Now showing items 1-20 of 85

    • Current thermal state of permafrost and potential impact on the El Niño Southern Oscillation (ENSO) in the Southern Peruvian Andes

      Yoshikawa, Kenji; Úbeda, Jose; Masías, Pablo; Pari, Walter; Vásquez, Pool; Apaza, Fredy; Callata, Betto; Luna, Gonzalo; Concha, Ronald; Iparraguirre, Joshua; et al. (2018)
      Tropical, high-mountain permafrost has a unique thermal regime due to its exposure to strong solar radiation and to the rougher surface snow morphology (due to an increased occurrence of penitentes -- that is, snow spikes and ridges ranging from centimeters to meters in height) which reduce convective sensible heat transfer from the surface. Latent heat transfer and higher albedo occurring during the wet season contributes to positive feedback that supports the presence of permafrost. This preliminary study reports on the thermal state of Peruvian permafrost. It evaluates the potential combined impact of the El Niño Southern Oscillation (ENSO), along with the eleven-year solar cycles of Coropuna (15°32′S; 72°39′W; 6,377 m a.s.l.), and the Chachani volcanic complexes (16°11′S; 71°31′W; 6,057m a.s.l.); both mountains are located in the western Central Andes (e.g., west edge of the Altiplano). Temperature monitoring boreholes were established at 5217m on Coropuna and 5331m at Chachani, and electric resistivity was surveyed to better understand permafrost spatial distribution in these locations. This seven-year record of permafrost temperature data encompasses historically extreme El Niño and La Niña events. Our results show that the current lower-altitude permafrost boundary (ca. 5100m) is critically influenced by the balance of wet and dry seasons: permafrost tends to deplete during drought years. Typical permafrost thickness was 10-20 m and contained ice-rich pore spaces. The presence of permafrost and its thermal resistance depends on ice content and on higher albedo, usually due to pyroclastic materials (especially pumice) which are ideal materials for supporting permafrost resilience.
    • Outreach and Technology Transfer on the Effectiveness of Wildlife Fences and Wildlife Crossing Structures in a Multifunctional Landscape

      Huijser, Marcel P. (2018-04)
      This project undertook outreach and technology transfer tasks on the effectiveness of wildlife fences and wildlife crossing structures in a multifunctional landscape. The tasks accomplished included (1) publication of an article in an international peer-reviewed journal on the effectiveness of wildlife mitigation measures along U.S. Highway 93 North; (2) submitting an abstract to, presenting at, and attending the 2017 International Conference on Ecology and Transportation in Salt Lake City, Utah; and (3) updating the website and outreach material of the People’s Way Partnership (
    • Quarterly Report 3: Progress on Evaluation of WTC7 Collapse

      Hulsey, J. Leroy; Xiao, Feng; Quan, Zhili (2016-11)
    • Quarterly Report 2: Progress on Evaluation of WTC7 Collapse

      Hulsey, J. Leroy; Xiao, Feng; Quan, Zhili (2016-03)
    • Quarterly Report 1: Progress on Evaluation of WTC7 Collapse

      Hulsey, J. Leroy; Xiao, Feng; Quan, Zhili (2015-10)
    • Competitive State-of-the-Art Structural Engineering

      Baffrey, Dylan; Anderson, Elliott; Estas, Kathryn (2017-05-15)
      The University of Alaska Fairbanks College of Engineering and Mines has a legacy with the Steel Bridge Competition. Each year, since starting nearly three decades ago, the university has pushed the limits of the competition through vigorous ingenuity and teamwork. Having a small team, where funding is hard to come by and manufacturing is all done in-house, the team would seem to be at a disadvantage. However, the team has used their obstacles as challenges to overcome rather than to deter them. Through various community outreach activities, volunteering, and professional networking the Steel Bridge team gets involved with Fairbanks and raises enough funds for materials and travel to the Pacific Northwest and then onto National Conferences. Through in-house fabrication, the Steel Bridge Team learns hands on welding and design testing, and the value of transparency between design and construction. The team also focuses on building itself, developing the people around them into better, well-rounded, well-spoken and hardworking engineers of Alaska’s future.
    • Development of a Design Method for H2Ri Wicking Fabric in Pavement Structures

      Lin, Chuang; Zhang, Xiong; Han, Jie (2016-11)
      A new roadway drainage design concept is proposed to reduce the roadway water content and enhance the overall pavement performance by implementing H2Ri geotextile with lateral wicking ability. Compared with conventional drainage materials, this type of geotextile has high tensile strength and higher specific surface area, which enable to continuously transport water under unsaturated conditions. SEM (Scanning Electron Microscope) images indicated that the geotextile functions effectively for soils with particle size larger than 12 microns. A series of tests were performed to establish the relationships among different parameters, including resilient modulus test, large-scale direct shear test, salt concentration test and pressure plate test. Test results indicated that the soil-geotextile system can work effectively to reduce the water content within the pavement structure by 2%. By doing so, the corresponding resilient modulus can be increased by 3 times and the permanent deformation can be reduced to half of that value. Meanwhile, the interface frictional strength between geotextile and soil was not sensitive to water content change.
    • Evaluation of Precut Transverse Cracks for an Asphalt Concrete Pavement in Interior Alaska (Moose Creek –Richardson Highway)

      Liu, Jenny; McHattie, Robert; Zhang, Xiong; Netardus, John (2015-08-31)
      Road-width thermal cracks (major transverse cracks) are perhaps the most noticeable form of crack-related damage on AC pavements throughout colder areas of Alaska. The main objective of this study is to recommend design strategies and construction practices aimed at controlling thermal cracking in AC pavements. In this report, literature review summarizes selected items of the engineering literature directly relevant to precutting of pavement-type structures and control of thermal cracking in general. Crack surveys and data collection were conducted at the test sections in an AKDOT&PF resurfacing project to compare various precut strategies (variations of cut spacing and depth), with the locations of natural major transverse cracks both before and after construction. Laboratory testing and numerical analysis were also presented to provide basic data about the physical properties of the AC and help explain some of the observed characteristics associated with natural thermal cracking. 17.
    • Unmanned Aircraft System Assessments of Landslide Safety for Transportation Corridors

      Cunningham, Keith; Olsen, Michael J.; O'Banion, Matt; Wartman, Joseph; Rault, Claire (2016-12)
      An assessment of unmanned aircraft systems (UAS) concluded that current, off-the-shelf UAS aircraft and cameras can be effective for creating the digital surface models used to evaluate rock-slope stability and landslide risk along transportation corridors. The imagery collected with UAS can be processed using a photogrammetry technique called Structure-from-Motion (SfM) which generates a point cloud and surface model, similar to terrestrial laser scanning (TLS). We treated the TLS data as our control, or “truth,” because it is a mature and well-proven technology. The comparisons of the TLS surfaces and the SFM surfaces were impressive – if not comparable is many cases. Thus, the SfM surface models would be suitable for deriving slope morphology to generate rockfall activity indices (RAI) for landslide assessment provided the slopes. This research also revealed that UAS are a safer alternative to the deployment and operation of TLS operating on a road shoulder because UAS can be launched and recovered from a remote location and capable of imaging without flying directly over the road. However both the UAS and TLS approaches still require traditional survey control and photo targets to accurately geo-reference their respective DSM.
    • Safety Data Management: Gathering and Using the Data

      Perkins, Robert A; Bennett, F. Lawrence (2016-07-14)
      How are roadway crash data acquired, stored, and utilized in engineering and management decisions regarding highway projects? This research answers that question by interviewing the engineers and professionals involved with that safety data management from six states and asking – How are safety (crash) data acquired and used in their states. Since most safety projects are funded by the federal FHWA, through the HSIP, the general flow of the safety data is similar in the states interviewed. But there are many differences in details, especially the computer hardware and software. The methods of data movement between the responder and the DOT often involve an intermediate agency, often the DMV – this varies between the states. Likewise, the program to extract these data for the DOT varies. Another pronounced difference is the transfer of HSIP funding to local agencies. Also pronounced is the use of historical crash data in the SPFs. The older method of only looking at the crash data from the location in question is not uncommon, while the more modern method of using data from similar locations via an EB analysis is becoming more common and is the currently recommended method. Most analysis software is geared to the EB analysis. Historical crash data, before and after countermeasures are installed, may be used to evaluate SPF and CMF for particular states and localities, but there are practical problems with this application of crash data, due to the time required to acquire adequate data for comparisons.
    • Laboratory Performance of Wicking Fabric H2Ri in Silty Gravel, Sand and Organic Silt

      Connor, Billy; Zhang, Xiong (16-05)
      The use of wicking fabric, H2Ri, is growing in its use to remove water from roadway and airport embankments. Past research has shown H2Ri to be effective in sands and fine grained materials in roadways up to 32 feet in width. However, there is a desire to use H2Ri for airports which require a minimum width of 75 ft. This project tested H2Ri in a 73-foot flume in a crushed surface course with 14 % fines. In addition, the fabric was tested in a 22-foot flume with a sand and with an organic clay. The intent was to bracket the material for which the H2Ri will work. The study showed that the fabric will easily move water 73 feet in a silty gravel. The study showed that the fabric was also able to readily remove water in sand. However, the fabric blinded when used in organic silt and proved ineffective. The study also showed that using simple overlap of the H2Ri as a splice, while effective, was not as efficient at moving water as the fabric itself. Consequently, moisture tended to build up around the splice.
    • Improving Performance, Knowledge, and Methods to Provide Quality Service and Products

      Connor, Billy; Bennett, Larry (2015-12)
      The objectives of this study were to educate staff about the impact of research in Alaska, enhance communication and coordination amongst stakeholders, and formulate a long-term research and implementation research plan for pavement and materials. Education begins with an overview of pavement design, construction and maintenance in Alaska since the 1900’s through a series of webinars. Interviews with five state materials engineers were used to explore best practices. Finally, a workshop focused on developing a coordinated research program and improve implementation activities. The workshop provided a series of recommendations to The Alaska Department of Transportation and Public Facilities which will enhance the value of the departments research program.
    • Wearing Surface Testing and Screening: Yukon River Bridge

      Hulsey, J. L.; Ward, Richard; Anderson, Elliott (2015-09)
      There is a demand and a need for cheaper and alternative surface coverings in environments with high temperature fluctuations. Our design for an alternative surface covering involves a basic twopart component epoxy with the addition of a solvent. The purpose of the solvent is to disrupt the reaction that forms the ordered chains to form a more disordered crystalline structure. The solvent in the finished product is 3% by volume of isopropyl alcohol. This mixture of epoxy and solvent has higher impact strength than epoxy alone, as well as a much lower brittle transition temperature of 27°C compared with 10°C for epoxy. An environmental chamber, tensile tester, Charpy impact tester, and 4- point bending test were used to determine these conclusions. The final product can be tailored with different aggregates to fit a specific need, such as decking surface material to coat the wooden planks on the Yukon River Bridge.
    • Evaluate H2RI Wicking Fabric for Pavement Application - Year 2

      Zhang, Xiong; Connor, Billy (2015-10-31)
      The Tencate H2Ri wicking fabric has proven to work well on two roadway sections on the Dalton Highway. In each the fabric has reduced the water content in the embankment resulting in a maintenance free section. This project used a 24 foot flume in the laboratory to evaluate the effectiveness of the fabric on well graded sand and organic silt. The fabric effectively removed the moisture in the well graded sand. However, the organic silt blinded the wicking fibers which eliminated the capillary moisture movement. The results also demonstrated that overlapping the fabric for joints is not efficient
    • Competitive State-of-the-Art Structural Engineering

      Hjortstorp, Daniel P. (2015-04-20)
      The annual Steel Bridge competition was created over two decades ago to foster excellence and ingenuity among civil engineering undergraduate and graduate students across the nation. The steel bridge competition is one of many great opportunities to get involved in extracurricular activities associated with the civil engineering field. The University of Alaska Fairbanks (UAF) has a long history of strong performance. We are nationally known for placing well in both the regional and national competition. Students design and manufacture 1/10 scale bridges with which they compete in a regional competition and if successful a national competition. The Pacific Northwest (PNW) Regional conference is usually held mid-April each year. Much preparation and work led up to this high point of the year. The steel bridge competition teaches students valuable skills that few other engineers have the chance or ability to learn, making steel bridge team members extremely valuable employees to their future employers. Together, students tackle and overcome tremendously technical work under conditions such as extreme sleep deprivation and strenuous class loads. As a team we overcame severe financial trials, technical challenges, and tight deadlines. The 2015 competition was held at the Idaho State University in Pocatello, Idaho. The UAF Steel Bridge team swept the competition by winning seven out of seven categories and will compete for the national title on May 23rd in Kansas City. In addition to designing and building a steel bridge, members of the team also fulfilled hundreds of hours of community service and public speaking. They also support and comprise the core of the UAF Associated General Contractors (AGC) and the American Society of Civil Engineers (ASCE) student organizations. Steel bridge members sacrifice time with loved and dear ones as well as sleep and time allotted for homework in order to conquer one common goal; to design and manufacture the best bridge in the Pacific Northwest!!!
    • The Effects of Load History and Design Variables on Performance Limit States of Circular Bridge Columns

      Goodnight, Jason Chad; Feng, Yuhao; Kowalsky, Mervyn J.; Nau, James M. (2015-01)
      This report discusses a research program aimed at defining accurate limit state displacements which relate to specific levels of damage in reinforced concrete bridge columns subjected to seismic hazards. Bridge columns are designed as ductile elements which form plastic hinges to dissipate energy in a seismic event. To satisfy the aims of performance based design, levels of damage which interrupt the serviceability of the structure or require more invasive repair techniques must be related to engineering criteria. For reinforced concrete flexural members such as bridge columns, concrete compressive and steel tensile strain limits are very good indicators of damage. Serviceability limit states such as concrete cover crushing or residual crack widths exceeding 1mm may occur during smaller, more frequent earthquakes. While the serviceability limit states do not pose a safety concern, the hinge regions must be repaired to prevent corrosion of internal reinforcing steel. At higher ductility demands produced by larger less frequent earthquakes, reinforcing bar buckling may lead to permanent elongation in the transverse steel, which diminishes its effectiveness in confining the concrete core. Bar buckling and significant damage to the core concrete represent the damage control limit states, which when exceeded lead to significant repair costs. Furthermore, rupture of previously buckled bars during subsequent cycles of loading leads to rapid strength loss. The life safety or collapse prevention limit state is characterized by fracture of previously buckled bars. The goal of the experimental program is to investigate the impact of load history and other design variables on the relationship between strain and displacement, performance strain limits, and the spread of plasticity. The main variables for the thirty circular bridge column tests included: lateral displacement history, axial load, longitudinal steel content, aspect ratio, and transverse steel detailing. A key feature of the experiments is the high fidelity strain data obtained through the use of an optical 3D position measurement system.Column curvature distributions and fixed-end rotations attributable to strain penetration of reinforcement into the footing were quantified. The following sequence of damage was observed in all of the cyclically loaded experiments: concrete cracking, longitudinal steel yielding, cover concrete crushing, confinement steel yielding, longitudinal bar buckling, and fracture of previously buckled reinforcement. The first significant loss in strength occurred when previously buckled reinforcement fractured. The measured data was used to refine strain limit recommendations. Particular attention was paid to the limit state of longitudinal bar buckling, since it limited the deformation capacity of all of the cyclically loaded specimens. Empirical expression were developed to predict the compressive strain at cover crushing, the compressive strain at spiral yielding, and the peak tensile strain prior to visible buckling after reversal of loading. In design, limit state curvatures are converted to target displacements using an equivalent curvature distribution. The Modified Plastic Hinge Method was developed to improve the accuracy of strain-displacement predictions. Key aspects of the proposed model which differentiate it from the current method include: (1) a decoupling of column flexure and strain penetration deformation components, (2) a linear plastic curvature distribution which emulates the measured curvature profiles, and (3) separate plastic hinge lengths for tensile and compressive strain-displacement predictions. In the experiments, the measured extent of plasticity was found to increase due to the combined effects of moment gradient and tension shift. The proposed tension hinge length was calibrated to match the upper bound of the measured spread of palsticity. The proposed compressive hinge length only contains a term related to the moment gradient effect. Expressions which describe the additional column deformation due to strain penetration of reinforcement into the adjoining member were developed. When compared to the current technique, the Modified Plastic Hinge Method improved the accuracy of both tensile and compressive strain-displacement predictions. Abstract for Volume 3: This report presents the numerical portion of the research project on the impacts of loading history on the behavior of reinforced concrete bridge columns. In well-detailed reinforced concrete structures, reinforcing bar buckling and subsequent bar rupture serve as common failure mechanisms under extreme seismic events. Engineers often use a strain limit state which is associated with bar buckling as the ultimate limit state, but the relationship between the strain demand and resultant bar buckling is not well understood. Past research has indicated large impact of the cyclic loading history on the strain demand to achieve reinforcing bar buckling. On the other hand, sectional analysis is widely implemented by engineers to relate strain to displacement. However, the cyclic load history also has potential impact on the relationship between strain limits and displacement limits. As a result, it is important to study the seismic load history effect on the strain limit state of reinforcing bar buckling and on the relationship between local strain and structural displacement. In addition, Performance-Based Earthquake Engineering (PBEE) strongly depends on an accurate strain limit definition, so a design methodology needs to be developed to identify the strain limit for reinforcing bar buckling including the seismic load history effect. Two independent finite element methods were utilized to accomplish the goal of this research work. First, fiber-based analysis was utilized which employed the Open System for Earthquake Engineering Simulation (OpenSees). The fiber-based method was selected because of its accuracy in predicting strains and its computational efficiency in performing nonlinear time history analysis (NTHA). The uniaxial material models in fiber-based sections were calibrated with data from material tests. In addition, strain data and force-deformation response from large scale testing assists selection of element types and integration schemes to ensure accuracy. The advanced beam-column elements and material models in OpenSees resulted in a very accurate prediction of strain at local sections as well as global dynamic response of structures. A number of nonlinear time history analyses with 40 earthquake ground motions were conducted to investigate the effect of seismic load history on relationship between structural displacement and strain of extreme fiber bars at the critical section. The second finite element model was established with solid elements to predict bar buckling. The model included a segment of reinforcing bar and its surrounding elements, such as spiral turns and concrete. This model separates itself from previous bar buckling research by utilizing actual sectional detailing boundary conditions and plastic material models instead of the simplified bar-spring model. The strain history is considered as the demand on this model. A series of strain histories from the experimental tests and fiber-based analyses were applied to the finite element model to study their impacts on the strain limit for reinforcing bar buckling. Initial analytical investigations have shown significant impact of load history on the strain demand to lead to reinforcing bar buckling in the plastic hinge region. This is also confirmed in the experimental observation which only included a limited number of load histories. The parametric study extended the range of load history types and also studied the effect of reinforcement detailing on bar buckling. On the other hand, analyses with fiber-based models showed that the load history rarely impacts the relationship between local strain and structural displacement. A design approach was developed to include the load history effect on the strain limit state of bar buckling.
    • Cordova Floating Ferry Dock

      Metzger, Andrew T. (2014-12)
      This study began the evaluation of the Cordova floating ferry dock using the ANSYS AQWA software. The AQWA software models the effects of waves, wind and current on floating structures. Floating bodies are modeled as a point-mass with inertial and hydrostatic characteristics. As part of the study, the critical wave characteristic was defined. During the modeling it was found that AQWA can only model rigid bodies and that the Cordova floats experience a wide range of wave periods and directions. Consequently, AQWA requires adaptation to fully model the ferry dock at Cordova.
    • Review of Power Sources for Alaska DOT&PF Road Weather Information Systems (RWIS): Phase I

      Wies, Richard (2014-08)
      This report documents the findings related to a review of power sources for six off-grid Road Weather Information Systems (RWIS) in Alaska. Various power sources were reviewed as a means of reliably operating the off-grid RWIS sites throughout the year. Based on information collected on current power sources and equipment used at the off-grid RWIS sites, and visits to off-grid installations in Alaska, some viable methods of reliable operation were discovered. Power sources included in the study were solar photovoltaics (PV), small wind turbines, fuel cells, and thermoelectric generators, all charging a battery bank which powers the weather sensors, cameras, and communication equipment. The results showed that while solar PV provides enough standalone power to keep the sites operational from early spring to late fall with wind supplementing this somewhat during the transition seasons, a fossil fuel based source is necessary to maintain operation through the winter. These findings suggest that a combination of power sources is required for reliable RWIS operation throughout the year and is dependent on the location of the site.
    • Phase II: Chulitna River Bridge Structurally Health Monitoring

      Hulsey, J. Leroy; Xiao, Feng; Dolan, J. Daniel (2015-01)
      This study is phase 2 of a two phase research project. In Phase 1 a structural health monitoring system (SHMS) was installed on the Chulitna River Bridge. This bridge is 790 feet long, 42 foot 2 inches wide and has 5 spans. As part of that effort, three loaded dump trucks were used to conduct seventeen static and dynamic loadings on the structure. In addition to studying the bridge using SHMS, two ambient free vibration tests were conducted a year apart by. In 1993, the deck on this 1970 five span bridge was widened from 34-feet to a 42 foot 2 inch concrete deck. Increased load was accounted for by strengthening two variable depth exterior girders and converting interior stringers to interior truss girders. Construction documents for the upgrade called for stage construction. At the time of this study, the bridge had five bearings that were not in contact with the superstructure. Feasibility of using Structural Health Monitoring Systems (SHMS) for Alaska Highway Bridges was examined. Also, SHMS data for the load tests of Phase 1 were used to calibrate a three-dimensional model (FEM) to predict response and conduct a 2014 Operating Load Rating.