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To date, the traffic-induced dynamic behavior of geosynthetic-encased stone column-supported embankments (GESC) under traffic cyclic loads accompanied by embankment consolidation has not been well studied. Three-dimensional (3D) coupled mechanical and hydraulic modeling is performed using FLAC3D, which considers the fluid flow during the lifespan of three stages: (1) embankment construction (EC): (2) consolidation (C) under embankment surcharge; and (3) cyclic loading (CYC). During the simulation, excess pore pressure, stress concentration, settlement, and lateral displacement are monitored, and the total settlement and lateral displacement could be easily obtained by accumulating the components of the three stages. Parametric analyses are conducted on the reinforcement forms and cyclic loading characteristics that include the dynamic stress amplitude and loading frequency. The ordinary stone (OSC) and GESCs could reduce the settlement and lateral displacement during each stage by improving the strength of the foundation and accelerating drainage consolidation; however, GESCs outperform the columns without geoencasement. In addition, the stress concentration ratio under embankment filling decreased with the increase in the dynamic stress amplitude and loading frequency, which led to the increase in the percentage of the cyclic loading-induced settlement to total settlement. [ABSTRACT FROM AUTHOR]

This article presents the impact of nonlocal parameters (NLP) on wave motion and deformation in a micropolar porous thermoelastic plate under memory-dependent derivatives (MDD). The basic equations are converted into dimensionless form and solved using normal form analysis. Two cases of boundary conditions, namely boundary conditions for stress free boundaries and boundary conditions for thermo-mechanical loading, are considered. The first case of boundary conditions is employed to formulate the propagation equations for symmetric and anti-symmetric systems. The phase velocity and attenuation coefficient under Lord–Shulman (LS), Green–Lindsay (GL) and dual-phase-lag (DPL) theories are examined for the first case. In the second case, thermomechanical conditions have been considered to derive the analytical terms for force stresses, couple stresses, volume fraction, and temperature. The analytically obtained results are numerically analyzed for aluminium–epoxy material under three memory-dependent theories. To depict the impact of nonlocal parameters, comparisons between DPL theory with NLP and DPL theory without NLP are shown graphically. [ABSTRACT FROM AUTHOR]

The paper proposes a spectral decomposition–based approach for implementing a multisurface coupled damage–plasticity model for concrete subjected to fire. The multisurface approach enables distinct flow rules to be used for plastic flow in compression and tension. The spectral decomposition–based procedure enables, for general multiaxial loading, the Jacobian for the return mapping algorithm to be determined analytically without the need for finite difference approximations or additional nested iterations. The proposed approach, developed in the context of a general multisurface plasticity model subject to the small strain assumption, is specialized to the case of a combined Drucker-Prager and Rankine yield surface, and can account for situations where the eigenvalues of the stress tensor are degenerate. It is verified by solving finite element models for concrete structural components subjected to high temperature under a wide variety of mechanical loads. The simulation results, obtained using a sequentially coupled approach, are found to closely match established experimental results. [ABSTRACT FROM AUTHOR]

The numerical modeling of thermomechanical fracture is an essential aspect of designing critical components in various industries, including aerospace, automobile, and nuclear. The phase-field method is a suitable approach for simulating thermomechanical fracture problems. However, this method can be computationally expensive. In this study, we propose a multilevel adaptive mesh refinement (ML-AMR) using a phase-field approach, for thermomechanical fracture problems. The proposed approach can efficiently and accurately capture the crack topology without the need for any pre-refinement or explicit marking of damage boundary. Our proposed ML-AMR algorithm introduces an error estimator based on effective crack driving energy computed based on thermomechanical loading using the three prominently used phase-field models (AT2, AT1, and PF-CZM). We demonstrate the accuracy and computational efficiency of the proposed method by simulating various thermomechanical fracture problems and comparing the results with the nonadaptive phase-field method that adopts a priori nonadaptively refined meshes. We consider different types of thermal and mechanical loading, including thermal shock, to evaluate the proposed approach comprehensively. Our results show that the proposed ML-AMR phase-field method reduces computation time by 78%–99% while accurately capturing the crack path, peak load, and total strain energy. [ABSTRACT FROM AUTHOR]

This paper develops a modeling method with an incremental stress–strain–environment constitutive model to predict the change in the plastic mechanical behavior of concrete caused by environmental action. The model regards the environmental factor as a constitutive variable, similar to stress and strain. The yield condition of the model is a function of stress, the plastic internal variable, and the environmental variable. The loading–unloading criterion is established in the space constructed by the strain and the environmental variable to determine the contribution of mechanical loads and environmental factors to plastic deformation. By considering the strain rate as an environmental factor and applying the proposed method, a stress–strain–strain rate constitutive model of concrete is developed to describe the plastic flow caused by the combined action of stress and strain rate. In addition, constant- and variable-strain rate loading tests are performed to evaluate the performance of the established model. In particular, the model's capabilities are further highlighted by comparing the simulation results of the dynamic stress–strain model and the proposed model under loading conditions with rapidly decreasing strain rates. [ABSTRACT FROM AUTHOR]

This study examines the load-deformation response of sands subjected to high- and low-stress cycles, i.e., both ends of the Wöhler's fatigue curve. At high peak cyclic stress σf , the terminal void ratio decreases with σf due to crushing-dependent densification, and it can be smaller than emin when the peak stress approaches the yield stress σf→σy. When σf≪σy , the soil retains memory of the initial fabric even after a very large number of cycles, and the terminal void ratio correlates with the initial void ratio eo. Data show that the maximum change in relative density leads to simple strategies to estimate the maximum settlement for first-order engineering analyses. In agreement with Wöhler's fatigue, tipping points in void ratio and stiffness trends occur at a small number of high-stress cycles or after a large number of small-stress cycles. During repetitive loading, sands stiffen with the number of cycles to reflect increased interparticle coordination following crushing, as well as contact flattening due to asperity breakage and fretting. The strong correlation between the resilient modulus Mr and the maximum shear modulus Gmax suggests the possible application of geophysical methods based on shear wave propagation to monitor geosystems subjected to repetitive loading cycles. [ABSTRACT FROM AUTHOR]

Many engineering materials have coupled nonlinear viscoelasticity and viscoplasticity, which are affected by complex thermomechanical loadings. This study addressed the challenge of accurately separating the viscoplasticity and the nonlinear viscoelasticity and formulated the viscoplasticity by considering the effects of temperatures and loading levels. First, the nonlinear viscoelastic constitutive equation was adopted to accurately separate the viscoplasticity and the nonlinear viscoelasticity. Then a kinetics-based viscoplastic model and a new viscoplastic activation energy indicator are proposed to consider the effects of the temperature and loading level on the viscoplasticity. As typical nonlinear viscoelastic viscoplastic materials commonly used in pavement engineering, asphalt binders were selected to demonstrate the principles in this study. It was found that the proportion of the viscoplastic strain is larger than the nonlinear viscoelastic strain for virgin asphalt binders (VBs) and it increases with the temperature, whereas the opposite is true for high-viscosity modified asphalt binders (HVBs) and rubber asphalt binders (RBs). The logarithm of the viscoplastic strain rate increases linearly with the reciprocal of the temperature, and the viscoplastic strain rates at different temperatures are correlated and can be predicted based on the established viscoplastic strain kinetics model. The viscoplastic activation energy indicator can characterize the viscoplastic deformation resistance for nonlinear viscoelastic viscoplastic materials, and the order of the viscoplastic deformation resistances of the three binders was VB

This paper studied the thermomechanical nonlinear stability analysis of simply supported geometrically imperfect porous functionally graded nanoplates (FG-nPs) resting on an elastic medium. The inverse trigonometric shear deformation theory was used in conjunction with the nonlocal strain gradient theory, which accounts for small-scale effects. The non-linear stability equations using the von Karman sense of the strain–displacement relation and generic imperfection function were derived for FG-nPs under thermomechanical loading conditions. The FG-nP was subjected to mechanical and thermal loading. An expression for the critical buckling load and temperature of a geometrically imperfect porous FG-nP was obtained. The impact of geometric imperfection, porosity inclusion, and geometric and boundary conditions on the nonlinear stability characteristics of FG-nPs was addressed thoroughly after validation of the superior accuracy of the derived expression. [ABSTRACT FROM AUTHOR]

This paper demonstrates the influence of pile head freedom on the thermomechanical performance of a belled pile. Field tests on the belled pile response to a cooling–heating cycle and incremental structural construction are carried out. The temperature changes, axial strain profiles, and pressures at the pile toe are recorded through the buried instruments. The variation in the degrees of freedom, tensile forces, and inferred pile head settlements along the pile depth for different test procedures are analyzed using the measured data. The degree of freedom close to the pile head calculated from strain rates decreases with the structure mass with a gradient of −2.8×10−5/kN. The reducing effect of the incremental superstructure on pile freedom decreases along with the orientation of the pile depth. Compared with the inferred thermal displacement of the pile without an applied structural load, the values decrease by about 10% when the pile was subjected to incremental floors, and an elastic recoverable characteristic response to cooling–heating-recovery phases is observed. Compared with the equal-diameter pile, the belled pile showed a significant constraint close to the toe. Mechanical loads can decrease the cracking risk because of a possible tensile force under cooling conditions. [ABSTRACT FROM AUTHOR]

Analytical solutions for axial displacement, strain, and stress in a single semifloating energy pile embedded in a layered soil profile subjected to thermal and mechanical loads were derived. An analytical solution for the location of zero displacement, also known as a null point, was derived for a pile subjected to thermal load. It was shown that the location of the thermal null point corresponds to the location of the maximum magnitude of thermal axial stress. It also was shown that the location of the null point moves toward the pile tip as the stiffness of the bedrock below the pile tip increases. The analytical solutions were validated against in situ full-scale energy pile tests. The solutions along with the validation process delineated the load transfer mechanism in energy piles subjected to thermal, mechanical and combined thermomechanical loads embedded in a four-layer soil profile. Flowcharts delineating the procedures for obtaining the analytical solutions for a single energy pile embedded in an arbitrary number of layers, and subjected to thermal and mechanical loads are provided. Although the continuity of stresses and displacements at the interface of different soil layers is maintained, displacement, strain, and stress diagrams exhibit a lack of smoothness, the amount of which depends on the difference in the stiffness of these layers. In summary, the presented solutions provide a rational, mechanics-based framework for advancing the understanding of thermomechanical response of energy piles that not only is essential for analysis and design, but ultimately contributes to a wider use of energy piles and increased sustainability of civil engineering infrastructure. [ABSTRACT FROM AUTHOR]

A quasi-three-dimensional (3D) theory considering transverse shear and normal deformation effects is presented for the static flexure of simply supported symmetric sandwich plates. The theory was developed based on the third- and fifth-order shear strain functions in terms of thickness coordinate. The displacement field accounts for nonlinear variation of in-plane displacements and transverse displacement through the plate thickness and enforces satisfying conditions of zero transverse shear stresses on the upper and lower surfaces of the plate. The present theory does not require the shear correction factor associated with the first-order shear deformation theory. Governing equations and boundary conditions were obtained using the principle of virtual work. The transverse shear and normal stresses were obtained from the stress equilibrium equations of theory of elasticity satisfying the continuity conditions at the layer interfaces and the stress-free boundary conditions at the top and bottom surfaces of the plate. The closed-form solutions for simply supported sandwich plates subjected to sinusoidal, uniform, and uniformly varying loads were obtained for various side to thickness ratios. The results of the present quasi-3D theory were compared with those of the exact theory, first- and third-order shear deformation theories, and the classical plate theory. Results showed that the present quasi-three-dimensional (3D) theory is in excellent agreement with the exact theory. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer (FRP) near-surface mounted (NSM) reinforcement represents an effective solution for strengthening and retrofitting existing concrete structures. As it is embedded into concrete, NSM reinforcement is protected from accidental impact, high temperature, and vandalism and it is less prone to debonding than externally bonded reinforcement. However, debonding of the NSM reinforcement remains the main issue associated with this strengthening technique. Numerous studies have focused on the bond behavior of NSM-concrete joints and in some of them analytical models for the prediction of NSM-concrete joint bond capacity were proposed. However, these models are often based on a few experimental results of a specific strengthening configuration. In this paper, a new analytical model to estimate the effective bond length and the bond capacity of NSM-concrete joints that fail due to cohesive debonding within concrete is proposed. The model is based on a pure fracture mechanics Mode-II loading condition and can be applied to either NSM strips, round bars, or rectangular bars. The accuracy of the model proposed and of existing analytical models was assessed by comparing analytical and experimental results of 117 NSM-concrete joints collated from the literature. The assessment showed that the model proposed provided accurate estimations of the NSM-concrete bond capacity for all types of reinforcement considered. [ABSTRACT FROM AUTHOR]

Steel beams are susceptible to large deformation and capacity reduction when subjected to elevated temperatures. Determination of collapse loads for structural steel members under fire is critical for realistic assessment of system vulnerabilities. Such determination, however, should be conducted within a probabilistic framework that allows for the integration of various uncertainties influencing the behavior. In addition, the assessment should address realistic fire exposure that arises due to typical fire scenarios. To date, evaluation of the collapse load of beams in the presence or absence of uncertainties under nonuniform temperature is lacking. This paper presents a new analytical formulation, based on virtual work, for calculating the collapse load of beams subjected to nonuniform longitudinal temperature distribution. Moreover, a new probabilistic framework is devised to generate fragility surfaces for beams under combined fire and applied loads. Randomness in load and resistance including applied mechanical loads, compartment ventilation, compartment geometry, and thermal characteristics of surrounding surfaces are accounted for by including the statistical variations in these parameters. Comparisons of collapse loads calculated using the proposed approach and those calculated using a commercial finite element software show excellent correlation. The outlined framework can allow structural and fire engineers to rapidly evaluate the collapse load and mechanism of beams under a nonuniform temperature distribution. [ABSTRACT FROM AUTHOR]

Embankments over pile-reinforced soft soil (called piled embankments) are known as one of the interesting techniques for soft soil improvement. They have been broadly applied in infrastructure projects thanks to their advantages, such as the decrease in settlement, the reduction in construction time, and the reasonable cost. The shearing and the soil-arching mechanisms within embankments result in an increase of the stress acting on the pile head and a reduction of the soft soil pressure. They can reduce the total and differential settlements. Numerous studies were carried out to better understand the behavior of this technique. However, most of the research focused on static loadings, and few studies concerning the cyclic loading were conducted. The aim of this study was to investigate the behavior of a piled embankment subjected to different traffic cyclic loadings. A three-dimensional numericalmodeling using the finite-element method (FEM) was conducted with the use of Abaqus. An advanced constitutive soil model based on the hypoplasticity concept was used for granular soil and compared with the conventional one (a linear elastic-perfectly plastic model with the Mohr-Coulomb failure criterion) for aspects of static and cyclic loading.A high number of load cycles applied to a piled embankment was also considered in the study. The numerical results show that the hypoplastic model is better than the linear elastic-perfectly plastic model to deal with the soil-arching decrease and cumulative settlements under cyclic loading. In addition, the influence of the number of traffic load cycles, the vehicle speed, and the embankment height on the arching effect and the cumulative settlements is presented. [ABSTRACT FROM AUTHOR]

This paper proposes a practical method of determining embankment loads-induced vertical superimposed stress in subsoil by incorporating the effects of contact stress and soil elastoplastic behavior. The particulate-probabilistic theory is introduced to establish a new way of determining contact stress for overcoming the assumptions in the traditional trapezoidal stress distribution approach with instantaneous loading and perfectly flexible loaded area along the base. Then, the Flamant solution is introduced to propose a practical method of determining the vertical superimposed stress in subsoil. A reduction coefficient of 0.85 is suggested for considering the effect of elastoplastic of subsoil. The measured values of contact stress and field settlements are compiled from literature available to validate the proposed equations. It is found that the suggested methods in this study can improve significantly the degree of accuracy of the Osterberg method (Osterberg 1957) in calculating embankment loads induced settlement. [ABSTRACT FROM AUTHOR]

This study presents a modified macromodel for calculating the anchorage slip of rebar under monotonic loading and its application to the fiber beam-column element model. The proposed macromodel reflects bond stress distribution along rebar and hence captures slip responses over the entire rebar stress range. The anchorage slip problem is formulated using three governing equations among four bond fields, namely, bond stress, rebar stress and strain, and slip. The general framework for macromodels with a given bond stress distribution and micromodels with a given bond-slip relationship is established. Then, the proposed macromodel is developed using a refined bond stress distribution function, which is established by solving a validated micromodel. Available experimental results are used to calibrate the bond stress parameter and to investigate the validity of the proposed model. Comparisons indicate considerably improved accuracy of the proposed macromodel over the conventional macromodel for capturing stress-slip relationships and bond field distributions. Finally, the proposed macromodel is implemented into a conventional fiber beam-column model. The modified fiber model is applied to simulate a bridge column shake-table test, and shows success in capturing anchorage slip contributions. Therefore, the model is validated for both slip responses and model applications. [ABSTRACT FROM AUTHOR]

Concrete highways and airfield pavements are subjected to a large number of traffic loads, which may cause failure of the pavement due to fatigue. In the present work, an experimental study has been carried out on plain concrete beam specimens to investigate the crack propagation and incremental damage characteristics of concrete under cyclic loading. A compliance test was conducted on beam specimens with different notch depths, and a relationship between notch depth and compliance was established. The fracture toughness of concrete was also estimated in a beam bending test. Fatigue tests were conducted on different sets of beam specimens under different load levels. Vertical displacement and crack mouth opening displacement were measured at each load cycle. The variation of stress intensity factor with load repetitions was observed using the crack lengths estimated from the compliance values corresponding to different load repetitions. The ratio of stress intensity factor to critical stress intensity factor (at failure), termed as toughness ratio in this work, has been found to influence the fatigue life. The fatigue life, as expected, also depended on stress ratio. A fracture mechanics-based damage prediction model was proposed for estimating the progressive damage at any intermediate load cycle. The damage prediction model was validated using the experimental results available in literature. Predicting fatigue damage at intermediate stages and due to variable sequence of loading is convenient for the design and evaluation of concrete pavements. Although the effects of frequency (in the ranges applicable for highway pavements) on the fatigue performance may not be significant, the applicability of the present model may be limited by the specific specimen size and loading waveform considered in this study. [ABSTRACT FROM AUTHOR]

Steel-concrete composite structures are widely used in modern buildings and bridges for their great rigidity, light weight, and simple construction. However, the mechanical behaviors of steel-concrete composite structures degrade over time because of environmental corrosion and long-term load. The existing research on structural durability has often focused on concrete or steel structures. Few studies have been conducted on steel-concrete composite structures, especially on structures under the coupled impact of corrosion and load. To investigate the coupled impact of corrosion and load on the performance of steel-concrete composite structures, a long-term test of 200 days was carried out on eight connectors. The corrosion of the studs was accelerated by DC current, and the test connectors were submerged in a salt solution with a concentration of 5% NaCl. Deformations including the concrete strain and relative slippage between the concrete slab and the steel beam were measured in the long-term test. The experimental results showed that at the end of the long-term test, the deformations induced by shrinkage were about three times larger than those induced by creep for the steel-concrete composite structures. Notably, the stiffness of the connectors degraded substantially with the aggravation of the corrosion of the studs, whereas the concrete strain was only slightly affected by the studs' corrosion. The measured deformations were also obviously larger than those calculated by the current specifications. As a reference, a suitable formula for the long-term elastic modulus is proposed to enhance the applicability of specifications. [ABSTRACT FROM AUTHOR]

ASCE 7 is moving toward adopting load requirements that are consistent with risk-informed design goals characteristic of performance-based engineering (PBE). ASCE 7-10 provided wind maps that correspond to return periods of 300, 700, and 1,700 years for Risk Categories I, II, and combined III/IV, respectively. The risk targets for Risk Categories III and IV buildings and other structures (designated as essential facilities) are different in PBE. The reliability analyses reported in this paper were conducted using updated wind load data to (1) confirm that the return periods already in ASCE 7-10 were also appropriate for risk-informed PBE, and (2) to determine a new risk-based return period for Risk Category IV. The use of data for wind directionality factor, Kd, which has become available from recent wind tunnel tests, revealed that reliabilities associated with wind load combinations for Risk Category II structures are, in fact, consistent with the reliabilities associated with the ASCE 7 gravity load combinations. This paper shows that the new wind maps in ASCE 7-16, which are based on return periods of 300, 700, 1,700, and 3,000 years for Risk Categories I, II, III, and IV, respectively), achieve the reliability targets in Section 1.3.1.3 of ASCE 7-16 for nonhurricane wind loads. [ABSTRACT FROM AUTHOR]

In this study, an adjustment factor was developed to better estimate the shear capacity of simple span prestressed concrete (PC) girders, for intended use in load rating. The adjustment factor is expressed as a function of several critical girder parameters including concrete strength, prestress level, stirrup spacing, and girder height. The adjustment factor was determined from a regression analysis of over 200 shear capacity results. The database was obtained from a parametric analysis conducted with a finite-element model validated with experimental data. Three different code methods were considered for comparison. Generally, code results were found to be inconsistently conservative. Application of the adjustment factor to an established procedure produced improvement in the accuracy and consistency of shear capacity estimation over existing code methods for the range of girder parameters considered. In addition, potential effects on rating factors for inventory and operational levels were quantified. [ABSTRACT FROM AUTHOR]

This paper presents two modifications to the traditional formulation of the load-transfer method; a distinct unloading path is defined for the load-transfer functions, and the displacement variable is modified to consider the effects of passive soil displacements. The discrete formulation can account for different properties along the pile depth, as in the case of soil layering. Modeling distinct unloading functions enables loading cycles to be simulated as well as the analysis of residual loads. An instrumented pile load test is used to calibrate the method. Example computations are presented and discussed, highlighting the main features of the model. [ABSTRACT FROM AUTHOR]

A proper traction-separation law based on the physical behaviors of the concrete-epoxy interface is needed to simulate the debonding behavior of fiber-reinforced polymers-strengthened concrete structures. However, no method is available to measure the traction-separation law of the concrete-epoxy interface under mode-I loading. To address this gap, this study proposes a novel testing method to directly measure the traction-separation law of the concrete-epoxy interface. This method uses a wedge-splitting test specimen that not only requires simple testing setups but also produces stable crack propagation in the specimen. By adopting a rigid body moment assumption, the traction in the concrete-epoxy interface is expressed as a function of the applied load and the crack opening displacement. As a result, this method can directly calculate the relationship between the traction and the separation of the concrete-epoxy interface by simply recording the crack opening displacement and the applied load during the test. The success of the new method has been confirmed through experimental study. Testing results show the traction-separation law of the concrete-epoxy interface under mode-I loading can be approximated by a tri-linear law. The new method is also used to evaluate the long-term durability of concrete-epoxy interface subjected to moisture attack. It has been found that conditioning the interface specimens in water can significantly reduce the tensile strength and fracture toughness of the interface. The effectiveness of applying silane coupling agent to enhance the durability of the concrete-epoxy interface has also been confirmed by this new testing method. [ABSTRACT FROM AUTHOR]

Drilled shaft foundations commonly experience torsional loads, in addition to axial and lateral loading. Such cases include loads on mast arm traffic sign and signal poles, or seismically induced inertial loading of foundations supporting skewed or curved bridges. Despite the prevalence of drilled shafts, the understanding of the actual resistance to torsion provided by these deep foundation elements is not well established. To help address this gap in knowledge, two instrumented drilled shafts were constructed to evaluate the torsional capacity and load transfer at full scale. Both monotonic quasi-static and cyclic loading tests were performed. The imposed rotation and corresponding torque was monitored using string potentiometers and load cells, respectively. Strain gauges installed to measure shear strains facilitated computation of the torsional load transfer, which is described in detail. Design procedures for the calculation of the ultimate total and unit torsional resistances of drilled shafts are proposed and resulting estimates compared against the resistances observed in the testing program and other studies reported in the literature. The rational design methodology proposed herein overpredicts or underpredicts the torsional capacity, indicating the need for the development of improved methods for assessing the torsional resistance of drilled shaft 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 overturning limits of single-column pier bridges subject to overloading can be predicted using various approaches ranging in complexity from close-form formulas to detailed finite-element simulations. A simple analytical method-dubbed here analytical overturning limit analysis (AOLA)-is proposed to predict the overturning loads for single-column pier bridges. AOLA is an iterative method that determines the minimum wheel loads (position and pattern) at which an overturning state is reached. It incorporates the effects of self-weight of the bridge and the sizes and intervals of its bearings. Data collected from two collapsed bridges in China and detailed finite-element simulations of those two events are used for validating and verifying the method. [ABSTRACT FROM AUTHOR]

Experimental and numerical studies were conducted to investigate the vertical load-carrying behavior and seismic performance of a composite frame structure with an innovative composite transfer beam, which was proposed to overcome the disadvantages of traditional reinforced concrete or steel reinforced concrete transfer beams. In the experimental study, a vertical monotonic loading test and a lateral cyclic loading test were conducted. The test observations, load-displacement curves, and strain measurements were discussed to investigate the structural performance and failure mechanism. The experimental results demonstrated the excellent vertical load-carrying behavior and seismic performance of the composite transfer frame. The characteristics of the plastic hinge distribution were investigated based on extensive data of the steel strains measured to reveal the typical failure mechanism of the composite transfer frame. In the numerical simulation analysis, a multiscale modeling scheme was developed to make full use of the fiber beam-column elements and multilayer shell elements. Comparisons with the experimental results showed that the developed model predicted the overall structural behavior, the individual story and component behavior, and the failure mechanism with a reasonable level of accuracy. In addition, both the experimental tests and numerical analyses indicated that the shear deformation mode and the energy dissipation in the composite joint core were also significant mechanical characteristics of the composite transfer frame. [ABSTRACT FROM AUTHOR]

An understanding of how corrosion affects fatigue behavior of reinforced concrete (RC) structures is essential for lifetime-oriented maintenance and design of existing bridges. This paper covers an experimental investigation on fatigue behavior of corroded RC beams. Corrosion in six RC beams was artificially accelerated by the impressed current method before fatigue loading was administered. All beams failed with fatigue fracturing of their tension steel bars. The fatigue test results indicated that the more severe the corrosion on steel bars was, the sooner the beams failed. The behavior of corroded steel bars determines the fatigue behavior of RC beams. This paper introduces a segmented linear model to simulate nonlinear behavior of corroded RC beams under fatigue loading, which was verified by experimental results. Of particular interest was the deterioration of corroded RC beams under fatigue loading, including the fatigue damage to concrete and corroded steel bars as well as the bond behavior between steel bars and concrete. The proposed model can simulate the development of strains in concrete and steel bars under fatigue loading, thereby permitting a fatigue life assessment. Further analysis investigated the effects of corrosion level, longitudinal variation of the cross-sectional areas, reinforcement ratio, load amplitude, and bond behavior as well. With the increasing degree of corrosion, load amplitude and longitudinal variation of the cross-sectional areas, or the decrease of the reinforcement ratio, the fatigue life of corroded RC beams decreased. The deterioration of bond behavior had little effect on fatigue life, but it led to a reduction in the flexural stiffness of beams. [ABSTRACT FROM AUTHOR]

This paper describes the development of reliability-targeted ground snow load maps for use in building (roof) design. The proposed procedures aim to ensure that structures designed achieve a target safety index, taken to be 3.0 as defined in ASCE 7 (ASCE 2010). When applied to the U.S. state of Colorado, the reliability-targeted mapping procedure shows that to achieve this target reliability index, design ground snow loads may need to be larger or smaller than the 50-year return period load that ASCE 7 currently stipulates for design, depending on the site and winter climate conditions at that site. Sites with larger coefficients of variation in the annual maximum snow load (in Colorado, lower-altitude sites) generally need design loads larger than the 50-year values. The paper also advances snow reliability assessment procedures through the proposal of a new model for the ground-to-roof conversion factor needed for quantifying roof snow loads as a function of ground snow loads. Spatial smoothing and altitude-dependent mapping procedures are described. [ABSTRACT FROM AUTHOR]

This paper describes a new method for fitting probability distributions for modeling annual maximum ground snow loads for use in structural design. These probability models are intended for use in reliability assessments to determine reliability-targeted ground snow loads, as described in the companion paper. The proposed method emphasizes the upper tail of the distributions, because the upper tail is most critical for the reliability assessment and for determination of design loads. A combination of site-specific and region of influence approaches results in annual maximum snow load distributions whose magnitudes are consistent with historical data observed at the site of interest but with upper tail shapes that are informed by historical snow records at a number of similar sites. Clusters of sites with similar snow accumulation patterns are utilized to improve the definition of the snow load distribution at sites in the cluster. [ABSTRACT FROM AUTHOR]

This study focuses on the use of a thermomechanical soil-structure interaction (load transfer) analysis to assess the axial strains, stresses, and displacements during thermomechanical loading of energy piles in various soil deposits with different end restraint boundary conditions. After providing details of the model and its novel features, this paper presents a parametric evaluation performed to understand the roles of the soil shear strength parameters, toe stiffness, head stiffness, side shear stress-displacement curve, and radial expansion, as well as the magnitude of temperature change. This evaluation showed that the end restraint boundary conditions play the most important role in controlling the magnitude and location of the maximumthermal axial stress. The soil type also causes changes in the nonlinearity of the axial stress distribution throughout the energy pile. The radial expansion did not affect the thermomechanical soil-structure interaction for the conditions investigated in this study. The thermomechanical load transfer analysis was then calibrated to identify the parameters that match the observed soil-structure interaction responses from four case studies of energy piles in nonplastic soil or rock layers during monotonic heating, including one field study and three centrifuge studies. The ranges of calibrated parameters provide insight into the behavior of energy piles in nonplastic soils and can be used for preliminary design guidance. [ABSTRACT FROM AUTHOR]

Considering the real irregular shapes of ballast particles and complete track skeleton, a two-dimensional discrete element model is built to investigate the dynamic behavior of high-speed railway (HSR) ballasted track. Taking the moving wheel loads obtained from railway vehicle-track coupled dynamics simulation as the excitation inputs, the dynamic behavior of ballast particles in terms of contact force, stress, and vibration response are simulated using the discrete element model. Numerical results show that the ballast particles within the depth of 200 mm under sleepers would be most likely to carry a higher stress level when a vehicle passes by. Vibration amplitudes of ballast particles increase with the increase of vehicle speed, and the acceleration amplitudes rise sharply when the vehicle speed is higher than 200 km/h. Spectrum analyses indicate that the dominant frequencies of particle displacement and velocity are lower than 100 Hz, whereas the acceleration responses contain not only low-frequency but also some medium-frequency components in the range of 150-300 Hz. Simulated results also demonstrate that the vibration amplitudes of ballast particles attenuate with the depth and the longitudinal distance from the sleeper center to the particle. This research work presents mechanical behavior of railway ballast and provides a potential way to reveal the deformation and degradation aspects of railway ballast from the mesoscopic to macroscopic level, while recognizing the limitations of the current discrete element model in quantifying particle breakage. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical studies of reinforced concrete flat-plate structures. Experiments were performed on six interior slab-column connections without structural integrity reinforcement to examine their punching and postpunching behaviors. The test variables included slab tensile reinforcement ratio and lateral restraint at the slab boundary. The experiments indicated that, under the level of restraint achieved in the tests, the compressive membrane action could enhance the punching resistance by as much as 9.5%. The tests also showed the slab-column connections without continuous compressive bars at the columns had a postpunching loading capacity of about 50% of the failure load, but this residual capacity cannot be maintained under large deformations. It was found that anchoring the slab tensile reinforcement into slab by hooks provided an alternative approach to achieve stable postpunching capacity. The numerical simulations confirmed the effectiveness of a macromodel for flat plates. The analyses also indicated the effects of compressive membrane action on punching resistance is a function of slab in-plane restraint and can significantly increase the resistance of a flat-plate building to progressive collapse. [ABSTRACT FROM AUTHOR]

The load-carrying capacity of reinforced concrete bridges can degrade over their service life through the initiation of deterioration mechanisms induced by fatigue, corrosion, cracks, and spalling. Analyses of residual capacity and time-dependent reliability of such bridges are significantly important information in the decision-making process of identifying the nature and timing of rehabilitation. It is noted in the literature that deterioration mechanisms such as chloride ingress, sulfate attack, and alkali-silica reaction have variable rates of deterioration governed by a large number of uncertain parameters. In such instances, a probabilistic approach provides a rational basis for estimating the uncertainties of residual capacity and reliability. In this paper, the authors present a probabilistic method to evaluate the time-dependent reliability and failure of concrete bridge elements. The probabilistic distribution of surface chloride concentration, diffusion coefficient, critical chloride concentration, and material variables were identified from literature. Monte Carlo simulation was employed for modeling the increases of live loads and the degradation of the component to obtain the time-dependent reliability curves for design service life. The methodology is further demonstrated by a pier column as an illustrative example. Results showed the reduction in resistance and the risk of failure periods. Further parametric studies showed that concrete cover depth and water-cement ratio have significant influence on the time-dependent probability of failure and reliability index. Overall, it has been shown that the methodology is generic and valuable information on residual capacity and time-dependent probability of failure can be applied to performance assessment and lifecycle for both new and existing structures. [ABSTRACT FROM AUTHOR]

Pile foundations are usually used when heavy superstructural loads have to be transmitted through weaker subsoil. Piles are also subjected to significant amounts of lateral loads and overturning moments besides axial loads. Lateral loads are in the order of 10-15% of the vertical loads in the case of onshore structures, whereas in the case of coastal and offshore structures, these lateral loads can exceed 30% of the vertical loads. Therefore, proper attention has to be given in designing such pile structures under lateral loads. In recent years, many investigations have addressed the externally bonded fiber-reinforced polymer composites for strengthening of concrete structures. This paper presents an experimental study on glass and carbon fiber-reinforced polymers (GFRP and CFRP) strengthened reinforced concrete (RC) piles subjected to cyclic lateral loads. The effects of GFRP and CFRP strengthening on RC piles were studied. The load deflection, stiffness degradation, and energy dissipation of piles are also presented. [ABSTRACT FROM AUTHOR]

The direct strength method (DSM) design rules for cold-formed steel members in shear have been incorporated recently into the North American specification for the design of cold-formed steel structural members and are being implemented in the Australian cold-formed steel structures standard. The method, which was calibrated for unperforated members only, requires two inputs including the buckling load Vcr and the shear yielding load Vy. For members with square web cutouts, Vcr can be computed by either the spline finite strip method or the tabulated values based on the shear buckling coefficients kv as in previous studies or the finite element method. However, Vy has not been accurately formulated including holes. This paper represents a practical model to obtain Vy for members with central openings subjected predominantly to shear. The model ranges from very small holes where traditional shear yielding predominates to large holes where Vierendeel action dominates. The model is verified with the DSM design formulas using the predominantly shear tests recently conducted at the University of Sydney and Queensland University of Technology with both square and circular web openings and for shear spans with aspect ratio of 1.0. [ABSTRACT FROM AUTHOR]

This paper investigates the limit states of a circular masonry arch supported on rectangular buttresses when subjected to lateral inertial loading in addition to gravity loading by employing the principle of stationary potential energy. Depending on the slenderness of the arch compared to the slenderness of the buttresses, the study identifies two lower failure mechanisms: (1) a four-hinge mechanism within the arch alone; and (2) hinging of the arch in three locations together with a hinge at the base of the downstream buttress. In this analysis, radial ruptures are assumed for the arch, while the buttresses may rupture either horizontally or develop an oblique elongation failure along which the compression-free portion of the buttress separates. It is concluded that the hinging mechanism that triggers an oblique elongation failure of the downstream buttress is the most critical and initiates at a lower value of the seismic coefficient than the value associated with the mechanism that involves a horizontal fracture at the buttress. Finally, it is shown that the discrete-element method (DEM) captures the results of the proposed variational method with remarkable accuracy. [ABSTRACT FROM AUTHOR]

Two full-scale, two-story, low-ductility steel concentrically braced frame (CBF) systems were tested to evaluate failure mechanisms, postelastic frame behavior, reserve capacity, and overall collapse performance. These frames were designed for a moderate seismic region, where reserve capacity is emerging as a parameter that can be employed instead of primary system ductility to economically prevent seismic collapse. One test unit used a split-x bracing configuration and satisfied seismic detailing and proportioning requirements in the AISC Seismic Provisions for an ordinary concentrically braced frame (OCBF) with R ¼ 3.25. The other test unit used a chevron CBF configuration with R ¼ 3 and included no seismic detailing. Each test unit was subjected to a quasistatic cyclic loading protocol and was cycled to total frame drifts in excess of 3.0%. The split-x OCBF exhibited ductile brace buckling behavior up to 1.5% total frame drift, but possessed little reserve capacity after two weld fractures. The R ¼ 3 chevron CBF exhibited brittle brace buckling and subsequently developed several distinct reserve capacity mechanisms. These tests demonstrate overall hysteretic behaviors that are highly dependent on two underlying design parameters: system type and system configuration. OCBF brace local slenderness and connection capacity design requirements are effective for providing ductile brace-buckling behavior. The split-x configuration appears more vulnerable to developing multistory mechanisms that possess limited reserve capacity, but this can be improved with strategically placed, enhanced beam-column connections. The chevron configuration is more prone to single-story mechanisms that possess significant reserve capacity developed through beam and column flexure. [ABSTRACT FROM AUTHOR]

In moderate seismic regions, engineers are permitted to use a response modification coefficient, R, of 3 in the design of steel systems without any specific seismic detailing or proportioning requirements. Recent research, however, has raised questions regarding the reliability of concentrically braced frame (CBF) systems designed using the R ¼ 3 provision because their performance under the maximum considered earthquake seismic hazard is inherently dependent on reserve capacity--lateral force-resisting capacity outside the primary seismic force-resisting system (SFRS). In a previous study by the authors, two full-scale two-story CBF tests were conducted to better understand seismic behavior and associated reserve capacity after significant damage in the primary SFRS. These tests were (1) an R ¼ 3 chevron; and (2) an R ¼ 3.25 split-x ordinary concentrically braced frame (OCBF). To complement the experimental program, a numerical parametric study was conducted to further distinguish the influence that two design parameters--system type and system configuration--have on overall system behavior including non-ductile limit states and reserve capacity. Although the prototype frames studied were designed for the same building and location, they exhibited a wide variety of limit states. The occurrence of particular classes of mechanisms and their associated reserve capacities was influenced by the system type and system configuration. Specific reserve capacity mechanisms depended on the location of damage within the primary SFRS. Predicting these damage locations is difficult because they depend on as-built weld overstrength. This paper explores the classes of reserve capacity mechanisms that were observed both experimentally and in the companion numerical simulations. [ABSTRACT FROM AUTHOR]

A new type of lightweight shear walls made with a laminated bamboo (glubam) stud frame and ply-bamboo sheathing panels is introduced in this paper. The lateral loading experiments of such shear walls and corresponding similar lightweight wood shear walls with three different panel-frame nailing connections and two thicknesses of sheathing panels were performed, in accordance with international standards. Test results demonstrate that the lightweight glubam shear walls have similar performance as conventional lightweight wood-frame shear walls, with higher initial stiffness and peak load, but less ductility. An increase in nail diameter can improve the load-bearing capacity of the shear walls until the failure mode of panel-frame connection changes from yielding of the nails to pull-through of nails from the ply-bamboo panels. Increased panel thickness can increase the bearing capacity and deformability of the shear walls when the failure pattern of panel-frame connection changes from panel failure to nail yielding. A new uplift hold-down device and improved design of edge studs were used to increase the ductile performance of glubam shear walls. [ABSTRACT FROM AUTHOR]

Longitudinal cracks in wood beams of heavy timber structures are commonly seen and can impair the load-carrying capacity of such beams. This paper presents the experimental and numerical modeling results on 35 pieces of full-scale wood beams with saw kerfs that simulate lengthwise checks. The influences of the checks and self-tapping screws used for retrofitting purposes were identified based on the normalized load-carrying capacity of the tested beams. It was found that a longitudinal check (up to 2/3 of the beam span) may cause a resistance loss up to 46.2% compared to an unchecked beam, and the use of self-tapping screws may increase the resistance to no less than 86% of that of an unchecked beam. A three-dimensional (3D) finite-element method based model was developed and verified to further quantify the stress intensity factor at the check tip. Based on the modeling and test results, a simple formula was established for prediction of the stress intensity factor, considering the geometry of the checks and the contribution of the self-tapping screws. The generated formula was verified with good agreement and therefore can be used for determination of the shear resistance of checked wood beams and the required screw spacing for retrofitting purposes. [ABSTRACT FROM AUTHOR]

In this study, cyclic triaxial tests under isotropic and anisotropic stress consolidation conditions were performed on Nuozhadu granular soil, and a constitutivemodel based on the Bouc-Wenmodel and endochronic theory was applied to investigate the dynamic stress-strain relationship and pore-water pressure of granular soils under cyclic triaxial stress states. In the isotropic stress consolidation condition, dynamic stress degradation occurred as a result of increased pore-water pressure and the reduction of effective stress. This paper presents the general validity of the model and its ability to describe several features of granular soil, including soil cyclic mobility, plastic strain accumulation, and stiffness and strength changes resulting from cyclic loading. Then, the equation of themodel and key model parameters related to soil behavior, such as hysteresis and contractive and dilative behaviors, are further discussed. The proposedmodel was used to simulate the dynamic stress-strain relationship, effective stress path, and increased pore-water pressure under undrained conditions. The numerical results were found to have good agreement with the experimental curves. [ABSTRACT FROM AUTHOR]

Because of the lack of adequate monitoring performance data for shield tunnel segments from either laboratory testing or in situ measurement, it is difficult to improve the current segment design codes. As a result, overdesign or excessive use of reinforcement in tunnel linings is common. To overcome these segment design inadequacies, this study aimed to investigate the bending behavior of RC members based on measured strain data and the modeling results from a proposed analytical model, which takes into account section nonlinearity resulting from concrete tensile cracking and the actual effective moment of inertia. The cyclic four-point loading test was performed on a RC beam with an embedded optical fiber sensor and on a smart tunnel lining segment, in which two vibrating wire strain gauges with thermistors were welded into a rebar cage on either side of the neutral axis. The measured strain data for the rectangular beam subject to concrete curing and subsequent four-point loading justify the applicability of the optical fiber sensor. The results of the load-moment relationship obtained from the model were found to be in good agreement with the theoretical solution, verifying the correctness of the proposed analytical model. Thismodel has been proposed to predict the bending behavior of the smart tunnel lining segment. The modeled load-deformation relationship matched reasonably well with the measured strain data, except for the modeled results of tensile strain after cracking. This discrepancy may have been caused by either the influence of the concrete tensile cracking on the local bonding condition at the concrete-sensor interface or the modeling difference of concrete tensile behavior. Despite the discrepancy between the modeling results and the measured strain data after cracking, the statistical parameters justify the application of the proposed analytical model to RC segment design and to the design of recently developed composite segments. [ABSTRACT FROM AUTHOR]

The uplift load test is the most widely used technique for assessment of the performance of micropiles. Although this static load test is easy to perform and interpret, it is expensive, slow to implement, and cannot be used systematically because it destroys the micropile. A new methodology based on a simple low-strain dynamic load test (LSDT) is proposed to develop a systematic and inexpensive method for assessment of performance of a large number of micropiles. The advantage of this methodology is that it is easy to carry out, requires lowimpact energy compared with a classical dynamic load test, and allows immediate interpretation. After describing the proposed methodology, the calibration, and the subsequent validation of the test method, results from full-scale micropiles at an experimental site and three real sites are presented. The results show that the methodology proposed allows confirming micropile performance under service loads in real time without disturbing the micropile. [ABSTRACT FROM AUTHOR]

The accuracy of energy estimation using building energy models is contingent on user inputs. Depending on the situation, energy models may use plug-load densities that are unsubstantiated for the specific building type and space conditions. A common standard in the literature lists plug-load density for educational facilities as 1 W/squarefoot (sf). However, plug-loads have changed because of technological advancements and the frequency and types of equipment usage. It is crucial to develop plug-load densities at the space level based on their functionality, especially with the current very limited knowledge of spaces and their equipment energy usage. This is particularly true for educational buildings situated on university campuses. They house a variety of spaces, such as classrooms, offices, study rooms, imaging rooms, auditoriums, lounges, teaching laboratories, etc. Through detailed sensing and monitoring of two educational buildings on a university campus, this paper discusses the methodology to calculate space-level plug-load densities. Furthermore, this paper compares the plug-load density values of university campus educational buildings calculated in this study with previous studies. [ABSTRACT FROM AUTHOR]

This paper provides results of a comprehensive investigation into the use of waste carpet fibers for reinforcement of clay soil slopes. The interaction between laboratory scale model slopes made of fiber-reinforced clay soil and surface strip footing load was examined. Results for the influence of two variables, namely fiber content and distance between the footing edge and the crest of the slope, are presented and discussed. The particle image velocimetry (PIV) technique was used to study the deformation of the slope under the surface loading. The front side of the tank was made of a thick Perspex glass to facilitate taking accurate images during the loading stage. To study the stress induced in the slope under footing pressure, excess pore-water pressure and total stress increase were measured at predetermined locations within the slope. The results showed that fiber reinforcement increased the bearing resistance of the model slope significantly. For instance, inclusion of 5% waste carpet fiber increased the bearing pressure by 145% at a 10% settlement ratio. [ABSTRACT FROM AUTHOR]

An empirical nondimensional reduction factor is proposed in this paper, which can be used for determining the ultimate bearing capacity of eccentrically and/or obliquely loaded shallow strip foundations embedded in sand. This was developed after analyzing a series of laboratory model test results available in the literature on strip foundations. The depth of foundation (D), eccentricity of load (e), and inclination of load (a)varied from 0 to 1B, 0 to 0.5B, and 0 to 20°, respectively, where B refers to the width of foundation. The proposed reduction factor was found to provide reasonably well results for calculating the ultimate bearing capacity of shallow strip foundation under eccentric and/or inclined loads. The results obtained by using the proposed method have been found to be in good agreement with widely used traditional methods available in the literature. [ABSTRACT FROM AUTHOR]

A two-dimensional elastoplastic analytical model of stress-strain analysis of the pipeline under strike-slip faults was established based on the plastic flow theory and elastoplastic-beam theory, considering the effects of service loads and the nonlinearities of the pipeline and the pipe-soil interaction. According to the plastic flow theory, the axial, radial, and hoop plastic strains were derived, and the stress-strain relation was established under the plane stress state. The axial stress and strain of the pipeline induced by fault displacements were analyzed based on the elastoplastic beam theory. Additionally, the axial stresses, hoop stresses, and strains induced by the service loads (i.e., the internal pressure and the temperature variation) were also considered. The proposed model was verified by comparing the analytical results and the finite-element results. The results show that the proposed model can predict accurately the mechanical response of the pipeline subjected to strike-slip fault displacements, with minor deviations of within 10%. [ABSTRACT FROM AUTHOR]

The use of p-multipliers in the analysis of the lateral loading behavior of pile groups is based on the concept of modifying the singlepile p-y curve to obtain the p-y curve for a pile in a group. The p-multipliers account for the reduced soil resistance mobilized at a given deflection as a result of overlapping of shear zones. Different factors can influence the p-multipliers; however, because of the lack of experimental data, most researchers and design guidelines consider only the normalized pile spacing in the direction of loading in their recommendations. In this study, the effects of pile spacing and clay stiffness on the p-multipliers were investigated using the results of two series of centrifuge tests. The soil profile consisted of four lightly overconsolidated clay layers overlying a dense sand layer. The pile groups had a symmetrical layout consisting of 2 × 2 piles spaced at center-to-center distances of 3.0 and 7.0 pile diameter (D) and were driven into improved (stiff clay) and unimproved soft clay. Ground improvement was done in situ using simulated cement deep soil mixing (CDSM). Computer analyses were performed to back-calculate the p-multipliers. There was very good agreement between the measured and computed responses for both the leading and trailing rows of piles in the unimproved and improved soft clay. The results reveal that increasing the clay stiffness and pile spacing in the direction of loading increase p-multipliers. No pile-soil-pile interaction was observed for the 7D spacing. The proposed set of p-multipliers for the soft clay was found to be in close agreement with some current guidelines, whereas other design guidelines appear to recommend relatively conservative values of p-multipliers for both soft and stiff clay (improved ground). [ABSTRACT FROM AUTHOR]

This paper presents the results from a series of physical modeling and three-dimensional finite-element (FE) analyses in which the authors examined the uniaxial vertical capacity of suction caissons for offshore wind turbines. The experiments were carried out in quartz sand and involved monotonic application of vertical load. It was found that the drained capacity of suction caissons is dependent on embedment ratio. In contrast, predictions from conventional semiempirical depth factors were found to somewhat underestimate when applied to rough foundations. On the basis of the tests and FE analyses, new expressions for the depth factor of shallow foundations were validated for embedment ratios (aspect ratios) up to unity, calibrating the fitting parameters by using data from a range of soil profiles. [ABSTRACT FROM AUTHOR]

This paper reports a novel concept of ground improvement technique using cemented stone columns for improvement of the soft clay ground. The experimental investigations and analytical studies led to evolution of the technology of soft ground improvement using such stone columns almost to the fullest extent. The study included the following aspects: relative degree of effectiveness of cemented stone columns over other reported approaches, theoretical analysis for predicting the ultimate load-carrying capacity of soft clay ground treated with cemented stone columns, analysis to estimate the probable short- and long-term settlements of a given structure founded on the treated ground under the applied foundation pressure intensity, and an illustrative design problemusing this technology. The failuremode and the load-transfer mechanism for this system were conceptualized on the basis of the unit-cell concept. The mathematical formulation resulted in equations enabling quantitative evaluation of the required design aspects related to the actual design of cemented stone column-soft clay systems. [ABSTRACT FROM AUTHOR]