging the form removal time and so on. This research is of practical reference value for the construction of the concrete structure which is built in the area where cold wave easily occurs.

The Impact of Temperature Difference between Day and Night on Thin-Walled Concrete Structure

2012 ◽  
Vol 212-213 ◽  
pp. 970-973
Author(s):  
Zhen Hong Wang ◽  
Shu Ping Yu ◽  
Liu Yi ◽  
You Zhi Liu
Keyword(s):  
Temperature Difference ◽  
Concrete Structure ◽  
Thermal Field ◽  
Reference Value ◽  
Large Temperature ◽  
Mass Concrete ◽  
Removal Time ◽  
Thin Walled ◽  
Heat Preservation ◽  
The Impact

When temperature difference between day and night is considered, there are worse effects on thin-walled concrete structure than its on mass concrete structure during construction. In the view of this problem, the 3-D FEM is adopted to simulate the thermal field and stresses field of thin-walled concrete launder during construction when temperature difference between day and night is considered. The simulation results show that the fluctuation of stress will appear not only in the surface but also in the inner of thin-walled concrete structure, so it brings a lot of difficulties for temperature control and crack prevention. In order to reduce the impact degree of temperature difference between day and night, some effective measures should be taken, including enhancing the level of external heat preservation and prolonging the form removal time and so on. If the variation of daily temperature is used to the simulation computation of thin-walled concrete structure during construction, the results should be very reasonable and effective. This research is of practical reference value for the construction of the concrete structure which is built in the area where large temperature difference between day and night easily occurs.

Stress Field Simulation of Concrete Structure Considering Influence of Temperature on Autogenous Volume Deformation

2012 ◽  
Vol 482-484 ◽  
pp. 1321-1324
Author(s):  
Xiao Yue Zhang ◽  
Shao Ping Liu
Keyword(s):  
Stress Field ◽  
Concrete Structure ◽  
Influence Factors ◽  
Effect Of Temperature ◽  
Hydration Reaction ◽  
Volume Deformation ◽  
Influence Of Temperature ◽  
Field Simulation ◽  
Influence Of Temperature On ◽  
The Difference

Aotugenous volume deformation is one of the influence factors of stress field of concrete structure. Generally, the influence of temperature on autogenous volume strain is not considered in calculation. In fact, the difference of internal and surface temperature of concrete structure can lead to different hydration reaction and different autogeneous volume deformation. In order to find out the effect of temperature difference on aotogenous volume deformation and stress field of concrete structure, a model is established and a corresponding example is given. The result shows that it is necessary to take temperature effect into consideration while calculate autogenous volume deformation in stress field simulation of concrete structure.

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