Monitoring of earth concrete damage evolution during drying

2021 ◽  
Vol 313 ◽  
pp. 125340
Author(s):  
Nathalie Kouta ◽  
Jacqueline Saliba ◽  
Nadia Saiyouri
Keyword(s):  
Damage Evolution ◽  
Concrete Damage

Damage Analysis for Quasi-Birttle Materials of CT Image under Uniaxial Compression

2010 ◽  
Vol 168-170 ◽  
pp. 373-379
Author(s):  
Cheng Yi ◽  
Hong Guang Zhu ◽  
Li Zhen Liu
Keyword(s):  
Density Distribution ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Fractal Theory ◽  
Threshold Value ◽  
Damage Analysis ◽  
Ct Image ◽  
Segmentation Method ◽  
Material Density ◽  
Concrete Damage

In the damage research before on the CT image of quasi-brittle materials such as concrete, the damage evolution is often described by the change of average CT values or image threshold segmentation method. However, the evolution of average CT values is insensitive to the damage, and the threshold value is always not only, which grimly depends on the researchers’ judgment. Because CT image is a gray image and different grayscale expresses different density distribution, it is tried in the paper to express the variety of material density with variety of grayscale of CT image. A description index of Rd from fractal theory is introduced in the paper to describe the variety of grayscale. Thereby, a damage variable is defined by Rd index, which can be used to study the developing process and evolving rule of concrete damage.

Further Advances on Concrete Coating Impact on Pipeline Strength

2017 ◽  
Author(s):  
Alberto Battistini ◽  
Luca Catena ◽  
Adelina Mancini ◽  
Lorenzo Marchionni ◽  
Antonio Parrella ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Damage Evolution ◽  
Bending Stiffness ◽  
The State ◽  
Fe Model ◽  
Deformation Capacity ◽  
Strain Concentration ◽  
Concrete Damage ◽  
Strength And Deformation ◽  
Concrete Coating

Concrete Weight Coating is used in offshore industry to provide for pipeline vertical and lateral stability against waves and currents and to guarantee protection against fishing activities. Reinforced concrete coating of adequate strength, especially in case of thick coatings for stringent in-place stability requirements, entails additional bending stiffness and consequently strain concentration at field joints, thus significantly affecting the state of stress and strain on the pipe steel during laying firstly, and then during operations. Attention of the offshore pipeline industry has been focused in the development of experimental and theoretical activities in a more scientific way, which aimed to satisfy the need of a better knowledge in this field. Both analytical and FEM solutions are available in the free literature and relevant standards to predict the contribution of concrete coating layer on global pipeline strength and deformation capacity and simplified threshold values for the concrete damage are provided, as well. Generally, for installation analysis purpose, a pipeline with equivalent mechanical behavior (bending moment-curvature relationship) and physical (weight) properties is used in installation and operation analyses. No assumptions are typically made on concrete damage evolution to evaluate the decay of pipe capacity beyond the elastic range. In this paper new advances in modelling the mechanical behavior of concrete coated joints are discussed. In particular an advanced ABAQUS finite element model is proposed to take into account the effect of concrete coating damage on the overall capacity. The following effects have been accounted: • Non-linear stress-strain relationship of the steel at large usage factors/curvatures on the strain concentration at the field joint. • Concrete coating damage evolution on global pipeline bending stiffness. In this paper: • The state-of-the-art about published materials, numerical studies and design approaches on concrete material modelling and concrete coated pipes is briefly presented; • A FEM based analysis methodology is drawn and proposed for the strength and deformation capacity assessment of a concrete coated pipe; • The FEM model is calibrated on available full scale tests; • The results of a project case study performed with ABAQUS FE Model are given.

Concrete damage evolution analysis by backscattered ultrasonic waves

2003 ◽  
Vol 36 (7) ◽  
pp. 461-469 ◽  
Author(s):  
Jean-François Chaix ◽  
Vincent Garnier ◽  
Gilles Corneloup
Keyword(s):  
Damage Evolution ◽  
Ultrasonic Waves ◽  
Evolution Analysis ◽  
Concrete Damage

scholarly journals Experimental Investigation of Damage Evolution Characteristics of C50 Concrete under Impact Load

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Mingfeng Lei ◽  
Linghui Liu ◽  
Yuexiang Lin ◽  
Jianjun Ma ◽  
Chenghua Shi ◽  
...  
Keyword(s):  
Damage Evolution ◽  
Rapid Development ◽  
Concrete Structures ◽  
High Energy ◽  
Measurement Technology ◽  
Impact Loads ◽  
Electromechanical Impedance ◽  
Energy Impact ◽  
Evolution Characteristics ◽  
Concrete Damage

Impact loads widely exist in practical engineering and often cause cumulative damage and cracks or even fracture failure of concrete structures with their repeated long-term action. This experimental research is conducted on the damage evolution characteristics of concrete under impact loads by regarding C50 nonreinforced concrete as the research object and using a self-developed drop-weight device with electromechanical impedance measurement technology. Results show the following. (1) Under low-energy impact, concrete damage has long continuous development process and remarkable cumulative effects. An apparently sudden break characteristic appears before failure. Under high-energy impact, concrete damage accumulates rapidly, and piezoceramic patch signals grow linearly. (2) The root mean square deviation (RMSD) of the concrete increases exponentially with impact times. Particularly, when the RMSD exceeds 0.075, the concrete damage process enters the rapid development stage and approaches the critical failure state. (3) Under the experimental conditions in this study, the relationship between the ultimate impact times (damage life) and impact heights of the concrete samples shows the development trend of the power function. The above results can provide reference for the research on service life prediction methods of concrete structures under impact loads.

scholarly journals Mechanical Properties and Damage Evolution of Concrete Materials Considering Sulfate Attack

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2343
Author(s):  
Qianyun Wu ◽  
Qinyong Ma ◽  
Xianwen Huang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Damage Evolution ◽  
Resistance Coefficient ◽  
Sulfate Attack ◽  
Micro Structure ◽  
Micro Cracks ◽  
Concrete Damage ◽  
Concrete Materials

In order to study the durability of concrete materials subjected to sulfate attack, in a sulfate attack environment, a series of concrete tests considering different fly ash contents and erosion times were conducted. The mechanical properties and the micro-structure of concrete under sulfate attack were studied based on the following: uniaxial compressive strength test, split tensile test, ultrasonic impulse method, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical properties were compressive strength, splitting tensile strength, and relative dynamic elastic modulus, respectively. Additionally, according to the damage mechanical theory, experimental results and micro-structure analysis, the damage evolution process of concrete under a sulfate attack environment were studied in detail. Finally, according to the sulfate attack time and fly ash content, a damage model of the sulfate attack of the binary surface was established. The specific results are as follows: under the action of sulfate attack, the change law of the rate of mass change, relative dynamic modulus of elasticity, corrosion resistance coefficient of compressive strength, and the corrosion resistance coefficient of the splitting tensile strength of concrete all increase first and then decrease. Under the same erosion time, concrete mixed with 10% fly ash content has the best sulfate resistance. Through data regression, the damage evolution equation of the sulfate attack was developed and there is an exponential function relationship among the different damage variables. The binary curved surface regression effect of the concrete damage and the erosion time and the amount of fly ash is significant, which can predict deterioration of concrete damage under sulfate attack. During the erosion time, the combined expansion of ettringite and gypsum caused micro cracks. With an increase of corrosion time, micro cracks developed and their numbers increased.

The Rock Failure Mechanism of Air-Decked Blasting in Hole Bottom

2012 ◽  
Vol 201-202 ◽  
pp. 375-378 ◽  
Author(s):  
Liang Wu ◽  
Yong Zhou ◽  
Zhi Hua Guo
Keyword(s):  
Failure Mechanism ◽  
Damage Evolution ◽  
Shear Failure ◽  
Dynamic Stress ◽  
Near Field ◽  
Blast Hole ◽  
Tensile Failure ◽  
Charge Structure ◽  
Concrete Damage ◽  
Bottom Rock

The application of air-decked blasting technology has enabled the efficient use of explosion energy, which proves that the air-decked blasting technology can overcome many disadvantages caused by column charge effectively, getting ideal explosion effect. Based on the JHC model of concrete damage evolution, the dynamic stress characteristics and failure mechanism of blast-hole near-field about bottom-air-decked charge structure is studied by numerical simulation. Result shows that the failure mechanism of typical elements changes from compression-shear failure into shear-tensile failure gradually with the increase of their position, for the effecting factors of the freedom and the loading from the hole. Comparing the dynamic stress characteristics of different detonating manners, indirect initiation can improve the static function intensity and delay the time of detonation gas, so it is easier to destroy the bottom rock of hole.

Microscopic Numerical Simulation of Reinforced Concrete Damage Evolution under Uniaxial Tension and Compression

2012 ◽  
Vol 424-425 ◽  
pp. 439-442
Author(s):  
Jian Yun Chen ◽  
Ming Zhang ◽  
Zhi Guang Liu
Keyword(s):  
Reinforced Concrete ◽  
Numerical Simulations ◽  
Damage Evolution ◽  
Aggregate Model ◽  
Brittle Damage ◽  
Steel Bar ◽  
Random Aggregate ◽  
Tension And Compression ◽  
Concrete Damage ◽  
The Impact

Based on the mesoscopic random aggregate model and brittle-damage constitutive model, the numerical simulations of tension and compression are performed on reinforced concrete, and the thickness method is employed to simulate the interface between steel bar and concrete. Then a series of samples are generated randomly based on Weibull distribution’ mechanical parameters, and these samples are used to investigate meso damage evolution process of reinforced concrete, as well as the impact of parameter selection on macro-strength characterization of reinforced concrete. The results of numerical simulations effectively reveal the accumulation of tensile damage of meso-units, which lead to the failure of reinforced concrete. In conclusion, this research provides an innovative method to investigate the mechanical properties of interface between steel bar and concrete.

Mechanism of High-strength Concrete Damage Evolution Based on CT Observation

2010 ◽  
Vol 168-170 ◽  
pp. 498-504
Author(s):  
Hui Zhang ◽  
Ren Shu Yang ◽  
Ling Zhao ◽  
Hui Cao
Keyword(s):  
Fractal Dimension ◽  
Release Rate ◽  
Modulus Of Elasticity ◽  
High Strength Concrete ◽  
Damage Evolution ◽  
High Strength ◽  
Negative Temperature ◽  
Damage Factor ◽  
Strength Concrete ◽  
Concrete Damage

To study damage evolution of high-strength concrete under the frozen environment, based on the background of YunCheng auxiliary shaft engineering, this paper studies the damage pattern of C100 concrete under loading by applying the method of industry CT scanning. It aims at showing the evolution process of concrete damage by contrasting of the damage factor on standard curing and negative temperature curing condition, which analyzes the trend of damage modulus of elasticity of C100 high-strength concrete uniaxial compression conditioned from the micro level, combining change of fractal dimension of concrete. The results showed that the change of fractal dimension can reflect the evolution trend of inner damage of concrete, fractal dimension is related with the size of concrete when it damaged. Negative temperature frozen brings about the increase of inner hole of high-strength concrete and decrease of modulus of elasticity, and the ratio of damage energy release rate and strain energy release rate decrease, the energy needed by concrete damage is very low. Moreover, the nonlinear positive correlation between fractal dimension and damage factor of high-strength concrete has been gained.

scholarly journals A Statistical Evolution Model of Concrete Damage Induced by Seawater Corrosion

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1007
Author(s):  
Hangjie Lv ◽  
Jiankang Chen ◽  
Chunsheng Lu
Keyword(s):  
Damage Evolution ◽  
Corrosion Damage ◽  
Evolution Model ◽  
Calcium Sulfoaluminate ◽  
Concrete Corrosion ◽  
Basic Law ◽  
Exponential Growth Model ◽  
Concrete Damage ◽  
Expansion Force ◽  
Statistical Evolution

The transmission of sulfate ions in concrete results in formation of calcium sulfoaluminate crystals due to chemical reactions. The expansion of calcium sulfoaluminate crystals is the main cause of concrete corrosion damage. In this study, ultrasonic analysis was used to detect the modulus change of concrete due to sulfate corrosion to obtain the basic law of corrosion damage evolution. An exponential growth model was developed for the internal expansion force based on the chemical reaction rate of calcium sulfoaluminate crystallization. Then, the evolution equation of the number density of microcracks was derived based on their initiation and balance conditions. Finally, a statistical model was developed for the concrete damage evolution by integrating the volume of microcracks. It is shown that the statistical evolution model can well characterize the evolution of concrete corrosion damage.

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