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Full-Text Articles in Engineering
Liquefaction Triggering In Low-Plasticity Silts And Effects Of Liquefaction-Induced Lateral Spreading On A Reinforced-Concrete Pile, Jared A. Martinez
Liquefaction Triggering In Low-Plasticity Silts And Effects Of Liquefaction-Induced Lateral Spreading On A Reinforced-Concrete Pile, Jared A. Martinez
Civil and Environmental Engineering Master's Project Reports
Liquefaction triggering and post-liquefaction effects on lateral loading of deep foundations is an emerging area of study. This project presents: the results of cyclic direct simple shear (CDSS) testing on a low-plasticity alluvial silt collected in Portland, Oregon; and analysis of the combined effects of liquefaction-induced lateral spreading on a reinforced-concrete pile using data collected from a shake table test. The former research determines the liquefaction susceptibility and post-liquefaction characteristics of a local transitional soil using stress-controlled CDSS testing, the latter explores the complex lateral loading a reinforced-concrete pile undergoes during seismic loading with liquefaction-induced lateral spreading of the ground …
Numerical Modeling Of A Pile-Supported Wharf Subjected To Liquefaction-Induced Lateral Ground Deformations, Milad Souri, Arash Khosravifar, Stephen Dickenson, Nason Mccullough, Scott Schlechter
Numerical Modeling Of A Pile-Supported Wharf Subjected To Liquefaction-Induced Lateral Ground Deformations, Milad Souri, Arash Khosravifar, Stephen Dickenson, Nason Mccullough, Scott Schlechter
Civil and Environmental Engineering Faculty Publications and Presentations
Fully-coupled nonlinear dynamic analysis is increasingly used for assessing the seismic performance of pile-supported wharf structures subjected to liquefaction-induced lateral ground deformations. Several numerical challenges exist for analysis of this highly nonlinear soil-structure interaction, which require robust, yet practical, solutions that are validated with experimental data. This study presents a numerical model of a pile-supported wharf and evaluates the applicability of a soil constitutive model, and modeling assumptions and methods by using recorded data from a well-instrumented, large-scale centrifuge test. The objectives of this study include: (a) evaluating the performance of a recently developed pressure-dependent multi-yield surface constitutive soil model …
Pile-Supported Wharves Subjected To Inertial Loads And Lateral Ground Deformations. I: Experimental Results From Centrifuge Tests, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Scott Schlechter, Nason Mccullough
Pile-Supported Wharves Subjected To Inertial Loads And Lateral Ground Deformations. I: Experimental Results From Centrifuge Tests, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Scott Schlechter, Nason Mccullough
Civil and Environmental Engineering Faculty Publications and Presentations
Five dynamic, large-scale centrifuge tests on pile-supported wharves were used to investigate the time- and depth-dependent nature of kinematic and inertial demands on the deep foundations during earthquake loading. The wharf structures in the physical experiments were subjected to a suite of recorded ground motions and imposed superstructure inertial demands on the piles. Partial to full liquefaction in loose sand resulted in slope deformations of varying magnitudes that imposed kinematic demands on the piles. It was found that the wharf inertia and soil displacements were always in phase during the critical cycle when bending moments were at their maximum values. …
Pile-Supported Wharves Subjected To Inertial Loads And Lateral Ground Deformations. Ii: Guidelines For Equivalent Static Analysis, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Scott Schlechter, Nason Mccullough
Pile-Supported Wharves Subjected To Inertial Loads And Lateral Ground Deformations. Ii: Guidelines For Equivalent Static Analysis, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Scott Schlechter, Nason Mccullough
Civil and Environmental Engineering Faculty Publications and Presentations
An equivalent static analysis (ESA) procedure is proposed for the design of pile-supported wharves subjected to combined inertial and kinematic loads during earthquakes. The accuracy of the ESA procedure was evaluated against measurements from five large-scale centrifuge tests. The wharf structures in these tests were subjected to a suite of recorded ground motions and the associated superstructure inertia, as well as earthquake-induced slope deformations of varying magnitudes. It is shown that large bending moments at depths greater than 10 pile diameters were primarily induced by kinematic demands and can be estimated by applying soil displacements only (i.e., 100% kinematic). In …
Kinematic Demands On Pile-Supported Wharves Due To Liquefaction-Induced Lateral Ground Deformations, Thomas John Torkelson Ii
Kinematic Demands On Pile-Supported Wharves Due To Liquefaction-Induced Lateral Ground Deformations, Thomas John Torkelson Ii
Dissertations and Theses
Kinematic demands from lateral soil deformations can be a major cause of damage to maritime and highway transportation structures such as wharves, ports, and bridges. Data from five centrifuge tests on pile-supported wharves were used to evaluate the accuracy of Newmark Sliding Block Analysis in estimating the kinematic demands on piles. The piles in the centrifuge tests were subjected to varying degrees of liquefaction-induced lateral ground deformations. Pile-pinning effects were included in the analysis by incorporating the lateral pile resistance in the limit-equilibrium slope stability analysis. The results of the analysis have shown that the median Newmark displacements better estimated …
Development Of A Design Guideline For Pile Foundations Subjected To Liquefaction-Induced Lateral Spreading, Milad Souri
Development Of A Design Guideline For Pile Foundations Subjected To Liquefaction-Induced Lateral Spreading, Milad Souri
Dissertations and Theses
Extensive loss of stiffness and strength in liquefied soils can cause large ground deformations during strong earthquake shaking. One of the major sources of damage in pile foundations in liquefied soil is the excessive deformation due to lateral spreading. Pile-supported wharves subjected to earthquake motions are expected to accommodate inertial loads imposed at pile head from the superstructure as well as the kinematic loads imposed on piles from the lateral ground deformations. Current design codes significantly vary on how to combine inertia and kinematic demands. Recent research on soil-foundation-structure interaction suffers from lack of experiment-based data. There is a serious …
Minimum Required Length For Geotechnical Lateral Stability Of Rocksocketed Pile Shafts, Arash Khosravifar, Zia Zafir
Minimum Required Length For Geotechnical Lateral Stability Of Rocksocketed Pile Shafts, Arash Khosravifar, Zia Zafir
Civil and Environmental Engineering Faculty Publications and Presentations
The original strong-rock (SR) p-y curves for rock-socketed shafts exhibit a brittle response where the post-peak resistance drops to approximately zero. This brittle response could result in a progressive failure of the rock p-y curves which, in turn, results in excessive pile lengths. This paper proposes a modification to the strong-rock (SR) p-y curves where the post-peak residual strength is equal to 20% of the ultimate resistance (0.2*pult). This residual resistance is proposed based on the assumption that the lateral resistance of cracked rock (after the peak point) should not be smaller than the lateral resistance of heavily weathered rock …
Modified Design Procedures For Bridge Pile Foundations Subjected To Liquefaction-Induced Lateral Spreading, Arash Khosravifar, Jonathan Nasr
Modified Design Procedures For Bridge Pile Foundations Subjected To Liquefaction-Induced Lateral Spreading, Arash Khosravifar, Jonathan Nasr
Civil and Environmental Engineering Faculty Publications and Presentations
Effective-stress nonlinear dynamic analyses (NDA) were performed for piles in the liquefiable sloped ground to assess how inertia and liquefaction-induced lateral spreading combine in long- and short-duration motions. A parametric study was performed using input motions from subduction and crustal earthquakes covering a wide range of durations and amplitudes. The NDA results showed that the pile demands increased due to (a) longer duration shakings, and (b) liquefaction-induced lateral spreading compared to nonliquefied conditions. The NDA results were used to evaluate the accuracy of the equivalent static analysis (ESA) recommended by Caltrans/ODOT for estimating pile demands. Finally, the NDA results were …
Inertial And Liquefaction-Induced Kinematic Demands On A Pile-Supported Wharf: Physical Modeling, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Scott Schlechter, Nason Mccullough
Inertial And Liquefaction-Induced Kinematic Demands On A Pile-Supported Wharf: Physical Modeling, Milad Souri, Arash Khosravifar, Stephen E. Dickenson, Scott Schlechter, Nason Mccullough
Civil and Environmental Engineering Faculty Publications and Presentations
Results of a centrifuge test on a pile-supported wharf were used to investigate the time-, depth-, and row-dependent nature of kinematic and inertial loading on wharf piles in sloping rockfill. P-y models were calibrated against recorded bending moments in different piles and different depths. It was found that full kinematic demands and full superstructure inertia should be combined to estimate bending moments at pile head and shallow depths (less than 10 diameters below the ground surface). On the contrary, it was found that applying full kinematic demands alone was adequate to estimate pile bending moments at large depths (greater than …
The Effects Of Long-Duration Subduction Earthquakes On Inelastic Behavior Of Bridge Pile Foundations Subjected To Liquefaction-Induced Lateral Spreading, Jonathan Nasr, Arash Khosravifar
The Effects Of Long-Duration Subduction Earthquakes On Inelastic Behavior Of Bridge Pile Foundations Subjected To Liquefaction-Induced Lateral Spreading, Jonathan Nasr, Arash Khosravifar
Civil and Environmental Engineering Faculty Publications and Presentations
Effective-stress nonlinear dynamic analyses (NDA) were performed for a large-diameter reinforced concrete (RC) pile in multi-layered liquefiable sloped ground. The objective was to assess the effects of earthquake duration on the combination of inertia and liquefaction-induced lateral spreading. A parametric study was performed using input motions from subduction and crustal earthquakes covering a wide range of motion durations. The NDA results showed that the pile head displacements increased under liquefied conditions, compared to nonliquefied conditions, due to liquefaction-induced lateral spreading. The NDA results were used to develop a displacement-based equivalent static analysis (ESA) method that combines inertial and lateral spreading …
A Computational Method To Predict And Study Underwater Noise Due To Pile Driving, Scott Schecklman, Nathan Laws, Lisa M. Zurk, Martin Siderius
A Computational Method To Predict And Study Underwater Noise Due To Pile Driving, Scott Schecklman, Nathan Laws, Lisa M. Zurk, Martin Siderius
Electrical and Computer Engineering Faculty Publications and Presentations
A hybrid modeling approach that uses the parabolic equation (PE) with an empirical source model is presented to study and predict the underwater noise due to pile driving in shallow, inhomogeneous environments over long propagation ranges. The empirical source model uses a phased point source array to simulate the time-dependent pile source. The pile source is coupled with a broadband application of a PE wave propagation model that includes range dependent geoacoustic properties and bathymetry. Simulation results are shown to be in good agreement with several acoustic observations of pile driving in the Columbia River between Portland, OR and Vancouver, …
Key Aspects For Lrfd Implementation For Driven Pile Capacity By Dynamic Methods, Natalie R. Ehrlich
Key Aspects For Lrfd Implementation For Driven Pile Capacity By Dynamic Methods, Natalie R. Ehrlich
Civil and Environmental Engineering Master's Project Reports
Inputs and interpretation procedures for pile wave equation analysis, which correlates measured field dynamic driving response to axial pile static capacity, are highly dependent on site-specific soil conditions and field practices. The 6th Edition of the AASHTO LRFD Bridge Design Specifications provide generalized guidelines for pile design, but do not account for variability in region-specific soils and field practices. A comprehensive literature review of region-specific resistance factor recalibration efforts across the U.S. has given insight into the range of implementation issues encountered, especially the key decisions around choosing a restrike (BOR), along with measures of efficiency and treatment of …
Reducing Seismic Risk To Highway Mobility: Assessment And Design Examples For Pile Foundations Affected By Lateral Spreading, Scott A. Ashford, Michael H. Scott, Deepak Rayamajhi
Reducing Seismic Risk To Highway Mobility: Assessment And Design Examples For Pile Foundations Affected By Lateral Spreading, Scott A. Ashford, Michael H. Scott, Deepak Rayamajhi
TREC Final Reports
Damage in pile supported structures due to liquefaction and liquefaction induced deformation were reported in past earthquakes around the world (e.g., Ansal et al. 1999; Seed et al. 1990; EERI 2010, EERI 2011; GEER 2010a, GEER 2010b, GEER 2011). For example, a reconnaissance report from a recent subduction zone event, the 2010 Chile earthquake (Mw=8.8), showed the pervasive nature of liquefaction and liquefaction-induced lateral spreading damage to bridge foundations (GEER 2010a, Yen et al. 2011). In terms of seismic hazard, the Pacific Northwest shares similar conditions from a Cascadia Subduction Zone (CSZ) earthquake source with the expected earthquake magnitude of …