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Title: Empirical Deck for Phased Construction and Widening.
Creator: Fuentes, Javier Alexander Muniz, Tawfiq, Kamal, Sobanjo, John O., Spainhour, Lisa K., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: A standard deck is defined as a deck slab on longitudinal beams with main reinforcement placed perpendicular to traffic. As outlined in Article 9.6.1 of the AASHTO-LRFD Bridge Design Specifications, it allows three design methods or procedures of bridge decks with primary reinforcement perpendicular to the main bridge beams Approximate Elastic or "Strip" Method of Analysis (AASHTO 4.6.2.1) Traditionally bridge deck designs have always been made by analyzing assumed transverse slab strips...
Show moreA standard deck is defined as a deck slab on longitudinal beams with main reinforcement placed perpendicular to traffic. As outlined in Article 9.6.1 of the AASHTO-LRFD Bridge Design Specifications, it allows three design methods or procedures of bridge decks with primary reinforcement perpendicular to the main bridge beams Approximate Elastic or "Strip" Method of Analysis (AASHTO 4.6.2.1) Traditionally bridge deck designs have always been made by analyzing assumed transverse slab strips within the concrete deck as flexure members and supported by the existing girders. This method is called the Approximate Method of Analysis. To simplify the length and complexity of the design, it is assumed that the girders are rigid supports. In addition, AASHTO specifications allow the maximum positive moment and the maximum negative moment to apply for all positive moment regions and all negative moment regions in the slab, respectively. Refined Methods of Analysis (AASHTO 4.6.3) - Refined Methods of Analysis are generally acceptable methods for analyzing concrete bridge decks. These methods are based mainly on finite element analysis, which requires a more complicated and lengthy set of calculations. Thus, these various methods are not typically used to analyze a standard or "typical" bridge deck. A refined analysis method would be better suited for a more complex deck slab structure, which would require a more detailed analysis. Empirical Method of Analysis (AASHTO 9.7.2) - Empirical Method of Analysis is generally based on the concept of internal "arching action" within concrete slab. In other words, the deck behaves more like a "continuous membrane" than a series of contiguous beams. This method takes into account in plane stresses generated by applying load to the deck. These in plane forces, which in traditional design are ignored, act to strengthen the overall response of the deck. This design procedure is generally accepted and is widely adopted and employed by many other countries and in-state agencies. This project was initiated with the goals of assessing the current and possibly future design methodologies to be used by the Florida Department of Transportation in future bridge deck design projects. This thesis focuses on evaluating and contrasting the benefits and disadvantages of the Traditional Method of Analysis (currently in general use by the FDOT) and the empirical method of analysis. This objective is achieved by conducting a Finite Element Analysis parametric study using specialized computer software, where a typical bridge is designed and tested based on designs derived from said methods. The analysis yielded data that was then collected, analyzed and used for benchmark purposes. This study allowed an extensive range of specimens to be tested, and a broad range of loads and reinforcement combinations to be analyzed using both methodologies. From the results obtained, potential recommendations were then formulated in contrast to current design practices.
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Date Issued: 2013
Identifier: FSU_migr_etd-8609
Format: Thesis

Title: Influence of Anomalies on Bond Layer to the Perfomance of Fiber Reinforced Polymer (FRP) Retrofit.
Creator: Shiyo, Wolta, Mtenga, Primus, Rambo-Roddenberry, Michelle, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: In recent decades, Fiber Reinforced Polymer (FRP) material has increased its importance in the construction industry. FRP is a non-metallic reinforcement material which has been used in the strengthening structures especially concrete structures. The applications of the FRP material in the construction industry brought about an interesting alternative for structural retrofitting. FRP materials are lightweight, high strength-to-weight ratio, stiffness-to-weight ratio has high chemical...
Show moreIn recent decades, Fiber Reinforced Polymer (FRP) material has increased its importance in the construction industry. FRP is a non-metallic reinforcement material which has been used in the strengthening structures especially concrete structures. The applications of the FRP material in the construction industry brought about an interesting alternative for structural retrofitting. FRP materials are lightweight, high strength-to-weight ratio, stiffness-to-weight ratio has high chemical resistance, ease to install, minimal labor cost and non-corrosive. These characteristics make FRP superior to traditional structural retrofit materials such as steel plates. Structural retrofit is a common phenomenon in the construction industry. Retrofitting is needed when one or a combination of the following situations are encountered: a) structural deterioration caused by the environmental changes, b) additional load carrying capacity needed due to occupancy change and c) when construction or design mistakes are made which result to inadequate reinforcement for a structure. FRP retrofit is done by mounting FRP to the tension side of a member to be retrofitted using epoxy which is used as the bonding agent. The nature and characteristics of the bond layer have some influence on the performance of a structure with anomalies in the bond layer, such as uneven thickness of epoxy or voids in structure itself which lead to debonding. Debonding is caused by high stress distribution on uneven location. These anomalies are usually a result of poor workmanship during the process of grinding the surface before the installation of FRP material. The objectives of this study were to assess the effects of anomalies on a structure that was retrofitted by FRP material and produce a remedy to the structure affected by these anomalies. The experiment conducted showed that anomalies affect structures that are retrofitted by FRP. One way of resolve this problem is by impregnating FRP material to a structure which is good in tension to avoid debonding. This method was found to be useful since it increases the load capacity for about 20%.
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Date Issued: 2008
Identifier: FSU_migr_etd-1745
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: Transverse Analysis and Field Measurements of Segmental Box Girder Bridges.
Creator: Kuhn, Dan, Rambo-Roddenberry, Michelle, Tawfiq, Kamal, Mtenga, Primus, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Parapets placed on bridge deck surfaces, commonly known as barriers, are purposely omitted from the structural analysis model for design or load rating. Barriers should not be considered primary structural members because they are designed to withstand the impact of a vehicular collision. After a forceful collision, a barrier would sustain some structural damage and would no longer support or strengthen the bridge deck. However, when completely intact, these secondary structural members do,...
Show moreParapets placed on bridge deck surfaces, commonly known as barriers, are purposely omitted from the structural analysis model for design or load rating. Barriers should not be considered primary structural members because they are designed to withstand the impact of a vehicular collision. After a forceful collision, a barrier would sustain some structural damage and would no longer support or strengthen the bridge deck. However, when completely intact, these secondary structural members do, significantly, absorb and distribute any applied load, thus acting as fully functional structural members. The amount that appurtenances, specifically parapets, contribute to deck strength is of interest to permitting agencies, such as the Florida Department of Transportation (FDOT). For a concrete segmental box girder bridge, load ratings for oversized load permits are currently determined with a calculation that involves the transverse analysis of the bridge without factoring in the extra strength of fully intact appurtenances. Moreover, within the transverse analysis, the maximum moment generated from the live load is typically calculated from Homberg charts. These generalized influence surfaces were designed based on plate surface models and are conservative. When added to the standard "error on the side of caution" design methods, this moment estimation and the lack of consideration for the appurtenances create an overly conservative transverse load rating for the bridge. With 3D finite element bridge models, created using LUSAS, it is shown, qualitatively and quantitatively, how much of an effect the barrier has on the live load distribution for three concrete segmental box girder bridges located in the Florida Keys. Data obtained from these models is directly compared to measurements obtained from FDOT load tests on the actual bridges and also to predictions made from Homberg influence surfaces. Modifying the current method of load rating, for structurally sound bridges, with fully functional appurtenances should interest permitting agencies and would prove beneficial to those transporting oversized loads.
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Date Issued: 2008
Identifier: FSU_migr_etd-2937
Format: Thesis

Title: Methane Emission and Oxidation Through Landfill Covers.
Creator: Yuan, Lei, Abichou, Tarek, Chanton, Jeffrey, Tawfiq, Kamal, Ping, Wei-Chou V., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: This dissertation presents the work of investigating methane emission and oxidation through landfill covers. Methane as a major source of greenhouse and is being emitted from solid waste landfill at a tremendous rates. These emissions could be mitigated by methanotrophic bacteria in enriched and non-enriched soil covers. Compost biofilters were constructed to study the methane oxidation capacity of compost. The aged chipped yard waste compost was obtained from Leon County landfill (Florida,...
Show moreThis dissertation presents the work of investigating methane emission and oxidation through landfill covers. Methane as a major source of greenhouse and is being emitted from solid waste landfill at a tremendous rates. These emissions could be mitigated by methanotrophic bacteria in enriched and non-enriched soil covers. Compost biofilters were constructed to study the methane oxidation capacity of compost. The aged chipped yard waste compost was obtained from Leon County landfill (Florida, USA). A one-dimensional dynamical numerical model was developed to simulate the methane transport and oxidation through the biofilter. This model was designed to incorporate dynamic parameters and use flux bottom boundary, which is measured by a flow meter. General agreements of methane outflux and oxidations were obtained between model simulation and experimental data. Field scale control cells and biocells were evaluated in the same landfill for methane emission and oxidation. Methane oxidation in biocells was significantly higher than in control cells. When outliers were removed, methane emission from biocells was significant less than from control cells. A numerical model was developed to separate blockage of the thicker biocells cover and the biological oxidation. Results showed that the low emission from biocells is caused by blockage of soil cover underneath the compost cover as well the high oxidation capacity of this compost cover. An additional modeling investigation was conducted to evaluate how landfill final earthen cover's construction and climate conditions affect methane emission and oxidation under different boundary condition and different soil oxidation capacities. This numerical model combined a water and heat flow model (HYDRUS1D) and a gas transport and oxidation model. Simulations showed that soil covers in subhumid areas can prevent high methane emission with blockage and decent oxidation capacity. In semi-arid sites, higher emission was obtained due to the higher air filled void space of the soil. Oxidation capacities in semi-arid sites are higher than those in subhumid sites since influxes of methane are higher in semiarid sites. High pressure underneath the cover caused higher emission in all sites. Even with active gas collection system (vacuum pressure), emissions were significant in semiarid climates.
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Date Issued: 2006
Identifier: FSU_migr_etd-0919
Format: Thesis

Title: Static Structural Implications of Bridge Pile Bents by Vessel Impact under Scoured Conditions.
Creator: Fung, Kakit, Sobanjo, John, Tawfiq, Kamal, Jung, Sungmoon, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Local scour has been a leading cause of bridge failure. The erosion of the soil at the bottom of the piles causes changes in the structural integrity of the bridge. Bridge piles are most vulnerable during the occurrence of scour and the process of the scour holes refilling. Outside forces such as vessel impact can occur and cause failure at that time. This solidifies the reason for providing insight on the structural implications of vessel impact on bridge substructures under scoured...
Show moreLocal scour has been a leading cause of bridge failure. The erosion of the soil at the bottom of the piles causes changes in the structural integrity of the bridge. Bridge piles are most vulnerable during the occurrence of scour and the process of the scour holes refilling. Outside forces such as vessel impact can occur and cause failure at that time. This solidifies the reason for providing insight on the structural implications of vessel impact on bridge substructures under scoured conditions in hopes that failure can be prevented. This research involves using FB-Multipier; a nonlinear finite element based program to analyze bridge pile bent induced with impact forces under scoured conditions. The first part of the research deals with exploring the working condition of pile bent under normal flood and scour conditions. The second part deals with the addition of vessel impact striking the substructure. The occurrence of these two conditions occurs under the assumption of an extreme load event occurring. The changes monitored in the piles were as follows: lateral resistance in the piles when scour occurs; demand/capacity; their fixity based on scour depth; and pile-load interaction. The parameters such as soil properties, bent dimensions, and hydraulic data are modeled after the Ernest Lyons West Island Access Bridge in Florida. This provides actual data that can be used as considerations for similar bridges. The results mimic the expectations established in the hypothesis. Besides this, interaction behavior of the applied force and piles are found. First off, the location of the applied lateral force is important. It greatly influences the static changes. Maximum shear occurs at the top of the soil during the unscoured and scoured conditions. Maximum negative moment does indeed occur at the fixity depth.
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Date Issued: 2013
Identifier: FSU_migr_etd-7382
Format: Thesis

Title: The Influence of Surface Friction and Other Parameters on Concrete's Response to Loading.
Creator: Bouchard, Nicholas, Rambo-Roddenberry, Michelle, Ping, Virgil, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: This thesis presents an evaluation of concrete behavior under loading. Currently, concrete theories and codes are inadequate in explaining the full gamut of concrete responses due to loading. It is, therefore, of great interest to formulate a theory that is capable of explaining the wide array of concrete responses in order to better understand concrete behavior and to build safer, stronger, and more cost effective structures. The purpose of this thesis is to aid in formulating a concrete...
Show moreThis thesis presents an evaluation of concrete behavior under loading. Currently, concrete theories and codes are inadequate in explaining the full gamut of concrete responses due to loading. It is, therefore, of great interest to formulate a theory that is capable of explaining the wide array of concrete responses in order to better understand concrete behavior and to build safer, stronger, and more cost effective structures. The purpose of this thesis is to aid in formulating a concrete failure theory that will account for variations in concrete behavior under loading. In order to achieve this, an extensive investigation of past concrete research is performed. Important concrete phenomena such as microcracking, Poisson's effect, size effect, response to confinement, and the response to loading rate are discussed. The procedure and test results of a concrete compression test with reduced surface friction are also presented. In this thesis, evidence is presented to dispute the existence and the influence of both size effect and the concrete response to the rate of loading. It is also proven that axial cleavage fracture is the true failure mode of concrete under uniaxial compression, not shear failure. The crack pattern of a cylindrical concrete specimen that reaches failure under uniaxial compression consists of a series of rather straight cracks running the entire length of the specimen parallel to the direction of the applied compressive load. This is a stark contrast to the typically expected cracks inclined toward the center of the specimen accompanied by uncracked ends. A case is also made that concrete failure in compression is due to lateral tensile strains caused by the existence of Poisson's effect. An investigation of strain is also performed. This investigation and the discussion of the topics previously listed lead to the development of a proposed strain failure theory. A series of proposed testing procedures is also presented.
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Date Issued: 2010
Identifier: FSU_migr_etd-7102
Format: Thesis

Title: Effects of Secondary Elements and Joints on Strain Distribution in Composite Steel Girder Bridges.
Creator: Lewis, Michael, Tawfiq, Kamal, Rambo-Roddenberry, Michelle, Jung, Sungmoon, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: When considering the design of bridge girders, the American Association of State Highway and Transportation Officials (AASHTO) determine how the loads will be transferred to each girder. The equations used in AASHTO Load and Resistance Factor Design (LRFD) neglect the inertia added from secondary elements such as barriers and curbs. By neglecting these added effects, many bridges that are already built could have more strength than initially designed for. If the effects of these secondary...
Show moreWhen considering the design of bridge girders, the American Association of State Highway and Transportation Officials (AASHTO) determine how the loads will be transferred to each girder. The equations used in AASHTO Load and Resistance Factor Design (LRFD) neglect the inertia added from secondary elements such as barriers and curbs. By neglecting these added effects, many bridges that are already built could have more strength than initially designed for. If the effects of these secondary elements were considered, it would be possible to reduce the distribution factors that are given for interior and exterior girders. The bridge of concern for this project has four spans and was built in the early 1950s. Some repair work and modifications were conducted on the bridge and a load test was performed a week afterwards. The tests were done to find out if the repairs were adequate based on full composite action between the girders and the slab. During this initial test, some problems were discovered in one of the interior spans. This interior span is unique because it contains an expansion joint and a physical barrier and curb joint at the mid-span of the bridge. After problems were discovered, the physical joints were recommended to be grouted and a second load test was conducted afterwards. The second load test yielded much lower strains in the exterior girders due to the decrease in localized stress at the physical joint. In order to prove that filling the joint could improve the bridges strength, a finite element model was constructed to simulate this activity. Two models were made, one prior to filling the physical barrier and curb joints and one after. The test data was compared to the data from the finite element model to ensure accuracy. After the model was calibrated, the secondary members of the bridge were modified to study their effects. The primary goal of this research is to prove that a physical joint in a continuous exterior secondary element will cause the same amount of strain at its location as if they weren't there to begin with. By analyzing the finite element model data, it was found that when the joint is filled the behavior of the bridge changes and the exterior girder has up to 50% reduction in strain. The effect of concrete cracking and stress distribution that is associated with it is a secondary topic that was discussed because it was a driving factor in the model calibration.
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Date Issued: 2012
Identifier: FSU_migr_etd-4986
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: Deficiency Analysis of Coastal Buildings for Storm Damage Reduction.
Creator: Dowgul, Ronald Walter, Yazdani, Nur, Tawfiq, Kamal, Leszczynska, Dauta, Martinko, Mark, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Since 1984 the author has provided engineering services to property owners, insurance companies, attorneys, and others. The scope of those services typically included identifying the cause and origin of damage to residential and commercial structures as well as an estimation of the magnitude of damage sustained by those structures. The majority of those damaged structures were located in proximity to a coastal region and have experienced recent exposure to a storm or other weather event. The...
Show moreSince 1984 the author has provided engineering services to property owners, insurance companies, attorneys, and others. The scope of those services typically included identifying the cause and origin of damage to residential and commercial structures as well as an estimation of the magnitude of damage sustained by those structures. The majority of those damaged structures were located in proximity to a coastal region and have experienced recent exposure to a storm or other weather event. The long-term performance of any building (structure) is directly related to, among other things, the design or physical features of the building, construction practices, routine maintenance, and exposure to severe weather events. During periods of increased external loading and water exposure, such as those resulting from severe weather events, deficiencies in design, construction, or maintenance often result in what would otherwise be avoidable building damage. As a result of more than one thousand case studies involving site inspections, it has become apparent that building related deficiencies are often found to exist as a common feature in similar structures. Some of those recurring deficiencies could be eliminated with alternate building design, better construction practices, or proper routine maintenance procedures. Compilation of those case studies has allowed identification and ranking of the occurrence of chronic building problems. Where applicable, proposed remedial solutions are presented for specific building deficiencies or problems identified. It appears that a significant lack of feedback to engineers, architects, and builders exists regarding long term building performance. An increased awareness of existing chronic deficiencies in the design and construction of buildings and a subsequent effort to eliminate those deficiencies is essential to the future performance of new construction, in general, and specifically to the storm survivability of many structures in coastal regions. Much of what has been learned as a result of this analysis can be of considerable value to professionals or future professionals involved in the building design and construction communities.
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Date Issued: 2005
Identifier: FSU_migr_etd-0681
Format: Thesis

Title: Design of Cost Effective Lysimeter for Field Evaluation of Alternative Landfill Cover Projects Using HYDRYS 2D Simulation.
Creator: Liu, Xiaoli, Abichou, Tarek, Hilton, Amy Chan, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Landfills are the most widely used facilities for solid waste disposal. Landfill covers are used to reduce the quantity of water that infiltrates into solid waste landfills, isolate solid waste from the environment and control gas migration. Resource Conservation and Recovery Act (RCRA) regulations prescribe that the covers employ layers which have low saturated hydraulic conductivity as hydraulic barriers. Those barriers can limit flow into underlying solid wastes, and consequently, reduce...
Show moreLandfills are the most widely used facilities for solid waste disposal. Landfill covers are used to reduce the quantity of water that infiltrates into solid waste landfills, isolate solid waste from the environment and control gas migration. Resource Conservation and Recovery Act (RCRA) regulations prescribe that the covers employ layers which have low saturated hydraulic conductivity as hydraulic barriers. Those barriers can limit flow into underlying solid wastes, and consequently, reduce the rate of leachate generation and risk of additional groundwater contamination. Experience has shown that the prescribed clay barrier layers are susceptible to failure caused by desiccation and cracking damage by freeze â thaw actions, and are expensive to build. An effective alternative cover design is Evapor-Transpiration (ET) cover. ET covers possess many advantages over prescribed covers such as working with nature, long life time, easy maintenance and lower cost. Once the feasibility of an ET cover is verified in a region, an evaluation of hydraulic equivalency is required for alternative cover to be approved by regulatory authorities. The hydraulic equivalency requires that percolation from the base of the alternative cover is less than or equal to percolation rate from the prescriptive cover. Lysimeters was suggested to be used in facilities measuring the percolation rate. There are some concerns about the precision with which percolation rate can be measured with lysimeters. A series of numerical simulations were performed in this study to investigate the performance of lysimeters of various geometries and develop the optimal lysimeters dimensions for percolation rate measurement. The simulations consist of inputting data for lysimeter geometry, soil hydraulic property, weather condition, boundary condition, vegetation distribution and density. The output cumulative flux data was used to evaluate the performance of lysimeters. The study shows at the specific weather condition, the lysimeters without sidewalls underestimate percolation rate by at least 25%. Installation of full sidewalls remarkably improved the lysimeter performance. The lysimeter with full scale sidewalls still underestimate by at least 10%. Lateral diversion and no-flow boundary at the bottom of lysimeter and the drainage layer right above the bottom pan caused the decrement of lysimeter performance. To measure percolation rate accurately, soil - specific and site - specific coefficients have to be determined. The coefficients can to be used to correct lysimeter performance.
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Date Issued: 2004
Identifier: FSU_migr_etd-1198
Format: Thesis

Title: Environmental Sustainability of Ethanol Production Using the Lifecycle Analysis Method.
Creator: Toliver, Tiffany L, Abichou, Tarek, Chan-Hilton, Amy, Chen, Gang, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Ethanol is a controversial source of alternative fuel. In the United States ethanol is produced predominantly from corn and has made headlines as a popular green energy, driven both politically and geographically. Green energy is defined as an energy that has little or no negative environmental impacts. The purpose of this study is to determine if ethanol is really a green energy. This determination can be made by quantifying the greenhouse gas emissions produced by ethanol production using...
Show moreEthanol is a controversial source of alternative fuel. In the United States ethanol is produced predominantly from corn and has made headlines as a popular green energy, driven both politically and geographically. Green energy is defined as an energy that has little or no negative environmental impacts. The purpose of this study is to determine if ethanol is really a green energy. This determination can be made by quantifying the greenhouse gas emissions produced by ethanol production using the LCA (Life Cycle Assessment) method of analysis. Using equivalent units, carbon dioxide emissions can be quantified and compared to other sources of alternative energies. Carbon footprinting is mainly used to understand the impacts humans have individually and as a mass on the environment. It can be computed and expressed as a quantity towards the computation of greenhouse gas contribution. In the case of ethanol, a carbon footprint can be developed by looking at the physical life cycle of a kernel of corn, cane of sugar or bushel of switchgrass. Comprehensively, the ethanol life cycle can be divided into four main parameters. The first parameter is feedstock, followed by technology, third is capital and the final parameter is off take. While each parameter is singularly important, this study focuses on greenhouse gas emissions. It was determined that in comparison, corn ethanol greenhouse gas emissions far exceed the greenhouse gas emission of both sugarcane and switchgrass (cellulosic) ethanol for any case. In the case where LCA is carried through distribution and use of ethanol, sugarcane ethanol is the less greenhouse gas emissive. In the case where the LCA stops at ethanol production, switchgrass is the less greenhouse gas emissive. It is important to note, however, that switchgrass (cellulosic) ethanol is in its infancy as of this writing and data provided is largely projected on the part of the respective researcher.
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Date Issued: 2008
Identifier: FSU_migr_etd-1287
Format: Thesis

Title: Correlation Between Falling Head and Double Ring Testing for a Full-Scale Infiltration Study.
Creator: Hayden, Audra H., Tawfiq, Kamal, Rambo-Roddenberry, Michelle, Ping, Wei-Chou V., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Stormwater management facility design is a branch of engineering that demands a full understanding of soil and permeability and how water infiltrates into the ground. With new residential and commercial developments, holding facilities for rainwater are required. Due to the cost associated with purchasing land for holding water, the idea is to make the pond dimensions as small as possible. With this idea, the engineer will need a precise way to determine the rate at which water will...
Show moreStormwater management facility design is a branch of engineering that demands a full understanding of soil and permeability and how water infiltrates into the ground. With new residential and commercial developments, holding facilities for rainwater are required. Due to the cost associated with purchasing land for holding water, the idea is to make the pond dimensions as small as possible. With this idea, the engineer will need a precise way to determine the rate at which water will infiltrate into the soil. This research centers on determining how permeability most accurately predicts a stormwater pond's actual infiltration rate. Several estimations for permeability have been evaluated: grain-size correlations, falling head permeameters, double ring infiltrometer tests and single ring infiltrometer tests. For this research, an existing stormwater facility was chosen. At this location, the field tests were conducted and subsurface samples were taken for laboratory analysis. In addition, to measure the actual field infiltration rate, a staff gage was installed and monitored after a precipitation event. The program MODRET was utilized to determine which of the various estimations of permeability yield an infiltration that most closely resembles that of monitored existing conditions.
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Date Issued: 2010
Identifier: FSU_migr_etd-4193
Format: Thesis

Title: Barrier, Joint, and Diaphragm Effects on Force Distribution in Prestressed Concrete Girder Bridges.
Creator: Chipperfield, Jonathan Darren, Rambo-Roddenberry, Michelle, Jung, Sungmoon, Tawfiq, Kamal, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The American Association of State Highway and Transportation Officials (AASHTO) determine the load effects to interior and exterior girders by the Bridge Design Specifications. The equations in both the AASHTO Standard and AASHTO Load and Resistance Factor Design (LRFD) specifications do not take into account secondary elements, such as barriers, curbs, or diaphragms. Research has shown that the AASHTO equations are conservative,and that girders could be overdesigned. With the addition of...
Show moreThe American Association of State Highway and Transportation Officials (AASHTO) determine the load effects to interior and exterior girders by the Bridge Design Specifications. The equations in both the AASHTO Standard and AASHTO Load and Resistance Factor Design (LRFD) specifications do not take into account secondary elements, such as barriers, curbs, or diaphragms. Research has shown that the AASHTO equations are conservative,and that girders could be overdesigned. With the addition of secondary elements in the equations it would be possible to reduce the distribution factors after the secondary elements have been placed. The Florida Department of Transportation (FDOT) Structures Research Lab made field strain measurements on two bridges, one a Florida Bulb-T bridge and the other an AASHTO Type IV Girder bridge. The Florida Bulb-T bridge strain measurements were taken before and after barriers were placed, and the AASHTO bridge strain measurements were only for a post-barrier condition. The purpose of this research was to create two finite element models (FEM) using ANSYS 11.0 and calibrate them to the measured test results. After the calibrated models were validated a parametric study was performed comparing the effects of secondary elements on live load distribution. Included in this parametric study are the effects of the barrier, the barrier joint, and the diaphragms, on the girders, both interior and exterior. The results of this project show the effects of secondary elements and whether they are localized or global on the longitudinal span of the bridge, as well as tell how the live load is being distributed. Also, for load testing, recommendations on placement of strain gages will be discussed.
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Date Issued: 2010
Identifier: FSU_migr_etd-3806
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

Environmental engineering (18)	+ -
Engineering (1)	+ -

Department of Civil and Environmental Engineering (18)	+ -
Florida State University (18)	+ -
Rambo-Roddenberry, Michelle (8)	+ -
Spainhour, Lisa (6)	+ -
Jung, Sungmoon (4)	+ -

Abichou, Tarek (3)	+ -
Mtenga, Primus (3)	+ -
Ping, Wei-Chou V. (2)	+ -
Sobanjo, John (2)	+ -
Wekezer, Jerry (2)	+ -
Abdullah, Makola (1)	+ -
Armaghani, Seyamend Bilind (1)	+ -
Bouchard, Nicholas (1)	+ -
Chan-Hilton, Amy (1)	+ -
Chandra, Namas (1)	+ -
Chanton, Jeffrey (1)	+ -
Chen, Gang (1)	+ -
Chipperfield, Jonathan Darren (1)	+ -
Dowgul, Ronald Walter (1)	+ -
Fuentes, Javier Alexander Muniz (1)	+ -
Fung, Kakit (1)	+ -
Hayden, Audra H. (1)	+ -
Hilton, Amy Chan (1)	+ -
Johnson, Stacy (1)	+ -
Kuhn, Dan (1)	+ -
Leszczynska, Dauta (1)	+ -
Lewis, Michael (1)	+ -
Li, Hongyi (1)	+ -
Liu, Xiaoli (1)	+ -

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