The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Hamid Nikraz - One of the best experts on this subject based on the ideXlab platform.
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Effect of Shaft Diameter of Pile on Lateral Winkler Springs’ Stiffness
Journal of Earthquake Engineering, 2012Co-Authors: Amir Bahrami, Hamid NikrazAbstract:Soil was modelled with linearly elastic three-dimensional finite elements. Lateral spring stiffness was calculated from FE results. Spring stiffness is shown varying linearly with Shaft Diameter. It is also found that spring stiffness is inversely proportional to powers (less than unity) of pile flexural rigidity. Scaling factors for Shaft Diameter and pile flexural rigidity are introduced. Basic stiffness of lateral spring is studied considering both full vertical slippage and zero slippage between the soil and the pile. Relevant relationships for stiffness are proposed. Some applications are suggested.
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Initial Soil Springs Stiffness for laterally loaded Piles
2012Co-Authors: Amir Bahrami, Hamid NikrazAbstract:Total number of 180 finite element models is created. Soil is modelled by three dimensional elastic isotropic brick elements with cylindrical Shaft cavity at the centre. Pile is modelled with ordinary Euler- Bernoulli beam elements. Different connectivity scenarios between the soil and the pile surface are examined. Elastic properties of the soil are changed for each FE model within wide range of possible values. A globally covering database is created for free - head pile stiffness from FE analysis results. Lateral springs stiffness are calculated by equating pile head stiffness from FE models to predicted value from beam on elastic support theory. Spring’s stiffness is correlated to mechanical properties of the soil, Shaft Diameter, and pile flexibility factor using curve fitting techniques. It is found that spring stiffness is dependent to Shaft Diameter. It is also found that relative connectivity between the soil and pile’s skin, highly affects the spring’s stiffness. Comparison to work by other researchers is made.
Jiang Jian-ping - One of the best experts on this subject based on the ideXlab platform.
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Vertical bearing behavior of belled pier in thick loess-like soil
Rock and Soil Mechanics, 2007Co-Authors: Jiang Jian-pingAbstract:Based on the load tests of 8 large Diameter belled piers and 2 friction piles,the vertical bearing behavior of the belled pier in non-collapsing loess-like soil is studied.The result shows that if other conditions are the same,the bearing capacity of belled pier(kN) increases and the end resistance decreases as the increase of the belled Diameter.When both belled Diameter(D) and Shaft Diameter(d) remain constants,the total ultimate side resistance enhances with L/d increasing.When the Shaft Diameter(d) is changeless,the bearing capacity of belled pier changes irregularly with L/D increasing;the percentage of total end resistance(greater than equal-Diameter pile) decreases;the average ultimate side resistance(smaller than equal-Diameter pile) increases;but better bearing behavior occurs as L/D=3.If the Shaft Diameter and the length of belled pier in soil are the same with the friction pile,the bearing capacity of the former is greater than the latter;and the settlement is smaller than the latter.
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Test and Research on Vertical Bearing Behavior of Belled Pile
Journal of Xinjiang University, 2007Co-Authors: Jiang Jian-pingAbstract:Today,belled pile is used more and more widely in industry architecture,.This paper has a research on vertical bearing properties of belled pile based on vertical load test.The result shows that when belled Diameter(D) and Shaft Diameter(d) are the same,ultimate friction(kN) enhances with L increasing;the bearing capacity of belled pile(kN) increases and end resistance(kPa) decreases along with the belled Diameter's increasing when other conditions are same.Compared with Shaft pile,the bearing behavior of belled pile is better than Shaft pile,and the settlement is less than Shaft pile when the Shaft Diameter(d) and the length of belled pile in soil are same with the Shaft pile.
Amir Bahrami - One of the best experts on this subject based on the ideXlab platform.
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Effect of Shaft Diameter of Pile on Lateral Winkler Springs’ Stiffness
Journal of Earthquake Engineering, 2012Co-Authors: Amir Bahrami, Hamid NikrazAbstract:Soil was modelled with linearly elastic three-dimensional finite elements. Lateral spring stiffness was calculated from FE results. Spring stiffness is shown varying linearly with Shaft Diameter. It is also found that spring stiffness is inversely proportional to powers (less than unity) of pile flexural rigidity. Scaling factors for Shaft Diameter and pile flexural rigidity are introduced. Basic stiffness of lateral spring is studied considering both full vertical slippage and zero slippage between the soil and the pile. Relevant relationships for stiffness are proposed. Some applications are suggested.
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Initial Soil Springs Stiffness for laterally loaded Piles
2012Co-Authors: Amir Bahrami, Hamid NikrazAbstract:Total number of 180 finite element models is created. Soil is modelled by three dimensional elastic isotropic brick elements with cylindrical Shaft cavity at the centre. Pile is modelled with ordinary Euler- Bernoulli beam elements. Different connectivity scenarios between the soil and the pile surface are examined. Elastic properties of the soil are changed for each FE model within wide range of possible values. A globally covering database is created for free - head pile stiffness from FE analysis results. Lateral springs stiffness are calculated by equating pile head stiffness from FE models to predicted value from beam on elastic support theory. Spring’s stiffness is correlated to mechanical properties of the soil, Shaft Diameter, and pile flexibility factor using curve fitting techniques. It is found that spring stiffness is dependent to Shaft Diameter. It is also found that relative connectivity between the soil and pile’s skin, highly affects the spring’s stiffness. Comparison to work by other researchers is made.
Ashok Kumar Gupta - One of the best experts on this subject based on the ideXlab platform.
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Laboratory investigation of pullout behavior of hollow and solid Shaft helical nail in frictional soil
Acta Geotechnica, 2020Co-Authors: Pankaj Sharma, Saurabh Rawat, Ashok Kumar GuptaAbstract:Helical soil nails are passive elements installed in the soil which attains its bond strength through skin friction and bearing from helices. The present study examines the behavior of helical soil nail installed in cohesionless soil subjected to pullout force under varying parameters such as helical nail configuration (Shaft Diameter, helical Diameter, helical pitch, number of helices), nail Shaft types (roughness and stiffness), installation torque, and overburden pressure. The installation torque and corresponding nail pullout capacity can be established using a torque correlation factor ( K _t). K _t value decreases with increasing embedded nail area and is inversely proportional to the nail Shaft Diameter. From pullout tests result, it is found that pitch in the range of 24.5–35.5 mm shows better pullout capacity. Also, results show that additional helices will only contribute to pullout capacity if located outside the region of soil mobilized in the failure mechanism of lower helix. Moreover, higher axial strains are found for hollow Shaft nail, which alters with the increase in number of helices. Test results also indicate that various hollow Shaft helical nails have nearly equal interaction friction angle to solid Shaft helical soil nails with lesser Shaft Diameter. Therefore, it is concluded that solid Shaft helical nails can be replaced by hollow nails without compromising on pullout capacity adding to reduction in construction cost. Tests results show linear correlation between maximum pullout shear stress and overburden pressure following a Mohr–Coulomb failure for different helical nail types.
Thomas L Dawson - One of the best experts on this subject based on the ideXlab platform.
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what women want quantifying the perception of hair amount an analysis of hair Diameter and density changes with age in caucasian women
British Journal of Dermatology, 2012Co-Authors: C Robbins, Paradi Mirmirani, A G Messenger, M P Birch, R S Youngquist, Makio Tamura, T Filloon, Thomas L DawsonAbstract:Summary Background It has long been known that women lose satisfaction with their hair with ageing. Our data show that caucasian women perceive a decrease in hair amount in their mid 40s with a further decrease in the mid to late 50s, which leads to this dissatisfaction. Neither loss of density (hairs per cm2) nor Shaft Diameter alone can fully account for this perception. A new metric, ‘hair amount’, is proposed as a quantitative metric combining the impact of both density and Diameter on the perception of hair loss. Objectives Creation of a single parameter combining the contribution of Diameter and density to perception of female age-related hair loss. Methods In total, 1099 caucasian women (ages 18–66 years) with self-perceived hair loss and 315 caucasian women (ages 17–86 years) with no complaint of hair loss were evaluated. Scalp hair Diameter was measured using optical fibre Diameter and image analysis. Scalp hair density was measured by phototrichogram with manual or automated counting. Results Parietal scalp hair Diameter increased from ages 20 to 40–45 years, then decreased. Hair density was highest in the youngest group, age 20–30 years, and decreased thereafter with increasing rate. In women self-perceiving hair loss, the rate of decrease in density was significantly faster than for women with no self-perception of hair loss. The combined metric ‘hair amount’ was relatively constant at younger ages, increasing very slightly to age 35 years, then decreasing significantly. Conclusions Increasing hair Shaft Diameter offsets decreasing hair density through the mid 30s. After that, a lower rate of Diameter increase combined with the decrease in density begins to significantly impact the perception of hair amount so that thinning becomes increasingly more noticeable in the mid 40s to the mid to late 50s. Quantitative determination of hair amount is a useful tool to combine the contributions of hair density and Diameter to women’s perception of age-related hair loss.