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This paper examines the shaft resistance mobilisation ratio as a predictor of cumulative displacement of small-scale floating and end-bearing energy pile foundations subjected to vertical compressive loads embedded in dry sandy soils. A reduced friction model pile was subjected to different mechanical loads and two long-duration, cyclic heating/recovery temperature changes. The pile, soil and container temperatures, pile strains, and vertical displacements are monitored, analysed, and discussed. The results further validate numerical analyses that propose the shaft resistance mobilisation ratio as a variable to identify thresholds above which permanent cyclic thermo-induced deformations may occur. Overall, the experimentally observed responses indicate incremental deformations as the shaft resistance mobilisation ratio increased. The results also suggest that a mobilisation ratio of 66% could be a potential conservative lower-bound limit that could control the increment of thermal-induced vertical displacements in the long term under free pile head conditions. This suggests that a performance-based design would be a reasonable approach for energy piles, and monitoring programs should be set in the field before loading and thermo-activation. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights • Mechanical behavior of bolted glulam beam-column connections subjected to combined loading was studied. • Various shear-to-bending ratios were considered in monotonic connection tests. • A FEM model considering elastic-plastic damage behavior of wood and wood foundation effect was established. • A quadratic/linear interaction function was proposed for the shear and moment interaction. Abstract Bolted glulam beam-column connections are often subjected to combined shear force and bending moment induced by the semi-rigid nature of such connections. This paper summarizes the results of a series of experimental and numerical studies on the mechanical behavior of such connections under various combinations of shear force and bending moment, defined by the shear-to-moment ratio λ. Monotonic loading tests, including pure bending tests (λ = 0), pure shear tests (λ = ∞), and combined shear and bending tests (λ = a limited value), were conducted. A three-dimensional finite element method based model was established, validated and used for a parametric study focusing on the influence of the shear-to-bending ratio on the combined load carrying capacity of the connections. The test results indicated that perpendicular to grain tensile splitting and parallel to grain shear splitting are the two major failure modes. The moment resistance decreased with the increase of the shear-to-bending ratio by up to 31.6% of the pure moment resistance, and the shear resistance decreased with the decrease of the shear-to-bending ratio by up to 46.1% of the pure shear resistance, implying a strong interaction between the shear force and the bending moment. Eventually, a quadratic interaction function was proposed for connections with the shear-to-moment ratio less than 1.53, otherwise a linear interaction function was proposed. [ABSTRACT FROM AUTHOR]

Increasing the bearing capacity in the soils could be rational and economical solution for the shallow foundations in the geotechnical design. When the soil is loose and incapable of carrying loads from foundation, soil improvement appears to be essential. For this reason, the usage of geogrids for reinforcement of foundation soils is one of the principal ways in soil improvement, which is used horizontally as the reinforcement to increase the soil strength. In this research, a geotextile layer with wraparound ends is accomplished on the granular soils because of increasing the load capacity. For this purpose, a modified form of the geogrid alongside the installation method was explored. In addition, PLAXIS (2D) finite element analysis software was employed to model and analyze the new design of the reinforcement. The acquired results demonstrated that the new geometrical form could improve the soil to a greater extent and reduced the settlements, compared to the horizontal reinforcement system. [ABSTRACT FROM AUTHOR]

The load sharing ratio (a„r) of piles is one of the most common problems in the preliminary design of piled raft foundations. A series of 3D numerical analysis are conducted so that special attentions are given to load sharing characteristics under varying conditions, such as pile configuration, pile diameter, pile length, raft thickness, and settlement level. Based on the 3D FE analysis, influencing factors on load sharing behavior of piled raft are investigated. As a result, it is shown that the load sharing ratio of piled raft decreases with increasing settlement level. The load sharing ratio is not only highly dependent on the system geometries of the foundation but also on the settlement level. Based on the results of parametric studies, the load sharing ratio is proposed as a function of the various influencing factors. In addition, the parametric analyses suggest that the load sharing ratios to minimize the differential settlement of piled raft are ranging from 15 to 48% for friction pile and from 15 to 54% for end-bearing pile. The recommendations can provide a basis for an optimum design that would be applicable to piled rafts taking into account the load sharing characteristics. [ABSTRACT FROM AUTHOR]

The stability of skirted foundations subjected to combined vertical, horizontal and moment loading is of importance to the offshore engineering. The paper reports a computer-aided study on the effects of strength anisotropy and foundation embedment depth on the combined bearing capacity of skirted foundations. The results show that when the traditional load reference point, i.e. the base center, is utilized, the shape of failure envelope for skirted foundations is strongly dependent on embedment ratio, however independent of soil strength anisotropy. To gain a unified equation to describe the shapes of failure envelopes for skirted foundations with a range of embedment ratios, the searching algorithm for the optimal load reference point is implemented. Based on the optimal load reference point, the failure envelope obtained can be approximated as an ellipse in normalized moment-horizontal load space. Then a closed-form equation is proposed, which can be used to evaluate the bearing capacity of skirted foundations in soft clay considering strength anisotropy effect. [ABSTRACT FROM AUTHOR]

A steel ruler supported by a flexible foam foundation, modelled as an Euler–Bernoulli beam on a Winkler foundation, exhibits receding contact when subjected to a point load. The system is analysed using simple beam theory and Laplace transformation – both of which are typically covered in the first two years of a UK Mechanical Engineering undergraduate programme. The design of a simple experiment is described. [ABSTRACT FROM AUTHOR]

Full-scale load tests are usually conducted to obtain the reliable soil resistance at the site and to determine that the foundation is capable of sustaining working loads with sufficient safety. The aim of this study is to evaluate the interaction between test pile or barrette and the reaction system using the finite element code Plaxis 3D. The results show that the interaction between the test pile and reaction piles is more important than that between the test barrette and reaction barrettes. In addition, the results indicated that the interaction phenomenon depends on the pile slenderness and on the spacing between the test pile or barrette and the reaction system. [ABSTRACT FROM AUTHOR]

Summary: The load‐sharing ratio of the prebored and precast pile in top‐down method foundation was investigated by using a numerical analysis and field case study. The emphasis was on quantifying the apparent load‐sharing ratio of the prebored and precast pile during the top‐down method construction process. A series of three‐dimensional finite element analysis were conducted, with special attention given to the pile load‐sharing ratio under various conditions, such as soil condition, pile geometry, pile length, and structure load. In addition, the load‐sharing ratio of a single pile was also investigated based on the location of the pile in the raft (footing). The analysis model was validated by comparing the analysis model with the field data of an actual construction site using the prebored and precast pile and the top‐down method. On the basis of the series of analysis results and the field measurements, when the soil condition is better than weathered rock and for moderate pile length, at least 15% of the total structure load was supported by the pile throughout the construction process. Furthermore, it was shown that the pile near the center of the raft carried more structure load compared with the piles in the side and the corner of the raft. [ABSTRACT FROM AUTHOR]

The complex soil-structure interaction factors to estimate load bearing capacity of a combined pile-raft foundation (CPRF) is scarce. A new prediction method is proposed to estimate both Ultimate Limit State (ULS) and Serviceability Limit State (SLS) bearing capacity of CPRF by evaluating the pile-raft and raft-pile interaction factors. The developed model is validated with available experimental results. The simplified expressions for the evaluation of load-sharing ratio and a mobilized factor of safety of CPRF considering the serviceability requirement of the structure are also proposed. It provides a simple design solution for CPRF subjected to vertical loading condition. [ABSTRACT FROM AUTHOR]

The mesh-free method is a numerical technique that typically uses higher-order approximate functions. The mesh-free method exhibits higher accuracy for problems of large deformation compared to the traditional finite element method. In this paper, a computational model was undertaken using a mesh-free technique called the natural element method. Furthermore, the disturbed state concept was used to evaluate the response of piles, including their softening behaviour under axial uplift loading. The results of two field tests were considered to justify the accuracy of the proposed method. The results showed a strong correlation between the proposed numerical method and field tests. [ABSTRACT FROM AUTHOR]

A method is developed for calculating the settlement of single double-bladed metallic screw piles in clayey soils for the foundations of temporary buildings. The method is based on the use of a patented design of a screw double-bladed pile and takes account of the nonlinear load dependence of its settlement. It is established that for clayey soils with semi-solid consistency the discrepancy obtained between the experimental final settlements of double-bladed screw piles and the computational data obtained by the proposed method does not exceed 20-30%. [ABSTRACT FROM AUTHOR]

Circular foundations are widely employed in offshore engineering to support facilities and are generally subjected to fully three-dimensional loading due to the harsh offshore environmental load and complex operational loads. The undrained capacity of surface circular foundations on soil with varying strength profiles and under fully three-dimensional loading is investigated and presented in the form of failure envelopes that obtained from finite element analyses. The combined ultimate limit state of circular foundations is defined as the two-dimensional failure envelopes in resultant H-M loading space accounting for the vertical load and torsion mobilisation. The effects of vertical load and torsion mobilisation, soil shear strength heterogeneity and loading angle from moment to horizontal load on the shape of normalised H-M failure envelopes are explored. A series of expressions are proposed to describe the shape of failure envelopes obtained numerically, enabling essentially instantaneous generation of failure envelopes and optimisation of a circular foundation design based on constraint of any input variable through implementation in an automated calculation tool. An example application is ultimately provided to illustrate how the proposed expressions may be used in practice. [ABSTRACT FROM AUTHOR]

Model pile load testing is effective to study the load-settlement behaviour of pile foundations given the controlled environment in which the testing is done. This paper reports a testing program in a large calibration chamber involving individual piles and pile groups installed in sand samples of three different densities. Tests on both nondisplacement and driven piles are evaluated to assess the influence of the pile installation process on pile load-settlement response. A method is proposed to predict the load-settlement response of a pile group based on the response of a single pile. The method is shown to produce estimates that are in good agreement with measurements. The influence of pile group configuration, pile spacing, soil density and method of pile installation is discussed. [ABSTRACT FROM PUBLISHER]

A series of 1 g model tests was conducted to investigate the accumulated vertical pullout displacement and unloading stiffness of bucket foundations embedded in dry and saturated sands. The foundations were subjected to vertical pullout cyclic loading with different load amplitudes. Cyclic load was applied up to 10 4 cycles. Test results showed that the accumulated vertical pullout displacement increased with the increase in the number of load cycles and cyclic load amplitudes. The unloading stiffness of the bucket foundations decreased with the increase in load amplitude and number of cycles. Empirical equations were proposed based on the test results to evaluate the accumulated vertical pullout displacement and unloading stiffness of the bucket foundations in saturated sand. These equations can be used for the preliminary design of single or tripod bucket foundations. [ABSTRACT FROM AUTHOR]

In this study, the uplift load-carrying capacity of micropiles was investigated, focusing on the effect of various installation conditions including installation angle (θ), spacing (S), and group configuration. For this purpose, a series of uplift model load tests was conducted using single micropiles (SMP) and group micropiles (GMP). The uplift load capacity of both SMP and GMP increased with θ up to 30° but decreased for a higher installation angle of θ = 45°. Micropile spacing had less effect on the uplift load capacity for GMP. The uplift loadcarrying mechanism of inclined micropiles is proposed based on decomposed axial and lateral loads and resistance components. Based on the proposed load-carrying mechanism, axial and lateral load capacity ratios were proposed and adopted to formulate the uplift load-capacity equation for inclined micropiles. For GMP, the group-effect factor was proposed based on the reduction effect of group micropiles on the overall uplift load capacity. Full-scale uplift load tests were conducted to check the validity of the proposed method. Both SMP and GMP were constructed and tested. It was observed that the estimated results using the proposed method were in good agreement with the measured results. [ABSTRACT FROM AUTHOR]

The results presented in this paper systematically quantify shape effects on undrained capacity of rectangular mudmat foundations under multi-directional loading for a practical range of soil shear strength heterogeneity. Mudmat foundations are extensively deployed to support infrastructure for subsea production systems, are typically rectangular in plan, ranging from square to a width-to-length aspect ratio of 0.2, and are subject to multi-directional loading from the attached pipelines and jumpers. The load-carrying capacity of rectangular mudmats on deposits with undrained shear strength linearly increasing with depth is analysed by the finite-element method, and presented in the form of ‘failure envelopes’. The results show that shape effects are significant and are dependent on the degree of soil strength heterogeneity and loading direction (relative to the orthogonal axes of the mudmat). General algebraic expressions are established that systematically define the coupled effects of width-to-length aspect ratio of the mudmats and the degree of strength heterogeneity of the subsoil. Expressions describing the uniaxial ultimate limit states and the normalised failure envelopes under multi-directional loading can be programmed into a calculation tool for automating optimised mudmat sizing for a range of foundation geometry and soil strength heterogeneity. [ABSTRACT FROM AUTHOR]

Model testing for soft soil foundations with and without a prefabricated vertical drain (PVD) was performed to assess the consolidation and long-term performance of PVDs. Surface settlements and excess pore-water pressures at different depths were monitored throughout the applied multistage loading. Classical methods with improved solutions that considered variations in the discharge capacity and non-Darcian flow were applied via a back-analysis of the consolidation results. Parameters related to the smear effect and well resistance were discussed in these solutions. It was found that the foundation improved with PVD had an approximately 20% increase in the total degree of consolidation compared with untreated soft soil foundations; the well resistance of the PVD system not only existed but it also changed over time; the average discharge capacity in the model test under multistage loading condition was far less than the reported value; and the advanced solutions, especially the solution that considered the varied discharge capacity (with qw0 = 3 cm³/s and Aw = 4.12 × 10-6 1/s), gained a better fitting result than the classical solution. [ABSTRACT FROM AUTHOR]

The article deals with the problem of extrusion of weak layer out of foundation base of finite width using analytical and numerical methods. It contains formulae to define the initial critical load on the foundation base, as well as the formulae to define the rates of the weak layer extrusion and foundation settlement. Design models for the soft ground are viscoplastic models with the undamped and damped rate according to the law of the hyperbolic sine and tangent, as well as S.P. Timoshenko elastoplastic model. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A piled raft is a composed foundation in which the raft is in contact with soil. The applied vertical load is transferred from the raft to the soil and to the pile heads. The load sharing between the piles and the soil is a function of the complex interaction among the raft, the soil and the pile. Considering the complexity of the problem, the best way to investigate about this interaction is to perform physical model tests at field scale. Vertical load tests on different types of foundations (single pile, unpiled raft, pile group with a free-standing cap and a piled raft composed by 5 piles) in pyroclastic soil have been performed. The raft settlement and the axial load distribution along the pile shaft were monitored during all the tests. [ABSTRACT FROM AUTHOR]

The combined pile-raft foundation (CPRF) has been widely recognized as economic and rational foundation for high-rise buildings when subjected to vertical loading because of its effectiveness in load sharing by both raft and pile components. This results in smaller total and differential settlements with a reduced number of piles as compared with group piles. Until recently, the behavior of CPRF when subjected to lateral and real earthquake loading conditions in addition to vertical loads has not been well understood as a result of the complexities involved in the interaction of the pile, soil, and raft under such loading considerations. In the present study, an attempt has been made to investigate the behavior of CPRF with the use of centrifuge testing and a numerical model under pseudostatic and dynamic loading conditions carried out with finite-element software. After successful validation of the present CPRF model with both centrifuge and numerical model results, the same model was used for further study under El-Centro 1979, Loma Prieta 1989, Bhuj 2001 and Sikkim 2011 real earthquake pseudostatic loading and real acceleration-time history. The maximum displacement and bending moment were observed at the pile head, which is attributable to the rigid fixity of the piles with the raft. The crossover point in the bending moment profile was observed at shallow depths for all cases of loading. The occurrence of the resonance condition that yielded maximum horizontal displacement of the CPRF as a result of one of the input motions is also highlighted in the present study. The difference in the response of soil just below the raft of the CPRF and at the far field indicated that near-field and far-field ground motions were not in tandem. A case study on an existing CPRF of Messeturm Tower, Frankfurt am Main, Germany, is also presented. The existing CPRF of Messeturm Tower was modeled and analyzed under static and pseudostatic loading conditions. Obtained results show good correlation with the static field-measured results. Results in terms of bending moment in piles, total settlements, and normalized lateral displacement (u/D) are reported. The present findings are useful because they provide broader understanding of the response of the CPRF under pseudostatic and dynamic loading conditions. [ABSTRACT FROM AUTHOR]

A finite-element model combining the frequency domain thin-layer method with paraxial boundary conditions to simulate the semi-infinite extent of a soil medium is presented in this paper. The combined numerical model is used to deal with harmonic vibrations of surface rigid foundations on non-horizontal soil profiles. The model can deal with soil media over rigid bedrock or significant depths of half-space. Structured finite elements are used to mesh simple geometry soil domains, whereas unstructured triangular mesh grids are employed to deal with complex geometry problems. Dynamic responses of homogeneous as well as layered soil profiles are simulated and validated against analytical and approximate solutions. Finally, the model is used to deal with surface ground vibration reduction, in which it is first validated against published results and then followed by an example involving a bridge. [ABSTRACT FROM AUTHOR]

In this study, the load carrying behavior of piled rafts embedded in sand were investigated using the 3-D finite element analysis. Focus was given on piled rafts installed with driven piles. Various foundation and soil conditions were considered in the analyses. To simulate driven piles, the soil influence zone around driven pile was set where the relative density and lateral stress were increased to reflect the changes in soil condition and stress state due to pile driving. For both bored- and driven-pile cases, the values of load sharing ratio showed non-linear variation with settlement. The load sharing ratios for driven piles were higher than for bored piles within a certain settlement range. With further increasing settlement, however, the values of load sharing ratio for driven piles became similar to those of bored piles with limited variation. This indicates that load-sharing model can be applied for both cases to estimate the load capacity of piled rafts. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of recycled materials and sustainability are two factors taken into consideration during the design of environmentally conscious buildings, but structural performance is still the foundation of sound design. Modern day building designs many times incorporate performance-based methodologies to combat the effects of extreme loadings. The key of such designs is to absorb high amounts of energy and sustain loadings under excessive deflections. Fiber-reinforced concrete and concrete containing rubber particles have increased levels of toughness in comparison with conventional concrete. This paper presents the results of an experimental investigation focused on the material properties of fiber-reinforced rubber concrete. Rubber particles were used at various concentrations to partially replace coarse and fine aggregates coupled with the addition of fiber reinforcement. The investigation includes an evaluation of standard fresh and hardened concrete properties. Results show fiber reinforcement counteracts the negative effects of using rubber particles to replace traditional aggregates, confirming the feasibility of combing the two constituents. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Precise assessment of cyclic plastic deformation of rail track subgrade is essential in designing cost effective rail tracks. Plastic deformation of rail tracks is often underestimated due to the omission of effects of principal stress axis rotation and water content on subgrade deformation. Moisture content of rail track subgrade is influenced by infiltration, seasonal ground water table variation and climate changes. To understand the influence of principal stress axis rotation and moisture content on the plastic deformation of soil, a series of cyclic moving wheel loading tests and cyclic triaxial compression tests were performed on unsaturated Toyoura sand, using a modified multi-ring shear apparatus. Results show that the presence of water in sand affects the cyclic plastic deformation of subgrade of rail tracks, significantly. The subgrade water content variation combined with the principal stress axis rotation further increases the accumulation of the cyclic plastic deformation of subgrade under moving wheel loads. Experimental results further conclude that the conventional experimental methods are unable to accurately assess the rail track deterioration process introduced by water content of rail track subgrade under repeated moving wheel load and highlight the requirements of realistic test methods such as the cyclic moving load multi-ring shear test, the cyclic hollow cylindrical test, or the model test in predicting rail track deterioration process of unsaturated subgrade under moving wheel loads. [ABSTRACT FROM AUTHOR]

Batter pile (or inclined pile) foundations are widely used in civil engineering structures. However, their behavior under dynamic loadings is not yet thoroughly understood. This paper presents an experimental work on the behavior of batter and vertical piles considering dynamic soil-pile-superstructure interactions. A series of dynamic centrifuge tests were performed using sinusoidal excitations. The influence of the base shaking (frequency content and amplitude) and of the height of the center of gravity of the superstructure is investigated. Seismic responses are analyzed considering the pile cap displacements and forces (total base shear, overturning and residual moments, axial forces). It is found that in certain cases batter piles play a beneficial role on the dynamic behavior of the pile foundation system. This novel experimental work provides an important database on the behavior of batter pile foundations under dynamic loadings. [ABSTRACT FROM AUTHOR]

Geosynthetic-reinforced soil (GRS) walls have been increasingly used to support bridge foundations as abutment walls. On the GRS abutment wall, large footing loads are applied adjacent to the wall facing. However, so far limited studies have been conducted to investigate the performance of GRS abutment walls subjected to static or dynamic loading. This study presents a series of model tests on the GRS walls to evaluate the effects of several influence factors, including the offset distance of a strip footing, the width of the strip footing, the length of geogrid reinforcement, and the connection mode between geogrid and facing, on the ultimate bearing capacities of the strip footings on the GRS walls. The settlements of the loading plate and the lateral displacements of the wall facing during loading were monitored. Thin colored sand layers were placed in the backfill sand to observe possible failure surfaces developing in the GRS walls. The experimental results showed that the footings on the GRS walls with 0.7H (H is the wall height) long reinforcement reached the maximum bearing capacities at the offset distances of 0.3 H and 0.4 H in the wall tests with mechanical and frictional connections, respectively. When the GRS walls had the geogrids with longer reinforcement length (2H), the ultimate bearing capacity increased with the offset distance of the footing and became constant when the offset was greater than 0.4H. It was observed that the failure surface started from the edge of the footing and exited from the facing of the wall. Based on the limit equilibrium analyses, under the footing loading, the slip surfaces by Spencer's two-part wedge method had a good agreement with those observed in the model tests. [ABSTRACT FROM AUTHOR]

A procedure for carrying out and examining the results of experimental studies on reinforced concrete foundations under a superstructure over the entire load interval, up to failure. Conclusions are drawn regarding the comparability of results from experimental studies of punching shear failure in reinforced concrete foundation models at design loads obtained using theory-of-reliability methods. [ABSTRACT FROM AUTHOR]

Recent years, there are many construction projects constructed on soft soil. Due to the characteristics of soft soil, the structures built on it are subject to differential settlements. Raft foundation is one of the methods for reducing the differential settlement. Although it has an adequate bearing capacity, it may cause excessive settlement. Piles can be used with a raft foundation as a piled raft foundation system. The addition of piles is to reduce the settlements to an acceptable amount. The aim of this study is to analyze the settlements of the raft foundation and by adding piles, as the pile raft foundation, under the same loading. The numerical analysis has been done by finite element method using PLAXIS 2D with considering the various number of piles. As the results, the addition of piles could reduce the settlement, but after reach a certain number of piles, increasing the number of piles showed the settlement tends to be constant. For an economic design, it is necessary to consider the optimum number of piles in piled raft foundation system based on the allowable settlements. [ABSTRACT FROM AUTHOR]

Centrifuge tests investigating the effect of compressive preloading and consolidation on the subsequent uplift capacity of shallow skirted foundations that rest on lightly over-consolidated kaolin clay are reported. The uplift resistance, total and pore pressures at the foundation invert were monitored during the installation, consolidation and uplift. The results show that uplift performed immediately after the preloading generates a lower capacity due to the remoulding of the clay and reduction in soil strengths that result from the application of preloading. The soil strength can be recovered and eventually enhanced by the subsequent consolidation process. A theoretical framework, where the variation of the soil operative strength with preloading and consolidation is interpreted using the critical state concept, is proposed to explain and justify the experimental observations. The framework is validated through retrospective prediction of the uplift resistance of the centrifuge model tests with good agreement for a wide range of levels of preloading and degrees of consolidation demonstrated. [ABSTRACT FROM AUTHOR]

The prime objective of this study is to look at the bearing capacity of a thin-walled spread foundation system in cohesionless soils. In this regard, laboratory-footing load tests were on the aforementioned footing in loose and dense sands. The Johor Bahru sand used is this study was dried and characterised in the laboratory. To investigate the beneficial effect of the thin walls on the bearing capacity of the footing, laboratory footing load tests were also conducted on a simple surface footing and the results were compared. For verification purposes, the experimentally obtained bearing capacities of thin-walled foundation were checked against finite-element analyses. The experimental findings show an enhancement of the bearing capacity by a factor of almost 2 when the thin-walled footing is used instead of a simple footing. The bearing capacities of the thin-walled footing in loose and dense sands predicted using finite-element analyses were different to the laboratory observations by 10%. [ABSTRACT FROM AUTHOR]

A model for one-dimensional non-linear consolidation of a soft foundation with an upper crust with depth-dependent additional stress was presented in this paper. The semi-analytical solution of this model with the boundary condition of the pervious top was derived, which was proved by comparing with the classical solution of a one-layered foundation under an instantaneous loading. Then, the effects of the depth-dependent additional stress on the consolidation of the double-layered foundation were revealed. The results show that the depth-dependent additional stress inside foundation has a great influence on the consolidation rate at the former stage and final settlement of the double-layered foundation. If the change of the additional stress along the depth is neglected, an underestimated consolidation rate and overestimated final settlement will be obtained. [ABSTRACT FROM AUTHOR]

A model for one-dimensional consolidation of a double-layered foundation considering the depth-dependent initial excess pore pressure and additional stress and time-dependent loading under different drainage conditions was presented in this study and its general analytical solution was deduced. The consolidation solutions of several special cases of single-drained and double-drained conditions under an instantaneous loading and a single-level uniform loading were derived. Then, the average degree of consolidation of the double-layered foundation defined by settlement was gained and verified. Finally, the effects of the initial excess pore pressure distributions, depth-dependent additional stress, and loading modes on the consolidation of the soft foundation with an upper crust with different drainage conditions were revealed. The results show that the distributions of initial excess pore pressure and additional stress with depth and loading rates have a significant influence on the consolidation process of the soft foundation with an upper crust. This influence is larger with the single-drained condition than that with the double-drained condition. Comparing the consolidation rate with a uniform initial pore pressure and additional stress, their decreasing distribution with depth quickens the consolidation at the former and middle stages. Moreover, the larger the loading rate is, the quicker the consolidation of the soft foundation with an upper crust is. [ABSTRACT FROM AUTHOR]

Fluctuations in axial load imposed on a rocking footing will affect its moment capacity, the shape of its moment-rotation hysteresis, and potentially the system's seismic performance. Structural asymmetry increases the likelihood of axial load variation during earthquake excitations. To investigate this issue, a unique centrifuge testing program was carried out on low-rise frame-wall-rocking foundation systems. In this paper, the seismic behaviors of asymmetric and symmetric models from this test program are systematically compared. Experimental results reveal that placing the lateral force resisting shear wall outboard produces significant axial load fluctuation, which in turn greatly deteriorate the lateral load-carrying capacity of a foundation rocking dominated frame-wall system, particularly in its weak direction. However, it strengthens the system when loading is towards the shear wall, leading to a highly asymmetric hysteretic response. During earthquake loading, all asymmetric rocking foundation systems observe smaller peak roof accelerations, but larger peak and permanent roof drifts compared with the symmetric systems. Despite these differences in response, the axial load fluctuation and structural asymmetry do not significantly change the relative energy dissipated by the rocking foundations and inelastic structural components within each framewall-rocking foundation model. [ABSTRACT FROM AUTHOR]

In the present study the accuracy of an efficient beam formulation for inelastic analysis of pile-foundation systems is validated against a series of Laboratory Pushover tests on vertical single piles embedded in dry sand under different load paths to failure in M – Q space conducted in the Laboratory of Soil Mechanics/Dynamics (LSMD) in NTUA. The obtained results are also compared to those from a fully 3D Nonlinear Finite Element (FE) simulation. The proposed beam formulation is based on the Boundary Element Method (BEM) accounting for shear deformation effect. A displacement based procedure is employed and inelastic redistribution is modeled through a distributed plasticity (fiber) model exploiting pile material constitutive laws and numerical integration over the cross-sections, while the surrounding soil is modeled through independent inelastic Winkler springs. The efficiency of the beam formulation is verified through the good agreement between the measured and the calculated results. [ABSTRACT FROM AUTHOR]

The results of investigations of the thermal energy obtained from different types of energy-efficient foundations under the conditions in Permskii Krai are presented. The general principles for designing energy-efficient foundations are described. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wu, K. and Fan, Q., 2015. Study on bearing capacity of bucket foundation subjected to horizontal loading. The bucket foundation is one parts of offshore platform and is wearing the wave or wind loading which causes the bucket foundation instability to offshore platform falling. So, the numerical simulation, limit analysis and model test are investigated and compared in order to reveal the bearing capacity of bucket foundation under horizontal loading. Based on the three analysis methods compared, it can be observed that: (1) the results of the three methods are in good agreement. (2) The bucket foundation subjected to horizontal loading is rotation and the center of rotation is located in the two-thirds of embedded depth. Under horizontal load, the coherent spoon plastic zone is formed in the bottom of bucket foundation. And, the wedge plastic zone is formed on both sides of the bucket foundation. While, in the same direction with horizontal load of the barrel side is passive area and larger earth pressure is being because of barreling into foundation soil. On the other side of the foundation is active area, which the foundation is separation with soil. [ABSTRACT FROM AUTHOR]

Wu, K.; Fan, Q., and Zheng, J., 2015. Effect of strength anisotropy on failure envelope of offshore shallow foundations under combined loading. The bearing capacity of offshore shallow foundations subjected to combined vertical, horizontal and moment loading is of interest particularly to the offshore geotechnical engineers. This paper reports a finite element (FE) study on the effects of strength anisotropy and foundation embedment depth on the combined bearing capacity. The Tresca failure criterion modified to allow for soil strength anisotropy and coupled with an elasto-perfectly plastic stress-strain relationship is assumed in the analysis which is conducted using the FE software ABAQUS. The undrained bearing capacities of shallow strip foundations under uniaxial vertical ( V), moment ( M) and horizontal ( H) loadings are predicted and compared with available solutions. The V- M- H capacity of embedded foundations under combined loading is represented by failure envelopes in H-M space for various vertical loading levels. The results presented in this paper show that the embedment ratio significantly affects the shape of the failure envelope expressed in terms of loads normalized by the pure moment or pure horizontal load-carrying capacity of the foundation. However, the shape of failure envelope defining the undrained capacity of shallow foundations under horizontal and moment loads is independent of soil strength anisotropy. [ABSTRACT FROM AUTHOR]

The undrained bearing capacity of a group of three rigidly connected skirted foundations (tripod) under vertical, moment or combined vertical-moment loading is investigated. Three-dimensional displacement finite element analyses of a single footing are first presented in order to validate the numerical modelling procedure. Various loading paths are considered and comparisons with known solutions are made. Subsequently, a series of analyses of undrained loading on a three-footing group is presented. Different footing spacings and loading directions are considered. The predominant failure mechanisms for characteristic load combinations are determined and the calculated failure loads are presented in dimensionless and normalized form. Based on the numerical results, a unique normalized failure load surface is proposed which applies to all loading directions and footing spacings for a given skirt length to footing diameter ratio. Undränierte Grenztragfähigkeit von Tripod-Gründungen mit Schürze unter außermittiger Belastung. Die undränierte Grenztragfähigkeit einer Gruppe von drei starr miteinander verbundenen Gründungselementen (Tripods) unter Vertikallast, Momentenbelastung oder unter einer kombinierten Vertikal- und Momentenbelastung wird untersucht. Zunächst werden dreidimensionale Finite-Elemente-Berechnungen von einem einzelnen Gründungskörper präsentiert, um die numerische Modellierung zu validieren. Unterschiedliche Belastungspfade werden untersucht und mit bekannten Lösungen verglichen. Anschließend wird eine Reihe von undränierten Analysen mit allen drei Gründungskörpern eines Tripods vorgestellt. Variiert werden die Fundamentabstände und die Lastrichtung. Die vorherrschenden Versagensmechanismen werden für charakteristische Lastkombinationen bestimmt und die berechneten Grenztraglasten in dimensionsloser und normierter Form dargestellt. Basierend auf den numerischen Ergebnissen wird eine einzige normierte Grenzzustandskurve vorgeschlagen, welche auf alle Lastrichtungen und Fundamentabstände für ein gegebenes Verhältnis von Schürzenlänge zu Durchmesser der Gründungskörper anwendbar ist. [ABSTRACT FROM AUTHOR]

With the existence of aging highway bridges within the U.S. transportation network, federal and local agencies typically encounter a wide assortment of maintenance issues ranging from cracking, spalls, delaminations, and corrosion to high load hits and fire damage. This paper presents an approach for capturing the full system-based behavior and stages of failure in the composite bridge superstructures as they approach ultimate capacity. This step is instrumental to understanding how redundant bridges behave in the presence of coupled and uncoupled damage and deteriorations. The investigation included a comprehensive nonlinear finite-element analysis of two representative intact composite steel girder bridges that were tested to failure and provided sufficient details for model validation. Results demonstrate the high degree of additional reserve capacity, inherent to redundant superstructures, over the theoretical nominal design capacity. A rational approach was established to describe the actual system-based ultimate capacity, which was not explicitly considered in the current design methodology. In addition, a limited sensitivity study was performed on one of the selected representative bridges to investigate the sensitivity of the characterized failure stages to variations in the geometrical parameters and material properties of the bridge system. [ABSTRACT FROM AUTHOR]