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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: 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: Finite Element Analysis on the Effect of Fire for Specified Duration, on a Reinforced Concrete Beam with Varied Boundary Conditions.
Creator: Chythanya, Meghana, Spainhour, Lisa K., Rambo-Roddenberry, Michelle, Jung, Sungmoon, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Concrete is a poor conductor of heat due to its incombustible nature and low thermal diffusivity, which guarantee a slow propagation of thermal transients within the structural members. Despite exhibiting a good behavior at high temperatures, it can suffer considerable damage when exposed to fire. The knowledge of high-temperature properties of concrete is critical for fire resistance assessment because the fire performance of structural members like beams depends on the properties of the...
Show moreConcrete is a poor conductor of heat due to its incombustible nature and low thermal diffusivity, which guarantee a slow propagation of thermal transients within the structural members. Despite exhibiting a good behavior at high temperatures, it can suffer considerable damage when exposed to fire. The knowledge of high-temperature properties of concrete is critical for fire resistance assessment because the fire performance of structural members like beams depends on the properties of the constituent materials. To predict the conditions within the RC beams subjected to fire, knowledge is required of the behavior of concrete subjected to high temperatures. To ensure the safety of RC structural systems in the event of fire, concrete members should be designed against fire. The temperature dependent properties that are important for establishing an understanding of the fire-response of RC structures include thermal and material properties at elevated temperatures. In this research, a finite element model was developed using ALGOR® to study the impact of fire on an RC beams. This model provides information about temperature distributions in the beam for given initial and boundary conditions. Using finite element analysis, the entire beam was meshed into small segments called elements. The elements hold information about the physical properties of their corresponding materials. Each element was bounded by nodal points. Boundary conditions were included on the appropriate nodes in the model. The different boundary conditions on which the analysis was conducted are pin-roller, pin-pin, fixed on both ends and cantilever. All the results obtained from the analyses are time dependent, including displacement, stresses and strains. The location and magnitude of maximum stress, strain and displacement for each boundary condition were determined with the analysis. The maximum principal stress in each case when compared to the compressive strength of normal strength concrete, implied that failure has occurred in all the four cases i.e. pin-roller, pin-pin, fixed on both ends and cantilever. The results obtained from the Transient Heat Analysis were compared with the temperature distribution from other studies. It was found that the temperature distribution determined in Kodur et al is very similar to the temperature distribution which results from the transient heat transfer analysis.
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Date Issued: 2009
Identifier: FSU_migr_etd-3609
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: Impact Performance of Steel Connections Used in Paratransit Buses.
Creator: Rawl, Christopher Franklin, Wekezer, Jerry, Jung, Sungmoon, Mtenga, Primus, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Due to the limited regulation in the construction of paratransit busses in the United States, manufactures are able to produce these busses with little regard to the crashworthiness of the vehicle. A paratransit bus consists of a custom built passenger cage installed on a chassis (including cab) produced by a major vehicle manufacturer. This lack of applicable crashworthiness standards pose a hazard to the passengers of these busses, as manufactures often use poor methods of construction to...
Show moreDue to the limited regulation in the construction of paratransit busses in the United States, manufactures are able to produce these busses with little regard to the crashworthiness of the vehicle. A paratransit bus consists of a custom built passenger cage installed on a chassis (including cab) produced by a major vehicle manufacturer. This lack of applicable crashworthiness standards pose a hazard to the passengers of these busses, as manufactures often use poor methods of construction to promote cost savings in production. As a result of this, the Florida Department of Transportation Transit Office has provided funding for research involving the safety evaluation of paratransit busses. The primary objective of this research was to develop a testing procedure to evaluate the performance of the two primary connections that comprise a paratransit passenger cage: roof to wall connection and wall to floor connection. The evaluation of the connections is done through the use of a testing apparatus instrumented with distance traducers and a load cell, from which the connections resistance as a function of rotation can be evaluated. From this, the energy absorption of different connections can be found. Evaluating the energy absorption of the connection over a range of motion, as opposed to simply looking at its peak resistance value, is critical as it accounts of the stiffness of the connection as well as its ductility. By conducting these tests, problematic designs are identified and modifications are suggested to the manufacturer for improved performance. The proposed testing procedure was accepted by FDOT in December 2009, as a major component of the pre-qualification process, which temporarily grants bus manufactures permission to sell paratransit buses to the FDOT pending further investigation. In addition to the experimental results of various connection constructions, one finite element model of a wall to floor connection is presented as well as a computational assessment of two sidewall structures subjected to an impact load.
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Date Issued: 2010
Identifier: FSU_migr_etd-1880
Format: Thesis

Title: Side Impact of a Paratransit Bus.
Creator: Turley, Joshua, Jung, Sungmoon, Wekezer, Jerry, Rambo-Roddenberry, Michelle, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: The Florida Department of Transportation--Transit Office has endeavored to quantify the safety of a paratransit bus in a side impact collision. They have provided funded to produce this work. The goal of this work is to determine the likeliness that an occupant in a paratransit bus will experience an unacceptable amount of harm during a side impact collision. A side impact experiment was performed. An impactor weighing 4,400 lbs consisting of a crash cart with an attached IIHS deformable...
Show moreThe Florida Department of Transportation--Transit Office has endeavored to quantify the safety of a paratransit bus in a side impact collision. They have provided funded to produce this work. The goal of this work is to determine the likeliness that an occupant in a paratransit bus will experience an unacceptable amount of harm during a side impact collision. A side impact experiment was performed. An impactor weighing 4,400 lbs consisting of a crash cart with an attached IIHS deformable barrier was suspended between two steel towers. The impactor was raised to a height of 31 ft and let swing into the side of a stationary paratransit bus in a pendulum motion impacting at an angle of 90 degrees. Inside the bus a Hybrid III 50th percentile Anthropomorphic Test Dummy (ATD) was seated near the region of impact. The ATD recorded values that were all below Injury Assessment Reference Values (IARV) which indicates a favorable crashworthiness result for a side impact of similar paratransit bus. There was a significant amount of crush in the deformable barrier where it contacted the bus deck and indicates that should the impactor impact the bus higher or the bus have a low deck construction the results may be significantly different. This should be investigated in future research.
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Date Issued: 2013
Identifier: FSU_migr_etd-7632
Format: Thesis

Title: Analysis of Tilt-Up Building Design and Industry Standard Practices in Tornado-Prone Regions.
Creator: Maldonado, Desiderio, Rambo-Roddenberry, Michelle, Jung, Sungmoon, Mtenga, Primus, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Tilt-up buildings are a popular building construction method used across the United States. These structures offer many benefits, but can also present unique design challenges when compared to other building types. Recent tornado outbreaks have caused over $20 billion in total damages and killed hundreds of people. As with most structures, tilt-up buildings tend to be susceptible to tornado events. These events have brought building performance and safety in tornado-prone regions to the...
Show moreTilt-up buildings are a popular building construction method used across the United States. These structures offer many benefits, but can also present unique design challenges when compared to other building types. Recent tornado outbreaks have caused over $20 billion in total damages and killed hundreds of people. As with most structures, tilt-up buildings tend to be susceptible to tornado events. These events have brought building performance and safety in tornado-prone regions to the forefront of consideration by residents, building owners, code officials, and design professionals. The research for this thesis was performed to study the major components and connections used in typical tilt-up buildings using current standard wind analysis methods and to identify limiting factors in building performance in hopes of improving future building designs. Standard wind design and analysis methods were used for this research, not tornado-specific wind design criteria. The components focused on are generally regarded as current industry standards and follow local building codes and manufacturer recommendations. Existing retrofit options traditionally used in high seismic regions were also studied to see if any available methods were suitable for preventing tilt-up building failure in tornado events. The construction of internal storm shelters was also investigated as a potential additional method of reducing injuries and deaths in tornado-prone regions. While large tornado-proof buildings may be impractical or cost prohibitive, it is important for design professionals to continue to take proactive approaches to region specific hazards in future designs to reduce property damage and casualties.
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Date Issued: 2013
Identifier: FSU_migr_etd-7484
Format: Thesis

Title: Mitigation of Vortex-Induced Vibrations in Cables Using Macro-Fiber Composites.
Creator: Munoz, Gustavo J., Jung, Sungmoon, Rambo-Roddenberry, Michelle, Spainhour, Lisa K., Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Vortex-Induced Vibration (VIV) in cables is a prevalent phenomenon affecting the structural health of bridges and their components. Past studies have shown both passive and active methods are beneficial in the reduction of vibrations, however, a number of issues such as excessive base moment, transformation of geometry, intrusive implementation and fatigue limit the effectiveness of current engineering. A method involving no intrusion, no geometrical manipulation and a mechanism to prevent...
Show moreVortex-Induced Vibration (VIV) in cables is a prevalent phenomenon affecting the structural health of bridges and their components. Past studies have shown both passive and active methods are beneficial in the reduction of vibrations, however, a number of issues such as excessive base moment, transformation of geometry, intrusive implementation and fatigue limit the effectiveness of current engineering. A method involving no intrusion, no geometrical manipulation and a mechanism to prevent and mitigate VIV is needed. A "skin" of material embedded with Macro-Fiber Composite (MFC) material and with the capabilities of perturbing the surface near the separation point of vortex shedding is explored and tested. Simplifications of the proposed material are made in order to understand the effects of the capabilities of a perturbing skin of MFC material. Construction of a 17-ft Open-circuit wind tunnel is done in order to make the VIV condition to be tested with the near method of VIV control. The VIV on cables is recorded. Experiments are run inside the tunnel at a Re of 11400 and 6400. In order to see the effects of surface perturbations, an MFC actuation mechanism is made and a cable section effectively able to cause surface perturbations is built. A test is then run to find the effect of different angles of perturbation. Finally, a testing and analysis of a phase-difference of a signal, at prescribed perturbation frequencies is done. This is analyzed against surface vortex formation theory. The data are analyzed in order to see the capabilities of an MFC skin on VIV of cables. The mechanism shows promise in both reducing VIV and providing for a low-key, non-intrusive control mechanism.
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Date Issued: 2012
Identifier: FSU_migr_etd-5058
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: 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: 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: 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: Dynamic Interaction Between Heavy Vehicles and Highway Bridges.
Creator: Ford, Eduardo E. Taft, Wekezer, Jerry, Jung, Sungmoon, Rambo-Roddenberry, Michelle, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Modern prestressed reinforced concrete bridges are designed per LRFD standards, and are lighter with smaller safety factors. At the same time bridges are loaded with heavier vehicles with substantial masses when compared to the mass of the bridge. It requires fairly detailed FE models of the vehicles (in addition to the FE models of the bridges) for a meaningful analysis of the vehicle-bridge dynamic system. Imperfections in road surfaces can trigger significant dynamic loads on the bridge...
Show moreModern prestressed reinforced concrete bridges are designed per LRFD standards, and are lighter with smaller safety factors. At the same time bridges are loaded with heavier vehicles with substantial masses when compared to the mass of the bridge. It requires fairly detailed FE models of the vehicles (in addition to the FE models of the bridges) for a meaningful analysis of the vehicle-bridge dynamic system. Imperfections in road surfaces can trigger significant dynamic loads on the bridge with adverse effects, which are not well understood. FDOT issues over 90,000 permits for heavy vehicles every year, therefore finding newer, easier, and more economical ways to study and understand the actual impact of dynamic loads on bridges is critical for design and maintenance of highway bridges. The main goal of this research was to develop numerical models of heavy vehicles and bridges and to use them for transient analysis of dynamic interaction between the vehicle and the bridge. An assessment of three finite element (FE) vehicle models and one bridge FE model was carried out and the necessary improvements were implemented. Additional bridges in North Florida were surveyed, and two substructures were selected for modeling. The two selected bridges had different geometric characteristics and their FE models were developed according to AASHTO specifications. Three FE models of heavy vehicles were used with three different bridges for computational dynamics analysis using the LS-DYNA computer code. The influence of several factors such as vehicle mass and speed, road surface condition, and loosely secured cargo were assessed. Dynamic load allowance (DLA) was determined for each vehicle-bridge combination. Practical conclusions regarding methods to mitigate DLAs were presented.
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Date Issued: 2010
Identifier: FSU_migr_etd-1753
Format: Thesis

Title: Mitigation Techniques for Aluminum Pool Enclosure Connections in High Wind Speeds.
Creator: Schellhammer, Michael Ryan, Jung, Sungmoon, Rambo-Roddenberry, Michelle, Wekezer, Jerry, Department of Civil and Environmental Engineering, Florida State University
Abstract/Description: Aluminum pool enclosures consistently yield significant insurance losses due to damage suffered during hurricanes and strong windstorms. The damaged pool enclosures frequently produce airborne debris, which can often lead to additional damage on the host structure. For this reason, pool enclosures represent an important area of concern when it comes to mitigating overall structural damage caused by hurricanes and strong windstorms. Most commonly, a pool enclosure fails due to insufficient...
Show moreAluminum pool enclosures consistently yield significant insurance losses due to damage suffered during hurricanes and strong windstorms. The damaged pool enclosures frequently produce airborne debris, which can often lead to additional damage on the host structure. For this reason, pool enclosures represent an important area of concern when it comes to mitigating overall structural damage caused by hurricanes and strong windstorms. Most commonly, a pool enclosure fails due to insufficient connection performance. Insufficient connection performance generally consists of screw pullout and/or other hardware failures. Improving the function of these aluminum connections can help alleviate pool enclosure failure and thus lessen the amount of insurance losses accumulated. This research investigates different mitigation techniques involving the pool enclosure connection with the host structure. Due to the extensive variety of connection designs used by contractors across Florida, several connection specimens were tested and analyzed to provide the best performing and most cost efficient results. The connection components under investigation mainly included angle size, screw layout, and screw size. These components were monitored with the overall goal of optimizing the hardware combination. Each specimen was tested against windward and uplift forces using an MTS machine capable of delivering axial forces to the specimens. In addition to continuous loading, fatigue loading was utilized to examine connection behavior once the connection was compromised and a load is re-applied. Load and corresponding displacement values were recorded during testing to provide comparable strength capacities for each specimen. In order to determine the probability of connection failure, fragility curves were constructed and interpreted then applied to a financial analysis to achieve benefit-cost ratios. The resulting financial and performance benefits serve as benchmarks for optimal connection configuration. The conclusions obtained from testing will provide valuable information to pool enclosure designers and contractors who hope to get clarification on the ambiguous range of connections used throughout Florida. Since little tangible research has been conducted on pool enclosure connection strength the insight provided by this research could prove useful to the pool enclosure industry.
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Date Issued: 2011
Identifier: FSU_migr_etd-2021
Format: Thesis

Department of Civil and Environmental Engineering (14)	+ -
Florida State University (14)	+ -
Rambo-Roddenberry, Michelle (11)	+ -
Spainhour, Lisa (4)	+ -
Tawfiq, Kamal (4)	+ -

Wekezer, Jerry (4)	+ -
Mtenga, Primus (3)	+ -
Spainhour, Lisa K. (2)	+ -
Armaghani, Seyamend Bilind (1)	+ -
Chipperfield, Jonathan Darren (1)	+ -
Chythanya, Meghana (1)	+ -
Ford, Eduardo E. Taft (1)	+ -
Fung, Kakit (1)	+ -
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