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The aspiration to act in a more sustainable manner has become a guiding principle across many aspects of life. Yet sustainability is still often perceived as poorly defined, and there are diverse opinions on what the implications of sustainability for the everyday practice of geotechnical engineers are. Against this background, this paper presents a survey conducted at the Norwegian Geotechnical Institute at the beginning of 2021 that engaged a group of geotechnical engineers with the fundamental question as to how the concept of sustainability relates to geotechnical engineering. The Q methodology, a mixed-method approach, was applied to analyse different perspectives on sustainability in geotechnical engineering as inferred from the survey results. Three distinct perspectives were revealed that have a focus on (a) striving a balance between human action and nature, (b) mitigating the adverse impacts of geotechnical projects and (c) reducing resource use. Two of the perspectives considered the development of sustainability assessment tools as the most relevant means of working towards sustainable geotechnical practices, while the third perspective considered multidisciplinary collaboration and research as more important. Reflection on these perspectives can help the development of future tools and strategies, provide a direction for future research and contribute to a more sustainable geotechnical engineering practice. [ABSTRACT FROM AUTHOR]

(4) and (5) along with the differential equations of I SB z sb i and I SB x sb i as follows: (7) HT ht (8) HT ht where the parameters I i SB 1 sb - I i SB 4 sb describe the rates of the variations of I u SB sz sb i and I u SB sx sb i with depth. [Extracted from the article]

A method for the estimation of the non-linear, time-dependent settlement of piled raft foundations (PRFs) embedded in saturated clayey soils subjected to uniformly distributed load under the single-drainage condition was developed. A total of 20 different rectangular PRFs resting on four different types of normally consolidated to moderately overconsolidated clays (overconsolidation ratios of 1, 2 and 5) were analysed to quantify their short- and long-term settlements. Rigorous three-dimensional, elasto-plastic finite-element (FE) analyses were performed with the critical-state-based modified Cam Clay soil constitutive model. Biot's coupled consolidation theory was used to model the time-dependent dissipation of excess pore pressure under the single-drainage condition. The FE analysis results were used to investigate systematically the influence of time and various soil and PRF parameters on the settlement responses of piled rafts. Fitted equations correlating PRF settlements and the degree of consolidation with various influencing parameters were developed. The proposed equations predicted the immediate and primary consolidation settlements and the degree of consolidation with reasonable accuracy and can be used in initial design stages. [ABSTRACT FROM AUTHOR]

The paper presents a framework for analysis of beams interacting with nonlinear‐poroelastic, layered continuums (e.g., clayey soils) when subjected to time‐dependent loads. The poroelastic layered continuum is characterized by a nonlinear‐elastic constitutive relationship that relates the secant shear modulus to the induced shear strain. The Biot's theory of consolidation is combined with a dynamic beam‐continuum interaction model to develop the analysis. The vertical consolidation settlement of the beam and the excess pore pressure in the porous continuum are assumed to be products of separable functions, and the extended Hamilton's principle of least action is applied to obtain the differential equations governing the inertial consolidation motion of the beam‐continuum system and the dissipation of excess pore pressure. An iterative numerical algorithm is used to solve these coupled differential equations following one‐dimensional finite element analysis in which the implicit Wilson‐Θ time integration scheme is used to obtain the time history of beam and continuum responses. The novelty of the framework is that it rigorously takes into account the nonlinear poroelastic soil‐structure interaction within a dynamic time‐integration framework with minimal computational resources. The characteristics of this newly developed model are illustrated through examples. [ABSTRACT FROM AUTHOR]

Geotechnical constructions involve consumption of a vast amount of non-renewable natural resources and energy- and carbon dioxide-intensive materials (e.g. cement and steel) that contribute significantly to global warming and climate change. This paper uses drilled shafts as an example to illustrate the importance of environmental impact assessment in the design phase of foundations. Life-cycle assessment (LCA) is used to quantify the environmental impacts of construction of single drilled shafts and groups embedded in sandy soil profiles. Parametric studies are conducted to investigate the effects of soil properties, design parameters and hauling distances of construction materials and equipment on the environmental impacts of single drilled shafts. For pile groups, different configurations, applied load, centre-to-centre spacing and thickness of pile cap are considered in the parametric study. The global warming impact and human toxicity of a typical drilled shaft are found to be 39 and 486% of annual world impact per person, respectively. Based on the study, charts and tables are developed that may be used for quick estimation of the global warming impact of drilled shafts without the use of specialised LCA software programs. [ABSTRACT FROM AUTHOR]

Piled raft foundations (PRFs) below stepped high-rise towers are often subjected to nonuniform triangular-shaped loads with eccentricities. In this study, 20 rectangular piled rafts with different pile configurations and orientations, embedded in medium-dense sandy soil, are analyzed using three-dimensional nonlinear finite-element (FE) analysis in which the critical state–based Clay and Sand Model (CASM) is used as the soil constitutive model. Different triangularly distributed loads with and without eccentricities are considered in addition to uniformly distributed loads. A systematic parametric study is performed by varying the different design parameters based on which the PRF behavior is systematically investigated in terms of multiple performance parameters such as maximum settlement, differential settlement, angular distortion, tilt, and load distribution between the raft and the piles and between the individual piles. It is observed that the pile diameter, number of piles, and raft plan area control the differential settlement, angular distortion, and tilt the most. Based on the insights gained from the parametric study, a design optimization exercise is performed, in which the most optimal pile configuration is selected based on the criteria of allowable settlement and angular distortion with additional considerations for tilt, load distribution, and the volume of concrete required. [ABSTRACT FROM AUTHOR]

Time-dependent response of piled raft foundations (PRFs) in saturated, normally consolidated and moderately overconsolidated clayey soils under the single-drainage condition is investigated using three-dimensional, elastoplastic finite-element (FE) analysis with the modified cam clay (MCC) soil constitutive model. Four different types of clay (Boston Blue Clay, San Francisco Bay Mud, London Clay, and Shanghai Clay) with different values of overconsolidation ratio (OCR) (OCR=1 , 2, and 5) and 20 different configurations of rectangular PRFs are considered for the study. The settlement response and load sharing of PRFs are investigated. Regression analyses are performed with the FE analysis results to obtain fitted equations for immediate settlement, primary consolidation settlement, and degree of consolidation of PRFs. These equations are applicable to PRFs with cast in situ bored piles similar in size to those considered in this study. The proposed equations can be used to estimate time-dependent PRF settlement in normally consolidated and moderately overconsolidated clay as part of preliminary design calculations. [ABSTRACT FROM AUTHOR]

A computationally efficient semianalytical framework for obtaining the consolidation settlement of flexible foundations such as beams and strip footings resting on nonlinear, saturated, poroelastic, and multilayered continua (soil) is developed. Two-dimensional (2D) plane strain is assumed, and Biot's consolidation theory is used in the analysis. The differential equations governing the displacements and excess pore pressure dissipation of the beam-soil system are developed using the variational principles of mechanics in which the soil is modeled as a simplified continuum and the foundation is modeled as an Euler-Bernoulli beam. The developed differential equations are coupled and are solved following a unique iterative algorithm using one-dimensional (1D) finite-element analysis. The numerical solution is less expensive than conventional 2D numerical methods. A distinct feature of the developed framework is that the effect of soil stress-strain nonlinearity is considered in the calculation of the consolidation settlement, which is usually not considered in Terzaghi's and Biot's consolidation theories. It is observed that soil nonlinearity and foundation flexibility can significantly impact the foundation settlement and consolidation rate. The developed framework provides a fast, easy-to-use, and accurate method for estimating the consolidation settlement of flexible shallow foundations. [ABSTRACT FROM AUTHOR]

• Soil porosity has a strong impact on the thermal performance of SBTES. • Seasonal variation in surface pressure has no effect on SBTES performance. • Ignoring subsurface moisture content may lead to errors in SBTES performance estimation. The thermal performance of soil borehole thermal energy storage (SBTES) systems in unsaturated soils is investigated to address three primary objectives: (1) to explore the impact of subsurface moisture content condition on the SBTES thermal performance, (2) to assess the effect of seasonal surface pressure variation on the SBTES thermal performance, and (3) to examine the influence of soil porosity on the thermal performance of SBTES in homogeneous and layered soils. Results indicate that a higher subsurface moisture content leads to a lower average temperature in the thermal storage domain. Notable hydrodynamic fluctuations are observed in the shallow depth of SBTES domain because of seasonal surface pressure variations although the average temperature and heat storage in SBTES remain mostly unaffected. The results show that a low soil porosity leads to superior SBTES thermal performance, while high porosity soils experienced more pronounced hydrodynamic fluctuations under surface pressure variation conditions. The impact of soil porosity on SBTES thermal performance is minimal in layered soil, except when one soil layer dominates and has a high volume fraction. [ABSTRACT FROM AUTHOR]

Piled raft foundations (PRFs) below stepped high rise towers are often subjected to non-uniform loads with eccentricities. In this study, twenty five cases of rectangular rafts with different pile configurations and orientations embedded in sand are analyzed using nonlinear three-dimensional finite element analysis. These PRFs are subjected to different triangularly distributed loads and uniformly distributed loads with and without eccentricities. The piled raft responses investigated are the maximum and differential settlements, angular distortion, tilt, load sharing between the raft and the piles, the load carried by the individual piles, and the subgrade modulus (spring constant) at the raft-soil and pile-soil interfaces. The PRF responses are greatly influenced by the distribution of the applied loads and the magnitudes of the load eccentricities. The study provides insights into the PRF behavior under nonuniform and eccentric loads and may help practitioners in making informed design decisions. [ABSTRACT FROM AUTHOR]

A hand-calculation method for estimation of nonlinear load–settlement response of piled raft foundations (PRFs) embedded in sandy soils is developed using three-dimensional finite-element (FE) analysis in which the elastoplastic constitutive behavior of the soil is modeled using the unified Clay And Sand Model (CASM). Three types of PRFs with rectangular, strip, and circular rafts and with a variety of pile dimensions and arrangements are considered in the study. The PRFs are assumed to be embedded in five different sands (Ottawa sand, Erksak sand, Sacramento sand, Portaway sand, and Decomposed Granite sand) with different elastic properties, critical state parameters, and relative densities. Systematic parametric studies are performed to develop equations for the estimation of the average nonlinear settlement of PRFs. The maximum and differential settlements are also estimated from the average settlement. The proposed equations require the relative density, elastic constants, and critical state friction angle of sand, and the piled raft geometry and properties as inputs. The settlement equations are applicable to PRFs of sizes similar to those considered in the study and can be used by practitioners for quick, initial estimation of PRF settlement as part of design calculations. [ABSTRACT FROM AUTHOR]

Adequate prediction of surrounding ground movement during braced excavation is critically important as excessive soil movement damages adjacent structures. The magnitudes and patterns of ground movement and wall deflection largely depend on excavation parameters like thickness of diaphragm wall, wall embedment depth, strut locations and soil parameters such as soil strength, compressibility and creep parameter. In the present paper a thorough, parametric study has been conducted using finite element (FE) analysis to address the influence of various parameters on deformation characteristics of braced excavation in soft clayey deposits. The importance of correct estimation of soil parameters for braced excavation design is also documented. The analysis of typical braced excavations in soft clay is carried out using PLAXIS 2D software where soft soil creep constitutive model is used. On the basis of numerical study a handy design guideline is recommended. Further multivariate regression models are developed incorporating various important excavation parameters for the adequate prediction of maximum wall and ground displacement along with wall and ground surface deformation profile. Here large numbers of data reported in case histories and generated artificially from FE analysis are used for formation of regression equations. The proposed model is validated comparing results from literatures not used for the development of the model. [ABSTRACT FROM AUTHOR]

A nonlinear analysis framework for laterally loaded piles is presented that is as accurate as equivalent three-dimensional nonlinear finite element analysis, but computationally one order of magnitude faster. The nonlinear behavior of sands and clays are account for by using hyperbolic modulus–reduction relationships. These nonlinear–elastic constitutive models are used to calculate the reduced modulus at different points in the soil based on the soil strains induced by lateral pile displacement. The reduced modulus at different points in the soil domain are spatially integrated to calculate the reduced soil resistance parameters associated with the differential equation governing the lateral pile displacement. The differential equations governing the lateral displacements of pile and soil under equilibrium are obtained by applying the principle of virtual work to a continuum-based pile–soil system. These coupled differential equations are solved using the one-dimensional finite difference method following an iterative algorithm. The accuracy of the analysis is verified against equivalent three-dimensional nonlinear finite element analysis, and the validity of the analysis in predicting the field response is checked by comparisons with multiple pile load test results. Parametric studies are performed to gain insights into the lateral pile response. [ABSTRACT FROM AUTHOR]

Short stubby piles like monopiles and large diameter drilled shafts undergo rigid body translation and rotation when subjected to a lateral force and/or a moment at the head. A method of analysis for these piles embedded in multi-layered elastic soil is developed using the variational principles of mechanics. Using this analysis, the soil resistance against pile movement can be rigorously related to the soil elastic constants, and the pile head displacement and rotation can be quickly calculated. The equilibrium equations for pile and soil displacements are obtained using the principle of virtual work and solved using an iterative algorithm. Pile responses obtained from the analysis match well with those obtained from three-dimensional finite element analyses in which the same inputs of loads, geometry, and material properties are given. Based on the new analysis, fitted equations for soil resistance parameters are developed, which can be used to directly calculate the pile head displacement and rotation without the use of the iterative algorithm. Numerical examples are provided that demonstrate how the method can be used to analyse practical problems. [ABSTRACT FROM AUTHOR]

A computationally efficient continuum-based model is developed for obtaining the nonlinear response of pile foundations subjected to a static horizontal force and/or moment at the pile head. In the analysis, the soil is modeled using nonlinear elastic constitutive relationships expressed as power-law or hyperbolic equations; these relationships relate the induced shear strain in soil to the secant shear modulus. The soil displacements in the horizontal plane are expressed as products of separable functions maintaining compatibility with the horizontal pile movement, and the principle of virtual work is applied to obtain the governing differential equations describing pile and soil displacements under equilibrium. These differential equations are solved using the one-dimensional finite-difference method following an iterative algorithm. The soil resistance parameters associated with the pile-displacement differential equation capture the effect of soil nonlinearity because these parameters are related to the secant shear modulus at different points in the soil. The accuracy and computational efficiency of the present analysis are established by comparing the pile and soil responses with those obtained from equivalent three-dimensional finite-element analysis which used the same soil constitutive relationships. The present analysis framework is further validated against the results of two full-scale field pile-load tests. Furthermore, monopile responses obtained from the present analysis are compared with those of three-dimensional finite-element analyses in which the soil is modeled as an elastoplastic material. It is shown that, for the purpose of design against lateral loads, elastoplastic approaches are not necessary because the present nonlinear elastic analysis can produce sufficiently accurate pile and monopile responses. [ABSTRACT FROM AUTHOR]

The traditional method for analysis and design of laterally loaded piles with non-circular cross-sections such as rectangular, H-shaped, and X-shaped piles involves the simplification of converting the non-circular pile to a circular pile with equivalent second moment of inertia. A rigorous semi-analytical method is developed for calculating the response for laterally loaded piles with arbitrary non-circular cross-sections in multi-layered elastic soil without using any simplification regarding the shape of the pile cross-section. The governing differential equations for the pile–soil system are obtained using the principle of virtual work. The soil displacements around the pile are described as products of separable functions that are compatible with horizontal pile movement. As a result, the three-dimensional (3 D) boundary value problem (BVP) is described by a fourth-order linear ordinary differential equation (ODE) governing horizontal pile displacement and second-order partial differential equations (PDEs) governing soil displacements. New solution techniques for the ODE and PDEs are proposed, and the accuracy of the present method is verified by comparing the predicted pile and soil responses with the corresponding results of equivalent 3 D finite element method. The effects of pile cross-section shape and lateral loading direction on the pile and soil responses are highlighted through a series of parametric analyses. [ABSTRACT FROM AUTHOR]

A semianalytical method is developed to obtain the dynamic response of laterally loaded piles in a multilayered soil. In the analysis, the soil is modeled as a three-dimensional viscoelastic continuum with frequency-independent hysteretic material damping and the pile as a circular elastic Timoshenko beam. Unlike the Euler-Bernoulli beam that is conventionally used to model laterally loaded piles in various analytical, semianalytical, and numerical studies, the Timoshenko beam theory accounts for the effect of shear deformation and rotatory inertia within the pile cross-section that might be important for modeling short stubby piles with solid or hollow cross-sections and piles subjected to high frequency of loading. In the analysis, the soil displacements in the horizontal direction are expressed as products of separable functions, and the extended Hamilton's principle in conjunction with the calculus of variations is used to obtain two sets of coupled differential equations governing pile and soil motions along with the relevant boundary conditions. The coupled equations are solved analytically and numerically following an iterative algorithm. The differential equation and boundary conditions governing pile motion are progressively reduced to model the pile as a Rayleigh beam and a Euler-Bernoulli beam; thus, a unified framework incorporating various beam theories for the dynamic soil-structure interaction of laterally loaded piles in a multilayered soil is developed. The accuracy of the present analysis is verified against the results of several analytical and numerical solutions available in the literature. It is shown from the solved example problems that rotatory inertia has practically no effect on the dynamic response of piles, whereas there is some effect of shear deformation on the response of piles with hollow cross-sections. [ABSTRACT FROM AUTHOR]

A new approximate analysis technique is developed to obtain the steady-state response of axially loaded pile embedded in a homogeneous, isotropic soil, and resting on a rigid base. In the analysis, the soil is modeled as an axisymmetric linear viscoelastic continuum with frequency independent hysteretic material damping and the pile is modeled as an elastic Euler rod with a circular cross-section. The soil displacement in the vertical direction is expressed as a product of separable functions, while the radial displacement is assumed to be zero for mathematical simplicity; although the effect of the radial displacement is indirectly taken into account by modifying the soil modulus. The Extended Hamilton's principle in conjunction with the calculus of variations is used to obtain the differential equations governing pile and soil displacements and the relevant boundary conditions. The pile and soil displacement equations are solved analytically following an iterative algorithm. The accuracy of the analysis is ensured by comparing the pile responses obtained from this analysis with those obtained by other methods available in the literature. A parametric study is performed to investigate the influence of the pile and soil parameters on the axial dynamic pile-head impedances. The plots developed from the parametric study can be used in the design. [ABSTRACT FROM AUTHOR]

A new method of analysis of rigid monopiles and poles based on the principle of virtual work is developed. The analysis considers three-dimensional interaction between the rigid pile and surrounding soil, and quickly produces pile response while maintaining accuracy comparable with that obtained from equivalent finite element analysis. Using this method, a systematic parametric study is performed to investigate the response of rigid piles in soil profiles where properties change either continuously or discretely with depth. Equations are developed based on the parametric study, which can be used to calculate pile head displacement and rotation. Numerical examples are provided that illustrate the use of the method. [ABSTRACT FROM AUTHOR]

A new method for calculation of head displacement and rotation of laterally loaded rigid monopiles and poles in multilayered heterogeneous elastic soil is presented. The analysis considers the soil as a layered elastic continuum in which the modulus vary linearly with depth within each layer. Rational pile and soil displacement fields are assumed, and the interaction between the pile and soil is taken into account by using the principle of virtual work. Two sets of equilibrium equations, one describing the pile displacement and rotation and the other describing the displacements in the soil, are obtained and solved analytically and numerically following an iterative algorithm. The new method produces pile responses as accurate as those obtained from three-dimensional finite element analysis but does not require any elaborate input for geometry and mesh. [ABSTRACT FROM AUTHOR]

The conventional approach in the design of laterally loaded piles with rectangular cross section involves the simplification of converting the rectangular cross section of the pile to an equivalent circular cross section. An analysis to determine the response of laterally loaded rectangular or circular piles in elastic soil is presented in which this simplification is not required. The analysis is based on the solution of differential equations governing the displacements of the pile–soil system derived using energy principles. The pile geometry and the elastic constants of the soil and pile are the input parameters to the analysis. Using this analysis, comparisons are made between the response of rectangular and circular piles in elastic soil. Based on the proposed solution scheme, a user-friendly spreadsheet program (LATPAXL) was developed that can be used to perform the analysis. In addition, simple equations obtained by regression analysis of the pile head deflection and bending moment profiles are proposed. Examples illustrate the use of the analysis. [ABSTRACT FROM PUBLISHER]

The built environment serves as a dynamic interface through which human society and the ecosystem interact and influence each other. Understanding this interdependence is a key to understanding sustainability as it applies to civil engineering. There is a growing consensus that delivering a sustainable built environment starts with incorporating sustainability thoughts at the planning and design stages of an infrastructure construction project. Geotechnical engineering can significantly influence the sustainability of infrastructure development because of its early position in the construction process. In this paper, the scope of geotechnical engineering towards sustainable development of civil infrastructure is reviewed. The philosophies and definitions of sustainability as applicable to geotechnical engineering are discussed. A comprehensive review of the research and case studies performed in geotechnical engineering, in relation to sustainable development, is presented in an effort to outline the scope and goals of sustainable geotechnical engineering. [ABSTRACT FROM AUTHOR]

We present quantum transport simulation results for InAs and In0.7Ga0.3As double-gate MOSFETs by using an atomistic full-band basis to evaluate the tunneling currents in the OFF state. While InAs has the advantage of lower mass and higher injection velocity, it also has lower bandgap. For low gate bias, the overlap in energy of the valence band in the channel with the source/drain conduction bands results in band-to-band tunneling (BTBT) between source and drain, which clamps the OFF current. Such current can be reduced by increasing the bandgap of the material either by increasing confinement or by lowering the In content, for example, using In0.7Ga0.3As. Grading the doping of the source/drain region to create a wider barrier also reduces BTBT, but to a lesser extent. [ABSTRACT FROM PUBLISHER]

The load-settlement behaviour of piled raft foundations (PRFs) resting on sand subjected to vertical uniformly distributed load is studied using three-dimensional elasto-plastic finite element (FE) analyses. The unified Clay and Sand Model (CASM), based on the critical state soil mechanics, is used as the soil constitutive model. In the present study, 38 rectangular, strip, and circular raft connected to different pile configurations resting on four different types of sands in their loose, medium, and dense states are considered. The accuracy of the finite element analysis is confirmed through verification and validation with other numerical and experimental studies. A detailed parametric study is conducted, which includes soil elastic and critical state parameters as well as different dimensions of PRFs. A guideline chart is provided, which will be helpful for a design practitioner to choose the suitable PRF configurations considering serviceability limit states of safety and economical design aspect. This flow chart is based on (i) combined effects of various parameters on PRF load settlement behaviour, (ii) load sharing between the raft and the pile groups, and (iii) a preliminary cost analysis. [ABSTRACT FROM AUTHOR]

The low-strain dynamic behavior of Leda clays is investigated using resonant column (RC) and bender element (BE) tests. Four undisturbed, lightly overconsolidated Leda clay samples, collected from two sites near the St. Lawrence River valley, are tested at different strains, confining stresses, and frequencies. To evaluate the effect of excitation frequency, simultaneous measurements of shear wave velocity using RC and BE tests are performed. The results show that the samples from the different sites behave differently. The high sensitivity of the Leda clays does not have a significant effect on the modulus degradation curves. However, the measured degradation curves are similar to those of soft clays with high plasticity, which is contrary to the expected behavior of these low plasticity (Ip = 6.2–20) specimens. Likewise, the measured damping ratios are on the lower end of the typical values reported for soils of high plasticity. Low values of damping ratio make the amplification of small seismic events more likely in Leda clay deposits. The difference in the shear wave velocity measurements from RC and BE tests ranges from 17% to 26% depending on the confinement, likely because of the strong influence of P-waves observed in the BE tests for these soils. [ABSTRACT FROM AUTHOR]

Perspectives on design of offshore wind turbine (OWT) monopile foundations are provided in this paper by logically adopting optimal analysis choices with a balance between accuracy and computational efficiency. A newly developed analysis framework is used for this purpose. The analysis framework consists of dynamic analysis with linear viscoelastic soil and static analysis with nonlinear elastic soil. The framework is used to show that the Timoshenko beam theory produces most accurate monopile response although the Euler-Bernoulli beam theory produces optimal results maintaining a balance between accuracy and computational efficiency. The rigid beam theory can be used only under very restricted soil and monopile conditions. The analysis further demonstrates that static analysis is sufficient and optimal in producing monopile-soil stiffness values that can be used for determining the natural frequency of vibration of the OWTs. Moreover, nonlinear elastic analysis is sufficiently accurate and quick to produce monopile responses that can be used in design and there is no need for elasto-plastic analysis. The aspect of cyclic degradation of soil stiffness over the design life of monopiles is not considered. Thus, an optimal pathway for monopile design is described using the newly developed analysis framework and demonstrated through a design example. • A new analysis framework for offshore wind turbine monopiles is presented. • Dynamic analysis is not required for monopile design. • Euler-Bernoulli beam theory produces optimal results for monopile analysis and design. • Elasto-plastic theories are not required for monopile design. • Design calculations using the analysis framework are demonstrated. [ABSTRACT FROM AUTHOR]

A new method for dynamic analysis of Euler-Bernoulli beams resting on multi-layered viscoelastic soil is presented. The governing differential equations for beam and soil displacements are obtained using the extended Hamilton's principle, and these equations are solved using one-dimensional finite element method and analytical solutions. An iterative solution algorithm is used in conjunction with an implicit time integration scheme to obtain beam and soil responses as functions of time. The developed model resembles the traditional two-parameter spring foundation model but the analysis shows that the traditional foundation spring parameters cannot be prescribed a priori but determined as part of the solution. The model produces accurate beam response as illustrated by comparisons with equivalent two-dimensional finite element analysis. A few problems are analyzed that illustrate the novel features of the dynamic foundation model. [ABSTRACT FROM AUTHOR]

Based on the recommended range of HT ht by Basile ([2]), HT ht and HT ht are assumed for the present calculations. The interaction factor HT ht is defined in such a way that it decreases with an increase in the raft thickness HT ht but increases with an increase in the raft Young's modulus HT ht [Figs. The induced vertical stresses in the soil reduce to 10% of the applied vertical load HT ht at a depth HT ht three to four times the width of the raft HT ht . [Extracted from the article]

The feasibility of installation and performance of vertical ground source heat pump (GSHP) systems for heating and cooling of a typical 9000 m2 office building located in ten metropolitan cities with tropical and subtropical climates are investigated. The heating and cooling loads of the identical building in the ten cities are simulated using the EnergyPlus software. For each location, the design of the GSHP system is performed using the ground loop design (GLD) software, and the performance of the GSHP system is assessed. A multi-year cost analysis is also carried out to assess the feasibility of installation of GSHP systems from an economic point of view. It is found that GSHP systems may not be economically viable for the cities in tropical climates, particularly those near the equator, because of inefficient performance and high cooling demand. Thermal imbalance in soil caused by significantly greater cooling demand than heating demand may further exacerbate the system in tropical cities. However, the implementation of GSHP may turn into a feasible option for some of the tropical cities located near the Tropic of Cancer by adopting special design techniques or including additional hybrid energy sources. GSHP systems seem to be economically feasible and operationally efficient in the cities with subtropical climates where more balance between heating and cooling loads exist. • GSHP system considered one of the most popular geothermal system for space heating-cooling. • GSHP with special design or energy sources a good option near Tropic of Cancer. • GSHP system may not be the best option in few cities near equator. • GSHP system mostly economical in subtropical cities. [ABSTRACT FROM AUTHOR]

Bender elements (BEs) are commonly used by geotechnical laboratories worldwide to measure the shear-wave velocity of soils. However, the actual behaviour of BEs inside the soil specimen has never been directly measured. There is experimental, numerical and analytical evidence that the shape and frequency content of the actual transmitter movement are different from the shape and frequency content of the input voltage signal, although this disparity has never been validated for BEs placed inside a soil specimen. In order to systematically investigate the disparity between the input signal and the actual transmitter response and to advance the understanding of the frequency response of the transmitter inside the soil, an experimental programme is designed to measure, for the first time, the responses of BEs placed inside soil specimens. To capture the transmitter response when placed inside the soil, a transparent granular soil is used to allow penetration of a laser beam from a laser vibrometer. The results show that, contrary to common assumptions, the transmitter response inside the soil specimen is different from the input excitation signal. The time delay between input excitation and transmitter response is found to be a function of frequency and the surrounding medium. Moreover, the vibration modes of BEs are studied by analysing the transmitter response to different input signals. These observations are used to understand the actual behaviour of the BEs placed inside the soil. [ABSTRACT FROM AUTHOR]

The dynamic behaviour of monopile supported offshore wind turbines (OWTs) is considerably influenced by inherent variabilities of soil properties and loading. This study investigates the effect of uncertainties in soil shear strength properties, and wind and wave loads on the reliability of OWT structures founded in clay. The OWT system is modeled as an Euler-Bernoulli beam and soil-structure interaction is incorporated using the American Petroleum Institute based cyclic p-y relationships. The uncertainties in soil undrained shear strength, in the parameters and equations of the p-y method, and in wind velocity are considered. Random wave loads are estimated from the code specified power spectral density function of the vertical sea surface elevation. Uncertainties in OWT responses are quantified using Monte Carlo simulations. The effects of length and diameter of the monopile, vertical sea surface displacement spectrum, and the probability distribution of wind speed on the dynamic responses of OWT are investigated. The study shows that the various power spectral density functions of wave surface displacement and various probability density functions of wind speed have a marginal effect on the response and fatigue life of OWTs. The mean fundamental frequency of the OWT system is significantly affected by the variability of the undrained shear strength of clayey soil. [ABSTRACT FROM AUTHOR]

Split Hopkinson pressure bar (SHPB) tests are performed on Himalayan phyllite rock with five different specimen sizes and with different gas gun pressures and striker bar lengths of the SHPB device. The high-strain-rate phyllite parameters investigated are the peak stress, strain at peak stress, dynamic increase factor (DIF), strain energy absorbed, and dynamic modulus. It is observed that the dimensions of the phyllite specimens and the SHPB loading characteristics (i.e., the gas gun pressure and striker bar length) have a strong impact on the phyllite response. Given that SHPB specimen dimensions are small compared to any field rock mechanics problem, the rate-dependent rock mass properties are also determined for each rock using Hoek–Brown criteria. Numerical simluations of the SHPB tests are performed using finite element (FE) analysis in conjunction with the strain rate-dependent Johnson–Holmquist (JH-2) constitutive model to calibrate the JH-2 model parameters for phyllite. The calibrated JH-2 model parameters are dependent on the phyllite specimen size and on the magnitudes of the gas gun pressure and striker bar length. The different calibrated parameters corresponding to different specimen sizes and different SHPB loading characteristics are used to perform FE analysis of a tunnel constructed in phyllite rock and subjected to a blast load. The FE results show that the tunnel responses can significantly differ with strain rate-dependent JH-2 model parameters with difference in the mean stress and vertical displacement at the crown of the tunnel in the phyllite rock as high as 126% and 250%, respectively. [ABSTRACT FROM AUTHOR]

Earthquakes threaten humanity globally in complex ways that mainly include various socioeconomic consequences of life and property losses. Resilience against seismic risks is of high importance in the modern world and needs to be sustainable. Sustainable earthquake resilience (SER) from the perspective of structural engineering means equipping the built environment with appropriate aseismic systems. Shape memory alloys (SMAs) are a class of advanced materials well suited for fulfilling the SER demand of the built environment. This article explores how this capability can be realized by the innovative SMA-based superelasticity-assisted slider (SSS), recently proposed for next-generation seismic protection of structures. The versatility of SSS is first discussed as a critical advantage for an effective SER. Alternative configurations and implementation styles of the system are presented, and other advantageous features of this high-tech isolation system (IS) are studied. Results of shaking table experiments, focused on investigating the expected usefulness of SSS for seismic protection in hospitals and conducted at the structural earthquake engineering laboratory of the University of Bonab, are then reported. SSS is compared with currently used ISs, and it is shown that SSS provides the required SER for the built environments and outperforms other ISs by benefitting from the pioneered utilization of SMAs in a novel approach. [ABSTRACT FROM AUTHOR]

Based on the estimated HT ht , the average PRF settlement HT ht . The average elastic settlement HT ht obtained directly from FE analysis is 19.5 mm. The maximum PRF settlement HT ht obtained directly from FE analysis is 20.4 mm. [Extracted from the article]

Continuum-based three-dimensional (3D) elasto-plastic finite element (FE) analyses of piled raft foundations (PRFs) resting on sandy soils and subjected to uniformly distributed vertical loads are performed using the software Abaqus, and equations are developed for estimating the nonlinear soil subgrade moduli (spring stiffnesses) beneath the raft, beneath the pile base, and along the pile shaft. The unified clay and sand model (CASM) is used as the soil constitutive model in the continuum-based 3D FE analysis. Four different types of sand with three different states (loose, medium and dense) and twenty different configurations of PRFs with rectangular, square, and strip rafts are considered in this study. The developed equations of the raft and pile spring stiffnesses are subsequently used in a soil spring-based nonlinear FE analysis of PRFs performed using a structural engineering software. It is shown through verification and validation studies that the developed equations of the raft and pile spring stiffnesses can be reliably used in spring-based FE analysis of PRFs, instead of the computationally expensive continuum-based 3D FE analysis, for quick and accurate estimate of PRF responses. The developed equations of spring stiffnesses are applicable to PRFs that are similar in dimensions considered in this study. [ABSTRACT FROM AUTHOR]

Earthquakes can create severe damage to retaining structures. A numerical study is carried out to understand the seismically induced active earth pressure force on free-standing gravity retaining walls. Dynamic behavior in terms of acceleration amplification/deamplification, deformation mechanism, and earth pressure force are examined. Further, the influence of input peak ground acceleration (PGA), retaining wall height, Young's modulus of the wall, relative density of soil, and soil-structure interaction on total active earth pressure force (P ae) are investigated. The results show that P ae decreases until PGA value is around 0.55 g and later increases for higher values. The primary cause for this response is the loss of wall-soil interaction due to the overturning effect, which dominates until PGA approaches 0.55 g. Also, the generation of failure wedges causes an increase in P ae after 0.55 g. Sensitivity analysis concludes that P ae is highly sensitive to PGA, wall height, and soil-structure interaction. Based on regression analysis, an equation is proposed for the total active thrust. Later, the accuracy of the equation is confirmed by comparing it with the response of FE analysis and established study. This study contributes to developing an equation that is anticipated to provide total active thrust at the initial design stage under comparable work environment. [Display omitted] • Non-linear amplification of acceleration up to k h = 0.55 followed by deamplification. • Overturning mode of wall failure is dominant with formation of multiple failure planes in backfill. • P ae decreases with increase in k h up to 0.55 followed by increase till k h reaches 1.2 • Proposed equation for P ae considering earthquake, wall, soil, and interface characteristics. • Useful to evaluate P ae at initial design stage under similar work environment. [ABSTRACT FROM AUTHOR]