The Arch Support Construction and Hydration Heat Analysis of the First Bridge over Yangtze River in Hejiang

2013 ◽  
Vol 291-294 ◽  
pp. 1122-1127
Author(s):  
Yan Feng Luo ◽  
Da Yan Qin ◽  
Yun Zhang
Keyword(s):  
Yangtze River ◽  
Casting Process ◽  
Hydration Heat ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Element Analysis ◽  
Early Hydration ◽  
Mix Proportion ◽  
Arch Support ◽  
Heat Preservation

The arch support of the First Bridge over Yangtze River in Hejiang used the stratified and graded casting process in mass concrete pouring process. By means of optimizing the concrete mix proportion design, using high mixing amount of fly ash concrete, reducing heat release rate of concrete early hydration heat, delaying the time of maximum temperature rise, and combining turn-over forms and water storage and other surface heat preservation measures, the temperature difference between inside and outside concrete was reduced and the cracking of mass concrete was avoided. Finite element analysis of hydration heat was done to verify the feasibility of the construction scheme.

Research on Thermodynamical Performance of Concrete with Excessive Fly Ash Added in the Pile Cap of Well Tower

2011 ◽  
Vol 243-249 ◽  
pp. 6087-6092
Author(s):  
Xiang Zong ◽  
Xiang Wang
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
Setting Time ◽  
Hydration Heat ◽  
Favorable Effect ◽  
Mass Concrete ◽  
Mix Proportion ◽  
Pile Cap ◽  
Time Test ◽  
Simulated Test

To meet the demand of high performance of mass concrete in a pile cap of well tower, excessive replacement of fly ash was applied to the mass concrete. Based on the theory of hydration heat of cement, several thermal parameters of mix proportion were analyzed and simulated test analyses and setting time test analyses were conducted in the laboratory. The results and data collected in the project locale both show that applying excessive replacement of fly ash reduces hydration heat of mass concrete in the pile cap of well tower, which extends setting time in mass concrete and avoids the cracks caused by temperature stress. The results achieve favorable effect and provide reference for design and construction of mix proportion in the project of mass concrete.

Analysis of Cracks on the Containment of Loop Nuclear Power Stations for 60 Days

2011 ◽  
Vol 105-107 ◽  
pp. 1056-1059
Author(s):  
Yu Zhuo Sun ◽  
An Hai Yi ◽  
Jie Lin ◽  
Peng Qiao
Keyword(s):  
Tensile Strength ◽  
Theoretical Calculation ◽  
Temperature Stress ◽  
Calculation Method ◽  
Nuclear Power ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Construction Methods ◽  
Power Stations ◽  
Heat Preservation

The relation of tensile strength ＆ temperature stress and concrete fissure was researched firstly , then it showed the causes of late cracks on concrete by theoretical calculation, the result provided a simple theoretical calculation method to avoid concrete fissure. The construction methods to control the fissure was proposed: early strengthening cooling, managing maximum temperature of concrete through lately heat preservation, and overtime to preserving concrete moisture for controlling the late strain on mass concrete. This research has a great significance for controlling the fissure.

scholarly journals Application of hydration heat inhibitor in crack control of mass concrete of tunnel side wall

2021 ◽  
Vol 283 ◽  
pp. 01032
Author(s):  
XiZhi Wang ◽  
MinSheng Shi ◽  
XinGang Wang
Keyword(s):  
Temperature Rise ◽  
Concrete Strength ◽  
Side Wall ◽  
Hydration Heat ◽  
Structural Deformation ◽  
Maximum Temperature ◽  
Optimal Dosage ◽  
Mass Concrete ◽  
Control Effect ◽  
Crack Control

The structural deformation caused by temperature change is the main reason for cracking of mass concrete. In order to avoid or reduce the crack of the side wall of cast-in-place mass concrete in tunnel, the effects of different dosage of hydration heat inhibitor on the internal temperature rise curve of concrete, strength and the properties of the mixture are analyzed through experimental research, and the optimal dosage of 1% of cementing material is finally determined. The engineering application results show that after adding hydration heat inhibitor to the tunnel side wall concrete, the maximum temperature rise in the tunnel side wall is obviously reduced, and the arrival time of the temperature peak is delayed. No cracks appear in the tunnel side wall, and the crack control effect is good.

Research on the Compatibility of Cement-Based Biomass Materials Modified by Early-Strength Agents

2015 ◽  
Vol 775 ◽  
pp. 287-291
Author(s):  
Hong Qi ◽  
Wei Qi ◽  
Guo Dong Sheng
Keyword(s):  
Hydration Heat ◽  
Hydration Process ◽  
Maximum Temperature ◽  
Mixed System ◽  
Maximum Temperature Difference ◽  
Early Hydration ◽  
Retarding Effect ◽  
Biomass Materials ◽  
Early Strength ◽  
Better Than

Aim at the slow and complicated hydration process of straw-cement mixed system and the retarding coagulation of cement-based biomass material in C3S reaction. To investigate the improving effect of early-strength agents on the hydration process of straw-cement mixed system by adding CaCl2, FeCl3 and Al2(SO4)3 which could increase the release of hydration heat, accelerate the hydration of cement and weaken the retarding effect of dissolved substances from straw. By testing the variation of temperatures in hydration process to analyze the highest hydration temperature (Tmax), the time of reaching the highest hydration temperature (t), the maximum temperature difference (△T) and the compatibility coefficients (CA) of cement-based biomass materials with modified agents and with no modified agents, and evaluate the compatibility of straw-cement mixed system. Experimental results show that Tmax, t and △T these indexes can intuitively reflect the changing characteristics of early hydration heat of cement-based biomass materials, while CA could reflect the early hydration behavior comprehensively and objectively. Meanwhile, when the dosage of early-strength agents is between 3%~8%, the growth of CA shows as follows: CaCl2 is the best, and FeCl3 is better than Al2(SO4)3.

Temperature Control Technique and Analysis of Mass Concrete in the Pile Cap of Main Pier in Yangtze River Bridge

2014 ◽  
Vol 587-589 ◽  
pp. 1407-1411 ◽  
Author(s):  
Jun Su ◽  
Guo Wang Zuo ◽  
Wei Li
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Temperature Control ◽  
Yangtze River ◽  
Cooling Water ◽  
Control Technique ◽  
Mass Concrete ◽  
Element Analysis ◽  
Pile Cap ◽  
Calculation Results

The paper analyzed the temperature control technique measures of mass concrete in the pile cap of main pier in Yangtze River Bridge. Consider the effect of the cooling pipe, ANSYS finite element analytical software was used to calculate the temperature field of the pile cap in the construction, the distribution rules of the temperature field was simulated by finite element analysis. It is shown that the cooling effect of the mass concrete is obvious by using cooling water pipe, the finite element calculation results can be used to lead to the design and construction. It also provides the reference to develop a reasonable temperature control solutions during the construction of the similar mass concrete.

scholarly journals Failure Analysis of a Modern High Performance Diesel Engine Cylinder Head

2014 ◽  
Vol 6 ◽  
pp. 862853 ◽  
Author(s):  
Bingbin Guo ◽  
Weizheng Zhang ◽  
Xiaosong Wang
Keyword(s):  
Diesel Engine ◽  
Failure Analysis ◽  
Cylinder Head ◽  
High Performance ◽  
Casting Process ◽  
Structure Type ◽  
Maximum Temperature ◽  
Element Analysis ◽  
Mechanical Coupling ◽  
Engine Cylinder

This paper presents a failure analysis on a modern high performance diesel engine cylinder head made of gray cast iron. Cracks appeared intensively at the intersection of two exhaust passages in the cylinder head. The metallurgical examination was conducted in the crack origin zone and other zones. Meanwhile, the load state of the failure part of the cylinder head was determined through the Finite Element Analysis. The results showed that both the point of the maximum temperature and the point of the maximum thermal-mechanical coupling stress were not in the crack position. The excessive load was not the main cause of the failure. The large cooling rate in the casting process created an abnormal graphite zone that existed below the surface of the exhaust passage (about 1.1 mm depth), which led to the fracture of the cylinder head. In the fractured area, there were a large number of casting defects (dip sand, voids, etc.) and inferior graphite structure (type D, type E) which caused stress concentration. Moreover, high temperature gas entered the cracks, which caused material corrosion, material oxidization, and crack propagation. Finally, premature fracture of the cylinder head took place.

Numerical Simulation Analysis on Mass Concrete Thermal Stress

2012 ◽  
Vol 204-208 ◽  
pp. 4396-4399 ◽  
Author(s):  
Guo Liang Tian ◽  
Yin Wang
Keyword(s):  
Numerical Simulation ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stress ◽  
Large Scale ◽  
Simulation Analysis ◽  
Hydration Heat ◽  
Mass Concrete ◽  
Concrete Construction ◽  
Element Analysis

Cement hydration heat temperature of the concrete could result thermal stress. Which is an important reason for the concrete structure’ cracks. The cracks could reduce the structure’ durability and structural stability. A spatial finite element model analysis on a mass concrete foundation board of a project was established using large-scale finite element analysis software. Temperature stress finite element analysis was carried on model. Numerical simulation analyzed the hydration heat of mass concrete construction phase and calculated the mass concrete’ temperature and stress distribution. Results of numerical simulation of crack control had certain guiding significance to mass concrete construction.

Establishing and Satisfying Thermal Requirements for Drilled Shaft Concrete Based on Durability Considerations

2021 ◽  
pp. 036119812199635
Author(s):  
Andrew Z. Boeckmann ◽  
Zakaria El-tayash ◽  
J. Erik Loehr
Keyword(s):  
Mechanical Response ◽  
Large Diameter ◽  
Thermal Cracking ◽  
Drilled Shafts ◽  
Maximum Temperature ◽  
Design Parameters ◽  
Mass Concrete ◽  
Temperature Differential ◽  
Thermal Requirements ◽  
Ettringite Formation

Some U.S. transportation agencies have recently applied mass concrete provisions to drilled shafts, imposing limits on maximum temperatures and maximum temperature differentials. On one hand, temperatures commonly observed in large-diameter drilled shafts have been observed to cause delayed ettringite formation (DEF) and thermal cracking in above-ground concrete elements. On the other, the reinforcement and confinement unique to drilled shafts should provide resistance to thermal cracking, and the provisions that have been applied are based on dated practices for above-ground concrete. This paper establishes a rational procedure for design of drilled shafts for durability requirements in response to hydration temperatures, which addresses both DEF and thermal cracking. DEF is addressed through maximum temperature differential limitations that are based on concrete mix design parameters. Thermal cracking is addressed through calculations that explicitly consider the thermo-mechanical response of concrete for predicted temperatures. Results from application of the procedure indicate consideration of DEF and thermal cracking potential for drilled shafts is prudent, but provisions that have been applied to date are overly restrictive in many circumstances, particularly the commonly adopted 35°F maximum temperature differential provision.

Study on Influences of Thickness of Flange of U Rib on Mechanical Behaviors of Orthotropic Monolithic Steel Bridge Deck System

2010 ◽  
Vol 163-167 ◽  
pp. 122-126 ◽  
Author(s):  
Ru Deng Luo ◽  
Mei Xin Ye ◽  
Ye Zhi Zhang
Keyword(s):  
Finite Element Analysis ◽  
Yangtze River ◽  
High Speed ◽  
Bridge Deck ◽  
Steel Bridges ◽  
Engineering Practice ◽  
Steel Bridge ◽  
Mechanical Behaviors ◽  
Element Analysis ◽  
High Speed Railway

Orthotropic monolithic steel bridge deck system stiffened by U rib is very fit for high-speed railway steel bridges because of its excellent mechanical behaviors. Thickness of flange is a very important parameter of U rib and has influence on mechanical behaviors of orthotropic monolithic steel bridge deck system. Based on the engineering practice of Anqing Yangtze River Railway Grand Bridge, the kind and the extents of influences of thickness of flange of U rib on mechanical behaviors of orthotropic monolithic steel bridge deck system are studied with finite element analysis. The results show that thickness of flange of U rib has relative large positive influences on rigidity, strength and stability of orthotropic monolithic steel bridge deck system. 14~18mm is the appropriate range of thickness of flange of U rib for high-speed railway steel bridges.

Abdominal Aortic Aneurysm: From Clinical Imaging to Realistic Replicas

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Sergio Ruiz de Galarreta ◽  
Aitor Cazón ◽  
Raúl Antón ◽  
Ender A. Finol
Keyword(s):  
Wall Thickness ◽  
Physiological Stress ◽  
Ex Vivo ◽  
Casting Process ◽  
Aortic Aneurysms ◽  
Optical Methods ◽  
Patient Specific ◽  
Uniaxial Tensile ◽  
Element Analysis ◽  
Abdominal Aortic

The goal of this work is to develop a framework for manufacturing nonuniform wall thickness replicas of abdominal aortic aneurysms (AAAs). The methodology was based on the use of computed tomography (CT) images for virtual modeling, additive manufacturing for the initial physical replica, and a vacuum casting process and range of polyurethane resins for the final rubberlike phantom. The average wall thickness of the resulting AAA phantom was compared with the average thickness of the corresponding patient-specific virtual model, obtaining an average dimensional mismatch of 180 μm (11.14%). The material characterization of the artery was determined from uniaxial tensile tests as various combinations of polyurethane resins were chosen due to their similarity with ex vivo AAA mechanical behavior in the physiological stress configuration. The proposed methodology yields AAA phantoms with nonuniform wall thickness using a fast and low-cost process. These replicas may be used in benchtop experiments to validate deformations obtained with numerical simulations using finite element analysis, or to validate optical methods developed to image ex vivo arterial deformations during pressure-inflation testing.

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