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The serviceability limit of the foundation system plays an important role in the safe long-term performance of a building. Under governing load cases in service life, the building foundation system should satisfy the serviceability limit state, i.e., total and differential settlement criteria. This study investigated the distress of a building through foundation performance assessment incorporating the soil–foundation–structure interaction (SFSI) effects. A spatially variable soil model [zonewise, obtained from field observation and electrical resistivity tomography (ERT) study] was used to obtain the settlement of the foundation system. Engineering properties of the subsurface were estimated from the collected soil samples and field tests. ERT result shows the variability of the subsurface layer. A three-dimensional finite-element model of soil, foundations, and structures was developed to estimate the settlement demand of the foundation and structures. The numerical model includes the geometric variability of all the foundations of the building and subsurface variability. Settlement and bearing capacity demand of the foundations were estimated and compared with the standard provisions. Results obtained show that the building foundation system satisfies the serviceability limit of the foundation system under total settlement criteria. However, the differential settlement of the system exceeds the required limit despite considering the SFSI effects, and is one of the major causes of distress to the building. The main contributions of this study also include establishing the spatial variability of the soil layer through ERT and correlating it with the crack zone in the building. [ABSTRACT FROM AUTHOR]

Monopiles are the most commonly used foundation type for offshore wind turbine (OWT) structures and are characterized by relatively large geometric dimensions, compared with offshore pile foundations typically used in the oil and gas industries. To date, there are no established technical guidelines tailored for the design and analysis of OWT monopiles. This paper first identifies various intrinsic drawbacks involved with the existing design and analysis methodologies as applied to OWT monopiles. Next, a comprehensive experimental program of 1g repeated lateral load tests, performed on a scaled rigid monopile installed in dry sand beds, is presented to investigate its behavior under various loading scenarios. The experimental results provide insights into the various blurry issues in the existing literature related to monopile behavior under long-term repeated lateral loading. Lateral soil resistance profiles were determined from the measured pile bending strain data and found to be markedly dependent on the degree of the polynomial function used for curve-fitting of the bending strain data. Finally, an experimental model is presented for estimation of the pile's accumulated rotation, which takes into account various basic characteristics of the applied lateral load cycles. [ABSTRACT FROM AUTHOR]

Difficulties in obtaining high-quality soil samples from offshore sites and heavy involvement of lab testing and engineering judgment have necessitated increasing reliance on in situ penetrometer tests, giving continuous penetration resistance profiles. This paper reports a framework for estimating spudcan penetration resistance directly from continuous resistance profile of a full-flow penetrometer (T-bar) test in single-layer clays and calcareous silts. The framework was validated chiefly against centrifuge test data, supplemented by some reported field data. [ABSTRACT FROM AUTHOR]

Ground movements observed during foundation installation and basement construction of a residential 53-story RC tower are presented. The One Museum Park West building is located in Chicago, Illinois, and was developed using a combination of bottom-up methods, used for the construction of a central concrete core of the building, and top-down methods to build five levels of basements. The excavation extended 13-15 m below grade and was made through soft to medium-stiff clays. The building was supported by drilled shafts and a perimeter wall formed by secant piles that transitioned to tangent piles below the bottom of the cut. The system was laterally braced with RC floor slabs structurally connected to the secant pile walls and the RC core. Field performance data were collected by means of settlement points and inclinometers located close to the walls on two sides of the excavation. The construction sequence and attendant ground movements during each main activity are summarized. As much as 160 mm of settlement was recorded in the adjacent streets throughout construction. Wall and foundation installation accounted for approximately 35% of the total settlements during construction, whereas top-down construction of the basement resulted in approximately 40% of the total settlements. These data emphasize the importance of considering all construction activities when making predictions of ground movements adjacent to deep supported excavations. [ABSTRACT FROM AUTHOR]

This paper reports advances in the prediction of spudcan resistance profiles during installation and preloading, based on the soil flow mechanisms observed in model tests and numerical analysis, and taking into account strain softening and rate dependency on the soil strength. Deep penetration of spudcan foundations was simulated for 14 case histories reported from different locations in the Gulf of Mexico, where the soils were single layer, predominantly normally to lightly overconsolidated clay. Axisymmetric and three-dimensional analyses were carried out using two large deformation finite-element (LDFE) approaches, modifying the simple elastic-perfectly plastic Tresca soil model to allow strain softening and strain-rate dependency of the shear strength. The field data were compared with the results of the finite-element analyses and with predictions using various design approaches. Excellent agreement was found, particularly when a mechanism-based design approach was used that differentiated between conditions before and after backflow of soil above the penetrating spudcan. [ABSTRACT FROM AUTHOR]

Successful waterproofing of concrete foundations prevents the degradation of environmental and health conditions and of building materials used in belowground stories and extends the service life of concrete constructions. However, despite the important role of waterproofing systems for concrete foundations and the fact that repairing them is either impractical or prohibitively expensive, there is very little useful information or discussion on membrane properties and the detailing required for a durable, watertight design. This paper presents a discussion of the requirements of waterproofing membranes and the auxiliary components used in waterproofing systems for concrete footings, mat-slabs, and pile foundations, along with a schematic representation of suggested systems and their detailing. Flexibility and mechanical resistance are particularly important and reasonably well-documented properties of buried waterproofing membranes, but knowledge of their long-term durability presently relies mostly on empirical data. The cost analysis of some of the suggested waterproofing systems revealed significant differences that, along with the other data presented, should aid building designers and contractors with the design and installation of effective waterproofing solutions for concrete foundations. [ABSTRACT FROM AUTHOR]

The exposure of pier foundations owing to scour significantly reduces the foundation-bearing capacity and diminishes the flood-resistant capacity of a bridge. This paper proposes a nonlinear quasi-static analysis procedure for the performance of bridges with pile foundations under flow-induced loads for the evaluation on the flood-resistant capacity of scoured bridges. The Winkler beam model is adopted for the modeling of the pile-soil system, and the distributed hinge model is utilized to simulate the possible flexural failure of the piles. Soil springs with nonlinear curves are used to represent the nonlinearity of the supporting soil. To demonstrate this procedure, a case study on the Shuang-Yuan Bridge in Taiwan was performed for various flood and scour conditions. This bridge was partially demolished in a major flood event caused by Typhoon Morakot in 2009. According to the analysis results, a possible scenario for the failure of the Shuang-Yuan Bridge is presented, and the proposed method is shown to give a reasonable assessment of the flood-resistant capacity of bridges with scoured pile foundations. [ABSTRACT FROM AUTHOR]

Difficulties are often encountered in a variety of seabed sediments during extraction of spudcan foundations of mobile jack-up rigs. This paper reports results from centrifuge model tests undertaken to provide insight into spudcan foundation behavior during vertical extraction through single, double, and multilayer soils. The model tests included half-spudcan tests against a transparent window, allowing the soil flow to be captured continuously by a digital camera and subsequently quantified through particle image velocimetry (PIV) analysis and separate full-spudcan tests to measure the uplift resistance. The observed soil-failure mechanisms provide insight with respect to the profile of extraction resistance. The mechanisms reveal evolving failure modes at different spudcan extraction depths and, in particular, changes in the failure patterns because of varying layer geometry, soil types, and properties. For single, double, and multilayer clays, suction at the spudcan base, shearing along a truncated cone above the spudcan, and weight of the soil above the spudcan constitute the extraction resistance. Maximum extraction resistance occurs in the stiffer soil layer. The extent to which suction is sustained at the spudcan base is critical in determining the extraction resistance. The presence of a sand layer beneath the penetrated spudcan, for example as part of the soil plug pushed down during spudcan penetration, allows the base suction to be released within a short distance of uplift and results in relatively low extraction resistance. Improved understanding of spudcan extraction mechanisms through layered soils resulting from this study will allow development of analytical solutions to model spudcan extraction behavior, assisting jack-up operators to plan properly for leg extraction based on seabed conditions. [ABSTRACT FROM AUTHOR]

The remarkable construction skills of the Inca are manifested in the superb site preparation, foundation design, and drainage of Machu Picchu. Decade-long field studies at the pre-Columbian archaeological site of Machu Picchu revealed that the Inca possessed the ability to prepare for structures that endure. This is evident in the vast amount of Inca construction that still exists for engineers to study and admire. Inca construction was sustainable because of their high standard of care, even in the absence of a written language, use of the wheel, or availability of iron or steel. This paper contains examples of good ancient site preparation, foundations, and drainage at Machu Picchu and details of a foundation failure and an ancient landslide. These examples serve to illustrate the site's challenging conditions for construction and the remarkable skills of the Inca engineers in addressing these difficulties. [ABSTRACT FROM AUTHOR]

Many of the older bridges in the United States have no original contract documents available, and about 26,000 bridges that are rated as scour critical have unknown foundation conditions. Thus, no information is available regarding the type, depth, geometry, or material of these scour critical bridge foundations. The unknown bridge foundations pose a significant problem to bridge owners because of safety concerns. This paper presents the determination of an unknown bridge foundation depth at Forth Worth, Texas. The bridge was supported by driven steel H-piles. Three nondestructive testing (NDT) techniques were utilized: (1) the parallel seismic (PS) method, (2) the sonic echo (SE) method, and (3) resistivity imaging (RI). The main objective of this present study was to compare the suitability of NDT techniques to determine the unknown bridge foundation depth. Based on the field test results, both PS and RI methods provided foundation depth close to actual foundation depth. However, the SE method was determined to be unsuitable for determining the unknown steel H-pile depth. [ABSTRACT FROM AUTHOR]

Construction on expansive soils is challenging and thus prone to some problems and litigation. The engineering community makes extensive use of local experience and empirical procedures to address these problems. Although there has been extensive study of expansive soils and foundations on expansive soils, data related to performance of residential structures are limited in general and limited in the Phoenix area, in particular. In this study, an overview of the Phoenix Valley, Arizona, geotechnical practice and foundation performance related to residential structures on expansive clays, was developed through surveys and interviews with geotechnical engineers, structural engineers, and homebuilders. Using data obtained from files of Phoenix area geotechnical firms and government agencies, the existing Natural Resource Conservation Service map showing expansive soil locations throughout the Phoenix region was updated through the use of correlation developed in this study relating expansion index to common soil index properties such as Atterberg limits and percent passing the No. 200 sieve. Files of forensic investigations linked to expansive soil regions were made available for this study by several geotechnical engineering firms, and Phoenix Valley areas where forensic investigations have been identified, were mapped for comparison to regions identified in the updated map as having expansive soils. Comparison of the forensic investigation map to the updated map of expansive clay locations revealed that most of the forensic investigations were in regions identified with clays labeled as high to moderately high expansion potential, with a few forensic investigations in regions of medium expansion potential. Finally, unsaturated flow analyses were conducted for an Arizona expansive clay profile for two very different landscaped conditions of well-irrigated turf and desert landscape. The results of the numerical analyses were consistent with the reported observations and modes of failure identified through the surveys and interviews conducted with engineering and homebuilder professionals, including the finding that site drainage was found to be extremely important to good foundation performance, regardless of the type of landscape selected. [ABSTRACT FROM AUTHOR]

This paper will focus on the legal liability issues facing the professional engineer engaged in the design and construction administration of facilities built on expansive soils. These legal liability issues will be discussed from the perspectives of the geotechnical, civil, and structural engineer to alert those professionals to the legal ramifications of their daily activities. By focusing on these legal aspects facing the engineers that are involved in the process of building on expansive soils, hopefully litigation can be avoided or successfully defended. Attention to the legal ramifications of engineering is mandated by today's litigious environment in the construction industry, especially when designing and administering the construction of facilities built on expansive soils. [ABSTRACT FROM AUTHOR]

This paper examines the background, history, and results of multiple investigations associated with pyrite-based expansive soils spanning almost 40 years in conjunction with a private elementary school located in western Pennsylvania. The school was initially designed in 1960. Original construction was completed in September 1961 and the first signs of distress, which were primarily related to slab heave, were reported in early 1962. One wing of the school, a 1965 classroom addition (1965 addition) with different structural and foundation systems, did not experience any expansive soil-related damages and served as a valuable comparison throughout multiple subsequent investigations. Pyritic soil material in the subgrade in conjunction with oxygen-rich groundwater was determined to be the cause of soil movement and building distress. Expansive soil-related problems at the school continued for decades despite an investigation, civil court action, and judgment in the late 1960s followed by a remediation program in the 1970s and 1980s. Following a second round of investigations and litigation in the late 1990s, all of the original classroom, office, and gymnasium building sections, with the exception of the 1965 addition, were demolished in late 2000 and early 2001 based on safety concerns and economic evaluation. Investigation and monitoring to confirm subgrade conditions continued throughout the demolition process. As a part of this paper, the history of this case dating back to one of the early identifications of pyrite as an expansive element of concern in building construction, including one of the earliest comprehensive identifications of the complete chemical-microbiological oxidation process is presented. The initial 1960s investigation and conclusions are identified as well as the series of engineering, procedural, and construction errors that took place during and after the first remediation process that led to ongoing soil expansion and structural damage, including misguided actions and misunderstandings that complicated and delayed a final resolution in this case. Today, the industry is more familiar with the potential for pyrite-related construction problems, nevertheless, the paper incorporates lessons learned for avoiding problems and in particular, the procedural failures that led to the eventual need to abandon and demolish the school facility. [ABSTRACT FROM AUTHOR]

The effect of foundation embedment on consolidation has not been considered previously in a systematic manner, although this is of particular interest for offshore foundations, where embedment is provided by skirts that enclose a compressible soil plug. For skirted foundations, critical uncertainties include what to assume in terms of the degree of drainage at skirt tip level, and the relative time scales of consolidation within the soil plug and beneath the foundation. In this paper, results from small strain finite-element analyses are used to quantify the immediate and time-dependent response of circular skirted foundations to uniaxial vertical loading. Foundations with frictionless and fully rough skirt-soil interfaces with varying ratio of embedment depth to foundation diameter are considered and the responses compared with those for surface foundations. The findings show that both skirt-soil interface roughness and embedment ratio have a significant effect on the consolidation response. [ABSTRACT FROM AUTHOR]

This paper presents an analytical solution for the consolidation of soft soil foundations reinforced by stone columns under time-dependent loadings. The differential equations of the foundations reinforced by stone columns are obtained including smear and well resistance under arbitrary applied loadings. The closed-form solutions of pore pressure and the overall average degree of consolidations are obtained for some common types of loadings, such as step loading, ramp loading, and cyclic trapezoidal loading. By solving the equations using a semianalytical method, the comparisons agree very well with the existing analytical solutions, which verify the correctness and accuracy of the proposed methods. Using the solutions obtained, some selected charts are presented and the relevant consolidation behavior is investigated and discussed. [ABSTRACT FROM AUTHOR]

A matrix formulation to determine the coupled response of rigid foundations where soil properties are modeled by springs and dashpots is presented. Location and orientation of springs and dashpots can be arbitrary, thus a general solution is determined. The response is given in terms of translational and rotational displacements considering coupled effects. Physics of the problem presented here has been extensively studied and a broad range of useful formulae to determine springs and dashpots properties for soil-structure interaction is available. These published formulae for springs and dashpots properties are an input to the approach presented. Thus, the novelty of this approach is a matrix manipulation that leads to a simple expression allowing coupling all degrees of freedom even when springs and dashpots are not orthogonally oriented. For validation purposes, finite element solutions are compared with the approach presented. [ABSTRACT FROM AUTHOR]

This paper is concerned with the vertical vibration of a flexible foundation resting on a saturated layered soil half-space that consists of a dry soil layer and an underlying semi-infinite saturated soil. The problem is of the mixed boundary value type and, by means of the Hankel transform technique, the determination of dynamic compliance coefficient and contact stress distribution leads to a pair of dual integral equations. These equations are then reduced to a Fredholm integral equation of the second kind, which is solved by standard numerical procedure. Some limiting cases existing in the literature are revisited to validate the accuracy of the present solution. Extensive numerical results are presented to illustrate the influences of the thickness of the overlying dry soil, the foundation flexibility, and the shear modulus ratio between dry and underlying saturated soils on the dynamic responses of the flexible foundations. [ABSTRACT FROM AUTHOR]

The aim of this contribution is a practice-oriented prediction of environmental building vibrations. A Green’s functions method for layered soils is used to build the dynamic stiffness matrix of the soil area that is covered by the foundation. A simple building model is proposed by adding a building mass to the dynamic stiffness of the soil. The vertical soil-building transfer functions with building-soil resonances are calculated and compared with a number of measurements of technically induced vibrations of residential buildings. In a parametrical study, realistic foundation geometries are modeled and the influence of incompressible soil, deep stiff soil layering, soft top layers, and increasing soil stiffness with depth is analyzed. All these special soil models reduce the resonant frequency compared to a standard homogeneous soil. A physically motivated model of a naturally sedimented soil has a stiffness increasing with the square root of the depth and yields a foundation stiffness that decreases with foundation area considerably stronger than the relatively insensitive homogeneous soil. This soil model is suited for the Berlin measuring sites and reproduces satisfactorily the experimental results. [ABSTRACT FROM AUTHOR]

Penetration of skirts is an essential design issue for offshore skirted foundations and anchors in sand. Skirts may not penetrate far enough into dense sand by the available submerged weight alone. It may therefore be necessary to apply underpressure inside the skirt compartment to produce an increased driving force and to reduce the penetration resistance. This paper recommends procedures to calculate penetration resistance and required underpressure for skirts penetrated in dense sand with and without interbedded clay layers. The recommendations are based on interpretation of skirt penetration data from prototypes, field model tests, and laboratory model tests in dense sand. The paper first presents a model to calculate the penetration resistance of skirts penetrated by weight, or other external vertical load that does not cause flow of water in the sand. Two models are considered; one based on bearing capacity equations with friction angles from laboratory tests, and the other one based on empirical correlations with CPT tip resistance. The bearing capacity model gives more consistent correlations with the empirical data than the CPT model. Thereafter, a model to account for the effect of underpressure applied inside the skirt compartment is proposed. This model is developed based on interpretation of available prototype and model test data from skirts penetrated by underpressure. The results show that underpressure facilitates skirt penetration in sand considerably by providing both an additional penetration force and a reduced penetration resistance. It is also shown that interbedded clay layers can prevent flow of water through the sand and eliminate the beneficial reduction in penetration resistance. [ABSTRACT FROM AUTHOR]

The effect of interface friction angle (δ) between the footing and underlying soil mass on the bearing capacity factor Nγ was examined by using the upper bound limit analysis, finite elements, and linear programming. The analysis was carried out by employing velocity discontinuities along all the interfaces of the chosen triangular elements. The development of the plastic strains within elements was incorporated by using an associated flow rule. It was clearly noted that an increase in δ leads to a continuous increase in Nγ. With δ=[lowercase_phi_synonym], the magnitude of Nγ becomes almost the same as that for a perfectly rough foundation, that is, when no slippage takes place between the footing and underlying soil mass. The size of the plastic zones increases with increase in δ and [lowercase_phi_synonym]. The obtained values of Nγ, for perfectly smooth and perfectly rough footings, compare quite favorably with those reported in literature. The study demonstrates that in the case when δ is smaller than [lowercase_phi_synonym], the assumption of a perfectly rough footing will lead to an unsafe prediction of the ultimate bearing capacity. [ABSTRACT FROM AUTHOR]

The effect of interface friction angle (δ) between the footing and underlying soil mass on the bearing capacity factor Nγ was examined by using the upper bound limit analysis, finite elements, and linear programming. The analysis was carried out by employing velocity discontinuities along all the interfaces of the chosen triangular elements. The development of the plastic strains within elements was incorporated by using an associated flow rule. It was clearly noted that an increase in δ leads to a continuous increase in Nγ. With δ=[lowercase_phi_synonym], the magnitude of Nγ becomes almost the same as that for a perfectly rough foundation, that is, when no slippage takes place between the footing and underlying soil mass. The size of the plastic zones increases with increase in δ and [lowercase_phi_synonym]. The obtained values of Nγ, for perfectly smooth and perfectly rough footings, compare quite favorably with those reported in literature. The study demonstrates that in the case when δ is smaller than [lowercase_phi_synonym], the assumption of a perfectly rough footing will lead to an unsafe prediction of the ultimate bearing capacity. [ABSTRACT FROM AUTHOR]

The present paper addresses a foundation problem in seismic resistant buildings braced by structural walls. In particular, the box-type foundation for an internal shear wall is investigated. This kind of foundation can be an alternative solution for direct foundations. It solves the problem where oversized ordinary raft foundations are needed. In fact, the box foundation gathers the gravity loads resting on the peripheral walls, so that the global soil reaction reduces its eccentricity. In most cases the elements constituting the box structure, such as peripheral walls, raft, and ground floors, are already part of any actual building; they only need a proper seismic design, which is herein proposed. A simplified theoretical approach is presented to allow a correct proportioning and design of each structural element, such as reinforcing ribs and panels constituting the box. Moreover, the solution given by this analytical procedure can be useful to check the reliability of any numerical analysis. Since the analytical approach is based on equilibrium conditions, it can be easily extended to the ultimate loading state. A practical application is finally presented for a seven floor building where both the shear walls and the box foundation are subjected to a severe seismic action. [ABSTRACT FROM AUTHOR]

The ultimate bearing capacity of two interfering strip footings was determined by using the method of stress characteristics. The analysis was performed by choosing two different possible failure mechanisms. The variation of the efficiency factor (ξγ) was computed with respect to change in the clear spacing (s) between the two footings. For a given s/B, the value of ξγ predicted on the basis of Mechanism 1 was always found to be smaller than those on the basis of Mechanism 2. For Mechanism 1, the maximum value of ξγ, which becomes always equal to 2.0, always occurs at s/B=0. On the other hand, the Mechanism 2 provides maximum value of ξγ even greater than 2.0, especially with [lowercase_phi_synonym]>20°, corresponding to s/B=scr/B. It was noted that the results from Mechanism 2 compare more closely with the theory of Stuart in 1962 and with the recent upper bound limit analysis solution of the writers. [ABSTRACT FROM AUTHOR]

A new full two-dimensional semianalytical method is developed to rigorously and efficiently solve the problem of a rigid cylinder rolling with any given constant speed over a viscoelastic foundation of finite thickness. In this new method, the solution is expanded into a set of Fourier series, the master curves of G′ and G″ characterizing the general viscoelastic properties for a viscoelastic material are used to relate Fourier coefficients, and a special boundary element based on the Fourier series is developed to handle viscoelasticity and the rolling contact boundary condition. A verification example is given to validate the methodology. Several numerical examples are given to study the influences of various factors on rolling resistance. The method as well as the conclusions drawn from the examples may be of interest to roller and belt-conveyor designers. This approach can be easily generalized to solve the general rolling contact problems of two viscoelastic bodies. [ABSTRACT FROM AUTHOR]

The paper examines the dynamic response of flexible conventional pavement systems to single wheel traffic loads in terms of the pavement design criteria, namely the fatigue strain at the bottom of the asphalt concrete layer and rutting strain at the top of the subgrade material. Model setup including geometry, boundary conditions, and load wave characterization are presented. The effect of elastoplasticity of the base material and elastoplasticity with strain hardening of the subgrade material on the dynamic response of the pavement system are first investigated. A detailed model parametric study then follows to show the effect of the base strength and thickness and the subgrade quality on the fatigue and rutting strains and the vertical surface deflection. The study, conducted with program ADINA, employs a three-dimensional, implicit dynamic, finite element method. [ABSTRACT FROM AUTHOR]

A new method is suggested to obtain approximate explicit expressions for the dynamic stiffness of rigid foundations on the surface of layered media. The method uses the dynamic stiffness matrices for layered media to compute the surface displacements due to two assumed stress distributions under the foundation and applies weighted residuals to obtain an optimum combination of the two solutions. Comparison with more rigorous “exact” solutions and some approximate methods shows the accuracy of the new method that is computationally very efficient. [ABSTRACT FROM AUTHOR]