Civil Engineering Commons^™

Structural Topology Optimization: Moving Beyond Linear Elastic Design Objectives, James K. Guest, Reza Lotfi, Andrew T. Gaynor, Mehdi Jalalpour

Civil and Environmental Engineering Faculty Publications

Topology optimization is a systematic, free-form approach to the design of structures. It simultaneously optimizes material quantities and system connectivity, enabling the discovery of new, high-performance structural concepts. While powerful, this design freedom has a tendency to produce solutions that are unrealizable or impractical from a structural engineering perspective. Examples include overly complex topologies that are expensive to construct and ultra-slender subsystems that may be overly susceptible to imperfections. This paper summarizes recent tools developed by the authors capable of mitigating these shortcomings through consideration of (1) constructability, (2) nonlinear mechanics, and (3) uncertainties.

Onsite Use Of Recycled Asphalt Pavement Materials And Geocells To Reconstruct Pavements Damaged By Heavy Trucks, Jie Han Ph.D., P.E., Bhagaban Acharya, Jitendra K. Thakur, Robert Parsons Ph.D., P.E.

Mid-America Transportation Center: Final Reports and Technical Briefs

Asphalt pavements deteriorate with traffic (especially heavy trucks) and time. Maintenance and overlaying may solve minor to medium pavement distress problems. When the condition of a pavement becomes badly deteriorated, reconstruction of the pavement may become an economic and feasible solution. Reconstruction of a pavement requires removal of pavement surfaces. On-site use of recycled asphalt pavement materials has obvious benefits from economic, to environmental, to sustainability points of view. One attractive option is to use recycled asphalt pavement (RAP) materials as base courses with a thin new overlay. However, RAP has its limitations; for example, it creeps under a sustained …

Initial Study And Verification Of A Distributed Fiber Optic Corrosion Monitoring System For Transportation Structures, Hai Xiao Ph.D., Genda Chen, Zhan Gao Ph.D., Ying Huang Ph.D, Fujian Tang Ph.D.

Mid-America Transportation Center: Final Reports and Technical Briefs

For this study, a novel optical fiber sensing system was developed and tested for the monitoring of corrosion in transportation systems. The optical fiber sensing system consists of a reference long period fiber gratings (LPFG) sensor for corrosive environmental monitoring and a LPFG sensor coated with a thin film of nano iron and silica particles for steel corrosion monitoring. The environmental effects (such as pH and temperature) are compensated by the use of the reference LPFG sensor. The sensor design, simulation, and experimental validation were performed in this study to investigate the feasibility of the proposed sensing system for corrosion …

Offset Right-Turn Lanes For Improved Intersection Sight Distance Final Report, Karen Schurr P.E., Timothy J. Foss Jr.

Mid-America Transportation Center: Final Reports and Technical Briefs

Many transportation agencies have started using offset right-turn lanes (ORTLs) at two-way stop-controlled intersections in the hope of improving driver safety by providing intersection departure sight distance triangles that eliminate through roadway right-turning vehicle obstructions. Currently, there are no specific geometric guidelines for key three-dimensional characteristics to allow drivers the optimal use of laterally-shifted right-turn lanes. Results of driver behavior studies at existing locations of offset right-turns lanes indicate that drivers are not performing as expected at parallel-type ORTLs, rendering its presence useless. Tapered-type ORTLs appear to be much more intuitive to driver expectancy and appropriate for the three-dimensional characteristics …

Evaluation Of Hvfa Cementitious Paste And Concrete Mixtures, David Newton Richardson, K. W. Beckemeier, D. D. Davis

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In the Paste Screening Study, 25 combinations of five Type I/II portland cements and five Class C fly ashes commonly used in Missouri were tested in paste form with no chemical or powder additives. Testing procedures included semi-adiabatic calorimetry, Vicat setting time, miniature slump, and compressive strength at one and 28 days. the two most reactive and two least reactive combinations (defined by one day strengths) were further evaluated in the Paste Main Effects Study. Eighty mixtures were examined.

Nonlinear Response Of Structures To Characteristic Loading Scenarios, Donya Hajializadeh, Eugene J. Obrien, Bernard Enright, Emma Sheils

Conference papers

To assess the safety of an existing bridge, the traffic loads to which it may be subjected in its lifetime need to be accurately quantified. In this paper the 75 year characteristic maximum traffic load effects are found using a carefully calibrated traffic load simulation model. To generate the bridge loading scenarios, an extensive weigh in motion (WIM) database, from three different European countries, is used. Statistical distributions for vehicle weights, inter-vehicle gaps and other characteristics are derived from the measurements, and are used as the basis for Monte Carlo simulations of traffic representing many years. An advantage of this …

The Effect Of Lane Changing On Long-Span Highway Bridge Traffic Loading, Bernard Enright, Colm Carey, Colin C. Caprani

Conference papers

Maximum loading on long-span bridges typically occurs in congested traffic conditions. As traffic becomes congested car drivers may change lane, increasing the tendency for trucks to travel in platoons. For long-span bridges this phenomenon may increase the regularity and severity of bridge repair programs, with potential significant associated costs. This research investigates the effect of lane changing by car drivers on bridge loading. A Monte Carlo simulation model in which individual car drivers probabilistically decide, based on a lane-changing bias probability, whether or not to change lane has been developed. The sensitivity of bridge loading to this factor is investigated …

Service Life Prediction Of Residential Interior Finishes For Life Cycle Assessment, Can B. Aktas Ph.D.

Civil Engineering Faculty Publications

Service life of building products has an important influence on life cycle assessment (LCA) results of buildings. The goal of this study was to propose a systematic approach to estimate service life of building products by including both technical and social factors. A hybrid service life prediction method, combining the statistical approach described in American Society for Testing and Materials (ASTM) standard G166, with the Factor Method adopted by International Organization for Standardization (ISO) standard 15686 was proposed. In their current forms, the two methods are not suitable to provide accurate lifetime estimates for the wide variety of products that …

Estimating Characteristic Bridge Loads On A Non-Primary Road Network, Eugene J. Obrien, Bernard Enright, Brendan Williams, Cathal Leahy

Conference papers

When collecting truck loading data on a primary road network a common approach is to install a large network of permanent pavement-based Weigh-In-Motion systems. An alternative to this approach would be to use one or more portable Bridge Weigh-In-Motion systems which could be moved between bridges at regular intervals to determine the traffic loading throughout the network. A data collection strategy is needed to put such a system to best use. This paper details the data collection strategies which were examined for the National Roads Authority in Ireland. The use of urban economic concepts including Central Place Theory are discussed …

Probabilistic Study Of Lifetime Load Effect Distribution Of Bridges, Donya Hajializadeh, Eugene J. Obrien, Bernard Enright, Colin C. Caprani, Emma Sheils, Simon Wilson

Conference papers

Assessment of highway bridge safety requires a prediction of the probability of occurrence of extreme load effects during the remaining life of the structure. While the assessment of the strength of an existing bridge is relatively well understood, the traffic loading it is subject to, has received less attention in the literature. The recorded traffic data are often limited to a number of days or weeks due to the cost of data collection. Studies in the literature have used many different methods to predict the lifetime maximum bridge load effect using a small amount of data, including fitting block maximum …

Reliability Model For Ductile Hybrid Frp Rebar Using Randomly Dispersed Chopped Fibers, Bashar Ramzi Behnam

Wayne State University Dissertations

RELIABILITY MODEL FOR DUCTILE HYBRID FRP REBAR USING RANDOMLY DISPERSED CHOPPED FIBERS

Fiber reinforced polymer composites or simply FRP composites have become more attractive to civil engineers in the last two decades due to their unique mechanical properties. However, there are many obstacles such as low elasticity modulus, non-ductile behavior, high cost of the fibers, high manufacturing costs, and absence of rigorous characterization of the uncertainties of the mechanical properties that restrict the use of these composites. However, when FRP composites are used to develop reinforcing rebars in concrete structural members to replace the conventional steel, a huge benefit can …

Monitoring The Effects Of Knickpoint Erosion On Bridge Pier And Abutment Structural Damage Due To Scour, Thanos Papanicolaou, David M. Admiraal, Christopher Wilson, Clark W. Kephart

Mid-America Transportation Center: Final Reports and Technical Briefs

The goal of this study was to conduct a field-oriented evaluation, coupled with advanced laboratory techniques, of channel degradation in a stream of the Deep Loess Region of western Iowa, namely, Mud Creek. The Midwestern United States is an ideal place for such a study, considering that approximately $1 billion of infrastructure and farmland has been lost recently to channel degradation. A common form of channel degradation in this region is associated with the formation of knickpoints, which naturally manifest as short waterfalls within the channel that migrate upstream. As flow plunges over a knickpoint face, scouring of the downstream …

Development Of A Methodology For Assessment Of Crash Costs At Highway- Rail Grade Crossings In Nebraska, Aemal Khattak, Eric Thompson

Mid-America Transportation Center: Final Reports and Technical Briefs

An accurate measure of crash costs is required to support effective decision-making about transportation investments. In particular, underinvestment will occur if measurement fails to capture the full cost of crashes. Such mis-measurement and underinvestment may be occurring in the case of crashes at highway-rail grade crossings (HRGCs). HRGC crash costs can be substantial because of the severity of crashes. However, another important potential cost is the disruption to the transportation and logistics system. Existing methodologies capture the first set of costs but often fail to fully capture the second set. This research provides a standardized methodology for assessing the expected …

Safety Improvements At Highway-Railroad Crossing For Pedestrians And Bicyclists And The Assessment Of Long- Term Effects Of Centerline Curbing, Aemal Khattak, Zheng Luo

Mid-America Transportation Center: Final Reports and Technical Briefs

The focus of the research reported herein was on assessing the long-term effectiveness of median barriers at highway-rail grade crossings (HRGCs), the impacts of barrier maintenance in resurrecting safety, and on exploring and assessing ways to improve pedestrian and bicyclist safety at HRGCs. Nebraska has about 7,000 HRGCs and each one represents a potential conflict point among trains and highway users, i.e., motorists, pedestrians, and bicyclists. Safety at HRGCs is compromised when highway users resort to unsafe maneuvers, such as passing around closed gates when trains are approaching. Gate-related violations by motorists, pedestrians, and bicyclists were studied at three selected …

Implementation Of Warm-Mix Asphalt Mixtures In Nebraska Pavements, Yong-Rak Kim, Jun Zhang, Hoki Ban

Mid-America Transportation Center: Final Reports and Technical Briefs

The primary objective of this research is to evaluate the feasibility of several WMA mixtures as potential asphalt paving mixtures for Nebraska pavements. To that end, three well-known WMA additives (i.e., Sasobit, Evotherm, and Advera synthetic zeolite) were evaluated. For a more realistic evaluation of the WMA approaches, trial pavement sections of the WMA mixtures and their HMA counterparts were implemented in Antelope County, Nebraska. More than one ton of field-mixed loose mixtures was collected at the time of paving and was transported to the NDOR and UNL laboratories to conduct comprehensive laboratory evaluations and pavement performance predictions of the …

Speed Limit Recommendation In Vicinity Of Signalized, High-Speed Intersection, Anuj Sharma Ph.D., Laurence Rilett Ph.D., Zifeng Wu M.S., Shefang Wang

Mid-America Transportation Center: Final Reports and Technical Briefs

This report presents the results of Nebraska Department of Roads (NDOR) research project SPR-P1 (11) M307, which evaluated the traffic operations and safety effects of 5 mph and 10 mph speed limit reductions in the vicinity of high-speed, signalized intersections with advance warning flashers (AWF). The methodology involved two studies: 1) field study of the impact of speed limit reduction at seven high-speed intersections, 2) crash analysis using the 10-year history from 28 high-speed intersections. In the field study, traffic operational effects of the reduced speed limits were analyzed for seven high-speed, signalized intersections with AWF, using the Quantile regression …

Assessing The Structural, Driver And Economic Impacts Of Traffic Pole Mounted Wind Power Generator And Solar Panel Hybrid System, Anuj Sharma Ph.D., Justice Appiah Ph.D., Scott K. Rosenbaugh

Mid-America Transportation Center: Final Reports and Technical Briefs

This project evaluates the physical and economic feasibility of using existing traffic infrastructure to mount wind power generators. Some possible places to mount a light weight wind generator and solar panel hybrid system are: i) Traffic signal pole and ii) Street Light pole. Traffic signal poles can themselves have multiple designs depending on type of mount (mast arm vs. span wire) and the width of the intersection (load carried) etc. The close proximity of street light poles and traffic signal poles to the traffic cabinets, which can be used for storing the battery banks, make them good candidates to mount …

Concrete Surface With Nano-Particle Additives For Improved Wearing Resistance To Increasing Truck Traffic, Genda Chen, Dongming Yan Ph.D., Chenglin Wu Ph.D., Nicholas Leventis Ph.D, Shruti Mahadik Ph.D., Zhibin Lin Ph.D

Mid-America Transportation Center: Final Reports and Technical Briefs

This study focused on the use of nanotechnology in concrete to improve the wearing resistance of concrete. The nano materials used were polymer cross-linked aerogels, carbon nanotubes, and nano-SiO2, nano-CaCO3, and nano-Al2O3 particles. As an indirect measurement of the concrete wearing resistance, the tensile and compressive properties and the permeability of concrete were evaluated for various mix designs. The optimal amount of nano material additives were determined following the American Society of Testing Methods (ASTM) standard test methodologies. The test results from the materials were compared for their mechanical behaviors. This type of technology may potentially improve the comfort level …

Pilot Study On Rugged Fiber Optic Brillouin Sensors For Large-Strain Measurements To Ensure The Safety Of Transportation Structures, Genda Chen, Zhi Zhou, Hai Xiao, Ying Huang

Mid-America Transportation Center: Final Reports and Technical Briefs

Brillouin-scattering Optical Time Domain Reflectometry (BOTDR) is a viable technology for simultaneous, distributed strain and temperature measurements for miles-long transportation structures. It is a promising tool to ensure the smooth operation and safety of bridge structures that are key links in surface transportation networks or between various transportation modes: i.e., from airport to train station. Currently, telecom-grade optical fibers are widely used in civil engineering for strain and temperature measurements. These fibers are very fragile and easy to break during installation and measurement. In order to understand the ultimate behavior of structures, more rugged optical fibers such as carbon/polyimide coated …

Use Of Fiber Bragg Grating (Fbg) Sensors For Performing Automated Bridge Pier Structural Damage Detection And Scour Monitoring, A.N. Thanos Papnicolaou Ph.D., Achilleas Tsakiris

Mid-America Transportation Center: Final Reports and Technical Briefs

The goal of this study was to evaluate the performance of Fiber Bragg Grating (FBG) sensors able to detect impacts with different frequencies on a bridge pier. The FBG technology was evaluated under controlled conditions in a laboratory flume set-up to mimic the flow, sediment, and design characteristics of a pier structure. The system was calibrated using site-specific properties to relate strain to a known magnitude force for different bridge pier designs, different scour depths, and structural impacts. The FBGs proved a reliable measure of strain and displacement for key components of bridge structures, such as piers, during varying flow …