Abstract:
This research developed tools and procedures for evaluating the stiffness of pile foundations in liquefiable soils during earthquakes. Previous research on dynamic stiffness performed for the Washington State Department of Transportation resulted in the development of a Manual that provided simple charts for estimating the stiffnesses of typical pile foundations in soil deposits typical of those encountered in Washington state. The tools and procedures developed in the current project were based on up-to-date models for liquefiable soil and for soil-pile interaction, which obviated the need for many of the simplifying assumptions used in the Manual. The tools were developed by updating and extending the capabilities of two computer programs developed in part during previous WSDOT research studies.A greatly improved model for describing the seismic response of liquefiable soil was implemented into a nonlinear, effective stress site response analysis (WAVE). This model, termed the UWsand model, allows estimation of the response of typical sands to the stresses induced by earthquake shaking. The model has the important advantage of being easily calibrated with commonly available data. It captures important aspects of the behavior of liquefiable soils, including the phase transformation behavior associated with cyclic mobility that strongly influences free-field response and soil-pile interaction. The model has been successfully validated against field observations of soil liquefaction.Soil-pile interaction analyses were performed with an extended version of the program DYNOPILE. DYNOPILE was modified to allow different pile head loading conditions, including the attachment of a single-degree-of-freedom structure to the pile head to allow coupled analysis of soil-pile-structure interaction. A Windowsbased version of DYNOPILE was developed.The modified WAVE and DYNOPILE programs were used to improve and extend the stiffness charts for liquefiable soils that were presented in the Manual. WAVE and DYNOPILE can also be applied to site-specific evaluation of dynamic pile stiffness by using the same procedures used to develop the improved charts.

Authors:
Arduino,P., Kramer,S. L., Ping,L., Baska,D. A.

Keywords:
piles, liquefaction, foundation stiffness, foundation damping, lateral spreading, seismic response, research

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External Links: http://www.wsdot.wa.gov/research/reports/fullreports/514.1.pdf http://wsdot.wa.gov/Research/Reports/500/514.1.htm

Abstract:
Liquefaction of soils has caused considerable damage to pile-supported structures such as bridges and buildings in earthquakes. This project attempted to identify the most important impacts of liquefaction on pile foundations and to develop and verify new tools that allow those effects on pile foundation performance to be evaluatedA literature review indicated that the majority of damage to pile foundations has been caused by lateral movement of liquefied soil. Evaluation of the effects of lateral spreading on pile foundations requires that the soil displacements caused by lateral spreading be predicted and that the response of a pile foundation to those lateral displacements be predicted. In answer to the shortcomings of currently available estimation procedures, this project developed computational models for predicting lateral spreading deformations and pile-soil interaction. To validate the models against closed-form elastic solutions, they were compared with other computer programs that have some of the capabilites of the models and with field performance from available case histories.Free-field ground surface displacements produced by lateral spreading vary widely, but they are influenced most strongly by the initial and residual shear strength of the liquefiable soil, the gradation of the liquefiable soil, the initial state of shear stress within the deposit, the earthquake magnitude, and the distance from the site to the fault rupture zone. Pile reponse to lateral spreading is strongly dependent on surface slope, soil strength, and pile flexural stiffness, but it is relatively independent of groundwater table depth, pile diameter, pile length, and p-y curve stiffness.Both models developed in this study account for nonlinear, inelastic soil behavior and consider the development of excess porewater pressure and its effects on soil stiffness and strength. The pile-soil interaction model accounts for frequency-dependent radiation damping behavior in the time domain and allows computation of dynamic pile displacements, bending moments, shear forces, and soil reactions. By allowing computation of free-field displacements both at and below the ground surface and by considering the effects of those motions on the pile throughout the earthquake shaking, the proposed model offers a practical, rational tool for evaluating lateral spreading effects on pile foundations.

Authors:
Horne,J. C., Kramer,S. L.

Keywords:
liquefaction, lateral spreading, piles, deep foundation, research

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Abstract:
Current seismic design criteria for highway bridges generally require that the effects of earthquake loading be evaluated using either an equivalent static load approach for simple bridges or a dynamic analysis for more complex bridges. These provisions usually provide detailed explanations and commentaries on techniques which are judged to be suitable for static and dynamic modeling of the bridge superstructure and supporting columns or piers. There is, however, a significant lack of guidance on exactly how the boundary conditions and soil-structure-interaction should be incorporated into the model.The purpose of this study is to present a simple analytical model of pile and pile group foundations for use as boundary conditions in a numerical model for seismic analysis of highway bridges. Both the axial and lateral response are considered. This simple model consists of a set of springs, dashpots, and masses for each degree-of-freedom on a pile, and it is based upon the Winkler hypothesis. The spring behavior is established by using the finite element method for static load conditions. The lumped dashpot constants and masses are based on realistic approximations. The effect of a sliding interface, nonlinearity of the soil and geometric, hysteresis, and viscous damping of the soil have been considered.The p-y curves for lateral and axial vibration of single piles of 0.457m (18") and 0.610m (24") diameter based on plane analysis for different depths have been presented. Similar curves for direct lateral, shear-lateral, and axial vibrations have also been presented for two-pile groups with three different spacings.Using these p-y curves, pile responses have been obtained which have been compared with those obtained from a rigorous analysis. Good agreement has been observed for a single pile response. The comparison justifies the use of this simple model.

Authors:
Modak,S., Cofer,W. F.

Keywords:
bridge, earthquake, piles, group, finite element

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Abstract:
In the seismic design criteria for highway bridges, there is a significant lack of guidance on ways to incorporate the effect of soil-structure interaction in determining seismic response. For this study, a simple analytical model for pile and pile group foundations is presented for use in dynamic modeling of bridge superstructures. Both the axial and lateral pile response is considered. This simple model consists of a set of nonlinear springs, dampers, and masses for each degree-of-freedom of the pile, and it is based on the Winkler hypothesis. The spring behavior was established by using the finite element method for static load conditions and a typical soil from Washington state. The lumped damping constants and masses were based on realistic approximations. The p-y and t-z curves for single piles and two-pile groups were presented for two pile diameters. Using these curves as near-field Winkler elements, combined with established far-field elements, the dynamic response of a single pile when subjected to a half-sine impulse load was compared to that of a more rigorous, nonlinear, three-dimensional finite element analysis. Close agreement was observed. For design, suggestions were made on ways to develop an approximately equivalent foundation model consisting of a single mass, spring, and damper.

Authors:
Cofer,W. F., Modak,S.

Keywords:
bridge, earthquake, piles, group, finite element

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Abstract:
A geotechnical investigation was performed to develop information needed for an evaluation of the seismic vulnerability of a series of interstate highway bridges that cross a thick peat deposit in Washington. The research focused on estimation of dynamic pile stiffness, characterization of dynamic properties of the peat, and prediction of ground motions. A series of free vibration and forced vibration tests were performed on an 8-in. diameter pipe pile installed in the peat. The results of these tests were used to develop methods of estimation of the dynamic stiffness of other piles. A three-phase laboratory testing program was undertaken to investigate the dynamic properties of the peat. Ground response analyses were performed to investigate the influence of the peat on seismic ground motions. The results of the analyses indicated that the ground response would be expected to vary along the alignment of the bridges in accordance with the variation in peat thickness. The peat exhibited very low stiffness in the field and laboratory tests, and is not expected to transmit large accelerations, particularly in the central portions of the bridges where it is thick. The investigation has improved understanding of the dynamic response of peat and its implications with respect to seismic ground motions, but has also revealed the need for further research in this area.

Authors:
Kramer, S.L.

Keywords:
Piles, seismic responses, peat, dynamic load testing, bender elements

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Abstract:
Dames & Moore And their subcontractor, Inco Engineers, have prepared this Manual of Practice for conducting bridge foundation-soil interaction analyses. The manual is intended to assist engineers in the Bridge Design office at the Washington State Department of Transportation (WSDOT) who perform dynamic analysis of bridge-foundation systems. The primary purpose of the manual is to present practical and accurate methods of estimating the foundation stiffness matrices for abutment or pier foundations supported on footings or piles. These matrices are needed for soil-structure interaction analysis to more accurately determine the seismic loads acting on the bridge superstructure and on the abutment and pier foundations.This Manual of Practice consists of two volumes. Volume I presents five bridge example problems:1. Coldwater Creek2. Deadwater Slough3. Ebey Slough4. Northup Way5. FHWAThe first four examples are actual WSDOT bridges and the fifth example is a fictitious bridge that appeared in a 1991 FHWA course notebook on seismic design of highway bridges.Volume II presents the input and output files of the SEISAB computer program for the dynamic soil-structure interaction analysis of bridges. The SEISAB computer program is currently used by WSDOT in the seismic design of Washington state bridges.Dames & Moore recommends the FHWA and Novak methods to estimate bridge foundation stiffness matrices. These methodologies are presented in detail in the Coldwater Creek example problem in Volume I. In this example, the basic theory and relevant equations or inputs for implementing these methodologies are provided first and are immediately followed by their application to the Coldwater Creek bridge. The appropriate equations or inputs from the FHWA and Novak methodologies presented not the Coldwater Creek example problem are identified and applied in the other four bridge example problems. Volume I also contains three appendices. The basis for the recommendation of the FHWA and Novak methods is provided in Appendix A, which is a reproduction of the 1992 Dames & Moore report to WSDOT on the evaluation of methods to estimate foundation stiffnesses. Appendix B consists of selected pages from the BMCOL 76 computer program user guide; this computer program, which computes the load-deflection and moment-rotation curves for single piles, is part of the FHWA methodology. Appendix C presents the method for transforming the foundation stiffness matrices from one coordinate system to another. This transformation process is important because the coordinate systems assumed in the FHWA and Novak methods are generally different and therefore are not necessarily the same as the SEISAB coordinate system. Coordinate transformations are also discussed in the ColdWater Creek example problem.

Authors:
Dames & Moore- Inca Engineering

Keywords:
Analysis, bridge, bridge design, bridge foundation, bridges, computer, computer program, design, equations, evaluation, Foudation-Soil, foundation, foundation stiffness, highway, interaction, loads, manual, methodology, methods, piles, program, seismic, seismic design, soil-structure interaction, superstructure, System, systems, transportation, volume, Volumes I & II, Washington, Washington state, WSDOT

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Abstract:
This report documents the results of a full-scale, field lateral load testing program conducted at two sites in Washington State. The sites were chosen to represent soil conditions WSDOT geotechnical engineers commonly encounter and for which little information on the response of laterally loaded piles was available. One site consisted of a deep deposit of soft silt in which 18-inch diameter piles were being installed for replacement of an existing bridge. The other site consisted of a moderately deep deposit of peat that was suspected of causing foundation movements in an adjacent bridge structure. Full-scale, field lateral load tests were performed on two instrumented piles at each site. A high degree of consistency was observed between the results of these two tests at both sites. The test results indicate that, for the loading conditions imposed during the tests, the response of the soil to lateral pile movement can be described by the Integrated Clay Criterion previously developed by researchers at the University of Houston. Integrated Clay Criterion parameters for the soils at each site are developed from interpretation of the test results.

Authors:
Kramer, S.L.

Keywords:
Bridge and construction, piles, foundation, lateral loads, p-y curves, silts

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Abstract:
There are only limited opportunities to add significantly to the transportation infrastructure in the Puget Sound region in the next 15 to 20 years. For this reason, there is a growing interest in improving the efficiency of the existing system. One way to do this is to increase the average vehicle occupancy (AVO) on freeways and arterials. Programs to accomplish this must be capable of evaluation. Therefore, accurate and up-to-date information on AVO is required. This research project investigated various methods to measure AVO in order to determine the feasibility and costs of a continuous, ongoing data collection program. Since it was determined that there are no promising approaches using automatic methods employing new technology, the study focused on the use of human observers. The degree of accuracy was studied using three observers counting the occupancy of the same vehicle at the same time. The results showed the observers can be highly accurate (correct 97 percent of the time) and that environmental conditions such as weather, light, traffic density, and traffic speed do not have exceptionally strong effects on accuracy (within reason). Furthermore, observers can easily count up to a half hour at a time without fatigue affecting their performance. Taking the results of this and previous research into account, it was determined that it is possible to provide quarterly counts of AVO at 26 sites that are accurate to within about 1.5 percent for about $50,000 per year. This is about the cost of one data analyst, when benefits and overhead are taken into account.

Authors:
Ulberg, C., McCormack, E. D.

Keywords:
Bridge and construction, piles, lateral loads, p-y curves, traffic surveillance and control, auto occupancy, traffic data, portable computer

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Abstract:
This research was undertaken to explore the interaction behavior of soil-pile systems subjected to static and dynamic lateral loads. The principal objective of the study was to access the applicability and accuracy of one of the prominent methods of analysis by comparing the predicted responses with the measured responses. Presented in this report are a brief survey of the related literature on the existing analysis techniques and previous experimental studies, the details of the experimental work performed under the current study, and the appraisal of the performance of a finite element program adopted for making theoretical predictions of the experimental responses.In the present study, both static and dynamic experiments were conducted to obtain experimental data against which the analytical predictions could be verified. The experiments included laboratory simulation of the response of piles subjected to static and dynamic lateral loads applied at the pile-head and of piles embedded in a soil deposit subjected to bedrock motions. Finite element analyses of the model systems were carried out using reasonable estimates of the system parameters. No attempts were made to establish the model parameters through rigorous identification procedures. It is shown that the agreement between the predicted and measured responses can be excellent even of the properties and parameters of the soil-pile system are only roughly estimated.

Authors:
Stanton, J. F., Banerjee, S., Izzat, H.

Keywords:
Piles, shaking table, lateral loads, seismic behavior, earthquake, earthquake simulator, dynamic load test, bridge and construction

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Abstract:
A comprehensive review of literature pertaining to p-y curves analysis of laterally loaded piles was conducted. Methods of analysis of laterally loaded piles were reviewed with particular emphasis on the applicability of p-y curves analysis. Various existing procedures for development of p-y curves, and the data on which they are based, were also reviewed. Case histories of well-documented, full-scale, field lateral load tests were identified and the soil conditions in which they were performed were summarized. The applicability of existing p-y curves criteria to western Washington soil conditions was evaluated. Analysis of the group behavior and full-scale, field lateral load test procedures were reviewed.

Authors:
Kramer, S.L.

Keywords:
Piles, lateral loads, P-Y -Curves

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Abstract:
A comparative study of ten pile driving formulas is described. The formulas are the Danish, ENR, Eytelwein, Gates, Hiley, Janbu, Navy-McKay, PCUBC, and Weisbach. The ultimate load for each of sixty-three load tests was determined using the Q-D over 30 method to determine ultimate capacity.The predicted pile capacity was by the measured capacity to obtain normalized values. analysis for coefficient of variation were performed on the logarithm of the normal capacities to determine which formula provided the most consistent prediction of pile capacity. The Gates formula proved to be the best and the widely used one of the worst with a coefficient of variation approximately 2-3 times higher than that for the Gates formula.

Authors:
Fragaszy, R.J., Higgins, J.D., Argo, J.D.

Keywords:
Analysis, factor of safety, pile capacity, pile driving formulas, pile formulas, pile-driving, piles, prediction, tests, ultimate capacity

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Abstract:
This Post Construction Report provides an overview of the selection of a chemical sealer and its use as a method of protecting the girders and piles of the Nasell River Bridge from the intrusion of chloride ions. The structure treated is located in a marine environment. Chem-Trete Silane sealer was used for this structure and applied as specified by the manufacture. After 1 1/2 years exposure to a salt environment no deteriation of the concrete has been detected. Monitoring of the structure will continue under Washinton State Department of Transportation\\\'s Bridge Inspection program.

Authors:
Toney, C.A.

Keywords:
Bridge, chloride, concrete, concrete sealer, construction, corrosion, deterioration, environment, exposure, inspection, ITS, marine, monitoring, piles, program, salt, seal coat waterproofing, sealer, transportation

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Abstract:
Darex Corrosion Inhibitor (DCI) was specified for use in the Dogfish Bay Bridge on SR 308 in Kitsap County. The bridge is a 90-foot long structure located within a tidal zone. The superstructure is an 18-inch deep prestressed concrete slab. Darex Corrosion Inhibitor (DCI) was specified for use in the Dogfish Bay Bridge on SR 308 in County. The bridge is a 90-foot long structure located within a tidal zone. The superstructure is an 18-inch deep prestressed concrete slab. The end piers and two intermediate piers each consist of six 16%-inch prestressed concrete piles. DCI was added to all concrete used in the slab and piles except for four control piles (one in each pier). The supplier, Grace Construction Products, claims that the Calcium Nitrite contained in DCI will, when used as an additive in the recommended dosage, strengthen the passivating film around the reinforcing steel \\\"making it more resistant to chloride penetration,\\\" thereby protecting the steel against corrosion. (The process is explained in detail in Appendix A. ) However, only half of the recommended amount of DCI was added to the test sections. At this dosage, DCI appears to be no more effective than standard Portland Cement Concrete in preventing corrosion of the reinforcing steel.

Authors:
Henley, E.H. Jr

Keywords:
Additive, bridge, bridges substructure, calcium nitrite, chloride, claims, concrete, construction, control, corrosion, counties, Darex Corrosion Inhibitor, DCI: calcium nitrite, deterioration, effectiveness, piers, piles, portland cement concrete, prestressed, prestressed concrete, reinforcing steel, steel, superstructure

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Abstract:
A side bearing block foundation is used to resist overturning moments and lateral forces. Theoretical and experimental investigations were made to determine the ultimate moment capacity of a reinforced concrete footing subjected to vertical and horizontal loads and an overturning moment. The theoretical ultimate moment capacity was assumed to occur when the ultimate soil resistance was reached along the side bearing walls. It was found the resultant friction force at the base of the foundation greatly influenced the foundation to resist an overturning moment. The experimental ultimate moment capacity was determined from a deflection curve obtained from field data. A theoretical ultimate moment capacity was determined with the use of a finite el computer The results each of the three determinations were in acceptable agreement. Recommendations for further are made.

Authors:
Sorensen, H., Toreh, R.

Keywords:
Base, computer, concrete, data, experimental, finite element, footing, forces, foundation, foundations, friction, loads, overturning, piles, reinforced concrete, resistance, soil, soil mechanics, soil pressure, stability, walls

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Abstract:
A literature review covering the use of dynamic pile driving equations, wave equation methods, pile analyzers, and current practices by State Transportation Departments is presented. The literature review shows that no one dynamic pile driving formula can be considered superior to all others. However, the Hiley, Janbu, and Gates equations appear to be consistently among the best in published ,omparisons of formula predictions versus pile load test results. The Engineering News formula and its modified versions are found, with one exception, to be among.the worst predictors of pile capacity in these studies. When wave equation methods are included in comparisons of predicted to measured capacity, the wave equation prediction is consistently equal to or better than the best formula. Pile analyzer results can be excellent; however, the ability of the operations is a crucial factor in its successful use.The majority of the 34 states responding to a survey indicated that they use the Engineering News formula in its original or modified form. No other dynamic equation was mentioned. Several states indicated a switch in recent years from the Engineering News formula to wave equation analyses with a resulting increase in accuracy. Only two states make regular use of a pile analyzer, but they are very satisfied with it.Recommendations are made for the improvement of current Washington State Department of Transportation procedures for construction control of pile driving and estimation of pile capacity. Recommendations for additional research are also included.

Authors:
Fragaszy,R. J., Higgins,J. D., Lawton,E. C.

Keywords:
bearing capacity, pile analyzer, pile driving formulas, piles, soil dynamics, state-of-the-art, wave equation analyses, research

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Abstract:
This analytical study was undertaken to investigate the theoretical performance of concrete piles in the seismic environment of the Puget Sound region and to evaluate the consistency of these results with those of some previous investigations. The intent of the study was neither to exhaustively cover all possible soil profile variations of this region nor to examine the effects of all likely earthquake events. A limited but realistic assessment of the problem was made in this study by selecting a severe local earthquake loading and two soil profiles representative of the area. While analyses of the type presented here are approximate in nature, they provide the designer with a reasonable estimate of the potential for damage and can be employed economically when questions arise as to the possible suitability of a given pile in a given soil condition.

Authors:
Banerjee, S.

Keywords:
Seismic event, earthquake, soil, piles, loading