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- Tech Transfer Briefs (3)
- Boundary element method (2)
- Centrifuge testing (2)
- Foundation vibration (2)
- Freeze-thaw (2)
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- Granular surfaced roads (2)
- Impedance (2)
- Low-volume roads (2)
- Mechanistic-based performance (2)
- Soil stabilization (2)
- Thaw weakening (2)
- Theses (2)
- Adaptive control (1)
- Adaptive systems (1)
- Algorithm (1)
- Alternative power (1)
- And Performance (1)
- Asphalt mixtures (1)
- Base isolation (1)
- Benefit-cost analysis (1)
- Black-box modeling (1)
- Civil structures (1)
- Complexity (1)
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- Cores (Specimens) (1)
- Crash frequency (1)
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- Damping devices (1)
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Articles 1 - 15 of 15
Full-Text Articles in Engineering
Low-Cost Rural Surface Alternatives: Demonstration Project, Cheng Li, Jeramy C. Ashlock, David White, Pavana Vennapusa
Low-Cost Rural Surface Alternatives: Demonstration Project, Cheng Li, Jeramy C. Ashlock, David White, Pavana Vennapusa
Jeramy C. Ashlock
A field demonstration project was conducted in Hamilton County, Iowa to compare the relative performance, durability, and costs of several stabilization methods for preventing or mitigating freeze-thaw damage to granular surfaced roads.
Low-Cost Rural Surface Alternatives: Demonstration Project, Cheng Li, Jeramy C. Ashlock, David White, Pavana Vennapusa
Low-Cost Rural Surface Alternatives: Demonstration Project, Cheng Li, Jeramy C. Ashlock, David White, Pavana Vennapusa
Jeramy C. Ashlock
The goals of this project were to implement several stabilization methods for preventing or mitigating freeze-thaw damage to granular surfaced roads and identify the most effective and economical methods for the soil and climate conditions of Iowa. Several methods and technologies identified as potentially suitable for Iowa were selected from an extensive analysis of existing literature provided with Iowa Highway Research Board (IHRB) Project TR-632.Using the selected methods, demonstration sections were constructed in Hamilton County on a heavily traveled two-mile section of granular surfaced road that required frequent maintenance during previous thawing periods. Construction procedures and costs of the demonstration …
Assessment Of Nondestructive Testing Technologies For Quality Control/Quality Assurance Of Asphalt Mixtures - Tech Transfer Summary, Shibin Lin, Jeramy C. Ashlock, Hanjun Kim, Jeremy Nash, Hosin David Lee, R. Christopher Williams
Assessment Of Nondestructive Testing Technologies For Quality Control/Quality Assurance Of Asphalt Mixtures - Tech Transfer Summary, Shibin Lin, Jeramy C. Ashlock, Hanjun Kim, Jeremy Nash, Hosin David Lee, R. Christopher Williams
Jeramy C. Ashlock
Asphalt pavements suffer various failures due to insufficient quality within their design lives. The American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide (MEPDG) has been proposed to improve pavement quality through quantitative performance prediction. Evaluation of the actual performance (quality) of pavements requires in situ nondestructive testing (NDT) techniques that can accurately measure the most critical, objective, and sensitive properties of pavement systems. The purpose of this study is to assess existing as well as promising new NDT technologies for quality control/quality assurance (QC/QA) of asphalt mixtures. Specifically, this study examined field measurements of density …
Optimal Deployment Of Hybrid Alternative Power System At Signalized Intersections, Mo Zhao, Anuj Sharma
Optimal Deployment Of Hybrid Alternative Power System At Signalized Intersections, Mo Zhao, Anuj Sharma
Anuj Sharma
Traffic signal power failures can degrade efficiency and safety at intersections that warrant traffic signal control. Alternative power sources (APSs) are typically used to supply traffic signals in power outages. Agencies that operate signals need a decision-making framework to identify locations and deployment schedules for APS installation. This paper presents a methodology for optimal deployment of APSs at signalized intersections. This methodology can also be used to investigate the economic viability of using wind and solar energy as APSs for signalized intersections. Benefit–cost analysis is used as an economic tool. The primary benefit of an APS is improving traffic operation …
Development Of Preliminary Load And Resistance Factor Design Of Drilled Shafts In Iowa - Tech Transfer Summary, Kam W. Ng, Sri Sritharan, Jeramy C. Ashlock
Development Of Preliminary Load And Resistance Factor Design Of Drilled Shafts In Iowa - Tech Transfer Summary, Kam W. Ng, Sri Sritharan, Jeramy C. Ashlock
Jeramy C. Ashlock
The Federal Highway Administration (FHWA) mandated utilizing the Load and Resistance Factor Design (LRFD) approach for all new bridges initiated in the United States after October 1, 2007. To achieve part of this goal, a database for Drilled Shaft Foundation Testing (DSHAFT) was developed and reported on by Garder, Ng, Sritharan, and Roling in 2012. DSHAFT is aimed at assimilating high-quality drilled shaft test data from Iowa and the surrounding regions. DSHAFT is currently housed on a project website (http://srg.cce.iastate.edu/dshaft) and contains data for 41 drilled shaft tests. The objective of this research was to utilize the DSHAFT database and …
Project Complexity Mapping In Five Dimensions For Complex Transportation Projects, Douglas D. Gransberg, Jennifer S. Shane, Carla Lopez Del Puerto
Project Complexity Mapping In Five Dimensions For Complex Transportation Projects, Douglas D. Gransberg, Jennifer S. Shane, Carla Lopez Del Puerto
Douglas D. Gransberg
Traditional three-dimensional project management theory is based on optimizing the cost-schedule-technical dimensions. Recent studies in the United Kingdom, Canada, and Australia have shown that the current project management body of knowledge may not be adequate to address interrelated and dependent variables encountered on complex projects. This paper reports the findings of an international research team’s detailed study of eighteen complex projects, which confirms the findings of the previous research and proposes a framework upon which a complex transportation project’s scope of work can be better conceptualized and a methodology to graphically display a project’s complexity in order to better understand …
Safety Impacts Of Signal-Warning Flashers And Speed Control At High-Speed Signalized Intersections, Zifeng Wu, Anuj Sharma, Fred L. Mannering, Shefang Wang
Safety Impacts Of Signal-Warning Flashers And Speed Control At High-Speed Signalized Intersections, Zifeng Wu, Anuj Sharma, Fred L. Mannering, Shefang Wang
Anuj Sharma
For many years, to reduce the crash frequency and severity at high-speed signalized intersections, warning flashers have been used to alert drivers of potential traffic-signal changes. Recently, more aggressive countermeasures at such intersections include a speed-limit reduction in addition to warning flashers. While such speed-control strategies have the potential to further improve the crash-mitigation effectiveness of warning flashers, a rigorous statistical analysis of crash data from such intersections has not been undertaken to date. This paper uses 10-year crash data from 28 intersections in Nebraska (all with intersection approaches having signal-warning flashers; some with no speed-limit reduction, and the others …
Wavelet Network For Semi-Active Control, Simon Laflamme, J.J.E. Slotine, J.J. Connor
Wavelet Network For Semi-Active Control, Simon Laflamme, J.J.E. Slotine, J.J. Connor
Simon Laflamme
This paper proposes a wavelet neurocontroller capable of self-adaptation and self-organization for uncertain systems controlled with semi-active devices, ideal candidates for control of large-scale civil structures. A condition on the sliding surface for cantilever-like structures is defined. The issue of applicability of the control solution to largescale civil structures is made the central theme throughout the text, as this topic has not been extensively discussed in the literature. Stability and convergence of the proposed neurocontroller is assessed through various numerical simulations for harmonic, earthquake, and wind excitations. The simulations consist of semi-active dampers installed as a replacement to the current …
Self-Organizing Inputs For Adaptive Neurocontrol Of Large-Scale Systems, Simon Laflamme, Jerome J. Connor
Self-Organizing Inputs For Adaptive Neurocontrol Of Large-Scale Systems, Simon Laflamme, Jerome J. Connor
Simon Laflamme
Black-box modeling for system identification and control can be constrained by the geometric scale of a plant. Those constrains arise from a technical or economical issue in obtaining input-output data sets for training purposes. A solution is sequential adaptation, which must be achieved in real time in the case of control systems, because a prescribed level of performance is required while external excitations are occurring. A major challenge is the proper selection of inputs that would lead to a quick and optimal adaptation. This paper proposes a new method for selection of inputs in black-box modeling. The method, termed the …
Effects Of Damping Device Nonlinearity On The Performance Of Semiactive Tuned Mass Dampers, C Lindh, Simon Laflamme, Jerome J. Connor
Effects Of Damping Device Nonlinearity On The Performance Of Semiactive Tuned Mass Dampers, C Lindh, Simon Laflamme, Jerome J. Connor
Simon Laflamme
Studies have already demonstrated the successful use of linear semiactive damping devices, such as variable orifice (VO) dampers, for semiactive TMD systems. More recently, nonlinear semiactive damping devices, such as magnetorheological (MR) dampers, have also been shown to be effective for semiactive control of TMDs. Though semiactive dampers differ widely, with responses ranging from linear (VO) to nonlinear (MR), criteria for choosing an optimal semiacive device for a TMD have not been rigorously developed. This paper expands knowledge of semiactive TMD systems by assessing the effect of nonlinearity in the damping device on the effectiveness of a semiactive TMD. This …
Large-Scale Capacitance Sensor For Health Monitoring Of Civil Structures, Simon Laflamme, Matthias Kollosche, Jerome J. Connor, Guggi Kofod
Large-Scale Capacitance Sensor For Health Monitoring Of Civil Structures, Simon Laflamme, Matthias Kollosche, Jerome J. Connor, Guggi Kofod
Simon Laflamme
In this paper, a new type of sensing technique for damage localization on large civil structures is proposed. Specifically, changes in strain are detected using a capacitance sensor built with a soft-stretchable dielectric polymer with attached stretchable metal film electrodes. This sensor is sensitive to a change in strain that causes a change in its capacitance. Fixed to a structure, small changes in the strain can be monitored directly by measuring the change in the capacitance of the unit. This technology allows for simple yet highly accurate measurements of cracks occurring due to deformation, aging, or other structural failures. The …
Intelligent Controller For Smart Base Isolation Of Masonry Structures, Simon Laflamme, T.Y. Yu, Jerome J. Connor
Intelligent Controller For Smart Base Isolation Of Masonry Structures, Simon Laflamme, T.Y. Yu, Jerome J. Connor
Simon Laflamme
In this paper, an intelligent controller to control a smart base-isolated masonry structure is proposed. The smart base isolation consists of rubber bearings and a magnetorheological damper. This semi-active scheme takes advantage of the low power requirement of magnetorheological devices to achieve structural control. The controller is capable of mapping the behaviour of the controlled structure sequentially, using a self-organizing neural network which has time-varying learning rates. This neurocontroller is augmented by a sliding mode controller to account for the uncertainty on the semi-active damping forces. Wavelets are used as functions in the single hidden layer for their capability of …
Artificial Neural Networks For Analyzing Concrete Airfield Pavements Serving The Boeing B-777 Aircraft, Halil Ceylan, Erol Tutumluer, Ernest J. Barenberg
Artificial Neural Networks For Analyzing Concrete Airfield Pavements Serving The Boeing B-777 Aircraft, Halil Ceylan, Erol Tutumluer, Ernest J. Barenberg
Halil Ceylan
An artificial neural network (ANN) model has been trained with the results of the ILLI-SLAB finite element program and has been used to predict stresses and deflections in jointed concrete airfield pavements serving the Boeing B-777 aircraft. The trained ANN model produces stresses and deflections with average errors of less than 0.5 percent of those obtained directly from the finite element analyses. Use of the ANN model has been found to be very effective for correctly predicting ILLI-SLAB stresses and deflections, in less than 1 s, with no requirements of complicated finite element inputs. On the other hand, elastic layered …
Computational And Experimental Modeling Of Dynamic Foundation Interactions With Sand, Phd Thesis, Jeramy C. Ashlock
Computational And Experimental Modeling Of Dynamic Foundation Interactions With Sand, Phd Thesis, Jeramy C. Ashlock
Jeramy C. Ashlock
The subject of dynamic soil-structure interaction (SSI) is fundamental to the design of structures and foundations to withstand dynamic events such as earthquakes, explosions and vibrations from traffic, wind, waves and machinery. With the tools of modern experimental and computational methods, a critical evaluation of current concepts and capabilities for the dynamic characterization of both surface foundations and embedded piles in granular soils is the first target. Well suited for this kind of fundamental study, a variety of scaled-model surface and pile foundations are designed and tested in a large geotechnical centrifuge using dynamic forced excitations. Used as a rigorous …
Experimental And Theoretical Modeling Of Dynamically Loaded Surface Foundations On Granular Soils, Jeramy C. Ashlock
Experimental And Theoretical Modeling Of Dynamically Loaded Surface Foundations On Granular Soils, Jeramy C. Ashlock
Jeramy C. Ashlock
The mechanical properties of a cohesionless granular medium are strongly dependent on the confining stress, which varies three-dimensionally under a surface foundation due to gravitational and surface loading effects. Success in predicting a foundation’s response to dynamic loading is therefore highly dependent on the appropriate choice of material properties for a given theoretical model. Presented in this thesis are critical results from an investigation of dynamically loaded square foundations on granular soil using a geotechnical centrifuge. From the results, it is shown that the characterization of the vertical mode of vibration of the square foundations via the homogeneous half-space theory …