Showing papers on "Embedment published in 2014"
TL;DR: In this paper, a generalised failure envelope for the prediction of the undrained capacity of circular shallow foundations under general vertical, horizontal and moment (VHM) loading is presented for shallow circular foundations over a practical range of embedment ratio and soil strength heterogeneity.
Abstract: This paper presents a generalised failure envelope for the prediction of the undrained capacity of circular shallow foundations under general vertical, horizontal and moment (VHM) loading. Uniaxial capacities and failure envelopes under combined loading are presented for shallow circular foundations over a practical range of embedment ratio and soil strength heterogeneity. An approximating expression is proposed to describe the shape of the normalised VHM failure envelope as a function of foundation embedment ratio, normalised soil strength heterogeneity index and vertical load mobilisation.
83 citations
TL;DR: In this article, the absorption properties of a metaporous material made of non-resonant simple shape 3D rigid inclusions (cube, cylinder, sphere, cone, and ring torus) embedded in a rigidly backed rigid-frame porous material are studied.
Abstract: The absorption properties of a metaporous material made of non-resonant simple shape three-dimensional rigid inclusions (cube, cylinder, sphere, cone, and ring torus) embedded in a rigidly backed rigid-frame porous material are studied. A nearly total absorption can be obtained for a frequency lower than the quarter-wavelength resonance frequency due to the excitation of a trapped mode. To be correctly excited, this mode requires a filling fraction larger in three-dimensions than in two-dimensions for purely convex (cube, cylinder, sphere, and cone) shapes. At long wavelengths compared to the spatial period, a cube is found to be the best purely convex inclusion shape to embed in a cubic unit cell, while the embedment of a sphere or a cone cannot lead to an optimal absorption for some porous material properties and dimensions of the unit cell. At a fixed position of purely convex shape inclusion barycenter, the absorption coefficient only depends on the filling fraction and does not depend on the shape below the Bragg frequency arising from the interaction between the inclusion and its image with respect to the rigid backing. The influence of the incidence angle and of the material properties, namely, the flow resistivity is also shown. The results of the modeling are validated experimentally in the case of cubic and cylindrical inclusions.
74 citations
TL;DR: In this article, a series of three-dimensional finite element analyses was conducted to investigate the effects of the embedment depth, the non-homogeneity of clay, and combined loads on the undrained bearing capacities of bucket foundations.
Abstract: A series of three-dimensional finite element analyses was conducted to investigate the effects of the embedment depth, the non-homogeneity of clay, and combined loads on the undrained bearing capacities of bucket foundations. The undrained shear strength and Young's modulus of clay were assumed to vary linearly with depth. Meanwhile, the stress-strain response of clay was simulated using the Tresca criterion. The numerical modeling adopted in this study was verified by comparing the calculated capacities with those from previous studies. Based on the results of the finite element analyses over 1400 cases, new equations were proposed to calculate the vertical, horizontal, and moment bearing capacities as well as to define the capacity envelopes under general combined loads. Comparisons with the capacity envelopes of previous studies showed that the proposed equations properly predicted the bearing capacities of the bucket foundation by considering the effects of the non-homogeneity of clay and embedment depth.
67 citations
TL;DR: In this article, an analytical model for the pullout behavior of single fibers embedded in a concrete matrix for various configurations of fiber type, matrix strength, and embedment condition is proposed.
Abstract: In the context of multiscale-oriented computational analyses of fiber-RC (FRC) structures, the modeling of single fiber pullout behavior represents the basic constituent to provide traction-displacement relations to be used for the modeling of FRC on a macroscopic scale. This essential ingredient needs to be formulated such that it only requires minimal computational effort. To this end, an analytical model for the pullout behavior of single fibers embedded in a concrete matrix for various configurations of fiber type, matrix strength, and embedment condition is proposed. An interface law is developed for the frictional behavior between the fiber and matrix. In the case of inclined fibers, the plastic deformation of the fiber and the local damage of concrete are also considered. For hooked-end fibers, the anchorage effect due to the deformed topology of the fiber ends is taken into account in the formulation. By combining these submodels, the pullout response of single fibers embedded in a concret...
64 citations
TL;DR: The absorption properties of a metaporous material made of non-resonant simple shape three-dimensional rigid inclusions embedded in a rigidly backed rigid-frame porous material are studied and a cube is found to be the best purely convex inclusion shape to embed in a cubic unit cell.
Abstract: The absorption properties of a metaporous material made of non-resonant simple shape three-dimensional inclusions (cube, cylinder, sphere, cone and torus) embedded in a rigidly backed rigid frame porous material is studied. A nearly total absorption can be obtained for a frequency lower than the quarter-wavelength resonance frequency due to the excitation of a trapped mode. To be correctly excited, this mode requires a filling fraction larger in the three-dimensions than in the two-dimensions for purely convex (cube, cylinder, sphere, and cone) shapes. At low frequencies, a cube is found to be the best purely convex inclusion shape to embed in a cubic unit cell, while the embedment of a sphere or a cone cannot lead to an optimal absorption for some porous materials. At fixed position of purely convex shape inclusion barycentre, the absorption coefficient only depends on and filling fraction and does not depend on the shape below the Bragg frequency arising from the interaction between the inclusion and its image with respect to the rigid backing. The influence of the angle of incidence is also shown. The results, in particular the excitation of the trapped mode, are validated experimentally in case of cubic inclusions.
63 citations
TL;DR: In this paper, the effects of flow ratio (steady current velocity vs. combined waves/current velocity), flow incidence angle and pipeline initial embedment depth on free span expansion rate were investigated.
57 citations
TL;DR: In this paper, the results of an experimental research related to chemical anchors in natural stone are presented. And the applicability of some numerical models for the prediction of the bearing capacity of the anchor is investigated, whereas the theoretical formulations are not feasible.
50 citations
TL;DR: In this paper, the results from a series of model tests undertaken to provide insight into the behavior of torpedo anchors during dynamic installation and pullout in lightly overconsolidated kaolin clay and calcareous silt were reported.
Abstract: This paper reports the results from a series of model tests undertaken to provide insight into the behavior of torpedo anchors during dynamic installation and pullout in lightly overconsolidated kaolin clay and calcareous silt. The tests were carried out in a drum centrifuge at 200g, varying the drop height (hence the impact velocity) and the time delay for consolidation before pullout. The pullout angle at the mudline was also varied to encompass various mooring systems, including catenary (0°), taut leg (45°), and tension leg (∼80°). Two geometries of torpedo anchors were explored, varying the fin and tip geometry. The results demonstrated that the anchor embedment depth increased as the drop height (and hence the impact velocity) increased and the soil undrained shear strength decreased. In stronger silt, the cavity above the installing anchor remained open, whereas in soft clay, it was fully backfilled and replenished. The corresponding anchor embedment depth was also about 0.63 times compared...
50 citations
TL;DR: In this paper, a new strain-hardening criterion is developed by calibrating failure criteria by employing data from small-scale tests on bucket foundations subjected to static loads, and the shape of the yield, potential, and failure surfaces are found to be dependent on the embedment ratio (i.e., ratio of skirt length to the diameter) and load path.
Abstract: Based on experimental investigations, the literature proposes different methods for modeling the behavior and capacity of foundations subjected to combined loading. Generally, two methods are used to predict the behavior of foundations: traditional approaches and hardening plasticity solutions. The first method is only capable of determining the capacity of the foundations and not the prepeak behavior. Thus, a new strain-hardening criterion is developed by calibrating failure criteria by employing data from small-scale tests on bucket foundations subjected to static loads. The shape of the yield, potential, and failure surfaces are found to be dependent on the embedment ratio (i.e., ratio of skirt length to the diameter) and load path. For the models tested, associated flow is observed to be plausible in the radial planes, whereas nonassociated flow is observed in the planes along the V-axis.
48 citations
TL;DR: In this paper, the monotonic capacity of dynamically embedded plate anchors (DEPLAs) in normally consolidated clay was studied using a three-dimensional large deformation finite element approach based on frequent mesh regeneration.
Abstract: Dynamically embedded plate anchors (DEPLAs) are a type of offshore anchor that combine the capacity advantages of vertically loaded plate anchors with the installation benefits of dynamically installed anchors. DEPLA capacity under monotonic loading conditions in clay has been investigated through centrifuge and field tests. In this paper, the monotonic capacity of DEPLAs in normally consolidated clay was studied using a three-dimensional large deformation finite element approach based on frequent mesh regeneration. Results from the numerical simulations were validated by comparison with centrifuge test data and existing numerical and analytical solutions for circular and rectangular plates. The effect of anchor embedment depth, anchor roughness, fluke (or plate) thickness, plate inclination, and DEPLA geometry were investigated in a parametric study where soil was prescribed to remain attached to the DEPLA base. The findings indicate that for a horizontal anchor subjected to vertical loading, most DEPLA geometries exhibit deep behaviour at an embedment ratio of 2.5, but that this embedment ratio is dependent upon the plate inclination, with vertical plates requiring the highest embedment depth for a deep localized failure mechanism. At a shallow embedment depth equal to one plate diameter, the reduction in capacity factor as the plate inclination changes from horizontal to vertical is 23.4%, compared with 1.3% at an embedment depth equal to four plate diameters. Plate roughness and fluke thickness are shown to have a minimal effect on the anchor capacity factor for vertical loading. Analyses that considered the breakaway (no tension) at the DEPLA base demonstrated that the anchor capacity factor approaches the no breakaway value as the embedment depth increases and as the soil strength (relative to the effective unit weight of the soil) decreases. The paper proposes a simple means of approximating the anchor capacity factor for breakaway conditions, by summing the capacity factor in weightless soil (which is unique for a given DEPLA geometry) and the normalized overburden pressure.
40 citations
TL;DR: In this article, a closed-form solution for the pressure-expansion relationship is used to predict the uplift capacity of strip anchors in undrained clay, and the proposed solution improves on the conventional cavity expansion theory and provides a new method for solving the non-asymmetric characteristics of elliptical cavity expansion.
Abstract: This note presents a new pressure-controlled elliptical cavity expansion model for elastic–perfectly plastic soil. The model accounts for the non-asymmetric characteristics of elliptical cavity expansion, which differ from conventional asymmetric cylindrical cavity expansion. A closed-form solution for the pressure–expansion relationship is used to predict the uplift capacity of strip anchors in undrained clay. Theoretical variations of the strip anchor breakout factor are compared with conventional cylindrical cavity expansion theory and laboratory test results and upper and lower bound finite-element limit analysis solutions from the literature. The results show that a pressure-controlled elliptical cavity expansion model can predict the uplift capacity of strip anchors in undrained clay more accurately than the conventional cavity expansion method at larger embedment depths (H/B>3). The proposed solution improves on the conventional cavity expansion theory and provides a new method for solving the non-...
TL;DR: In this article, the conceptual design of an innovative seismic-resistant steel framing system capable of providing stiffness and ductility to new or existing structures is presented, which consists of concentric X-braces connected in series with rectangular sacrificial shear panels.
Abstract: The conceptual design of an innovative seismic-resistant steel framing system capable of providing stiffness and ductility to new or existing structures is presented. The bracing system consists of concentric X-braces connected in series with rectangular sacrificial shear panels. The braces are designed to remain elastic during seismic events while the shear panels are sized and configured to dissipate ample energy through plastic deformation-induced stable hysteretic behavior. Detailed three-dimensional nonlinear finite-element analyses using ABAQUS are performed to characterize and quantify the effects of the design parameters on the local response of the bracing system and to adjust the design so that potential buckling of the elements is mitigated. The finite element predicted force-displacement curves of bracing systems that achieve the desired local behavior when subjected to a specified interstory drift are in turn translated into a SAP2000 nonlinear link element. Embedment of the link elem...
TL;DR: In this paper, the performance of reinforced concrete (RC) T-beams retrofitted in shear with prefabricated L-shaped carbon fiber-reinforced polymer (CFRP) plates is evaluated.
Abstract: This paper presents the results of an experimental investigation on reinforced concrete (RC) T-beams retrofitted in shear with prefabricated L-shaped carbon fiber–reinforced polymer (CFRP) plates. Shear strengthening of RC beams with L-shaped fiber-reinforced polymer (FRP) plates has proved effective. In this method, grooves are made throughout the beam flange to fully embed the vertical leg of the L-shaped CFRP plate perpendicular to the longitudinal axis of the RC beam and in the RC beam web surface. However, in some cases, drilling grooves in the concrete flange might not be feasible because of the presence of obstacles such as longitudinal steel in the flange of the RC beams. Therefore, the main objective of this investigation was to evaluate the performance of the RC beams strengthened in shear with externally bonded (EB) L-shaped plates as affected by the embedment length of the L-shaped FRP plates. In total, six tests were performed on 2,500-mm long T-beams. Three specimens were strengthened in shear using epoxy-bonded L-shaped CFRP plates with different embedment lengths in the RC beam flange. One specimen was shear-strengthened with fully embedded CFRP plates in the concrete beam flange. The second specimen was strengthened with partial embedment of the L-shaped CFRP plate. This specimen is representative of the case where full penetration of the CFRP plate is not feasible because of an obstacle. In this specimen, the embedment length was set to 25 mm to simulate the minimum concrete cover thickness in RC beams. The third specimen was shear-strengthened with L-shaped CFRP plates with no embedment in the concrete beam flange. In addition, the performance of the beams strengthened with L-shaped CFRP plates was compared with that of a similar specimen strengthened with EB FRP sheets without embedment. Results show that the performance of the specimens strengthened with partially and fully embedded L-shaped CFRP plates in the beam flange was superior to that of the beams strengthened with EB FRP sheets and L-shaped CFRP plates with no embedment.
27 Oct 2014
TL;DR: In this article, the authors present a list of FIGURES, TABLES, ACKOWLEDGEMENTS, and CHAPTER 7, Section 7, Chapter 7.
Abstract: ................................................................................................................................................ iii LIST OF FIGURES .................................................................................................................................... vii LIST OF TABLES ..................................................................................................................................... xix ACKOWLEDGEMENTS .......................................................................................................................... xxi CHAPTER
27 Oct 2014
TL;DR: In this article, an advanced hysteretic non-linear riser-seabed interaction model has been implemented into the seabed enabling the automatic simulation of different stiffness in the seafloor response through the touchdown zone and gradual embedment of riser.
TL;DR: In this paper, a design procedure is proposed to identify the wood and fastener capacities under possible brittle, mixed and ductile failure modes of timber connections, where the effective wood thickness is taken into account at each potential failure zone.
Journal Article•
TL;DR: In this paper, the state-of-the-art in procedures for designing and optimizing bolted or riveted joints is reviewed. Methods and data desired for the design procedure are defined and compared with what is available today.
Abstract: The paper is an attempt to review the state of the art in procedures for designing and optimizing bolted or riveted joints. Methods and data desired for the design procedure are defined and compared with what is available today. Following major steps in the design procedure may be identified: Calculation of the force distribution in the joint, which requires methods and data to account for fastener flexibility, excentricities and bending support from surrounding structure. Calculation of the fatigue quality or the fatigue life, which requires that the influence from bypass stress, load transfer and secondary bending on the fatigue performance must be known for various combinations of material qualities (of the joined members), hole qualities and fastener types. Particular attention is paid to experimental techniques and specimen types for determination of fastener flexibility and fatigue data. Some recent findings about the interplay between friction and bearing during fatigue cycling of bolted joints are reviewed. The static design of joints with shear loaded fasteners is treated very briefly.
TL;DR: In this article, an analytical model to predict strand slip within both transmission and anchorage lengths in pretensioned concrete members is presented, which is derived from an experimental research work by analysing the bond behavior and determining the transmission and anchor lengths of seven-wire prestressing steel strands in different concrete mixes.
TL;DR: In this article, a model based on coefficient adjustment is established to match the conductivity and embedment of SMA-treated proppant for fracture stabilizer treated fracture conductivity.
TL;DR: In this article, the 3D interaction between steel catenary riser and typical clay seabed through large-scale indoor tests in 1g condition is modeled through applying cyclic motion at one end of the pipe.
TL;DR: In this paper, a component-based joint model is introduced into macromodel-based finite-element analysis (macro-FEA), in which beams are modelled as fibre elements.
Abstract: The behaviour of structures subjected to progressive collapse is typically investigated by introducing column-removing scenarios. Previous experimental results show that large-deformation performances of reinforced concrete (RC) assemblages under a middle column removal scenario (MCRS) involve discontinuity due to bar slip and fracture near the joint interfaces. To consider the effects of the discontinuity on structural behaviour, a component-based joint model is introduced into macromodel-based finite-element analysis (macro-FEA), in which beams are modelled as fibre elements. The joint model consists of a series of non-linear springs, each of which represents a load transfer path from adjoining members to a joint. The calibration procedures of spring properties are illustrated systematically. In particular, a macro-bar stress–slip model is developed to consider the effects of large post-yield tensile strains and finite embedment lengths on the bar stress–slip relationship. Comparisons of simulated and o...
TL;DR: In this article, a series of direct shear tests were performed using an idealised two-dimensional test medium consisting of rhombically stacked steel rods to facilitate displacement computations for reinforced slopes using a force-equilibrium-based finite-displacement method.
Abstract: A series of direct shear tests were performed using an idealised two-dimensional test medium consisting of rhombically stacked steel rods to facilitate displacement computations for reinforced slopes using a force-equilibrium-based finite-displacement method. A series of pullout tests using extensible and stiff reinforcement with various embedment lengths (Lt) were also performed. Modelling for the non-linear behaviour of shear stress–displacement and pullout force–displacement relationships was performed using hyperbolic models. In modelling shear stress–displacement relationships for the steel rod backfill, a linear Mohr–Coulomb failure envelope was assumed for the investigated range of confining pressures. It was found that model parameters for the initial shear stiffness, namely K and n, are significantly different from those for ordinary soils because of the regular and dense packing of the steel rods, but are advantageous as a backfill material for model tests because of its consistency an...
TL;DR: In this paper, the uplift performance of a single vertical helical anchor embedded in dry sand was investigated and an empirical model was proposed to determine the effect of the embedment ratio, shaft diameter ratio and sand density against the uplifting capacity of the anchor.
TL;DR: In this article, a detailed three-dimensional finite element models of the pullout behaviour of strands in the keyway of precast concrete blocks and of the ductility behavior of floor joints subjected to uniform and line loads exerted from upper walls were developed.
TL;DR: In this article, the analytical treatment of an axisymmetric rigid punch indentation of an isotropic half-space reinforced by a buried extensible thin film is addressed.
Abstract: The analytical treatment of an axisymmetric rigid punch indentation of an isotropic half-space reinforced by a buried extensible thin film is addressed. With the aid of appropriate displacement potential functions, Hankel transforms, and some mathematical techniques, the mixed boundary value problem under consideration is reduced to a Fredholm integral equation of the second kind. The most interesting results of the problem, including the equivalent normal stiffness of the system and the contact stress distribution beneath the rigid punch, are expressed in terms of the solution of the obtained Fredholm integral equation. Some limiting cases corresponding to inextensible and extremely extensible thin films, a surface-stiffened half-space, axisymmetric surface loading, and infinite embedment are studied and the available results in the literature are used for verification purposes. Some dimensionless plots are provided to show the effects of extensibility of the membrane on the system stiffness. It is observed that neglecting the elastic behavior of thin films and utilizing the simplified inextensible assumption for their modeling can lead to unrealistic predictions. It is shown that the axisymmetric problems concerning the elastic half-spaces including surface effects can be equivalently modeled by a surface-reinforced elastic medium. Taking the surface effects into account, the problem of an isotropic half-space under the action of a surface patch load is treated by employing the present approach.
TL;DR: In this article, the authors compared the performance of large-deformation finite-element analysis with a small-strain finite element analysis to model the failure of skirted shallow foundations in uplift and compression with a range of embedment between 10 and 50% of the foundation diameter.
Abstract: Large-deformation finite-element analysis has been used to model the undrained response of skirted shallow foundations in uplift and compression. Large-deformation effects involve changes in embedment ratio and operative local soil shear strength with increasing foundation displacement—either in tension or compression. Centrifuge model testing has shown that these changes in geometry affect the mobilized bearing capacity and the kinematic mechanisms governing failure in undrained uplift and compression. Small-strain finite-element analysis cannot by definition capture the effects of changing foundation embedment ratio and variation in local soil strength with foundation displacement. In this paper, load-displacement relationships, ultimate capacities, and kinematic mechanisms governing failure from large-deformation finite-element analyses are compared with centrifuge model test results for circular skirted foundations with a range of embedment between 10 and 50% of the foundation diameter. The re...
TL;DR: In this article, the optimal internal skirt spacing for the maximum undrained capacity of subsea skirted mudmats was identified for fully-three-dimensional loading, and the number of internal skirts required to ensure soil plug rigidity under 3D loading was presented as a function of skirt embedment ratio, soil heterogeneity index and vertical load mobilisation.
TL;DR: In this article, a physical model test was conducted using the large shaking table at E-defense to investigate the factors influencing stress distributions of piles during earthquakes, and the results showed that when the natural period of a superstructure was shorter than or close to that of the ground, the inertial force of the superstructure mainly controlled pile stresses, in which both shear force and bending moment tended to be the largest in the leading pile.
01 Jan 2014
TL;DR: In this paper, a design model is proposed for the calculation of the load-carrying capacity and stiffness of screws with different shank to grain angles subjected to loads perpendicular to the grain by accounting for the effective embedment of the screw in the timber.
Abstract: In order to benefit from the advantages of fully threaded self-tapping screws as reinforcing elements, it is essential to have detailed knowledge about the strength and stiffness of screws with different shank to grain angles subjected to combined axial and lateral loading. In this paper a design model is proposed for the calculation of the load-carrying capacity and stiffness of screws with different shank to grain angles subjected to loads perpendicular to the grain by accounting for the effective embedment of the screw in the timber. The proposed model is based on commonly used material properties and other established design models and fits well the influence of the angle between shank and grain direction on the joint’s capacity and stiffness. However, detailed knowledge about the specific input parameters in the design approaches is necessary in order to achieve a reliable prediction of the load-carrying capacity and stiffness of the individual screw.