Vertical uplift capacity of a group of two coaxial anchors in a general c–ϕ soil

2012 ◽  
Vol 49 (3) ◽  
pp. 367-373 ◽  
Author(s):  
Jyant Kumar ◽  
Tarun Naskar
Keyword(s):  
Finite Element ◽  
Lower Bound ◽  
Friction Angle ◽  
The Other ◽  
Unit Weight ◽  
Uplift Capacity ◽  
Soil Cohesion ◽  
Uplift Resistance ◽  
Vertical Spacing ◽  
Unit Cohesion

The vertical uplift resistance of a group of two horizontal coaxial strip anchors, embedded in a general c–[Formula: see text] soil (where c is the unit cohesion and [Formula: see text] is the soil friction angle), has been determined by using the lower bound finite element limit analysis. The variation of uplift factors Fc and Fγ, due to the components of soil cohesion and unit weight, respectively, with changes in depth (H) / width (B) has been established for different values of vertical spacing (S) /B. As compared to a single isolated anchor, the group of two anchors provides a significantly greater magnitude of Fc for [Formula: see text] ≤ 20° and with H/B ≥ 3. The magnitude of Fc becomes almost maximum when S/B is kept closer to 0.5H/B. On the other hand, with the same H/B, as compared to a single anchor, hardly any increase in Fγ occurs for a group of two anchors.

Effect of anchor width on pullout capacity of strip anchors in sand

2011 ◽  
Vol 48 (3) ◽  
pp. 511-517 ◽  
Author(s):  
Vishwas N. Khatri ◽  
Jyant Kumar
Keyword(s):  
Finite Element ◽  
Linear Programming ◽  
Lower Bound ◽  
Granular Medium ◽  
Iterative Procedure ◽  
Friction Angle ◽  
Pullout Capacity ◽  
Anchor Plate ◽  
Uplift Pressure ◽  
Uplift Resistance

By incorporating the variation of peak soil friction angle ([Formula: see text]) with mean principal stress (σm), the effect of anchor width (B) on vertical uplift resistance of a strip anchor plate has been examined. The anchor was embedded horizontally in a granular medium. The analysis was performed using lower bound finite element limit analysis and linear programming. An iterative procedure, proposed recently by the authors, was implemented to incorporate the variation of [Formula: see text] with σm. It is noted that for a given embedment ratio, with a decrease in anchor width (B), (i) the uplift factor (Fγ) increases continuously and (ii) the average ultimate uplift pressure (qu) decreases quite significantly. The scale effect becomes more pronounced at greater embedment ratios.

GENERALIZED SOLUTION FOR SEISMIC UPLIFT CAPACITY OF STRIP ANCHORS USING PSEUDO-STATIC APPROACH

2007 ◽  
Vol 01 (04) ◽  
pp. 311-328 ◽  
Author(s):  
DEEPANKAR CHOUDHURY ◽  
K. S. SUBBA RAO
Keyword(s):  
Limit Equilibrium ◽  
Failure Surface ◽  
Friction Angle ◽  
Present Theory ◽  
Generalized Solutions ◽  
Unit Weight ◽  
Uplift Capacity ◽  
Principle Of Superposition ◽  
Seismic Acceleration ◽  
Acceleration Coefficient

Generalized solutions for uplift capacity of inclined shallow strip anchors embedded in general c–ϕ soils with inclined slope carrying a uniform surcharge is developed in this paper for seismic condition. The individual effects of unit weight, surcharge and cohesion components on the computation of uplift capacity of anchors are considered. Limit equilibrium method with logspiral failure surface is adopted in the analysis and the effects of seismic forces are considered as pseudo-static forces. The results have been presented in the form of seismic uplift capacity factors as functions of anchor inclination, ground inclination, embedment ratio, soil friction angle and seismic acceleration coefficients both in the horizontal and vertical directions. Both the seismic accelerations change significantly the uplift capacity of anchors. Effect of the vertical seismic acceleration coefficient has been found to always reduce the uplift capacity whereas the effect of horizontal seismic acceleration coefficient has been found to reduce the uplift capacity in most of the cases. Results are presented in graphical and tabular forms. Estimation of error while using the principle of superposition to compute the seismic uplift capacity is also conducted. A comparative study between the present theory and available results in literature shows the merits and requirement of the present analysis.

Estimation of Uplift Capacity of Excavated Foundation of Transmission Lines

2014 ◽  
Vol 680 ◽  
pp. 361-364
Author(s):  
Dong Xue Hao ◽  
Yu Cong Gao ◽  
Rong Chen
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Transmission Lines ◽  
Earth Pressure ◽  
Friction Angle ◽  
Element Model ◽  
Uplift Capacity ◽  
Sliding Surface ◽  
Back Calculation ◽  
Homogeneous Soil

Finite element model for the system of foundation and its surrounding homogeneous soil is established based on software ABAQUS to analyze the uplift behavior of excavated foundation of transmission lines. The influence of soil properties and embedment ratio were analyzed. Deep mode occurs when embedment ratio is more than 4. As for shallow mode, the shearing method based on cylinder sliding surface was used to estimate uplift capacity. The expression of nominal uplift coefficient of earth pressure Ku in the formula was determined via back-calculation and fitting, which is the function of embedment ratio, friction angle and cohesion simultaneously. The errors of uplift capacity from fitting formula and numerical analysis are all within 15%.

scholarly journals Generalized framework to predict undrained uplift capacity of buried offshore pipelines

2016 ◽  
Vol 53 (11) ◽  
pp. 1841-1852 ◽  
Author(s):  
Shubhrajit Maitra ◽  
Santiram Chatterjee ◽  
Deepankar Choudhury
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Small Strain ◽  
Unit Weight ◽  
Soil Parameters ◽  
Burial Depth ◽  
Uplift Capacity ◽  
Finite Element Analyses ◽  
Simple Method ◽  
Offshore Pipelines

Estimation of undrained uplift capacity is essential for the determination of optimal burial depth of buried offshore pipelines. However, a generalized prediction model that incorporates various factors influencing this capacity is scarce in the literature. In this paper, results from a series of small-strain finite element analyses are presented that explore the effects of pipe embedment, pipe–soil interface roughness, interface tensile capacity, soil shear strength, and unit weight on pipe uplift response. From the study, a simple method to predict the undrained upheaval resistance of buried pipelines for any practical range of pipeline and soil parameters is proposed. Factors associated with transition in failure mechanism with embedment are also examined. The numerical model is validated by comparing the results with available analytical and experimental data. Large-deformation finite element analyses have also been performed independently for a few cases to justify the applicability of small-strain methods in modelling pipe upheaval. Accuracy of the model for generalized shear strength profile is then examined by considering practical values of parameters over broad ranges. The proposed methodology gives results with maximum error less than 8% for all ranges of parameters and hence can be adopted in design practices.

scholarly journals Numerical Analysis on the Behavior of Existing Tunnels Subjected to the Undercrossed Shield Tunneling at a Small Proximity

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Chunqing Fu ◽  
Yuchun Gao
Keyword(s):  
Finite Element ◽  
Friction Angle ◽  
Element Model ◽  
Shield Tunnel ◽  
Soil Parameters ◽  
External Diameter ◽  
Equivalent Stiffness ◽  
Shield Tunneling ◽  
Stiffness Model ◽  
Vertical Spacing

Shield excavation in a proximity to existing tunnels inevitably causes deformation and stress change of the adjacent tunnels. Based on the project of new metro line in Beijing where the shield tunnel was constructed under existing tunnel, a modified equivalent stiffness model for the existing tunnel is proposed. Based on this, a three-dimensional finite element is established, and subsequently the proposed modified equivalent stiffness model and the previous model are implemented into the finite element model (FEM), respectively, and then the effectiveness of it is verified through comparison with the field measurements. The results indicate that the modified equivalent stiffness model has excellent agreement with the monitoring value. The impacts of key parameters including undercrossing angle, vertical spacing, and soil parameters on the crown settlement of the existing tunnel are investigated. The maximum settlement of the existing tunnel crown decreases as the undercrossing angle increases. The decease of vertical spacing between the newly constructed tunnel and the existing tunnel leads to an increase of the peak value of crown settlement. As for the soil parameters, friction angle φ is the dominant parameter affecting crown settlement of the existing tunnel whereas the cohesion c is least influential. During the process of route selection, it is suggested to keep the vertical spacing between new tunnel and the existing tunnel greater than the external diameter of the new metro tunnel. For the situation of undercrossing an existing tunnel within an extremely small clearance, it is recommended to strengthen the soil as necessary.

ROLE OF THE THYROID GLAND IN DEVELOPMENT AND MAINTENANCE OF RENAL HYPERTENSION IN RATS

1960 ◽  
Vol XXXIV (III) ◽  
pp. 411-429 ◽  
Author(s):  
Melvin J. Fregly ◽  
Kenneth M. Cook
Keyword(s):  
Blood Pressure ◽  
Rate Increase ◽  
Renal Hypertension ◽  
The Other ◽  
Elevated Blood Pressure ◽  
Unit Weight ◽  
Elevated Blood ◽  
Inhibition Of Growth ◽  
Testicular Size

ABSTRACT The anti-thyroid drugs, thiouracil, propylthiouracil, and methimazole, prevented both development of elevated blood pressure and cardiac hypertrophy usually accompanying kidney encapsulation with latex envelopes. These drugs also reduced elevated blood pressure of rats with hypertension of 13 to 40 weeks' duration prior to drug administration. Addition of desiccated thyroid powder to diet containing an anti-thyroid drug overcame the anti-hypertensive effect of the latter. Withdrawal of thyroid powder only was followed by return of blood pressure to previous low level within 3 weeks. The results suggest that the anti-hypertensive effect of these drugs is related directly to the hypothyroidism produced rather than to extrathyroidal effects of the drugs. Comparison of potencies of the 3 drugs in terms of anti-hypertensive effect, inhibition of growth rate, increase in testicular size, and increase in thyroid size suggests that propylthiouracil and methimazole are equally potent per unit weight of drug. Thiouracil has approximately half the potency of the other two.

scholarly journals Density Guarantee on Finding Multiple Subgraphs and Subtensors

2021 ◽  
Vol 15 (5) ◽  
pp. 1-32
Author(s):  
Quang-huy Duong ◽  
Heri Ramampiaro ◽  
Kjetil Nørvåg ◽  
Thu-lan Dam
Keyword(s):  
Lower Bound ◽  
State Of The Art ◽  
The State ◽  
The Other ◽  
Exact Methods ◽  
Practical Solution ◽  
Novel Approach ◽  
Wide Range ◽  
Real World Datasets ◽  
Tensor Data

Dense subregion (subgraph & subtensor) detection is a well-studied area, with a wide range of applications, and numerous efficient approaches and algorithms have been proposed. Approximation approaches are commonly used for detecting dense subregions due to the complexity of the exact methods. Existing algorithms are generally efficient for dense subtensor and subgraph detection, and can perform well in many applications. However, most of the existing works utilize the state-or-the-art greedy 2-approximation algorithm to capably provide solutions with a loose theoretical density guarantee. The main drawback of most of these algorithms is that they can estimate only one subtensor, or subgraph, at a time, with a low guarantee on its density. While some methods can, on the other hand, estimate multiple subtensors, they can give a guarantee on the density with respect to the input tensor for the first estimated subsensor only. We address these drawbacks by providing both theoretical and practical solution for estimating multiple dense subtensors in tensor data and giving a higher lower bound of the density. In particular, we guarantee and prove a higher bound of the lower-bound density of the estimated subgraph and subtensors. We also propose a novel approach to show that there are multiple dense subtensors with a guarantee on its density that is greater than the lower bound used in the state-of-the-art algorithms. We evaluate our approach with extensive experiments on several real-world datasets, which demonstrates its efficiency and feasibility.

scholarly journals Tripartite entropic uncertainty relation under phase decoherence

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. A. Abdelghany ◽  
A.-B. A. Mohamed ◽  
M. Tammam ◽  
Watson Kuo ◽  
H. Eleuch
Keyword(s):  
Lower Bound ◽  
Uncertainty Relation ◽  
Nearest Neighbors ◽  
The Other ◽  
Uncertainty In Measurement ◽  
Entropic Uncertainty Relation ◽  
Specific Choice ◽  
Phase Decoherence ◽  
Time Invariant ◽  
Incompatible Observables

AbstractWe formulate the tripartite entropic uncertainty relation and predict its lower bound in a three-qubit Heisenberg XXZ spin chain when measuring an arbitrary pair of incompatible observables on one qubit while the other two are served as quantum memories. Our study reveals that the entanglement between the nearest neighbors plays an important role in reducing the uncertainty in measurement outcomes. In addition we have shown that the Dolatkhah’s lower bound (Phys Rev A 102(5):052227, 2020) is tighter than that of Ming (Phys Rev A 102(01):012206, 2020) and their dynamics under phase decoherence depends on the choice of the observable pair. In the absence of phase decoherence, Ming’s lower bound is time-invariant regardless the chosen observable pair, while Dolatkhah’s lower bound is perfectly identical with the tripartite uncertainty with a specific choice of pair.

scholarly journals Finite element analysis of reinforced concrete deep beam with large opening

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Elsayed Ismail ◽  
Mohamed S. Issa ◽  
Khaled Elbadry
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
The Other ◽  
Deep Beam ◽  
Web Openings ◽  
Design Load ◽  
Large Opening

Abstract Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.

Sign in / Sign up

Export Citation Format

Share Document