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.

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 footing width on Nγ

2008 ◽  
Vol 45 (12) ◽  
pp. 1673-1684 ◽  
Author(s):  
Jyant Kumar ◽  
V. N. Khatri
Keyword(s):  
Linear Programming ◽  
Finite Elements ◽  
Lower Bound ◽  
Iterative Procedure ◽  
Friction Angle ◽  
Rigorous Solution ◽  
Good Comparison ◽  
Triangular Finite Elements ◽  
Bearing Capacity Factor ◽  
Lower Bound Limit Analysis

By incorporating the dependency of soil friction angle (ϕ) on mean principal stress (σm), the effect of footing width (B) on bearing capacity factor (Nγ) is examined for a rough strip footing. The analysis is performed by means of a numerical lower bound limit analysis in conjunction with triangular finite elements and linear programming. To account for the variation of ϕ with σm, a solution is obtained by using an iterative procedure. Two well defined ϕ–σm curves from the literature, associated with Hoston and Toyoura sands that correspond to relative densities of 18% and 74.5%, respectively, are used. The magnitude of Nγ is computed for different footing widths. It is noted that for B greater than about 0.2 m, the magnitude of Nγ varies almost linearly with B on a log–log scale. For different footing widths, a good comparison is seen between the obtained rigorous solution and that obtained by using a constant value of ϕ, which corresponds to the equivalent mean normal stress level as defined by De Beer.

The ultimate pullout capacity of anchors in frictional soils

2006 ◽  
Vol 43 (8) ◽  
pp. 852-868 ◽  
Author(s):  
R S Merifield ◽  
S W Sloan
Keyword(s):  
Finite Element ◽  
Lower Bound ◽  
Limit Analysis ◽  
Numerical Study ◽  
Past Research ◽  
Pullout Capacity ◽  
Current Design ◽  
Pullout Load ◽  
Ultimate Pullout Capacity ◽  
Frictional Soils

During the last 30 years various researchers have proposed approximate techniques to estimate the uplift capacity of soil anchors. As the majority of past research has been experimentally based, much current design practice is based on empiricism. Somewhat surprisingly, very few numerical analyses have been performed to determine the ultimate pullout loads of anchors. This paper presents the results of a rigorous numerical study to estimate the ultimate pullout load for vertical and horizontal plate anchors in frictional soils. Rigorous bounds have been obtained using two numerical procedures that are based on finite element formulations of the upper and lower bound theorems of limit analysis. For comparison purposes, numerical estimates of the break-out factor have also been obtained using the more conventional displacement finite element method. Results are presented in the familiar form of break-out factors based on various soil strength profiles and geometries and are compared with existing numerical and empirical solutions.Key words: anchor, pullout capacity, finite elements, limit analysis, lower bound, sand.

Recent Advances in Lower Bound Shakedown Analysis

2009 ◽  
Author(s):  
Dieter Weichert ◽  
Abdelkader Hachemi
Keyword(s):  
Finite Element ◽  
Lower Bound ◽  
Process Engineering ◽  
Operating Conditions ◽  
Structural Elements ◽  
Shakedown Analysis ◽  
Material Models ◽  
Practical Engineering ◽  
Safe Operating ◽  
New Algorithms

The special interest in lower bound shakedown analysis is that it provides, at least in principle, safe operating conditions for sensitive structures or structural elements under fluctuating thermo-mechanical loading as to be found in power- and process engineering. In this paper achievements obtained over the last years to introduce more sophisticated material models into the framework of shakedown analysis are developed. Also new algorithms will be presented that allow using the addressed numerical methods as post-processor for commercial finite element codes. Examples from practical engineering will illustrate the potential of the methodology.

A Study of Wall Ironing by the Finite Element Technique

1978 ◽  
Vol 100 (1) ◽  
pp. 31-36 ◽  
Author(s):  
E. I. Odell
Keyword(s):  
Finite Element ◽  
Lower Bound ◽  
Cone Angle ◽  
Reduction Ratio ◽  
Operating Parameters ◽  
Finite Element Technique ◽  
Elastic Plastic ◽  
Maximum Reduction ◽  
Load Displacement ◽  
Element Technique

Wall ironing has been analyzed using an elastic-plastic finite element technique. The effects that the ironing ring semi-cone angle and friction have on the maximum reduction ratio are studied in detail. Stress contours are given for a typical set of operating parameters. Several ram load/displacement curves are provided and compared with upper and lower bound loads.

scholarly journals A numerical finite element study on connections of SFRC offshore wind towers with prestressed CFRP reinforcement and steel connectors

2020 ◽  
Vol 5 ◽  
pp. 101-113
Author(s):  
Chandan Gowda ◽  
Fabio P. Figueiredo ◽  
Joaquim A. O. Barros ◽  
António Ventura-Gouveia
Keyword(s):  
Finite Element ◽  
Friction Angle ◽  
Offshore Wind ◽  
Advanced Materials ◽  
Limit States ◽  
Steel Fibre Reinforced Concrete ◽  
Shear Friction ◽  
Nonlinear Features ◽  
Parametric Analyses ◽  
Material Nonlinear

The growing need for sustainable production of electricity highlights the importance and the necessity of having higher number and more effective offshore wind towers. The rapid growth of offshore wind towers is estimated to produce 4% of electricity demands in Europe by the end of 2020. The research described in this paper is part of a project dedicated for the development of innovative structural system using advanced materials for lightweight and durable offshore towers. Specifically, it discusses the nonlinear finite element modelling of the connection between representative prefabricated rings of offshore wind tower made by steel fibre reinforced concrete (SFRC), and prestressed by a hybrid system of carbon fibre reinforced polymers (CFRP) bars and steel strands. This connection is assured by post-tension high steel strength cables and concrete-concrete shear friction width an idealized geometric configuration of the faces in contact. The model takes into account the loads from the rotor, wind and water currents, by considering the critical loading conditions for the safety verifications of serviceability and ultimate limit states. The material nonlinear analyses are carried out with FEMIX V4.0 software, considering a 3D constitutive model capable of simulating the relevant nonlinear features of the SFRC, and interface finite elements for modelling the shear friction of the concrete-concrete surfaces in contact. The parametric analyses involve the influence on the relevant results of the SFRC fracture parameters, pre-stress level of the reinforcements, shape of interlock mechanism, friction angle and interface cohesion.

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