scholarly journals Optimization of Structure Parameters of Airfield Jointed Concrete Pavements under Temperature Gradient and Aircraft Loads

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Bangshu Xu ◽  
Wanzhi Zhang ◽  
Jie Mei ◽  
Guangyao Yue ◽  
Laihua Yang
Keyword(s):  
Tensile Strength ◽  
Temperature Gradient ◽  
Tensile Stress ◽  
Fatigue Limit ◽  
Maximum Tensile Stress ◽  
Concrete Pavement ◽  
Large Temperature ◽  
Concrete Slabs ◽  
Flexural Tensile Strength ◽  
Comparison Results

Daily changing temperature causes significant thermal stress in concrete pavement. Tensile stress obtained can exceed flexural tensile strength when the concrete slabs are subjected to large temperature gradient and traffic loads, resulting in pavement damages. In this paper, maximum tensile stresses in concrete slabs with different slab sizes, thicknesses, and length to width (L/W) ratios were investigated by using the finite element (FE) method. The important parameters in the design of concrete pavement are the flexural tensile strength and the fatigue limit. By analyzing the comparison results between the maximum tensile stress and the fatigue limit, the optimum slab size and the critical thickness were determined. The results indicate that the maximum tensile stress obtained is higher for larger slab size with thin thickness. Furthermore, to reduce cutting work and the amount of dowel bars, the optimum slab sizes of the regional airport concrete pavement are recommended as 4 m × 4 m to 6 m × 6 m. The critical thicknesses of 4 m × 4 m slab and 6 m × 6 m slab are determined as 28.2 cm and 34.7 cm, respectively, based on the most unfavorable coupling between positive and negative temperature gradients and the Boeing 737–800 aircraft load. Moreover, the maximum tensile stress increases as the L/W ratio increases. When the slab length is less than 6 m, it is better to use square slab in airport jointed concrete pavement (JCP).

scholarly journals Finite Element Simulation and Multi-Factor Stress Prediction Model for Cement Concrete Pavement Considering Void under Slab

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5294
Author(s):  
Bangyi Liu ◽  
Yang Zhou ◽  
Linhao Gu ◽  
Xiaoming Huang
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Mesh Size ◽  
Maximum Tensile Stress ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Void Size ◽  
Tensile Stresses

Uneven support as result of voids beneath concrete slabs can lead to high tensile stresses at the corner of the slab and eventually cause many forms of damage, such as cracking or faulting. Three-dimensional (3D) finite element models of the concrete pavement with void are presented. Mesh convergence analysis was used to determine the element type and mesh size in the model. The accuracy of the model is verified by comparing with the calculation results of the code design standards in China. The reliability of the model is verified by field measurement. The analysis shows that the stresses are more affected at the corner of the slab than at the edge. Impact of void size and void depth at the slab corner on the slab stress are similar, which result in the change of the position of the maximum tensile stress. The maximum tensile stresses do not increase with the increase in the void size for relatively small void size. The maximum tensile stress increases rapidly with the enlargement in the void size when the size is ≥0.4 m. The increments of maximum tensile stress can reach 183.7% when the void size is 1.0 m. The increase in slab thickness can effectively reduce maximum tensile stress. A function is established to calculate the maximum tensile stress of the concrete slab. The function takes into account the void size, the slab thickness and the vehicle load. The reliability of the function was verified by comparing the error between the calculated and simulated results.

Study on Stressed MSFAC Attacked by Sodium Sulfate Solution

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%.

Thermal Stress Analysis of a Tubesheet with a Welding Clad

2011 ◽  
Vol 201-203 ◽  
pp. 302-307 ◽  
Author(s):  
Hui Fang Li ◽  
Cai Fu Qian ◽  
Xiao Dong Yu
Keyword(s):  
Numerical Simulation ◽  
Tensile Strength ◽  
Thermal Expansion ◽  
Tensile Stress ◽  
Thermal Stresses ◽  
Tube Bundle ◽  
Maximum Tensile Stress ◽  
Tensile Stresses ◽  
Heat Expansion ◽  
Thermal Tensile Stress

In this paper, numerical simulation was carried out for the tube bundle of a slurry oil steam generator with concentration on the thermal stresses at the tubesheet with or without a welding clad on the tubesheet surface. It is found that as having a larger heat expansion coefficient, thermal expansion of the welding clad is constrained and most areas are in compressive state. But the tensile stresses in the clad are also notable especially at the interface and could break the clad if added by the tensile stresses produced by pressure loadings. Presence of the welding clad causes significant tensile stresses in the base tubesheet. It is possible that the maximum tensile stress comprised by the thermal tensile stress and pressure induced tensile stress will exceed the tensile strength of the material and cause initiation of cracks in the tubesheet.

scholarly journals Finite element simulation and multi-factor stress prediction model for cement concrete pavement considering void under slab

2021 ◽  
Author(s):  
Liu Bangyi ◽  
Huang Xiaoming
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Maximum Tensile Stress ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Void Size ◽  
Tensile Stresses ◽  
The Impact

Uneven support as result of voids beneath concrete slabs can lead to high tensile stresses at the corner of the slab and eventually cause many forms of damage, such as cracking or faulting. Three-dimensional (3D) finite element models of the concrete pavement with void are presented. The accuracy of the model is verified by two methods. The analysis shows that the impact of void size and void depth at the slab corner on the slab stress are similar, which result in the change of the position of the maximum tensile stress. The maximum tensile stresses do not increase with the increase of the void size for relatively small void size. The maximum tensile stress increases rapidly with the enlargement in the void size when the size≥0.4m. The increments of maximum tensile stress can reach 183.7% when the void size are 1.0m. The increase of slab thickness can effectively reduce maximum tensile stress. A function is established to calculate the maximum tensile stress of the concrete slab. The function takes into account the void size and the slab thickness. The reliability of the function was verified by comparing the error between the calculated and simulated results.

Analysis of the Tensile Cracking of Rock-Concrete Materials Based on Elasto-Viscoplastic Model

2011 ◽  
Vol 243-249 ◽  
pp. 4569-4575
Author(s):  
Yao Ying Huang ◽  
Hong Zheng
Keyword(s):  
Tensile Strength ◽  
Tensile Stress ◽  
Time Course ◽  
Maximum Tensile Stress ◽  
Viscoplastic Model ◽  
Stress Criterion ◽  
Plastic Yield ◽  
Concrete Materials ◽  
Stability Issues ◽  
Maximum Tensile Stress Criterion

Suppose there is time course during the cracking and deforming process, the tensile cracking of rock-concrete materials was analyzed by means of elasto-viscoplastic model and its calculation steps were illustrated as well in this paper. The expression of function Φ in elasto-viscoplastic theory was studied; what’s more, it was comparatively analyzed the tensile cracking of rock-concrete materials by elasto-viscoplastic model and the maximum tensile stress criterion respectively. There are some differences comparing with the study of plastic yield by elasto-viscoplastic model, when analyzing the tensile cracking of rock-concrete materials on the basis of elasto-viscoplastic model, the function Φ should be the stress or stress formula of the direction where the principal stress firstly reaches the tensile strength; it is proved by the example analysis that it is feasible to study the tensile cracking of rock-concrete materials by elasto-viscoplastic model and there is no iteration stability issues.

Importance of quantification of steel fibre orientation for residual flexural tensile strength in FRC

2015 ◽  
Vol 49 (9) ◽  
pp. 3861-3877 ◽  
Author(s):  
Giedrius Žirgulis ◽  
Oldřich Švec ◽  
Elena Vidal Sarmiento ◽  
Mette Rica Geiker ◽  
Andrzej Cwirzen ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Steel Fibre ◽  
Fibre Orientation ◽  
Flexural Tensile Strength

scholarly journals Roller Compacted Concrete with Recycled Concrete Aggregate for Paving Bases

2020 ◽  
Vol 12 (8) ◽  
pp. 3154 ◽  
Author(s):  
Hedelvan Emerson Fardin ◽  
Adriana Goulart dos Santos
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Modulus Of Elasticity ◽  
Splitting Tensile Strength ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Roller Compacted Concrete ◽  
Flexural Tensile Strength ◽  
Mechanical And Physical Properties

This research aimed to investigate the mechanical and physical properties of Roller Compacted Concrete (RCC) used with Recycled Concrete Aggregate (RCA) as a replacement for natural coarse aggregate. The maximum dry density method was adopted to prepare RCC mixtures with 200 kg/m³ of cement content and coarse natural aggregates in the concrete mixture. Four RCC mixtures were produced from different RCA incorporation ratios (0%, 5%, 15%, and 30%). The compaction test, compressive strength, splitting tensile strength, flexural tensile strength, and modulus of elasticity, porosity, density, and water absorption tests were performed to analyze the mechanical and physical properties of the mixtures. One-way Analysis of Variance (ANOVA) was used to identify the influences of RCA on RCC’s mechanical properties. As RCA increased in mixtures, some mechanical properties were observed to decrease, such as modulus of elasticity, but the same was not observed in the splitting tensile strength. All RCCs displayed compressive strength greater than 15.0 MPa at 28 days, splitting tensile strength above 1.9 MPa, flexural tensile strength above 2.9 MPa, and modulus of elasticity above 19.0 GPa. According to Brazilian standards, the RCA added to RCC could be used for base layers.

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