Abstract: Load sharing of piled raft foundations is known as an economical design for deep foundations. Nevertheless, research in this area has been lagging because of the complexity of the problem and lack of field data. Numerical modeling can be used to provide valuable data with a high level of success. A three-dimensional finite-element model of a piled raft foundation was developed to simulate the case of a piled raft foundation. The model accounts for pile-to-pile, raft-to-pile, pile-to-soil, and raft-to-soil interactions. The model was used to examine the effect of the key parameters governing the performance of this foundation during loading and, accordingly, the load shared by the piles and the raft. After validating the numerical model with available data in the literature, the model was used to develop data for a wide range of parameters and to examine the role of the foundation geometry, including pile spacing in the group, pile length, pile shape, pile diameter, and raft thickness. Furthermore,...

Abstract: Accurately predicting risks during the construction of deep foundation pits is pivotal to ensuring the safety of the workforce of public and adjacent structures. Existing methods for assess...

Abstract: Sofja Kovalevskaja Award from the Alexander von Humboldt Foundation of Germany US National Science Foundation AST-1311862

Abstract: This book provides a comprehensive guide to the design of foundations for tall buildings. After a general review of the characteristics of tall buildings, various foundation options are discussed followed by the general principles of foundation design as applied to tall buildings. Considerable attention is paid to the methods of assessment of the geotechnical design parameters, as this is a critical component of the design process. A detailed treatment is then given to foundation design for various conditions, including ultimate stability, serviceability, ground movements, dynamic loadings and seismic loadings. Basement wall design is also addressed. The last part of the book deals with pile load testing and foundation performance measurement, and finally, the description of a number of case histories. A feature of the book is the emphasis it places on the various stages of foundation design: preliminary, detailed and final, and the presentation of a number of relevant methods of design associated with each stage.

Abstract: Generally, the maximum differential settlement appears at the overlapping area of existing and new road pavement after highway widening project. However, lots of longitudinal cracks and other kinds of distresses were found on the existing pavement after the widening project of Guangsan Highway. The field investigation was carried out to find out the reason that the large settlement appeared on existing lanes induced by the weak foundation under the existing lanes, which leaded the cracks observed on the existing pavement. In addition, numerical method was adopted to verify this explanation. The parameter sensitivities were studied to discuss the characteristics of subgrade settlement after the highway widening project. Factors considered include different layouts of cement-fly ash-gravel (CFG) piles, different strengths of CFG piles and different filling materials of new embankment. The results showed that the settlement of pavement became larger when the existing road has weaker foundation. The maximum settlement on the ground surface shifts toward the new embankment when the foundation of existing road has higher strength. The lightweight filling material was proved to have advantage in reducing the settlement of the existing embankment.

Abstract: Unlike the use of bonded reinforcement to anchor a masonry wall to its foundation, the use of unbonded posttensioning may result in a controlled rocking response of the wall. Considering th...

Abstract: The present work explains the use of a piled-raft foundation in a raw materials storage building in South Ba Rịa–Vũng Tau Province of Vietnam. The proposed foundation comprises an 81 m by 55·5 m raft that connects 581 precast hollow concrete piles 20 m long with 400 mm outer diameter. The proposal takes into consideration a specific in situ soil profile and a loading scenario. After the effectiveness of a single bay of the foundation had been checked, the entire foundation system was modelled using finite-element-based geotechnical software to enable a detailed soil–structure interaction analysis. Field pile load test data were used to validate the finite-element model. Various loading conditions, such as all compartments full to all compartments empty, were considered in the analysis. The results of the analyses indicate the importance of the raft in sharing 23–31% of the total vertical load. The results obtained – such as vertical settlement, differential settlement, tilt in the raft and axial load in t...

Abstract: Excavation-induced ground settlement causes adverse impact or damage on adjacent facilities. If a foundation pit is connected to the facilities, the responses of the facilities can be influ...

Abstract: This paper presents two case studies of the dynamic response of a ballastless track, X-section cast-in-place concrete (XCC) pile–raft (referred to as BTXPR) foundation embedded in sand subsoil. Mod...

Abstract: Bottom-fixed offshore wind turbines (OWTs) involve a wide range of engineering fields. Of these, modelling of foundation flexibility has been given little priority. This paper investigates the modelling of bottom-fixed OWTs in the non-linear aero-hydro-servo-elastic simulation tool FAST v7. The OWTs considered is supported on a monopile. The objective of this paper was to implement a non-linear foundation model in this software. The National Renewable Energy Laboratory's idealized 5MW reference turbine was used as a base for the analyses. Default modelling of foundation in FAST v7 is by means of a rigid foundation. This implies that soil stiffness and damping is disregarded. Damping may lead to lower design loads. A softer foundation, on the other hand, will increase the natural periods of the system, shifting them closer to the frequencies of the environmental loads. This may in turn lead to amplified moments at the mudline. Therefore, it is important to include soil stiffness and damping in analyses. In this paper, a non-linear foundation model is introduced in FAST v7 by means of uncoupled parallel springs. To verify that the implementation is successful, non-linear load-displacement curves of the foundation spring are presented. These show the typical hysteresis loops of an inelastic material, which confirms the implementation. Copyright © 2016 John Wiley & Sons, Ltd.

Abstract: The full potential of pile optimization has not been realized as the interactions between superstructures and foundations, and the relationships between material usage and foundation performance ar...

Abstract: The response of wind turbines is induced by dynamic loads such as wind, transient and cyclic loads, and also extreme loads such as earthquakes. Thus, the structural design requires an accurate evaluation of the modal parameters of the system because it is strongly required that no resonances are excited. Moreover, it has been concluded from previous research works that soil–structure interaction (SSI) should be accounted for the analysis. In the present paper, the structural dynamic response of wind turbine towers is investigated considering different soil conditions using a numerical model. This research is focused on SSI effects. Firstly, changes in the modal parameters of three different wind turbines considering the effect of three soils are evaluated. The results show that the evaluation of the natural frequency and the resulting classification of the wind turbine design type can be affected by SSI. The obtained results could be used to evaluate the decrement of the natural frequency of the wind turb...

Abstract: The lateral bearing behaviors of suction bucket foundations for offshore wind turbines are investigated by centrifuge modelling in this paper. The centrifuge tests were performed in lightly over-consolidated clay and heavily over-consolidated clay, and three bucket foundation models with aspect ratios of 0.38, 0.5, and 1.3 were tested. The tests were force-controlled, and both static loads and cyclic loads were applied. In static tests, ultimate bearing capacities of suction bucket foundations were extracted from load-displacement curves as the first method, and the results were reinforced by stiffness-displacement curves. The displacement rates were calculated to find critical bearing capacities and ultimate bearing capacities of the foundations as the second method. The cyclic tests include cyclic loads with uniform and increased amplitudes. The accumulated lateral displacements and secant stiffnesses were discussed, and their variations with cycle numbers were studied.

Abstract: A new analytical solution for ground surface settlement induced by deep excavation is proposed based on the elastic half space Melan’s solution, and the analytical model is related to the physical and mechanical properties of soil with the loading and unloading action during excavation process. The change law of earth pressure of the normal consolidation soil after the foundation pit excavation was analyzed, and elastic displacement calculation methods of analytic solution were further established given the influence of excavation and unloading. According to the change of stress state in the excavation process of foundation pit, the planar mechanical analysis model of the foundation excavation problem was established. By combining this model with the physical equations and geometric equations of plane strain problem with consideration of the loading and unloading modulus of soil, constitutive equation of the plane strain problem was also established. The loading and unloading modulus formula was obtained by using the parameter calculation method in Duncan-Chang curve model. The constitutive equation obtained from the model was used to calculate the soil stress state of each point to determine its loading and unloading modulus. Finally, the foundation pit displacement change after excavation was calculated, and thus the soil pressure distribution after retaining structure deformation. The theoretical results calculated by making corresponding programs were applied to engineering practice. By comparing the conventional calculation results with monitoring results, the practicability and feasibility of the calculation model were verified, which should provide a theoretical basis for similar projects.

Abstract: This dissertation examines the history of the Methodist Building in Washington, D.C., in order to understand how the building exhibited aspirations for public Protestantism during the Prohibition era. Over four chronological chapters, this dissertation examines how the Methodist Building was a contested site, revealing the tensions of race, nation, religion, and politics in twentieth-century American Methodist identity. The project focuses on how the Board of Temperance, Prohibition, and Public Morals of the Methodist Episcopal Church wanted to construct the Methodist Building to announce the national ambitions of Methodism and counter perceived influences of Catholicism in Washington; how the Board employed material culture and public ceremonies to position the new Methodist Building as a platform for public Protestantism that would reform the nation; how the public Protestantism that the Board sought to embody in the Methodist Building sparked a debate over whether it was a lobby; and the campaign to make the Methodist Building the headquarters of the new national Methodist Church once the Northern and Southern branches reunited in 1939. Close examination of the Methodist Building illustrates how the Board used the building to argue for the moral and cultural authority of Methodism and Protestantism in society, and how others challenged that public role. This study of the Methodist Building invites a reconsideration of the early twentiethcentury era of Methodist and mainline Protestant institution building. This thematic research challenges the view that Methodist institution building during this period was an afterthought or even a declension to the nineteenth-century revivals and itinerant preaching. A deeper appreciation of the institutions and physical structures Methodists built during the early twentieth century helps to explain how this religious tradition transitioned from a revivalist movement into

Abstract: Elastic lateral dynamic impedance functions are defined as the ratio of the lateral dynamic force/moment to the corresponding lateral displacement/rotation at the top ending of a foundation at very small strains. Elastic lateral dynamic impedance functions have a defining influence on the natural frequencies of offshore wind turbines supported on cylindrical shell type foundations, such as suction caissons, bucket foundations, and monopiles. This paper considers the coupled horizontal and rocking vibration of a cylindrical shell type foundation embedded in a fully saturated poroelastic seabed in contact with a seawater half‐space. The formulation of the coupled seawater–shell–seabed vibration problem is simplified by treating the shell as a rigid one. The rigid shell vibration problem is approached by the integral equation method using ring‐load Green's functions for a layered seawater‐seabed half‐space. By considering the boundary conditions at the shell–soil interface, the shell vibration problem is reduced to Fredholm integral equations. Through an analysis of the corresponding Cauchy singular equations, the intrinsic singular characteristics of the problem are rendered explicit. With the singularities incorporated into the solution representation, an effective numerical method involving Gauss–Chebyshev method is developed for the governing Fredholm equations. Selected numerical results for the dynamic contact load distributions, displacements of the shell, and lateral dynamic impedance functions are examined for different shell length–radius ratio, poroelastic materials, and frequencies of excitation. Copyright © 2016 John Wiley & Sons, Ltd.

Abstract: The offshore wind market has grown rapidly over recent years. The most widely used foundation type for offshore wind turbines is the monopile. Current design guidance for monopile foundations dates back to the 1950s and 1960s and was originally developed for the oil and gas industry, where both the pile dimensions as well as the design load conditions are different than for offshore wind. The PISA project was aimed at investigating the behaviour of monopile foundations and reducing the conservatism in design. The project used state of the art numerical modelling, which was validated through a field testing campaign. The numerical modelling was focused on capturing the monotonic response of the foundation to failure. The field testing provided valuable additional data for the rate effects and the cyclic behaviour of monopile foundations. Data analysis methods are presented to accurately interpret the foundation response. The data analysis is focused on capturing the ground level foundation response as well as the pile behaviour below ground. Additionally, the cyclic behaviour is analysed in detail. These results are used as a basis for the development of numerical models for capturing the observed behaviour in the field tests. This thesis outlines plasticity models which are integrated in a generalised Winkler model. The model development makes use of the Hyperplasticity framework. These numerical models include: (1) the kinematic hardening model to capture plastic unloading; (2) the rate effect model to capture increased foundation capacity with increasing load rate; (3) the ratcheting model to capture accumulated rotation under cyclic loading; (4) the combined rate and ratcheting model and (5) the gapping model to capture gapping on the active side of the pile. Each of the models is calibrated to the PISA eld tests illustrating the capabilities and limitations of the models for capturing the eld test response. Finally, the kinematic hardening model is integrated in software to calculate the dynamic behaviour of an operating wind turbine. Integrating more accurate soil-structure interaction models could lead to improved predictions of the turbine behaviour and reduce the cost of monopiles.

Abstract: Bacteria are known to catalyze degradation of concrete, and have more recently been used to repair micro-cracks in or form protective biofilms on cement mortar. However, the microbial communities in and on concrete under ordinary weathering conditions have not been characterized, in part because of difficulty in extracting DNA from inside concrete specimens. Here, we report a method for extraction of nucleic acids directly from hardened concrete. Using this method and classical cultivation methods, we demonstrate that most bacteria in or on concrete belong to two taxonomic groups, that the bacterial diversity is similar on the concrete surface and in the interior, and that many bacteria in and on concrete are related to microbes found in other dry, saline, or alkaline environments. This method lays the foundation for the creation of bioindicators for concrete and may open new avenues for the fields of non-destructive evaluation and assessment of concrete structures.

Abstract: Summary This paper proposes a dynamic centrifuge model test method for the accurate simulation of the behaviours of a liquid storage tank with different types of foundations during earthquakes. The method can be used to determine the actual stress conditions of a prototype storage-tank structure. It was used in the present study to investigate the soil-foundation-structure interactions of a simplified storage tank under two different earthquake motions, which were simulated using a shaking table installed in a centrifuge basket. Three different types of foundations were considered, namely, a shallow foundation, a slab on the surface of the ground connected to piles and a slab with disconnected piles. The test results were organised to compare the ground surface and foundation motions, the slab of foundation and top of structure motions and the horizontal and vertical motions of the slab, respectively. These were used to establish the complex dynamic behaviours of tank models with different foundations. The effects of soil–foundation–structure interaction with three foundation conditions and two different earthquake motions are focused and some important factors, that should be considered for future designs are also discussed in this research. Copyright © 2017 John Wiley & Sons, Ltd.