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Title: Verification, Validation and Optimization of Finite Element Model of Bus Structure for Rollover Test.
Creator: Bojanowski, Cezary, Wekezer, Jerry, El-Azab, Anter, Spainhour, Lisa, Mtenga, Primus V., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Paratransit buses consist of a custom body mounted to a GM/Ford cutaway chassis by a secondary manufacturer called body builder. Paratransit buses form a significant segment of the bus market in the US nowadays. They are used as a complementary service for regularly scheduled routes and usually are prepared to transport disabled passengers in their wheelchairs. Their construction method and the lack of applicable national crashworthiness standards result in a wide variance of passenger...
Show moreParatransit buses consist of a custom body mounted to a GM/Ford cutaway chassis by a secondary manufacturer called body builder. Paratransit buses form a significant segment of the bus market in the US nowadays. They are used as a complementary service for regularly scheduled routes and usually are prepared to transport disabled passengers in their wheelchairs. Their construction method and the lack of applicable national crashworthiness standards result in a wide variance of passenger compartment structural strength amongst manufactures - as reported by the Florida Department of Transportation (FDOT). The primary objective of this dissertation was to develop a testing procedure with the performance rating system for paratransit buses acquired by the state of Florida. Sponsored by FDOT an assessment and improvement methodology was developed using joint computational and empirical approach. It prioritizes the strength of the structure in a rollover type accident utilizing as a basis the European Regulation ECE-R66. New measure of safety margin in rollover tests, a Deformation Index, was proposed. Detailed Finite Element (FE) model of selected paratransit bus was developed and used to perform explicit LS-DYNA simulations of the tilt table rollover test. Experimental tests on the bus subsections were conducted for validation purposes and weak spot identification. Discrete optimization using the Successive Response Surface Methodology in LS-OPT was also utilized to indentify parts of the structure critical to rollover performance. Improvements were suggested that minimize the addition of mass. Early results showed the connections between major structural components (floor/wall/roof) to be particularly weak. Proposed structural modifications increased the remaining safety margin from an initial level of 16% to 29% (In respect to the Deformation Index). The structural modifications resulting from the validation testing were incorporated in the currently produced buses. The proposed testing procedure was accepted by FDOT in August 2007 as the Crash and Safety Assessment Program. It received attention of the state and federal transportation agencies and support from the transit bus industry.
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Date Issued: 2009
Identifier: FSU_migr_etd-3610
Format: Thesis

Title: Optimal Design of Passive Fluid Viscous Dampers for Controlling Vibrations in Seismically-Excited Truss Towers.
Creator: Kalyanam, Sujatha, Rambo-Roddenberry, Michelle, Spainhour, Lisa, Jung, Sungmoon, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Truss towers form a vital part of the communication infrastructure, and the control of responses for such structures during adverse events such as an earthquake is of significant importance. The objective of this research venture is to combine the linear quadratic regulator (LQR) algorithm for optimal design of supplemental dampers of buildings with the bi-model method for a truss tower. Damping coefficients are calculated for the 3D truss model by analyzing the dynamically equivalent 2D...
Show moreTruss towers form a vital part of the communication infrastructure, and the control of responses for such structures during adverse events such as an earthquake is of significant importance. The objective of this research venture is to combine the linear quadratic regulator (LQR) algorithm for optimal design of supplemental dampers of buildings with the bi-model method for a truss tower. Damping coefficients are calculated for the 3D truss model by analyzing the dynamically equivalent 2D lumped mass model which is developed using the bi-model method. The dynamic responses of the structure for given seismic loads are computed for the conditions with and without dampers. The results are then compared to determine the efficiency of the method to design passive fluid viscous dampers (PFVD) to control the excess vibrations due to seismic loads in towers.
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Date Issued: 2009
Identifier: FSU_migr_etd-3359
Format: Thesis

Title: Safety Analysis of Florida Urban Freeways with Special Focus on the Influence of Truck Lane Restriction Policy.
Creator: Kobelo, Doreen, Moses, Ren, Spainhour, Lisa, Sobanjo, John, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Urban freeways and tollways in the United States are characterized by a significant number of truck traffic hauling freight between various origins and destinations. The truck traffic varies in size from single-unit trucks to multi-unit tractor trailers. Trucks also have different operational characteristics dissimilar to those of passenger cars such as low deceleration capabilities resulting in longer stopping distances. Statistics show over 200 percent increase in truck vehicle miles of...
Show moreUrban freeways and tollways in the United States are characterized by a significant number of truck traffic hauling freight between various origins and destinations. The truck traffic varies in size from single-unit trucks to multi-unit tractor trailers. Trucks also have different operational characteristics dissimilar to those of passenger cars such as low deceleration capabilities resulting in longer stopping distances. Statistics show over 200 percent increase in truck vehicle miles of travel in the United States since 1970. The increase in truck vehicle miles of travel on US urban highways has posed significant challenges to policymakers given that truck traffic contributes to the reduction of efficiency and safety of the highway systems especially on limited access roadways. To address challenges and concerns posed by the growth of truck traffic on highways, policymakers have implemented a number of strategies including changing highway design standards to accommodate trucks, introduction of intelligent transportation systems, and the implementation of operational control policies aimed at heavy vehicles. One of the most prevalent operational control policies is the truck lane restriction. The implementation of truck lane restriction is mainly predicted on the principle that the restriction would increase the level of service and operational safety on limited access highways especially those located in urban areas. Like many other states, Florida has implemented truck lane restriction on approximately 430 miles of the state highway system. However, the effectiveness of this strategy in improving safety and efficiency of these highways has not been properly studied or documented. The objective of this study was therefore to analyze the effect of truck lane restriction on safety of the urban limited access highways in Florida. The analysis of safety was achieved through performing a before-after study that compared crash characteristics of highway sections before truck lane restriction was imposed to crash characteristics after the imposition of truck lane restriction. In addition, a negative binomial regression model was used to determine the influence of truck lane restriction as a modeling variable together with other variables derived from geometrics, traffic, and socio-economic characteristics related urban limited access highway sections in different metropolitan areas in the state of Florida. Data on geometric, traffic, and crash attributes were collected from various databases maintained by the Florida Department of Transportation including the Roadway Characteristics Inventory (RCI) database, the Crash Analysis Reprot (CAR) database and various other data provided by FDOT district offices and through field data collection. The before-and-after crash analysis data were from 200x to 200x while the geometric, traffic, and crash data used in the negative binomial regression modeling were from year 2005. All the data were checked for accuracy to eliminate sections that were under construction to avoid skewing the results. The results of the crash prediction model that was based on negative binomial regression model showed that the coefficient of the truck lane restriction variable in the model was negative but insignificant (p ≤ 0.808). The negativity of the variable indicates that highway sections with truck lane restriction had insignificantly less crashes than sections without truck lane restriction. A statistical marginal effect analysis was used to determine the percentage decrease in crashes that can be expected if truck lane restriction was implemented on a highway section. The results showed that in year 2005 there was a 4 percent decrease in crashes on sections with truck lane restriction compared to sections that did not have truck lane restriction. In addition, the results showed that when truck percentage variable was changed from minimum of 2 percent to a maximum of 15 percent in the model, there was a decrease of crashes by 22 percent. These results coupled with the results of the before-and-after analysis suggests that there is no clear cut safety benefits associated with the imposition of truck lane restriction. These results are in line with literature findings which showed mixed results arising from a number of studies conducted on different highways in different states in the United States. However, it should be noted that truck lane restriction has documented operational benefits such as decreasing lane changing by passenger cars and is generally popular with the traveling public.
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Date Issued: 2007
Identifier: FSU_migr_etd-2862
Format: Thesis

Title: Mitigation of Vortex Induced Response in Long Span Bridges.
Creator: Patil, Atul Sudhakar, Jung, Sungmoon, Spainhour, Lisa, Rambo-Roddenberry, Michelle, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Span length of bridges is ever increasing. With the increase in span, bridges are becoming more slender, making them more prone to wind-induced forces and vibrations. Some bridges show significant wind-induced vibrations after the construction, which were not anticipated during the design. In order to improve the performance of these bridges, two strategies of retrofit are commonly used. First, tuned mass dampers (TMDs) may be added to dissipate the energy. Second, cross-section of the bridge...
Show moreSpan length of bridges is ever increasing. With the increase in span, bridges are becoming more slender, making them more prone to wind-induced forces and vibrations. Some bridges show significant wind-induced vibrations after the construction, which were not anticipated during the design. In order to improve the performance of these bridges, two strategies of retrofit are commonly used. First, tuned mass dampers (TMDs) may be added to dissipate the energy. Second, cross-section of the bridge may be retrofitted so that it is aerodynamically more favorable. Both methods are effective in reducing the magnitude of the wind-induced vibration. Among many types of wind-induced vibrations, this thesis deals with vortex-induced vibrations. The various parameters involved in retrofit have conflicting objective. For example if the maximum displacement is required to be reduced the cost involved is more. In such a case of conflicting objectives, multi-objective optimization can be used to find various solutions from the solution space. These solutions are termed as Pareto-optimal solutions. There is no specific solution which can be called as the best solution due to conflicting objectives. Multi-objective optimization gives the various options to choose from, to arrive at a decision for a particular real world problem. In our case, the problem is to decrease the magnitude of vortex-induced vibrations. The conflicting objectives are the cost of the retrofit and the displacement in terms of the performance. In thesis, the multi-objective optimization will be used to obtain various strategies of retrofit under conflicting objectives. The approach is illustrated with an example bridge modeled after Rio-Niterói Bridge.
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Date Issued: 2010
Identifier: FSU_migr_etd-2132
Format: Thesis

Title: Analytical Modeling of Fiber Reinforced Post-Tensioned Concrete Anchorage Zones.
Creator: Johnson, Stacy, Tawfiq, Kamal, Mtenga, Primus, Wekezer, Jerry, Spainhour, Lisa, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The use of post-tensioning in bridge girders causes tensile bursting stresses to occur some distance ahead of the anchorage device in a region known as the general zone. Large amounts of mild steel reinforcement are placed in this area of the bridge girder in order to resist these highly tensile stresses. This causes congestion in the area of the steel and poses difficulty during concrete placement. The objectives of this study were to determine the feasibility of reducing the mild steel...
Show moreThe use of post-tensioning in bridge girders causes tensile bursting stresses to occur some distance ahead of the anchorage device in a region known as the general zone. Large amounts of mild steel reinforcement are placed in this area of the bridge girder in order to resist these highly tensile stresses. This causes congestion in the area of the steel and poses difficulty during concrete placement. The objectives of this study were to determine the feasibility of reducing the mild steel reinforcement by adding fibers to the general zone and to determine the impacts of doing so. Fiber reinforced concrete (FRC) improves the mechanical properties of non-fibrous concrete. So it is expected to support the proposed reduction of mild steel reinforcement in the post-tensioned anchorage zone. The first phase of the study involved researching past studies on the use of FRC in order to determine the material and mechanical properties pertaining to the fibers. Steel fiber was deemed to be the most useful for enhancement of non-fibrous concrete properties. The second phase of the study was to determine a realistic and reasonable specimen for FRC application. The pier segment of a currently used bridge in Florida was chosen. This selection was based on having common and less complex geometry. After selection, information was gathered about the segment such as the volume of concrete, mild steel reinforcement details, and post-tensioning system details. In the final phase of this study, a finite element model was developed for the segment using design required mild steel reinforcement. Using the initial model, duplicate models were analyzed with varying steel fiber volumes. The theoretical results indicate that a maximum reduction of 65% of the design mild steel reinforcement can occur when replaced by 0.50% steel fiber to the concrete volume of the general zone. However, it is recommended that a mild steel reinforcement reduction of 50% be replaced by 0.50% steel fiber in order to stay conservative and safe. It was also observed that higher volumes of steel fiber could increase stresses in the general zone. Therefore, it is recommended that experimental testing of these procedures be done for complete verification.
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Date Issued: 2006
Identifier: FSU_migr_etd-3651
Format: Thesis

Title: Ground Tire Rubber as a Component Material in Concrete Mixtures for Paving Concrete.
Creator: Twumasi-Boakye, Richard, Sobanjo, John, Tawfiq, Kamal, Spainhour, Lisa, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The management of solid waste is a major environmental concern in the United States. Waste tire rubber forms a major part of this problem and a rather severe one since tire rubbers are not biodegradable hence its disposal into landfills are of great concern. This research primarily focused on finding the best way of producing paving concrete with the use of ground tire rubber as a component material. Tests on rubber concrete were performed in two stages. Preliminary tests were performed using...
Show moreThe management of solid waste is a major environmental concern in the United States. Waste tire rubber forms a major part of this problem and a rather severe one since tire rubbers are not biodegradable hence its disposal into landfills are of great concern. This research primarily focused on finding the best way of producing paving concrete with the use of ground tire rubber as a component material. Tests on rubber concrete were performed in two stages. Preliminary tests were performed using both 40-mesh GTR and 3/8-inch rubber chips (RC) to replace fine aggregates and coarse aggregates respectively by weight in the concrete mix. This stage of testing considered zero to 40 percent GTR replacement of fine aggregates by weight at 10 percent increment and for zero to 30 percent RC replacement of coarse aggregates by weight at 10 percent increment. Observations from this stage guided the formulation of a second and final stage of testing which involved only zero to 20 percent GTR replacement of fine aggregate by weight at 5 percent increment. The mix design for this stage involved the use of water reducers, air-entrainer and fly-ash. In addition to concrete mechanical property tests, coefficient of thermal expansion (CTE), plastic shrinkage and drying (free) shrinkage tests were also conducted. Results from preliminary tests indicated that GTR and RC concrete specimens were of relatively low strength, improved toughness and showed more elasticity when compared to normal concrete specimens. The final stage of laboratory testing however showed improved strength characteristics, with the initial observations of improved toughness and low modulus of elasticity still evident. Coefficient of thermal expansion (CTE) test results did not show significant difference between mix-types, with the range of results falling within the typical limit for normal concrete. Plastic shrinkage test results showed that the inclusion of GTR helped in reducing plastic shrinkage cracks in concrete. Preliminary results at the second stage testing on drying shrinkage using 10% GTR concrete indicated a reduction in free shrinkage when compared to the control specimens.
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Date Issued: 2014
Identifier: FSU_migr_etd-9107
Format: Thesis

Title: Dynamic Response of Highway Bridges Subjected to Heavy Vehicles.
Creator: Li, Hongyi, Wekezer, Jerry, Chandra, Namas, Abdullah, Makola, Spainhour, Lisa, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Evaluation of existing structures is critical for an efficient management of transportation facilities, especially bridges. Knowledge of actual load effects and structure resistance can be very helpful for the determination of the load carrying capacity and condition of structures. It can help to make management decisions, such as establishing permissible weight limits, and can have important economical and safety implications. In particular, the dynamic nature of live loads and bridge...
Show moreEvaluation of existing structures is critical for an efficient management of transportation facilities, especially bridges. Knowledge of actual load effects and structure resistance can be very helpful for the determination of the load carrying capacity and condition of structures. It can help to make management decisions, such as establishing permissible weight limits, and can have important economical and safety implications. In particular, the dynamic nature of live loads and bridge-vehicle interaction is not sufficiently considered in current bridge codes. Impact factors suggested by the codes usually lead to inappropriate solutions for overweight vehicles which are the major concern of the Florida department of transportation which is involved every day in processing overload permit applications from trucking companies. This research consisted of analytical work validated by field tests. Static and dynamic field tests were performed on a selected two-lane highway bridge on US 90 over Mosquito Creek in northern Florida. The three-span bridge was a concrete structure with simply supported, precast girders and continuous, cast-in-place deck. One or two fully loaded truck(s) crossed over the bridge, which was instrumented with strain gauges, accelerometers and displacement transducers. Data collected from the tests were used for comprehensive assessment of the bridge under dynamic loading and validation of analytical procedures. The vehicle-bridge interaction was investigated using finite element models with different levels of representation. In the simple analytical model, the vehicle was modeled as a 3D mass-spring-damper system with eleven degrees of freedom. The bridge was discretized to a combination of plate and beam elements which represented slab and girders, respectively. The equations of motion for the vehicle were formulated with physical components while with modal components for the bridge. The coupled system was solved step by step using central difference method. More sophisticated bridge models with consistent stiffness and mass distribution and truck models with detailed representation of suspension systems and wheels were developed using LS-DYNA, a commercial explicit FE code. The advanced features of multi point constraint (MPC) and contact algorithm made it suitable in analysis of vehicle – bridge interaction. The advanced features of the truck model included the suspension system allowing wheel rotation, as well as application of internal pressure in tires. Good agreement was found between the field measurement and FE simulations in both frequency domain and time domain. Impact factors were calculated for some overweight vehicles using the validated finite element procedures. The effect of some parameters to bridge response was also investigated, including road roughness, bridge length, vehicle weight, vehicle speed and vehicle/bridge frequency ratio.
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Date Issued: 2005
Identifier: FSU_migr_etd-3067
Format: Thesis

Title: Behavior of Plywood and Fiberglass Steel Composite Tube Structures Subjected to Impact Loading.
Creator: Armaghani, Seyamend Bilind, Jung, Sungmoon, Spainhour, Lisa, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Paratransit buses are custom built as the major vehicle manufacturer produces the custom built passenger cage installed on the chassis for the Paratransit bus. In order for these Paratransit bus members to be sufficient, they have to be evaluated for crashworthiness and energy absorption. This has prompted Florida Department of Transportation (FDOT) to fund research for the safety evaluation of Paratransit busses consisting of crash and safety analysis. There has been a large body of research...
Show moreParatransit buses are custom built as the major vehicle manufacturer produces the custom built passenger cage installed on the chassis for the Paratransit bus. In order for these Paratransit bus members to be sufficient, they have to be evaluated for crashworthiness and energy absorption. This has prompted Florida Department of Transportation (FDOT) to fund research for the safety evaluation of Paratransit busses consisting of crash and safety analysis. There has been a large body of research done on steel subjected to static loads, but more research is needed for steel applied under dynamic loading and high speeds in order to improve crashworthiness in events such as rollovers and side impacts. Bare steel Hollow Structural Section (HSS) tubing are used a lot as structural members of Paratransit buses because of their lightness and progressive buckling under loading. The research will be conducted on quantifying the tubing's behavior under bending by conducting static three point bending and impact loading tests. In addition to the bare tubing, plywood and fiberglass composites are investigated because they are both strong and lightweight and their behavior under dynamic loading hasn't been quantified. As a result, the main purpose of this research is to quantify the differences between the dynamic and static behavior of plywood steel composite and fiberglass steel composite tubing and compare these findings with those of bare steel tubing. The differences will be quantified using detailed and thorough experiments that will examine the composites behavior under both static and dynamic loading. These tests will determine if there are any advantages of using the composite materials and thus allow for recommendations to be made to the FDOT with the goal of improving the safety of Paratransit busses. Tensile tests were conducted to determine the material properties of the tested specimens. Before the static and dynamic experiments are run to investigate the differences between static and dynamic behavior, Preliminary three point bending testing was conducted to determine the parameters for the final experiments. Static bending testing was conducted on the bare, plywood composite, and fiberglass composite steel tubing. The point of these experiments was to produce a Moment vs. Rotation plot to determine the specimens' maximum moments and their associated rotation, as that is when the steel buckles and fails. The dynamic three point bending experiments were conducted using the impact loading apparatus and had the same purpose as the static experiments. For both static and dynamic experiments, the performances of the different types of specimens were compared based upon their Moment vs. Rotation plots. This will determine the effect that the composite has on the rotation and maximum moment at which the tubing fails. After conducting these experiments, amplification factors were established for each specimen by comparing the maximum moment and their associated rotation between static and dynamic testing. λ was calculated to quantify the ratio between the static and dynamic maximum moments. β was used to quantify the ratio between the rotation needed to produce the maximum moment between static and dynamic events. A small amplification factor denotes that material performs well under impact loading and the material doesn't experience dramatic change in behavior during dynamic events. Amplification factors were compared between the bare, plywood, and fiberglass composite steel tubing in order to evaluate the performance of the composites. After comparing the amplification factors of the different types of tubing, recommendations can be made. Fiberglass and plywood composite were shown to be valuable because it decreased the effect of dynamic forces as β was reduced by a factor of 2 in comparison to bare tubing. Based upon the amplification factors, it was recommended to use 14 gauge fiberglass composite tubing as Paratransit bus structural members because it was affected the least by dynamic loading.
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Date Issued: 2014
Identifier: FSU_migr_etd-8933
Format: Thesis

Title: Development of a Measure of Effectiveness for the Florida Elder Road User Program.
Creator: Pierre, Velouse, Spainhour, Lisa, Mussa, Renatus, Sobanjo, John, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Older drivers may have more difficulty than the general driving public in attending to the driving task, and they may be slower at processing information, especially when required to make complex decisions. Traffic crashes caused by elderly drivers have been attributed to neglect of, or inattention to, relevant information from road signs, as well as to other cars and pedestrians on the road. This is especially true at intersections. To combat these safety issues, implementation of the...
Show moreOlder drivers may have more difficulty than the general driving public in attending to the driving task, and they may be slower at processing information, especially when required to make complex decisions. Traffic crashes caused by elderly drivers have been attributed to neglect of, or inattention to, relevant information from road signs, as well as to other cars and pedestrians on the road. This is especially true at intersections. To combat these safety issues, implementation of the Florida Elder Road User Program began on state-maintained roads. This program sought to improve roadways by increasing visibility and adding advanced signage and reflective pavement markings. This study sought to evaluate the effectiveness of the Florida Elder Road User Program by building a crash prediction model that examines older driver crash frequency using variables obtained from quantitative variables such as maximum posted speed limit and qualitative variables such as sign visibility. Crash data was collected for 601 intersections in the state of Florida for the years 2000-2002. Detailed analysis of geometric and traffic data collected from various resources, such as crash reports, Roadway Characteristics Inventory data, and video log archives, was performed to determine the correlation between these independent factors and crash frequency. The crash distribution was found to be negative binomial; the model needed to be inflated due to the presence of many zero-crash intersections. Therefore, a Zero-Inflated Negative Binomial (ZINB) crash prediction model was developed. The response variable in the model was crash frequency, and independent variables included roadway geometrics, traffic characteristics, and intersection characteristics. Crash frequency was found to have a very strong relationship with most of the independent variables as indicated by their p-values. Traffic volumes, signalization, and sign visibility had positive coefficients, indicating that, higher traffic volumes, signalized intersections, and sign visibility were associated with increased crash frequency. Many of the improvements, including sign visibility and reflective pavement markers listed in the Florida Elder Road User Program were found to be significant but did not reduce elderly driver crashes, proving that the program is not effective.
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Date Issued: 2006
Identifier: FSU_migr_etd-0792
Format: Thesis

Title: The Evaluation of the Distribution of Interchange Crashes Based on Severity Level.
Creator: Kobelo, Doreen, Moses, Ren, Wu, Wei, Spainhour, Lisa, Sobanjo, John, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: For the past decades many studies have focused on the operation and safety of limited access roadways. However, the accessibility of these facilities are made possible by interchanges which are systems of interconnecting roadways with one or more grade separations providing movement for traffic between two or more roadways of similar or different characteristics such as speed characteristics, traffic characteristics and roadway class. Most studies have focused on the total number of crashes...
Show moreFor the past decades many studies have focused on the operation and safety of limited access roadways. However, the accessibility of these facilities are made possible by interchanges which are systems of interconnecting roadways with one or more grade separations providing movement for traffic between two or more roadways of similar or different characteristics such as speed characteristics, traffic characteristics and roadway class. Most studies have focused on the total number of crashes that occur on these facilities but a few studies have been conducted on severity crashes. The main question that researchers have not answered is whether there are differences in crash severity level distributions when comparing them with each other and further when comparing them with the total crashes distribution. Severity of crashes depend on a number of characteristics on a given network such as distribution of traffic, speed, driver behavior, environmental conditions, lighting conditions and pavement conditions. Since interchanges are roadway sections which are different from the basic freeway segment there are different safety characteristics that could be encountered. The hypothesis is that different types of interchanges have different safety characteristics depending on the type of traffic serves and the configuration. Moreover, different types of interchanges will have different distribution of severity crashes which are also a function of the configuration and the traffic it serves. Another hypothesis is that the different levels of severity have different distribution on interchanges which could also impact the total number of crashes on limited access roadways. The objectives for this research were; to compare the crash characteristics of the types of interchanges in Florida. Secondly, to compare the probability distribution for the different severity crashes on these interchanges. The third objective was to produce a crash prediction model for the types of interchange and a general crash prediction model for the all crashes and make a comparison between them for total crashes and severity crashes. Forth objective was to perform a time series and forecast analysis for total interchange crashes From the models that were produced, simulations were used to produce the comparison of the severity level crash distributions and the interchange type crash distributions with the total crash distributions and the most common distribution used for rare events which is Poisson distribution. The results from this study showed that there were mathematical differences in the distributions but since statistics is one of the major evaluator of traffic characteristics and conditions, statistically there were no differences among the distributions. However, the regression analysis performed showed that interchange types have an impact on the occurrence of crashes. Furthermore, the time series analysis showed that there was a time dependency in the occurrence of crashes and also when other time related variable were considered in the analysis.
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Date Issued: 2010
Identifier: FSU_migr_etd-2863
Format: Thesis

Title: Risk Assessment of Florida's Coastal Bridges Exposed to Hurricane-Induced Storm Surge Wave Forces.
Creator: Stanford, Scott Steven, Sobanjo, John, Rambo-Roddenberry, Michelle, Spainhour, Lisa, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The purpose and focus of this research was on studying the hazard to Florida's coastal bridges from storm surge induced wave forces inflicted on the bridges during hurricanes. It has been observed in recent years that bridges located in the coastal environment are vulnerable to deck unseating during the applied loading of storm surge wave forces. The goal of the research is to use modern and up-to-date analysis methods to address the risk and vulnerability of coastal bridges to being damaged...
Show moreThe purpose and focus of this research was on studying the hazard to Florida's coastal bridges from storm surge induced wave forces inflicted on the bridges during hurricanes. It has been observed in recent years that bridges located in the coastal environment are vulnerable to deck unseating during the applied loading of storm surge wave forces. The goal of the research is to use modern and up-to-date analysis methods to address the risk and vulnerability of coastal bridges to being damaged from storm surges during hurricanes along Florida's coastline. Implementing the current analysis methods will be useful for determining the magnitude of wave parameters and coinciding wave forces imposed on structural elements of a bridge superstructure. It is also the intention of this manuscript to address the need for an analysis of the entire network of Florida's coastal bridges, not just one specific bridge case study. This has been regarded as one of the largest limitations of current analysis in this field of work. This research provides an improved understanding of addressing bridge vulnerability from hurricane hazards on both local and network level as well as providing further insight into preventing and limiting the amount of damage that can occur during the event of a major hurricane making landfall.
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Date Issued: 2012
Identifier: FSU_migr_etd-5200
Format: Thesis

Title: Prefabricated Bridge Elements and Systems for off-System Bridges.
Creator: Servos, Joseph, Roddenberry, Michelle, Sobanjo, John, Spainhour, Lisa, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The Federal Highway Administration's (FHWA) ``Every Day Counts'' initiative aims to shorten the overall project delivery time, enhance safety, and protect the environment both on and around construction projects. Using innovative planning, design, and construction methods, Accelerated Bridge Construction (ABC) techniques reduce on-site construction time for new or replacement bridges. One aspect of ABC is Prefabricated Bridge Elements and Systems (PBES), where bridge components are fabricated...
Show moreThe Federal Highway Administration's (FHWA) ``Every Day Counts'' initiative aims to shorten the overall project delivery time, enhance safety, and protect the environment both on and around construction projects. Using innovative planning, design, and construction methods, Accelerated Bridge Construction (ABC) techniques reduce on-site construction time for new or replacement bridges. One aspect of ABC is Prefabricated Bridge Elements and Systems (PBES), where bridge components are fabricated offsite to reduce on-site construction activities. Many state departments of transportation, including Florida DOT, are currently making efforts to implement PBES for their bridge construction projects. The purpose of this research project was to investigate other statesÕ standards and to evaluate them for possible implementation in Florida. An exhaustive search was made, and new literature was reviewed, to learn about current DOT standards and practices. The search revealed that the states with the most prefabricated bridge standards or activities are as follows: Utah, Alabama, Texas, Minnesota, and a collaboration of Northeastern states. These standards were reviewed for details such as the presence of post-tensioning, joint types, design load, and inspectability. The three standard bridge types that show the most promise for adoption by FDOT are: Florida DOT District 2Õs Truncated ``Florida I-Beam'' (FIB), MinnesotaÔs Inverted Tee Beam, and PCI's ``Northeastern Extreme Tee'' (NEXT) Beam. A summary of the findings, including advantages and disadvantages of the bridge systems, is included in this report. Also included is a comprehensive list of web links to standard drawings from all state DOTs, which could also be helpful to expedite other research that involves standards and bridge construction/design practices.
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Date Issued: 2012
Identifier: FSU_migr_etd-5173
Format: Thesis

Title: Investigation of Carbon Fiber Composite Cables (CFCC) in Prestressed Concrete Piles.
Creator: Joshi, Kunal, Rambo-Roddenberry, Michelle, Mtenga, Primus, Jung, Sungmoon, Spainhour, Lisa, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The Florida Department of transportation most commonly uses prestressed concrete piles as foundation in bridges. It has been observed since past few years that the piles installed in aggressive marine environments are subjected to corrosion which generates a need to retrofit them. Although many solutions have been applied to address this issue, these solutions have seem to be ineffective in long term and hence use of advanced materials in piles, to avoid degradation due to corrosion, is...
Show moreThe Florida Department of transportation most commonly uses prestressed concrete piles as foundation in bridges. It has been observed since past few years that the piles installed in aggressive marine environments are subjected to corrosion which generates a need to retrofit them. Although many solutions have been applied to address this issue, these solutions have seem to be ineffective in long term and hence use of advanced materials in piles, to avoid degradation due to corrosion, is necessarry. The ACI and AASHTO equations used to determine the bond properties of a prestressing strand, need to be satisfied by this material, to render this material's suitability as replacement to steel strands. 5--24 in. square prestressed concrete piles which included 3--40 ft. piles and 2--100ft. piles, were cast using 0.6in. diameter carbon fiber composite cables manufactured by Tokyo Rope Mfg. Co. to asses the performance of CFCC as reinforcement. A different anchoring system was used to anchor the CFCC to the abutment in order to prestress the strands. Transfer length was monitored on each pile end and compared to the ACI and AASHTO equations to evaluate the bond characteristics of the CFCC. In addition to that, development length tests and flexural tests were performed at the Marcus. H. Ansley research laboratory to further judge the bond properties of the CFCC with concrete. The results of these tests show if the performance of CFCC is comparable to steel and also describe the technique used to prestress these strands. The 2--100 ft. piles were cast to be driven on site to monitor the static resistance of the piles and would be long term monitored to asses the performance of CFCC against corrosion.
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Date Issued: 2013
Identifier: FSU_migr_etd-8578
Format: Thesis

Title: Analysis of Cost Change in Air Force Construction Projects from Planning to Completion.
Creator: Barnes, Robert J., Sobanjo, John O., Abdelrazig, Yassir, Spainhour, Lisa, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Construction is a major industry in the United States. In 2010, over $506 billion was spent in construction and construction-related activity, amounting to over 3.4% of Gross Domestic Product (GDP). $21.2 billion, or 0.6% of federal outlays for 2010 was spent on military construction. This accounts for nearly 4% of total construction annually. This study examined three variables in the life of an Air Force military construction (MILCON) project: the programmed amount (PA), the contract award ...
Show moreConstruction is a major industry in the United States. In 2010, over $506 billion was spent in construction and construction-related activity, amounting to over 3.4% of Gross Domestic Product (GDP). $21.2 billion, or 0.6% of federal outlays for 2010 was spent on military construction. This accounts for nearly 4% of total construction annually. This study examined three variables in the life of an Air Force military construction (MILCON) project: the programmed amount (PA), the contract award (CA), and the final current working estimate (CWE). These variables, respectively, reflect the initial planning budget (PA), the actual contractor's estimate and bid (CA), and the final, actual cost of the project to the Air Force (CWE). Statistical hypothesis tests showed there is an appreciable difference between each variable. Generally speaking, the PA is higher than the CA, but the CWE approaches the PA at end of the project. The study suggests several reasons for this, including contractor estimate errors or "bad faith", non-inclusion of inflation, and initial estimate inaccuracy. The results of this study can be used to better analyze contractors' bids as well as initial budgetary estimates to get a more accurate picture of the cost of a particular MILCON project.
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Date Issued: 2012
Identifier: FSU_migr_etd-5317
Format: Thesis

Title: Exploration of Monostrand Use in Segmental Box Girder Bridges.
Creator: Spear, Herbert Houston, Rambo-Roddenberry, Michelle, Spainhour, Lisa, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: For the past several decades the segmental box girder bridge has proven itself to be one of the more efficient bridge types. Using reusable form work, segments are match-cast, ensuring a more perfect connection during the construction phase. These benefits in conjunction with the fact that the costs of startup and form work are absorbed into the total cost of each segment mean that the longer the final bridge is, the less the cost is per segment, making the segmental box girder bridge one of...
Show moreFor the past several decades the segmental box girder bridge has proven itself to be one of the more efficient bridge types. Using reusable form work, segments are match-cast, ensuring a more perfect connection during the construction phase. These benefits in conjunction with the fact that the costs of startup and form work are absorbed into the total cost of each segment mean that the longer the final bridge is, the less the cost is per segment, making the segmental box girder bridge one of the most popular long bridge types constructed in the U.S. To minimize cost, it is important to design each segment for efficiency in terms of quantity of longitudinal and transverse post-tensioning and reinforcing steel. The inclusion of post-tensioning technology results in an overall compressive state in the longitudinal and transverse directions of the segments, improving structure strength and service life. However, despite the benefits inherent in using post-tensioning technology, the webs still contain standard deformed reinforcement. The goal of this research is to fit a greased and sheathed monostrand within a segment in a way that both webs and bottom flange would be placed in a state of compression, thereby reducing the demand for standard web reinforcement and, hopefully, segment cost. The research objectives include analyzing principal stresses in the webs of the segment, modifying the segment so as to restrain the monostrand within the webs, designing any additional reinforcement that may be necessary, and finally comparing the estimated construction cost of the new design with that of a pre-existing structure. The results from this research have shown that it is indeed possible to place a greased and sheathed monostrand within the webs of a segment with beneficial results and that the demand for standard deformed reinforcement will thus be reduced.
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Date Issued: 2010
Identifier: FSU_migr_etd-0375
Format: Thesis

Title: Fatigue Evaluation of Structural Composite Lumber (SCL) T-Beam Bridge Girders.
Creator: Enam, Muhammad Badre, Mtenga, Primus V., Tawfiq, Kamal S., Spainhour, Lisa, Kalu, Peter N., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Recent innovation in the engineered wood industry has produced Structural Composite Lumber (SCL) that tends to achieve maximum strength, stiffness and efficient use of wood. Product variations of SCL such as Laminated Veneer Lumber (LVL) and Parallel Strand Lumber (PSL), are currently being used in the transportation sector to produce bridge girders, decks etc. for rural and other low traffic volume roads. Although, the elastic and shear properties of SCL materials are clearly understood, no...
Show moreRecent innovation in the engineered wood industry has produced Structural Composite Lumber (SCL) that tends to achieve maximum strength, stiffness and efficient use of wood. Product variations of SCL such as Laminated Veneer Lumber (LVL) and Parallel Strand Lumber (PSL), are currently being used in the transportation sector to produce bridge girders, decks etc. for rural and other low traffic volume roads. Although, the elastic and shear properties of SCL materials are clearly understood, no attempt has been made to estimate fatigue performance of these bridge girders. With their increasing use, they are repeatedly being subjected to numerous cycles of wheel load that raises concern about their behavior under fatigue. The current research tested 12 newly procured and 2 old and weathered pre-built SCL T-beam bridge girders for flexural fatigue under a stress controlled test setup. The girders were of 20 ft span and having variation in their constituent material types and applied preservatives. Loading was applied according to the AASHTO LRFD specifications for bridge design. The number of load application cycles was consistent with expected traffic volume for a sixty year time span. In a regular bridge structure comprised of pre-built SCL T-beam girders, transverse post-tension is applied to adjacent girders to form a stress laminated deck. This effect had been simulated on the girders and the effect of fatigue loading on the loss of post-tension force was observed. Results from the study indicated that the SCL Tbeam bridge girders were capable of withstanding the repetitive loads coming from the heavy truck traffic. Most of the beams did not suffer any physical damage. A few of them had severe de-lamination at the SCL-epoxy interface. The girders without any damage due to fatigue were loaded statically up to failure. This result was compared to the ultimate flexural strength of fresh beams of similar material type, to investigate their residual strengths after fatigue loading. Some weathered girders were also fatigued under the same experimental setup for comparison purposes. This provided a comparison of the fatigue performance of fresh and weathered SCL T-beam bridge girders. Comparably high strength fatigue loading was applied to two additional girders. The fatigue lives for these girders were less and compared well with those of clear wood at the same stress level. A rudimentary fatigue curve was proposed based on the data. A finite element model was developed, using layered shell elements, to simulate the structural behavior of these girders. Subsequent analyses of this model produced results that were highly representative of the data obtained in experimental testing of SCL T-beam girders.
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Date Issued: 2008
Identifier: FSU_migr_etd-0565
Format: Thesis

Title: Evaluation of Geometric and Traffic Characteristics Affecting the Safety of Six-Lane Divided Roadways.
Creator: Chimba, Deo, Mussa, Renatus, Spainhour, Lisa, Sobanjo, John, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The analysis of traffic crashes that occurred in Florida in 2002 has shown that six-lane divided highways had higher crash rates than two-lane and four-lane highways. Variation of roadway geometrics and traffic characteristics on six-lane highways compared to four and two-lane highways are suspected to be the source of the difference. The goal of this study was to make a comparison of crashes on four and six-lanes in terms of descriptive analysis and to build a crash prediction model which...
Show moreThe analysis of traffic crashes that occurred in Florida in 2002 has shown that six-lane divided highways had higher crash rates than two-lane and four-lane highways. Variation of roadway geometrics and traffic characteristics on six-lane highways compared to four and two-lane highways are suspected to be the source of the difference. The goal of this study was to make a comparison of crashes on four and six-lanes in terms of descriptive analysis and to build a crash prediction model which can be used to predict annual number of crashes. Detailed analysis of geometric and traffic data collected from the archives and in the field was undertaken to establish the correlation between independent factors and crash frequency. The results of descriptive analysis showed distribution of crashes on four and six-lanes to be dependent. In most crash attributes, crash rates on six-lane sections were higher. A Zero-Inflated Negative Binomial (ZINB) crash prediction model was developed. The response variable in the model was crash frequency and independent variables were roadway geometrics and traffic characteristics. Crash frequency was found to have a very strong relationship with most of the independent variables indicated by their p-values. Section length, number of access points, sidewalk, percentage of trucks and traffic volumes had a positive coefficient with the crash frequency. Posted speed limit, shoulder width, median width, surface width and curvature had negative coefficients indicating that when they increase in magnitude, crash frequency decreases. Transformation of some variables like posted speed limit, horizontal degree of curve from numerical to categorical resulted into a well-fitted model.
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Date Issued: 2004
Identifier: FSU_migr_etd-3814
Format: Thesis

Title: A Multi-Criteria Approach for Rating Roadway Sustainability.
Creator: Campbell, Ashley J., Sobanjo, John O., Spainhour, Lisa, Chen, Gang, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: "Green engineering" is the newest technology implemented for sustainability in the design of buildings and most recently highways. Sustainability concepts applied to the design and construction of roadways includes long term planning, new technologies and methods, construction management techniques and resource reuse. Green engineering is part of the global goal of long-term sustainability, which is to meet the needs of today without compromising those of the future. Leadership in Energy and...
Show more"Green engineering" is the newest technology implemented for sustainability in the design of buildings and most recently highways. Sustainability concepts applied to the design and construction of roadways includes long term planning, new technologies and methods, construction management techniques and resource reuse. Green engineering is part of the global goal of long-term sustainability, which is to meet the needs of today without compromising those of the future. Leadership in Energy and Environmental Design (LEED®) rating systems have been heavily promoted and utilized in the construction industry, but only with applications to buildings. There is no such criteria for rating roadway construction. Only one documented attempt has been made to adapt the LEED rating system to highway construction but with limited results. While predominantly used and accepted, the LEED rating points are not quantitative and are not based on any traditional decision making theory. This research presents an evaluation of using the LEED rating system techniques for highway construction. A multi-criteria decision making model (MCDM) is then formulated as a framework for evaluating sustainability in roadway construction. Within Leon County, Blueprint 2000 is an intergovernmental organization to efficiently manage and plan roadway construction projects within Tallahassee, Florida. In cooperation with Blueprint 2000, one of their projects will be used as the local sustainable roadway example. This project will serve as the case study and be evaluated for successful applications of sustainable engineering utilized during roadway design and construction. This research will also include an analysis of the multi-criteria rating system developed on a local roadway project. Research will be comprehensive on the topics of stormwater design, erosion control and the usage of various construction materials. The completion of this research will offer a new insight into rating sustainability and also on both new technologies and innovative practices within the transportation and construction management fields.
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Date Issued: 2009
Identifier: FSU_migr_etd-0099
Format: Thesis

Title: Development of User Cost Model for Movable Bridge Openings in Florida.
Creator: Buxton-Tetteh, Bernard, Sobanjo, John O., Mussa, Renatus N., Spainhour, Lisa, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The Florida Department of Transportation (FDOT) is currently implementing the AASHTO Pontis® Bridge Management System (BMS) to support network-level and project-level decision making at the state and district levels. User cost models in the Pontis BMS quantify in economic terms, the potential safety and mobility benefits of maintenance, repair and replacement of bridge structures. Movable bridge openings force vehicles traveling over the bridges to be held in queues and this results in extra...
Show moreThe Florida Department of Transportation (FDOT) is currently implementing the AASHTO Pontis® Bridge Management System (BMS) to support network-level and project-level decision making at the state and district levels. User cost models in the Pontis BMS quantify in economic terms, the potential safety and mobility benefits of maintenance, repair and replacement of bridge structures. Movable bridge openings force vehicles traveling over the bridges to be held in queues and this results in extra travel time for motorists. The extra travel times are quantifiable as traffic delays costs, which are indirectly borne by commerce and the motoring public, and can be used in an economic analysis to justify the replacement of movable bridges. This thesis presents a study that involved the collection of Florida specific data on vehicular and vessel traffic, including vehicle queue counts, average daily traffic, hourly distribution of vehicular traffic, movable bridge openings, vessel counts and vessel heights at six (6) selected, geographically unbiased, movable bridge sites within the Florida. The data were analyzed and used in development of a user cost model for movable bridge openings for implementation in the Florida Pontis BMS. The movable bridge openings were modeled as bottleneck incidents on the roadways carried by the movable bridges and a deterministic queue model was used in analyzing the resulting delays to vehicular traffic. The developed model was used in a network analysis of Florida's inventory of 147 movable bridges to estimate the economic benefits of bridge replacement projects with the objective of correcting load carrying capacity deficiencies and elimination of traffic delays that were caused by the movable bridge openings. Results obtained showed that the savings in delays to vehicular traffic caused by movable bridge openings would contribute about eight (8) times more than the economic benefits that may be obtained from strengthening movable bridges in Florida.
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Date Issued: 2004
Identifier: FSU_migr_etd-2395
Format: Thesis

Title: Decision Support System to Rank and Evaluate Crash Attenuators.
Creator: Roth, Jason, Spainhour, Lisa, Mtenga, Primus V., Sobanjo, John, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Understanding the behavior and performance of roadside safety devices, such as guardrails, concrete barriers, end terminals, and crash attenuators, is of great importance to improving the safety of roadways and intersections. Crash attenuators have saved numerous lives by reducing the severity of vehicle crashes. However, while a great deal of crash test data exists on barriers and end terminals, information on their performance under field conditions is limited. Because of a variety of...
Show moreUnderstanding the behavior and performance of roadside safety devices, such as guardrails, concrete barriers, end terminals, and crash attenuators, is of great importance to improving the safety of roadways and intersections. Crash attenuators have saved numerous lives by reducing the severity of vehicle crashes. However, while a great deal of crash test data exists on barriers and end terminals, information on their performance under field conditions is limited. Because of a variety of reasons described in more detail below, the field performance of barriers and attenuators can vary drastically from their behavior during crash tests. Four research objectives were established for this project. They are as follows: 1) Develop a database system. 2) Design and implement a framework for a Decision Support System (D.S.S.). 3) Input the appropriate data from FDOT into the database. 4) Use the D.S.S. and data to rank and evaluate attenuators. The DSS is a computer program, based on a decision tree, which recommends an action that best meets a set of prioritized goals. The designer specifies goals, measures (criteria by which the goals can be quantified), and alternates (different ways in which the goal can be met). Weights are used to prioritize or indicate the relative importance of each goal and measure. They are also used to indicate the degree to which each alternate meets the objectives. A series of graphs were developed to explain and compute the relationship between each DSS site criteria and the relevant site characteristics; these graphs are known as the importance functions. The importance functions range from zero (meaning that the site characteristic is not relevant at all for the given value of the DSS criteria) to one (meaning that the site characteristic is very important for the given value of the DSS criteria). In some cases, the graphs were developed based on numeric evidence found through researching accident reports, roadway design and attenuator selection standards, and other relevant literature. For relationships where numeric values could not be found, common sense was used to develop the graph. Based on the test cases included in Chapter 5 and other test cases that were run, the Decision Support System does work and recommends different attenuators to meet different site characteristics and/or situations. It was determined that the Decision Support System results are more sensitive to changes in the objective weights and test standards and not so sensitive to changes in the site characteristics. The only time there were significant changes in the recommendations based on site characteristics is when the type of site was drastically changed. In the case of a mild site, based on the current setup, the recommendation could be that an attenuator may not be needed. Therefore, the importance functions should be fine-tuned to help in different recommendations. Another recommendation is that more data needs to be added to the database. This could help give better or more accurate recommendations, since the recommendations are based on historical performance data. More historical data is required on attenuators that meet the NCHRP-350 standards. As with any program that gives results based on its database, the more data that is available the more accurate the results will be.
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Date Issued: 2004
Identifier: FSU_migr_etd-1781
Format: Thesis

Title: Bulb-T Girder Bridge Barrier Effect on Live Load Distribution.
Creator: Stricker, Tal, Rambo-Roddenberry, Michelle, Spainhour, Lisa, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Bulb-T girder bridges are composed of precast, prestressed concrete beams with a reinforced concrete slab. Typically, the slab extends transversely beyond the exterior beam, and there is a traffic barrier on the edge. The bridges are designed for dead and live loads and prestressing effects. For the live loads, the transverse distribution of moment and shear load effects to interior and exterior girders is determined by using equations in the American Association of State Highway and...
Show moreBulb-T girder bridges are composed of precast, prestressed concrete beams with a reinforced concrete slab. Typically, the slab extends transversely beyond the exterior beam, and there is a traffic barrier on the edge. The bridges are designed for dead and live loads and prestressing effects. For the live loads, the transverse distribution of moment and shear load effects to interior and exterior girders is determined by using equations in the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications. These equations give the designer a factor, which is then multiplied by the moment or shear load effect determined by a line analysis. The equations assume that barriers are not present. The Florida Department of Transportation (FDOT) Structures Research Lab has made field measurements on a Bulb-T bridge, both before and after the barriers were placed, due to a truck loaded with blocks. For this project, this data was analyzed to determine the barrier's effect on the live load distribution. The results of this project may be used to determine if load ratings can be improved by consideration of the barrier effect, which can be done as a Posting Avoidance (Exception) technique.
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Date Issued: 2008
Identifier: FSU_migr_etd-1542
Format: Thesis

Title: Stochastic Preservation Model for Transportation Infrastructure.
Creator: Thomas, Omar St. Aubyn Alexander, Sobanjo, John, Chicken, Eric, Spainhour, Lisa, Mtenga, Primus, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: In this dissertation new methodologies were developed to address some of the existing needs as it relates to Transportation Asset Management Systems (TAMS). The goal of TAMS is to model the performance and preservation of transportation infrastructure. Currently, traditional Bridge Management Systems (BMS) such as Pontis® and BRIDGIT® utilize Markov chain processes in their performance and preservation models. Markov models have also been suggested and used at some State transportation...
Show moreIn this dissertation new methodologies were developed to address some of the existing needs as it relates to Transportation Asset Management Systems (TAMS). The goal of TAMS is to model the performance and preservation of transportation infrastructure. Currently, traditional Bridge Management Systems (BMS) such as Pontis® and BRIDGIT® utilize Markov chain processes in their performance and preservation models. Markov models have also been suggested and used at some State transportation agencies for modeling the performance of highway pavement structures. The Markov property may be considered restrictive when modeling the deterioration of transportation assets, primarily because of the "memoryless" property. In other words, the Markov property assumes that the sojourn times in the condition states follows an exponential distribution for the continuous-time Markov chain, and a geometric distribution for the discrete-time Markov chain. This research addresses some of the limitations that arise from the use of purely Markov chain deterioration and performance models for transportation infrastructure, by introducing alternative approaches that are based on the semi-Markov process and reliability functions. The research outlines in detail an approach to develop semi-Markov deterioration models for flexible highway pavements and American Association of State Highway Transportation Officials (AASHTO) Commonly Recognized (CoRe) Bridge Elements. This takes into consideration the probability of transitions between condition states and the sojourn time in a particular condition state before transitioning to another condition state. The proposed semi-Markov models are compared against the traditional Markov chain models. With Weibull distribution as the assumed distribution of the sojourn time in each condition state, for both the pavement and bridge deterioration models, Maximum Likelihood Estimation (MLE) was used to determine the estimates of the distribution parameters. For the pavement deterioration, the comparison of the semi-Markov and Markov chain models is presented, based on a Monte Carlo simulation of the condition. For the bridge element deterioration, the proposed semi-Markov model is compared against another semi-Markov approach outlined by Black et al. (2005a,b). A Bayesian-updated model was also compared to the proposed semi-Markov model. The research findings on the semi-Markov modeling validates the hypothesis that the rate of deterioration of pavements and bridge elements tends to increase over time. The results obtained from this study outlined a feasible alternative method in which historical condition data can be used to model the deterioration of pavement and bridge elements based on semi-Markov processes. For pavement deterioration, the semi-Markov model appeared to be superior to that of the Markov chain model in predicting the pavement conditions for the first five years subsequent to a major rehabilitation. The approach by Black et al. (2005a,b), which was applied to bridge element deterioration, assumes that the proportion of asset in state i at interval t is equal to the total probability of that asset being in state i after the t-th interval. It was discovered that this may not be true when the sample size of the asset being analyzed gets relatively small. Black et al. (2005a,b) used a least squares optimization technique to estimate the parameters of the (Weibull) sojourn time distribution, obtaining local optimal values, which may not best estimate the condition of the asset. An adaptive control approach for modeling the preservation of CoRe Bridge Elements based on Semi-Markov Decision Processes (SMDP) is also outlined in this dissertation. The methodology outlined in this study indicated that the use of SMDP can be used to determine the minimum long-term costs for the preservation of bridge elements from the CoRe Bridge Element data. The use of semi-Markov process to model deterioration relaxes the assumption of the distribution of the sojourn time between condition states for deterioration and improvement works, and therefore the SMDP model is less restrictive than Markov Decision Process (MDP) model. Also, Reliability (survival) functions were developed for both pavement segments and bridge elements to estimate their service lives. The Weibull regression and Cox Proportional Hazards models developed showed the association between factors, such as Average Daily Traffic (ADT) and the environment, and the condition of the asset over time. The proposed methodology outlined above is being researched at a time when there is a need for increased efficiency in the spending of government resources, while ensuring the preservation of the nation's transportation assets and network. The proposed stochastic models are based on the principles of semi-Markov processes, and address some of the limitations of the traditional Markov chain model. The survival analyses using the historical condition data allows for quick estimations as it relates to the service lives for bridge segments and bridge elements.
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Date Issued: 2011
Identifier: FSU_migr_etd-1564
Format: Thesis

Title: Simulation of Traffic Crashes Using Cell Based Microsimulation.
Creator: Muchuruza, Victor, Mussa, Renatus, McGee, Daniel, Spainhour, Lisa, Sobanjo, John, Thuo, Gikiri, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The deterioration of the safety of operation, coupled with the persistent increase in rearend crashes, is of great concern in finding accurate and realistic methods of modeling traffic flow and preventing traffic crashes. For some decades safety evaluation methods have relied on analysis of historical crash data. Since crashes are random and rare events and, in most cases, are independent events, it is difficult to find a sufficient number of crashes on a road section in a relatively short...
Show moreThe deterioration of the safety of operation, coupled with the persistent increase in rearend crashes, is of great concern in finding accurate and realistic methods of modeling traffic flow and preventing traffic crashes. For some decades safety evaluation methods have relied on analysis of historical crash data. Since crashes are random and rare events and, in most cases, are independent events, it is difficult to find a sufficient number of crashes on a road section in a relatively short time period (e.g., a month or even a year). Thus, multi-year collection of crash data is used in safety analysis. Another safety evaluation method that has been practiced though in small scale is traffic conflict techniques (TCT). The advantage of using TCT in safety evaluations is the ability to test or study a safety strategy or improvement applied on the roadway facility in a relatively short period of time compared with traditional methods, which are dependent on crash data. However, use of TCT is not popular; perhaps because it needs extensive resources to collect, extract, and analyze conflict information. Moreover, like crash data analysis, use of TCT also makes concerned authorities reactive to the problem by responding to the crashes that have already occurred. Therefore, alternative proactive safety evaluation techniques that can improve the quality of traffic safety evaluation are needed at this time. One way of using proactive safety evaluation techniques and thus become more preventive than reactive towards dealing with the overall safety problem is to utilize the capability of traffic micro-simulation to assess safety on highways through examination of hazardous vehicle movements in the traffic stream. Using micro-simulation predictive methods, it may be possible to diagnose safety problems and apply appropriate remedial measures, rather than waiting until a crash occurs to remedy the problem. This means, a hazard can be early identified and possibly corrected before implementation of highway projects. In addition, the use of simulation tools to evaluate the safety of a traffic system can be advantageous because such tools provide extensive results for any study area within a relatively short time along with other traffic operational measures like level of service, delays, travel times, and capacities.
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Date Issued: 2006
Identifier: FSU_migr_etd-2210
Format: Thesis

Title: Modeling Highway Crashes Using Bayesian Belief Networks Technique and GIS.
Creator: Sando, Thobias, Mussa, Renatus, Liu, Xiuwen, Spainhour, Lisa, Sobanjo, John, AbdelRazig, Yassir, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Modeling traffic crashes is a complex undertaking. Previous research studies have used a variety of techniques to analyze crashes. Conventionally, traffic crashes have been modeled using regression models. Recently, intelligent systems have been applied in highway safety modeling. Such methods include artificial neural networks, decision trees, nearest-neighbor rule, Bayesian methods, and clustering algorithms. One method that has not been well used in analyzing highway safety data is...
Show moreModeling traffic crashes is a complex undertaking. Previous research studies have used a variety of techniques to analyze crashes. Conventionally, traffic crashes have been modeled using regression models. Recently, intelligent systems have been applied in highway safety modeling. Such methods include artificial neural networks, decision trees, nearest-neighbor rule, Bayesian methods, and clustering algorithms. One method that has not been well used in analyzing highway safety data is Bayesian Belief Network technique. This research investigated the use of Bayesian Belief Networks technique in highway safety modeling. A prediction model using Bayesian Belief Networks technique is proposed as part of the efforts to enhance traffic safety data analysis. The technique takes advantage of the knowledge of causal relationships or statistical dependencies (or independencies) among the model variables. A simple hypothetical Belief Network that comprised of six variables i.e., annual average daily traffic (AADT), section length, number of lanes, surface width, maximum posted speed limit, and number of crashes per year for each road segment was constructed. The model allows for the prediction of number of crashes per year at a roadway segment given a set of values of each of the model variables. Geographical Information Systems (GIS) was incorporated in the model for displaying model results. A stand alone GIS application was developed using MapObjects software package. Programming was done in Visual Basic environment. The final output of the model was the map of the roadway network showing predictions of crash category for each roadway section. Two different datasets were used in modeling – state roadways with a maximum number of lanes of 6 (subset 1) and exclusively six lane highways classified as high crash locations (subset 2). The performance of the proposed model was evaluated using the prediction accuracy. The prediction accuracy is hereby defined as the percentage of the roadway sections whose crash occurrence was correctly predicted. The results obtained in this study yielded the prediction accuracy of 68.08% and 78%, for subset 1 and 2, respectively.
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Date Issued: 2005
Identifier: FSU_migr_etd-2088
Format: Thesis

Title: Evaluation of Truck Lane Restriction on Non-Limited Access Urban Arterials.
Creator: Mwakalonge, Judith L., Moses, Ren, Spainhour, Lisa, Sobanjo, John, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The increase in commodity flow and just-in-time pick up and delivery activities in urban areas have led to increase in truck traffic on urban roadways which raises safety and operational concerns. The concerns are related to trucks' large dimensions and operating characteristics which tend to conflict with passenger cars traffic operating characteristics. A number of strategies for managing trucks have been implemented on interstates highways, arterial streets, and local roads. The truck lane...
Show moreThe increase in commodity flow and just-in-time pick up and delivery activities in urban areas have led to increase in truck traffic on urban roadways which raises safety and operational concerns. The concerns are related to trucks' large dimensions and operating characteristics which tend to conflict with passenger cars traffic operating characteristics. A number of strategies for managing trucks have been implemented on interstates highways, arterial streets, and local roads. The truck lane restriction strategy is very prevalent on limited access highways in Florida and other States. The perceived and real success of truck lane restriction on freeways have led to increasing demands from the public for highway agencies to institute similar measures on non-limited access arterial streets. The review of State statutes, policies, and practices have so far revealed that five States—Alabama, Delaware, Florida, Georgia, and New Jersey—have roadway sections on non-limited access highways with truck lane restriction. However, the literature search revealed that the efficacy of truck lane restriction on non-limited access highways has not been thoroughly studied The objective of this study was therefore to evaluate the influence of various geometric, traffic, and signalization factors that might affect the effectiveness of truck lane restriction on non-limited access highways, primarily on urban arterial roadways with significant amount of truck traffic. Because of lack of sufficient sites to conduct a longitudinal field study, VISSIM simulation software was used to evaluate operational and safety effects of truck lane restriction by varying various parameters related to the restriction. A 5-mile section of SR 70 in Fort Pierce, Florida was selected for simulation analysis. Furthermore, a network consisting of 22 roadway sections with 121 signalized intersections was simulated. The results of various simulation scenarios showed that restricting trucks to the right lane do not have deleterious effects compared to no restriction at all, and in fact could improve travel speed on the highway corridor, although not by much. However, restricting trucks to the left lane or to center lane would cause excessive lane changing, reduced travel speed, increased queue length, and stopped delay. The imposition of truck lane restriction increases speed difference between cars and trucks and among different lanes the effect of which is to increase lane changing maneuvers. This phenomenon is likely to increase vehicular conflicts in real life but the exact extent of its operational and safety implications need to be studied in the field.
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Date Issued: 2007
Identifier: FSU_migr_etd-2155
Format: Thesis

Title: Large Wind Missile Impact Performance of Public and Commercial Building Assemblies.
Creator: Scheer, Daniel L., Yazdani, Nur, Spainhour, Lisa, Abdullah, Makola, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Hurricanes produce phenomena during the duration of the storm that are not particularly addressed in Standard Building Code Loading Combinations. One such phenomenon is the horizontally projected missiles due to high wind velocities generated by Hurricane weather systems. The data contained in the manuscript is an initial attempt to categorize what typical building systems in use throughout Florida, based on previous testing and testing performed in conjunction with this project, are able to...
Show moreHurricanes produce phenomena during the duration of the storm that are not particularly addressed in Standard Building Code Loading Combinations. One such phenomenon is the horizontally projected missiles due to high wind velocities generated by Hurricane weather systems. The data contained in the manuscript is an initial attempt to categorize what typical building systems in use throughout Florida, based on previous testing and testing performed in conjunction with this project, are able to withstand the instantaneous impact of a projected missile against the wall and roof system at different loading points. The projectile used in this testing was a 9lb and 15lb 2 by 4 timber wall stud of standard dimensions. This is beginning to be recognized as the testing standard throughout the country and State of Florida. In depth background information, details on the method of projection, definition of failure, and complete tables listing the results of the testing are included in the manuscript. It is important to understand that this is not an exhausted list by any means, and further testing of different wall system types, new technologies, and strengthened typical systems must happen to keep a current record of proven systems to be used in Residential and Commercial construction throughout the state of Florida.
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Date Issued: 2005
Identifier: FSU_migr_etd-2050
Format: Thesis

Department of Civil and Environmental Engineering (26)	+ -
Florida State University (26)	+ -
Sobanjo, John (12)	+ -
Rambo-Roddenberry, Michelle (6)	+ -
Tawfiq, Kamal (6)	+ -

Jung, Sungmoon (4)	+ -
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