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The present research intends to study the effects of the seismic soil-pile-structure interaction (SSPSI) on the dynamic response of buildings with various heights by conducting a series of shaking table tests on 5-, 10-story, and 15-story model structures. Two types of foundations for each case are investigated, including (1) a fixed-base structure, representing the situation excluding the soil-structure interaction; and (2) a structure supported by an end-bearing pile foundation in soft soil. An advanced laminar soil container has been designed that uses three-dimensional numerical modeling to minimize the boundary effects and to simulate free-field motion during the shaking table tests. Four real earthquake events, including Kobe 1995, Northridge 1994, El Centro 1940, and Hachinohe 1968, are imposed to each model. According to the experimental measurements, it is observed that the SSPSI amplifies the maximum lateral deflections and in turn interstory drifts of the structures supported by end-bearing pile foundations in comparison with the fixed-base structures. The rocking component plays an important role in increasing the lateral deflection of the superstructures, which can shift the performance level of the structures to near collapse or even collapse levels and as a result should be assessed precisely in the seismic design of buildings resting on soft soils. [ABSTRACT FROM AUTHOR]

Meshfree method is one of the numerical methods that typically use higher-order approximate functions and a weighted-residual approach to formulate the shape functions that are independent of the grids. In this paper, a series of computational modeling were conducted using the meshfree local Petrov-Galerkin (MLPG) method to evaluate the bearing capacity and response behavior of extended-length piles. The computational program codes and boundary conditions were generated based on the elastic-plastic behavior of the surrounding soil, reinforcements, and the noncontinuous interfaces between the piles and the soil. Compared to the traditional finite-element method (FEM), the MLPG exhibited higher accuracy in the results and indicated that the optimal length of the pile is directly related to the stiffness of the soil, i.e., the stiffer the soil, the longer the allowable pile length. Overall, the MLPG meshfree method was found to be a reliable and potentially promising numerical method for studying the bearing behavior of pile foundations. [ABSTRACT FROM AUTHOR]

Pile-soil interaction in an expansive soil foundation has been primarily analyzed by an analytical solution in our previous study. As a complementary work, this paper briefly reviews the derivation process in more detail and extends the capability of the solution in dealing with the pile-soil interaction issue under various conditions. The results show that (1) increasing pile length is able to effectively decrease the upward pile movements, but meanwhile, the tensile stresses along the pile shaft increase as well; (2) a critical pile diameter exists (d≈0.04L); (3) when the diameter is less than this value, the upward pile movements can be reasonably reduced, but for the pile with a larger diameter, it has little effect on reducing the upward pile movements, and as irrigation proceeds, both the displacements and tensile stresses increase and both tend to be much less sensitive to the water's incoming over time; and (4) a critical applied pressure for preventing the upward pile movements that is induced by soil's swelling pressure is found to be 2.5 times of the maximum tensile stress of the free pile only under swelling pressure in expansive soil foundation. [ABSTRACT FROM AUTHOR]

A study to evaluate corrosion rates was conducted using pile foundations abandoned during the reconstruction of I-15 through Salt Lake Valley, Utah. Corrosion rates were measured for 20 piles extracted from five sites after service lives of 34–38 years. Measurements were made of soil index properties, resistivity, pH, cation/anion concentrations, and water table elevation. The critical zone for corrosion was typically located within the groundwater fluctuation zone; but correlations with soil properties were generally poor. Despite low resistivity, average corrosion rates for pile caps in native soil were typically between 2 and 9 μm/year with a maximum of 19 μm/year and did not pose any structural integrity problems. Nevertheless, for abutment piles where chloride concentration was very high, the average pile corrosion rate increased to 13 μm/year within the embankment and the maximum corrosion rate was 48 μm/year in the underlying native soil. Based on data from this and previous studies, equations were developed to predict maximum corrosion loss for piles in nonaggressive soil as a function of time. [ABSTRACT FROM AUTHOR]

The principal objective of this study is the development and calibration of a macroelement model for soil-pile interaction under simultaneously applied lateral and vertical loads. Herein, we focus on cast-in-drilled-hole single piles that are partially or fully embedded in soil, which are frequently used as support structures in highway construction. The model is calibrated and verified using primarily three-dimensional finite-element simulations and, whenever possible, with experimental data obtained from open literature. These data indicate that lateral loads significantly affect the vertical response of single piles, whereas the converse coupling is negligible. The proposed macroelement model is capable of mimicking this phenomenon. As such, it is a computationally efficient alternative to finite-element analyses, and is feasible to be utilized in practical applications. [ABSTRACT FROM AUTHOR]

This note studies settlement ratio, Rs, of pile groups in sandy soils, defined as the ratio of the settlement of a pile group to that of a single pile at the same average load per pile. 31 cases of field pile-group load tests and the corresponding field single-pile load tests were collected for this study. More than one-half of the cases consist of 3-diameter spaced, 9-pile groups. Based on the field test data, statistical analyses of Rs at different load levels were conducted for pile groups with cap-ground contact (PGCs) and pile groups with freestanding caps (PGFs), respectively. The mean of Rs decreases with the load level for both PGCs and PGFs, whereas the coefficient of variation of Rs increases with the load level. The influence of cap-ground contact on Rs does not appear to be significant based on a comparison of the mean Rs values of these PGCs and PGFs. In addition, a comparative study on Rs and group resistance ratio Rr, which is defined as the ratio of the average resistance of a pile in a group to that of a single pile at the same settlement, was conducted to clarify possible misunderstanding between Rs and pile group efficiency factor η for driven pile groups in sandy soils. The value of Rs compares settlement at the working load and is often larger than unity. The value of η compares failure loads, which occur at different settlements for pile groups and their respective single piles. η is usually larger than unity due to soil densification and additional contributions from the cap-ground contact for PGCs. [ABSTRACT FROM AUTHOR]

This paper identifies some of the causes of imperfections in real pile foundations and then examines their possible effects on pile behavior. The imperfections considered arise from two main sources, natural imperfections caused by the geological circumstances and imperfections related to the construction of the piles. In each case, single piles are considered first, and then pile groups are addressed separately. Case histories are presented to illustrate the effects on pile performance which are predicted by theoretical analyses. The analyses with which these examinations are carried out will still inevitably involve some degree of idealization, but at least attempt to incorporate the key “nonideal” aspects. The paper also discusses the particular problems involved in investigating and analyzing underperforming pile foundations and reviews some methods by which the consequences of imperfections may be overcome or ameliorated. [ABSTRACT FROM AUTHOR]

The author discusses the paper "Shaft Resistance of Drilled Shafts in Clay" by Tanusree Chakraborty, Rodrigo Salgado, Prasenjit Basu and Mônica Prezzi. He commends the paper for examining the influence of the method of pile installation on the alpha factor used in determining the unit shaft resistance. He also describes the process of removal and reinsertion of the auger during the installation.

The authors focus on research into deep building foundations and its behavior under axial and lateral loading. They mention that the prediction of load-transfer curves, both for side resistance and for end bearing, allow for the analysis of deep foundations under a range of conditions. They talk about soil properties around deep foundations after installation and how the pile capacity under axial load differs depending on if the pile was driven into consolidated clay or loose cohesionless soil. They state that research can lead to an improvement of design methods of deep foundations.