Chloride interaction with concretes subjected to a permanent splitting tensile stress level of 65%

2011 ◽

Vol 314-316 ◽

pp. 1889-1894

Author(s):

Yu Fan ◽

Philip Shipway ◽

Geoff Tansley ◽

Zheng Chen

Keyword(s):

Tensile Stress ◽

Laser Welding ◽

Tensile Test ◽

Thin Plate ◽

Stress Level ◽

Continuous Wave ◽

Stress Test ◽

Welding Distortion ◽

Fibre Laser

Distortion is one type of defect in the weld, which is troublesome for some reasons, especially in thin plate welding. Distortion was found in fibre laser welding processing for 0.7mm thickness Ti6Al4V plate. The purpose of this paper is to understand and evaluate the effect of distortion on stress level by FEA and tensile test. A group of 0.7mm Ti6Al4V plates welded using continuous wave fibre laser. FEA models were established for fibre laser welded Ti6Al4V in abaqus 6.7.

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Study on Stressed MSFAC Attacked by Sodium Sulfate Solution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.742.197 ◽

2013 ◽

Vol 742 ◽

pp. 197-201

Author(s):

Feng Lan Li ◽

Li Yun Pan ◽

Yan Wei Guo

Keyword(s):

Tensile Strength ◽

Tensile Stress ◽

Stress Level ◽

Sulfate Solution ◽

Ion Concentration ◽

Sulfate Ion ◽

Ion Content ◽

Near Surface ◽

Flexural Tensile Strength ◽

Stress Levels

The paper introduces the experiments of sulfate attack on concrete under stress state. The concrete (MSFAC) was made with machine-made sand and fly ash. Before immersed in sodium solution with sulfate-ion concentration of 50000mg/L, the concrete beams with 100mm×100mm ×400mm dimension were in flexural tensile stress at levels of 20%, 40% and 60% of flexural tensile strength by the special designed stress devices. The sulfate-ion content in different erosion depths of concrete was measured at attack age of 30, 90, 180, 270, 360, 540 and 720 days by the chemical titration method. The results show that the apparent damage such as rough surface and cement past peeling off became more serious with the increasing tensile stress level and the prolongation of attack age, while much more obvious crystallization of gypsum was in surface cracks, the sulfate-ion content in the first layer near surface did not reflect the real status of concrete affected by tensile stress levels. The sulfate-ion contents of inside layers increased basically with the attack age at stress levels lower than 60% of tensile strength of concrete. In conditions of the experiment, the sulfate-ion content reduced when the attack age was longer than 540 days at the stress level of 60%.

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Investigation on Neutralization Rules of Concrete under Loads Subjected to Acid Rain Attack

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.5768 ◽

2011 ◽

Vol 243-249 ◽

pp. 5768-5771

Author(s):

Jian Gang Niu ◽

Hai Tao Zhai ◽

Di Tao Niu

Keyword(s):

Fly Ash ◽

Tensile Stress ◽

Acid Rain ◽

Compressive Stress ◽

Stress Level ◽

Fly Ash Concrete ◽

Concrete Corrosion ◽

Simultaneous Attack

The neutralization of fly ash concrete under loads subjected to the simultaneous attack of acid rain was investigated in this paper. And the influence of stress level and fly ash replacement on neutralization of fly ash concrete was analyzed. It was found that, the bending tensile stress accelerated the acid rain attack. The higher the stress level, the more serious the concrete corrosion. In contrast, the bending compressive stress slowed down the acid rain attack. The results also showed that the neutralization depth of fly ash concrete was increasing and concrete corrosion attacked by acid rain was more serious as the fly ash replacement increased.

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Lining Fatigue Test and Influence Zoning of Tridimensional Cross-Tunnel under High-Speed Train Loads

Applied Sciences ◽

10.3390/app10165694 ◽

2020 ◽

Vol 10 (16) ◽

pp. 5694

Author(s):

Weichao Yang ◽

E Deng ◽

Chenghua Shi ◽

Ning Liu ◽

Ruizhen Fei ◽

...

Keyword(s):

Numerical Simulation ◽

Tensile Stress ◽

Initial Stress ◽

Fatigue Damage ◽

Stress Level ◽

High Speed ◽

Tunnel Lining ◽

Design Parameters ◽

Tunnel Design ◽

The Cross

Tridimensional cross tunnels usually manifest the vulnerable components of a high-speed railway caused by the sophistication of the structural pattern and the continuous shock from the train. The frequent defect of tunnel lining at the intersection would affect the safe operation of the two rails. As a result, attention has been paid to fatigue damage caused by the long-term dynamic load from a running train, in order to ensure the safety and serviceability of the cross tunnel lining. However, an influence zoning method with respect to tunnel crossing for the direct estimation of whether the lining structure is damaged due to the train load, and to what extent, is unavailable. In this paper, a systematic study that consists of numerical simulation and fatigue damage experiment is conducted to develop an approximate method to enable practicing engineers to evaluate reasonable design parameters. The initial static stress, which corresponds to the static tensile stress of secondary lining under the stratum load, and the maximum dynamic stress, which refers to the maximum dynamic tensile stress under the train load, are estimated according to the numerical simulation. A simplified damage evolution model and its parameters are identified on the basis of a systematic fatigue damage experiment. Finally, the influence zoning method is conducted on the basis of two criteria, namely (1) that initial stress level should not exceed 0.6, and (2) that load cycles should not exceed N = 2 × 106 times. Thus, the practicing parameters during the cross tunnel design, such as surrounding rock mass, cross angle, rock pillar thickness between two tunnels, and train speed can be utilized conveniently by using the proposed calculation charts, according to the identification of initial stress level and the magnitude of dynamic stresses caused by the train load.

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Improvement Methods for Reduction of the High Stress of Ultra-High Asphalt Concrete Core Dams

Applied Sciences ◽

10.3390/app9214618 ◽

2019 ◽

Vol 9 (21) ◽

pp. 4618

Author(s):

Jun Gao ◽

Faning Dang ◽

Zongyuan Ma ◽

Yi Xue ◽

Jie Ren

Keyword(s):

Shear Stress ◽

Internal Friction ◽

Tensile Stress ◽

Stress Level ◽

Asphalt Concrete ◽

Friction Angle ◽

Internal Friction Angle ◽

High Shear ◽

High Shear Stress ◽

Concrete Core

With the rapid development of asphalt concrete core rockfill dams (ACCRDs), the construction of ultra-high asphalt concrete core rockfill dams (UACCRDs) has been improved significantly. However, the security problems of asphalt concrete core (ACC) become very prominent with the increase of dam height. The shear failure control standard and tensile failure control standard of ACC are suggested. The mechanisms of ACC that generate high shear stress and high tensile stress are investigated. Based on the definition of stress level and the transmission mechanism of arch structures, the improvement methods that reduce the high shear stress and high tensile stress of ultra-high asphalt concrete core (UACC) are proposed and investigated. The results show that the stress level of ACC can be reduced significantly by the increase of the strength parameters of ACC (failure ratio, cohesion, and internal friction angle). The following value ranges of the failure ratio, cohesion, and internal friction angle of ACC for the suitable construction of UACCRDs are recommended: Rf ≥ 0.75, C ≥ 0.30 MPa, and φ ≥ 28.5° (h = 150 m), with the growth gradient adjusted by 5%, 15%, and 5%/25 m. The tensile stress and tensile stress area can be reduced obviously by the new type of dams (curved asphalt concrete core rockfill dams (CACCRDs)). The value ranges of the curvature of CACC (k ≥ 1.0 × 10−3) for the suitable construction of UACCRDs are recommended.

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