Caisson Capacity in Clay: VHM Resistance Envelope: Part 3—Extension to Shallow Foundations

2011 ◽  
Author(s):  
S. Kay ◽  
E. Palix
Keyword(s):  
Shear Strength ◽  
Load Resistance ◽  
Analysis Tool ◽  
Foundation Soil ◽  
Finite Element Program ◽  
Near Surface ◽  
Wide Range ◽  
Soil Shear Strength ◽  
Non Linear ◽  
Element Program

Suction embedded caissons are efficient and economic solutions to anchor floating structures. A more recent caisson application is to support seafloor structures such as manifolds, PLEMs, pumps, etc. For a deepwater hydrocarbon field, many types of seafloor structures are required, each with their own characteristics and slightly different design. Caisson designs increasingly use resistance envelope methodology. This eliminates non-linear 3D FE analyses (except for assessing responses or soil reactions), and facilitates probabilistic and optimisation analyses. In general, there is a requirement for a reliable method of assessing caisson capacity under general VHM load. Resistance envelope equations for “deep” circular caissons (1.5 < L/D < 6) have been presented by Kay and Palix (2010) for a wide range of soil undrained shear strength profiles. This paper extends the study to cover near-surface caissons (i.e. 0 ≤ L/D ≤ 1.5). As in previous studies, a quasi 3D non-linear finite element program (HARMONY) was the primary numerical analysis tool. Three soil shear strength profiles were investigated for 13 caisson embedment ratios. In the range 0 ≤ L/D ≤ 1.5, VHM envelope shapes transform from a “scallop” at L/D ≈ 0 into a “tongue” above a critical caisson embedment ratio (L/D)crit of about 0.5 The equations originally developed for the rotated ellipse/ellipsoid (i.e. “tongue”-shaped envelope) in Kay and Palix (2010) for L/D ≤ 1.5 have been extended for (L/D)crit ≥ L/D. All parameters are simple functions of L/D and soil shear strength profile. Major limitations and assumptions made were (a) foundation-soil tension was permitted and (b) no internal scoop failure (i.e. within the soil plug inside the caisson) was possible. These are important for low L/D: both may adversely affect VHM resistance.

scholarly journals The Ocean Version of the Lagrangian Analysis Tool LAGRANTO

2017 ◽  
Vol 34 (8) ◽  
pp. 1723-1741 ◽  
Author(s):  
Sebastian Schemm ◽  
Aleksi Nummelin ◽  
Nils Gunnar Kvamstø ◽  
Øyvind Breivik
Keyword(s):  
Case Studies ◽  
Potential Temperature ◽  
Analysis Tool ◽  
Lagrangian Analysis ◽  
Ocean Reanalysis ◽  
Near Surface ◽  
Mean Values ◽  
Spatial And Temporal Scales ◽  
First Case ◽  
Wide Range

AbstractThe Lagrangian Analysis Tool (LAGRANTO) is adopted and applied to ECMWF’s latest ocean reanalysis. The primary motivation behind this study is to introduce and document LAGRANTO Ocean (LAGRANTO.ocean) and explore its capabilities in combination with an eddy-permitting ocean reanalysis. The tool allows for flexibly defining starting points, within circles, cylinders, or any user-defined region or volume. LAGRANTO.ocean also offers a sophisticated way to refine a set of computed trajectories according to a wide range of mathematical operations that can be combined into a single refinement criterion. Tools for calculating—for example, along-trajectory cross sections or trajectory densities—are further provided. After introducing the tool, three case studies are presented, which were chosen to reflect a selection of phenomena on different spatial and temporal scales. The case studies also serve as hands-on examples. For the first case study, at the mesoscale, ocean trajectories are computed during the formation of a Gulf Stream cold-core ring to study vertical motion in the developing eddy. In the second example, source waters are traced to the East Greenland Spill Jet. This example highlights the usefulness of a Lagrangian method for identifying sources or sinks of buoyancy. The third example, on annual time scales, focuses on the temporal evolution of extreme potential temperature anomalies in the South Pacific and the memory of the involved water parcels. Near-surface trajectories reveal that it takes approximately 5 months after the highest temperature anomaly before the involved water parcels cool to their climatological mean values at their new positions. LAGRANTO.ocean will be made publicly available.

On Modeling the Mechanical Behavior of Amorphous Polymers for the Micro-Hot-Embossing of Microfluidic Devices

2008 ◽  
Author(s):  
Vikas Srivastava ◽  
Lallit Anand
Keyword(s):  
Three Dimensional ◽  
Amorphous Polymers ◽  
Hot Embossing ◽  
Compression Tests ◽  
Predictive Capability ◽  
Finite Element Program ◽  
Rate Dependent ◽  
Wide Range ◽  
Element Program ◽  
Simple Compression

In this paper, a brief summary of some of our recent work [1, 2] is presented, with the goal of developing an engineering science-based process-simulation capability for micro-hot-embossing of amorphous polymers. To achieve this goal: (i) a three-dimensional thermo-mechanically-coupled large deformation constitutive theory has been developed to model the temperature and rate-dependent elastic-viscoplastic response of amorphous polymers; (ii) the material parameters in the theory were calibrated by using new experimental data from a suite of simple compression tests on Zeonex-690R (cyclo-olefin polymer), that covers a wide range of temperatures and strain rates; (iii) the constitutive model was implemented in the finite element program ABAQUS/Explicit; and (iv) the predictive capability of the numerical simulation procedures were validated by comparing results from the simulation of a representative micro-hot-embossing process against corresponding results from a physical experiment.

Numerical Analysis of Underground Concrete Arch Structure Strengthened with Near-Surface Bonded CFRP Strips

2012 ◽  
Vol 594-597 ◽  
pp. 1324-1330
Author(s):  
Mei Rong Jiang ◽  
Feng Nian Jin ◽  
Shuai Ling Luo ◽  
Hua Lin Fan ◽  
Bo Wang
Keyword(s):  
Ultimate Load ◽  
Nonlinear Finite Element ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Strengthening Effect ◽  
Finite Element Program ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Element Program ◽  
Arch Structure

To strengthen underground arch structure, the method with near-surface bonded carbon fiber reinforced polymer (CFRP) strips is proposed. A nonlinear finite element program is built to analyze concrete arch structure strengthened with CFRP. Factors that influence the strengthening effect are discussed. After arch strengthened with near-surface bonded CFRP strips, the cracking load, the yield load and the ultimate load has been greatly improved, the stiffness has also been greatly improved. The bearing capacity and the stiffness of arch structure increase with the layer quantity of CFRP increasing, increase with the strip quantity of CFRP in units increases. In the condition of the layer quantity and the strip quantity of CFRP being identical, the increasing ratio of load decreases with the reinforcement ratio increasing.

scholarly journals Effect of Reinforced Concrete Column Capital on Punching Shear Strength of Flat Slab

2019 ◽  
Vol 54 (5) ◽  
Author(s):  
Haider K. Ammash ◽  
Safa S. Kadhim
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Reference Model ◽  
Punching Shear ◽  
Concrete Column ◽  
Reinforced Concrete Column ◽  
Finite Element Program ◽  
Flat Slab ◽  
Size And Shape ◽  
Element Program

In the present study, the effect of using reinforced concrete column capital on the punching shear strength of flat slab was investigated. The study was divided into two lines, the first line was the experimental study involves the molding four reinforced concrete flat slab models with dimensions (1600×1600×100 mm) with three different dimensions of column capital (400×400 mm, 600×600 mm, and 800×800 mm) in addition to reference model without columns capital (column dimension 200×200 mm). The second line that numerical modeling through the ABAQUS finite element program was introduced. Effect of column’s capital size and shape of column’s capital (rectangular and circular) were studied experimentally and numerically. A good agreement was obtained between the experimental and theoretical study. The main conclusion that the punching shear strength of reinforced concrete flat slab was affected on the size and shape of a column capital.

scholarly journals Modeling of soil shear strength using multiple linear regression (MLR) at Penang, Malaysia

2021 ◽  
Vol 9 (3A) ◽  
Author(s):  
Bala Balarabe ◽  
◽  
Andy Anderson Bery ◽  
Keyword(s):  
Shear Strength ◽  
Linear Regression ◽  
Multiple Linear Regression ◽  
Friction Angle ◽  
Accurate Estimation ◽  
Near Surface ◽  
Independent Variables ◽  
Refraction Tomography ◽  
Soil Shear Strength ◽  
Mlr Model

This paper presents multiple linear regression (MLR) soil shear strength models developed from electrical resistivity and seismic refraction tomography data. The MLR technique is used to estimate the value of dependent variables of soil shear strength based on the value of two independent variables, namely, resistivity and velocity. These parameters were regressed using regression statistics technique for generating MLR model. The results of MLR model, which is based on the estimation of model dependent parameters (Log10 resistivity and Log10 velocity), calculated for p-value, are less than 0.05 and VIF value less than 10 for cohesion and friction angle models. This result shows that there is a statistically significant relationship between cohesion and friction angle with geophysical parameters (independent variables). The estimation accuracy of the MLR models is also conducted for verification, and the result shows that RMSE value for predicted cohesion and predicted friction angle is 0.77 kN/m2 and 1.73° which is close to zero. Meanwhile, MAPE value was found to be 4.57 % and 7.61 %, indicating highly accurate estimation for the MLR models of predicted cohesion and predicted friction angle. Based on the application of near surface, the study area was successfully classified into two regions, namely, medium and hard clayey sand. Thus, it is concluded that MLR method is suitable in estimating the subsurface characterization that covered more regions compared to the traditional method (laboratory test).

Stability Behavior of a Natural Circulation Loop with End Heat Exchangers

2005 ◽  
Vol 127 (7) ◽  
pp. 749-759 ◽  
Author(s):  
N. M. Rao ◽  
B. Maiti ◽  
P. K. Das
Keyword(s):  
Heat Exchangers ◽  
Natural Circulation ◽  
Circulation Rate ◽  
Finite Element Program ◽  
Stability Behavior ◽  
Wide Range ◽  
Element Program ◽  
The Stability ◽  
The One ◽  
Two Parameters

The present investigation describes the stability behavior of NCL with end heat exchangers. The one-dimensional transient conservation equations of the loop fluid and the two fluid streams of cold end and hot end heat exchangers are solved simultaneously using the finite element program. For the stability analysis the loop response is found for an imposed finite perturbation to the loop circulation rate. Though the stability may depend on the number of parameters, variation of two nondimensional parameters, namely Ch* and GrL, is studied. Selecting the specific combinations of the above two parameters three different cases of stability, namely, stable, neutrally stable, and unstable, are demonstrated. The stability behavior is scanned over a wide range of Ch* and GrL values and the stability envelope is also constructed.

Numerical Analysis on Influencing Factors of U-Shaped Disease of Asphalt Pavement Using ABAQUS Program

2012 ◽  
Vol 466-467 ◽  
pp. 479-484
Author(s):  
Li Liu ◽  
Pei Wen Hao
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Mechanical Model ◽  
Asphalt Pavement ◽  
Rigid Base ◽  
High Grade ◽  
Interface Conditions ◽  
Finite Element Program ◽  
Remarkable Effect ◽  
Element Program

The U-shaped cracking of high-grade semi-rigid base asphalt pavement was studied. A finite element program (ABAQUS) was used to conduct a mechanical model to analyze the effects of the interlayer conditions and overloads on U-shaped cracking. The results show that the generation and development of U-shaped cracking is significantly influenced by interlayer conditions and overloads. Furthermore, the asphalt-to-asphalt pavement layer conditions provide for a more remarkable effect on U-shaped cracking than the asphalt–to-base pavement layer conditions. To reduce the development of U-shaped cracking, two aspects work must be reinforced: (1) the interface conditions should be improved to ensure the shear strength between layers of surface course and avoid slippage failure between layers of asphalt pavement, (2) over loading vehicles must be limited.

scholarly journals Comparison between Experimental and 3D Finite Element Analysis of Reinforced and Partially Pre-Stressed Concrete Solid Beams Subjected to Combined Load of Bending, Torsion and Shear

2008 ◽  
Vol 5 (1) ◽  
pp. 79
Author(s):  
A. S. Alnuaimi
Keyword(s):  
Finite Element ◽  
Prestressed Concrete ◽  
Failure Load ◽  
Element Analysis ◽  
Finite Element Program ◽  
3D Finite Element ◽  
Combined Load ◽  
Perfectly Plastic ◽  
Non Linear ◽  
Element Program

This paper presents a non-linear analysis of three reinforced and two partially prestressed concrete solid beams based on a 20 node isoparametric element using an in-house 3D finite element program. Anon linear elastic isotropic model, proposed by Kotsovos, was used to model concrete behaviour, while steel was modelled as an embedded element exhibiting elastic-perfectly plastic response. Allowance was made for shear retention and for tension stiffening in concrete after cracking. Only in a fixed direction, smeared cracking modelling was adopted. The beams dimensions were 300x300 mm cross section, 3800 mm length and were subjected to combined bending, torsion and shear. Experimental results were compared with the non-linear predictions. The comparison was judged by load displacement relationship, steel strain, angle of twist, failure load, crack pattern and mode of failure. Good agreement was observed between the predicted ultimate load and the experimentally measured loads. It was concluded that the present program can confidently be used to predict the behaviour and failure load of reinforced and partially prestressed concrete solid beams subjected to a combined load of bending, torsion and shear. 

scholarly journals Assessment of the non-linear behaviour of plastic ankle foot orthoses by the finite element method

2000 ◽  
Vol 214 (5) ◽  
pp. 527-539 ◽  
Author(s):  
S Syngellakis ◽  
M A Arnold ◽  
H Rassoulian
Keyword(s):  
Finite Element ◽  
Experimental Studies ◽  
Careful Consideration ◽  
Foot Orthoses ◽  
Finite Element Program ◽  
Ankle Foot Orthoses ◽  
Non Linear ◽  
Linear Behaviour ◽  
Element Program ◽  
Alternative Means

The stiffness characteristics of plastic ankle foot orthoses (AFOs) are studied through finite element modelling and stress analysis. Particular attention is given to the modelling and prediction of non-linear AFO behaviour, which has been frequently observed in previous experimental studies but not fully addressed analytically. Both large deformation effects and material non-linearity are included in the formulation and their individual influence on results assessed. The finite element program is subsequently applied to the simulation of a series of tests designed to investigate the relation between AFO trimline location and stiffness for moderate and large rotations. Through careful consideration and identification of key modelling parameters, the developed finite element solution proves to be a reliable and effective alternative means of assessing variations of a typical plastic AFO design so that particular patient requirements could be met, in the long term.

An Analysis of the Effects of Burnishing in Internal Broaching

2000 ◽  
Vol 28 (2) ◽  
pp. 163-173 ◽  
Author(s):  
V. Sajeev ◽  
L. Vijayaraghavan ◽  
U. R. K. Rao
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Material Behaviour ◽  
Element Analysis ◽  
Finite Element Program ◽  
Left Behind ◽  
The Finite Element Analysis ◽  
Non Linear ◽  
Element Program ◽  
Linear Material

The finite element analysis gives the stresses and deflections of the broach and workpiece while cutting and burnishing. This has been achieved by developing a suitable finite element program for solving linear and non-linear material behaviour problems. The broach has been considered to behave elastically. In case of burnishing, the stresses on the workpiece result in yielding, and hence, non-linear material behaviour is considered for the workpiece. The program has been further modified to compute residual stresses on the broached component. The movement of a single burnishing tooth through the workpiece is simulated in a step-by-step manner, leading to residual stresses on the broached surface. The burnishing tooth and corresponding portion of the workpiece are modelled using FEM. The effect of tool-work interference and the ratio of radial to axial force on the stresses and deflections while burnishing have been studied. The residual stresses left behind on the broached component have been analytically evaluated.

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