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Title: Accelerated durability testing of reinforced and unreinforced concretes in a simulated marine environment.
Creator: Jeedigunta, Giridhar V., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: Durability of marine reinforced and unreinforced concretes was tested under accelerated environmental conditions. The specimens were subjected to alternate wet and dry cycles in specially constructed durability testing tanks. The specific objective was to evaluate the durability of different types of concretes with varying water-cementitious material ratios (0.3, 0.4, and 0.6), cement types (Types I and II), mineral admixtures (blast furnace slag, fly ash, microsilica), and steel types (black...
Show moreDurability of marine reinforced and unreinforced concretes was tested under accelerated environmental conditions. The specimens were subjected to alternate wet and dry cycles in specially constructed durability testing tanks. The specific objective was to evaluate the durability of different types of concretes with varying water-cementitious material ratios (0.3, 0.4, and 0.6), cement types (Types I and II), mineral admixtures (blast furnace slag, fly ash, microsilica), and steel types (black, galvinized and epoxy-coated rebars). The unreinforced cylindrical specimens were tested for compressive and splitting tensile strengths and the reinforced prismatic specimens for corrosion. The test results after 300 cycles of accelerated exposure indicated the adverse effects of the marine environment on the durability of concretes, resulting in loss of strength and corrosion resistance. The specimens with lower w/c ratios (0.3 and 0.4) showed good performance, whether or not they were admixture modified. However, mineral admixture inclusions improved the properties of strength and corrosion resistance of the specimens even with high w/c ratios (0.6). The specimens with regular rebars indicated least resistance to corrosion induced from the accelerated marine exposure compared to the ones with galvanized and epoxy-coated rebars.
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Date Issued: 1998
PURL: http://purl.flvc.org/fcla/dt/15551
Subject Headings: Reinforced concrete--Corrosion, Reinforced concrete--Environmental testing, Concrete--Environmental testing
Format: Document (PDF)

Title: Correlation of Chloride Diffusivity and Electrical Resistance for Cracked Concrete.
Creator: Merantus, Stanley W., Reddy, Dronnadula V., College of Engineering and Computer Science
Abstract/Description: The Durability of Reinforced Concrete (RC) structures in the Marine environment is causing increasingly serious concern in the structural infrastructures. RC structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that cause degradation is Chloride Diffusion, with tide-simulated wet and dry conditions at the air-water interface. This investigation, jointly project with...
Show moreThe Durability of Reinforced Concrete (RC) structures in the Marine environment is causing increasingly serious concern in the structural infrastructures. RC structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that cause degradation is Chloride Diffusion, with tide-simulated wet and dry conditions at the air-water interface. This investigation, jointly project with Cemex (a cement mixing company), will address the change of chloride diffusion current resistivity due to macro and micro cracking, which is inevitable in all concrete structures. The correlation of Chloride Diffusivity with Electrical Current Resistivity of Sound and Cracked Concrete is studied experimentally, and the results compared with Analytically Determined values. The principal benefit of the research is the formulation of models to predict time-dependent Chloride Penetration into Sound and Cracked Concrete in the Marine environment.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00005203
Subject Headings: College students --Research --United States.
Format: Document (PDF)

Title: Durability testing of reinforced concrete beams under fatigue loading in a simulated marine environment.
Creator: Ahn, Woo-Suk., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: This thesis addresses the evaluation of the durability of reinforced concrete marine structures subjected to fatigue loading. The laboratory investigation was carried out on full and half size reinforced concrete specimens with three different water cement ratios (0.3, 0.4, and 0.56), static and fatigue loading conditions, and epoxy-coated and regular black steel reinforcements; a mineral admixture (silica fume), and a corrosion inhibitor (calcium nitrite) were used for specimens made with...
Show moreThis thesis addresses the evaluation of the durability of reinforced concrete marine structures subjected to fatigue loading. The laboratory investigation was carried out on full and half size reinforced concrete specimens with three different water cement ratios (0.3, 0.4, and 0.56), static and fatigue loading conditions, and epoxy-coated and regular black steel reinforcements; a mineral admixture (silica fume), and a corrosion inhibitor (calcium nitrite) were used for specimens made with water/cement ratio 0.4 concrete. The marine tidal zone was simulated by alternate filling and draining of the tank (wet and dry cycles), and a galvanostatic corrosion technique to accelerate corrosion of rebar was introduced. Half-cell potentials and changes of crack width were measured periodically during the exposure and followed by ultimate strength testing. The significant findings include adverse effect of fatigue loading, existence of an explicit size effect, poor performance of epoxy coated steel, and negative effect of the increasing water/cement ratio.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15178
Subject Headings: Concrete beams--Fatigue, Underwater concrete construction, Reinforced concrete--Fatigue, Seawater--Corrosion
Format: Document (PDF)

Title: Feasibility study of a prestressed concrete double-tee bridge system for interstate highways.
Creator: Badve, Anil Pandurang., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: This dissertation is a study of 1:3.5 scale model of a two-span transversely and longitudinally post-tensioned continuous double-tee bridge system, representing a target bridge of 70 ft. span. Theoretical analysis was carried out for comparison using different modelling techniques, such as isotropic and orthotropic material behavior, and the load distribution theory. Behavior of the bridge system was evaluated in terms of deflections, wheel load distributions, crack patterns and growth with...
Show moreThis dissertation is a study of 1:3.5 scale model of a two-span transversely and longitudinally post-tensioned continuous double-tee bridge system, representing a target bridge of 70 ft. span. Theoretical analysis was carried out for comparison using different modelling techniques, such as isotropic and orthotropic material behavior, and the load distribution theory. Behavior of the bridge system was evaluated in terms of deflections, wheel load distributions, crack patterns and growth with increasing number of cycles of fatigue loading. The precast model beams were assembled and tested at the Department of Ocean Engineering, Florida Atlantic University. AASHTO HS20-44 truck loading was simulated by applying constant amplitude fatigue loading at typical locations. The study established the feasibility and structural adequacy of the precast prestressed concrete double-tee concept for short and medium span interstate highway bridges for use in Florida and elsewhere.
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Date Issued: 1989
PURL: http://purl.flvc.org/fcla/dt/14513
Subject Headings: Prestressed concrete beams--Fatigue, Bridges, Concrete--Joints
Format: Document (PDF)

Title: Experimental Evaluation of the Structural Integrity of the Repairs for Corrosion-Damaged Marine Piles.
Creator: Bolivar, Juan Carlos, Reddy, Dronnadula V., Florida Atlantic University
Abstract/Description: Corrosion damage is the mam cause of deterioration for reinforced concrete marine structures. Given the current economic downturn, it has become increasingly important to repair existing structures with techniques that prolong their life-cycle. The process to identify suitable repairs is affected by the lack of a consistent methodology to predict the outcome of the repairs. This investigation intends to compare the performance of seven different repairs, in terms of corrosion resistance,...
Show moreCorrosion damage is the mam cause of deterioration for reinforced concrete marine structures. Given the current economic downturn, it has become increasingly important to repair existing structures with techniques that prolong their life-cycle. The process to identify suitable repairs is affected by the lack of a consistent methodology to predict the outcome of the repairs. This investigation intends to compare the performance of seven different repairs, in terms of corrosion resistance, structural integrity, and cost-effectiveness. Following initial exposure to corrosion, the specimens were repaired using the proposed techniques. They were then tested for durability under simulated tidal conditions with periodic corrosion monitoring. The structural integrity was evaluated by crack scoring and ultimate load testing, and a comprehensive evaluation matrix was prepared, to determine which repairs were most adequate for corrosion damage. The results of this investigation substantiate that the repairs including carbon wrapping, HDPE jacketing, and MMFX steel, outperformed the rest of the repairs.
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Date Issued: 2008
PURL: http://purl.flvc.org/fau/fd/FA00012506
Subject Headings: Reinforced concrete--Corrosion, Underwater concrete construction--Maintenance and repair, Materials--Deterioration--Prevention, Fibrous composites--Evaluation
Format: Document (PDF)

Title: Performance characteristics of coal fly ash and wood ash-modified asphalt binder.
Creator: Butul, Boris., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: Coal fly ash and wood ash were added singly to asphalt mixes as partial replacements of the asphalt cement. Mechanical property testing and cost analysis were carried out with the following percentages: 0, 10, 15, 20, and 25. The objective of the investigation was to determine the changes in mechanical properties and cost-effectiveness of ash modification. The softening point, penetration, creep displacement, and modulus of elasticity indicated stiffening of the mix with increased ash...
Show moreCoal fly ash and wood ash were added singly to asphalt mixes as partial replacements of the asphalt cement. Mechanical property testing and cost analysis were carried out with the following percentages: 0, 10, 15, 20, and 25. The objective of the investigation was to determine the changes in mechanical properties and cost-effectiveness of ash modification. The softening point, penetration, creep displacement, and modulus of elasticity indicated stiffening of the mix with increased ash proportion. The indirect tensile and compression strengths reached peak values for the 10 and 15% mixes. The Marshall stability, the bulk density, and the maximum density, decreased with ash addition. The cost analysis indicated a saving of 6% for ash replacement of 15%. Therefore, the replacement of 10 to 15% of asphalt cement is an excellent solution to decrease the mix costs and to reduce the amount of ash in landfills without compromising the mechanical properties of the mix.
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Date Issued: 2000
PURL: http://purl.flvc.org/fcla/dt/12674
Subject Headings: Coal ash, Fly ash, Waste products as road materials, Asphalt cement--Additives
Format: Document (PDF)

Title: IMPACT BEHAVIOR OF CONCRETE BEAMS WITH CORRODING REINFORCING STEEL.
Creator: DESNOYERS, JEAN-FRANCOIS., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: This thesis presents an analytical and experimental investigation of the remaining impact strength of concrete beams with corroding reinforcement. Concrete beams were subjected to impact using a centrally loaded instrumented dropweight system. Three different amounts of steel corrosion were used to simulate ten, twenty, and thirty years of seawater exposure. The first part in the analytical investigation involved the use of the finite element code ADINA. The second included development of...
Show moreThis thesis presents an analytical and experimental investigation of the remaining impact strength of concrete beams with corroding reinforcement. Concrete beams were subjected to impact using a centrally loaded instrumented dropweight system. Three different amounts of steel corrosion were used to simulate ten, twenty, and thirty years of seawater exposure. The first part in the analytical investigation involved the use of the finite element code ADINA. The second included development of three physical models; the first based on a beam impact equation of forced vibration for a pin-ended beam with center span impact, the second a two-degree-of-freedom model, and the third a three-degree-of-freedom model taking into account the stiffness of the supports for the impacted beam specimens. The different analytical results showed good correlation with the test values of the impact energies. Also, the energy values for the different corrosion periods obtained from the ADINA analysis compared well with experimental ones.
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Date Issued: 1987
PURL: http://purl.flvc.org/fcla/dt/14371
Subject Headings: Concrete beams, Metals--Impact testing
Format: Document (PDF)

Title: Long-term performance of buried high-density polyethylene plastic piping.
Creator: Gazagnaire, Cyril., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: The primary goal of this study was to evaluate the service life of HDPE (High Density PolyEthylene) pipes. The following experimental tasks were carried out: (i) procurement of materials, and fabrication of test setups; (ii) creep evaluation: the performance of buried pipes (notched/unnotched), subjected to live loading, was studied in soil chambers for three levels of loading (service, 2/3 and 1/3 of service). The long-term behavior was accelerated with super-ambient temperatures; (iii)...
Show moreThe primary goal of this study was to evaluate the service life of HDPE (High Density PolyEthylene) pipes. The following experimental tasks were carried out: (i) procurement of materials, and fabrication of test setups; (ii) creep evaluation: the performance of buried pipes (notched/unnotched), subjected to live loading, was studied in soil chambers for three levels of loading (service, 2/3 and 1/3 of service). The long-term behavior was accelerated with super-ambient temperatures; (iii) field monitoring: strains and diametral changes were measured for 10,000 hours. The analytical investigations were as follows: (i) extrapolation of the long-term performance at ambient temperature, based on the Bi-directional and the Arrhenius methods and (ii) 2-D Finite Element Analysis, using the software CANDE. The findings include: (i) the deflection threshold (7.5% vertical change of diameter) as the governing failure condition, (ii) similar life predictions, for Bi-directional and Arrhenius methods, with service lives of about 80 and 30 years at ambient temperature, for unnotched and notched specimens, respectively, subjected to maximum loading, and (iii) a reasonable agreement between analytical and experimental values.
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Date Issued: 2000
PURL: http://purl.flvc.org/fcla/dt/15757
Subject Headings: Pipe, Plastic--Testing, Underground pipelines--Design and construction, Underground plastic pipe
Format: Document (PDF)

Title: Long-term pullout resistance of geogrid reinforcement for retaining walls.
Creator: Gao, Shangsui., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: An experimental and analytical investigation is presented for two types of geogrids: HDPE (High Density Polyethylene) and PET (Polyester). Sand and limerock were used for the backfill material, which meet the FDOT (Florida Department of Transportation) Material Specifications, with simulation of unsaturated and saturated condition. Eight pullout test boxes were designed and constructed, each with a specially designed stainless steel clamp. The measured strain-time relations for unsaturated...
Show moreAn experimental and analytical investigation is presented for two types of geogrids: HDPE (High Density Polyethylene) and PET (Polyester). Sand and limerock were used for the backfill material, which meet the FDOT (Florida Department of Transportation) Material Specifications, with simulation of unsaturated and saturated condition. Eight pullout test boxes were designed and constructed, each with a specially designed stainless steel clamp. The measured strain-time relations for unsaturated and saturated soils for various levels of the pullout force until the peak value (up to 10,000 hours of exposure), and varying distances from the loading end were plotted. The normal and principal stresses in the soil, and the strains along the geogrid were determined from the finite element analysis for the unsaturated soil condition for various pullout force levels. The results were analyzed and a generalized method proposed for practical design using sliding resistance factors.
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Date Issued: 1999
PURL: http://purl.flvc.org/fcla/dt/15689
Subject Headings: Retaining walls, Geogrids, Soil stabilization
Format: Document (PDF)

Title: Crack propagation in concrete structural members strengthened with bonded fiber reinforced polymer plastic (FRP) laminates.
Creator: Gervois, Gonzague., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: This thesis presents an experimental and analytical investigation of concrete structural members strengthened with externally bonded composite laminates with varying configurations. Parameters, such as size, type of laminate, debond, etc., are evaluated from the viewpoint of stress patterns and their influence on interfacial debonds. Stress patterns in the structure and stress intensity factors around crack tips are determined using a finite element model developed for this purpose. The study...
Show moreThis thesis presents an experimental and analytical investigation of concrete structural members strengthened with externally bonded composite laminates with varying configurations. Parameters, such as size, type of laminate, debond, etc., are evaluated from the viewpoint of stress patterns and their influence on interfacial debonds. Stress patterns in the structure and stress intensity factors around crack tips are determined using a finite element model developed for this purpose. The study also includes a precise description of cracking and the failure function of each parameter investigated. Besides the development of an innovative finite element program, which enables the study of interfacial cracks in structures with highly nonlinear behavior and multiple irregular cracking patterns, the significant contributions include the effect of laminate geometry, the inefficiency of laminate prestressing, the negative effect of end debond, and the insignificant effect of midspan debond on the cracking and the strength of a laminated concrete structural member.
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Date Issued: 1997
PURL: http://purl.flvc.org/fcla/dt/15498
Subject Headings: Fiber reinforced plastics, Laminated materials, Concrete--Cracking
Format: Document (PDF)

Title: Comparative evaluation of the performance of concrete wall panels, with and without fiber reinforcement.
Creator: Germain, Gerson S., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: This investigation addresses the evaluation of the increase in structural integrity of concrete wall panels by the addition of polypropylene fibers. The test methodology used was the evaluation of flexural (simply-supported and cantilever), shear (in-plane and punching), and impact behavior. The concrete panels comprised sets with (i) regular reinforcement (ACI code based), (ii) Reinforced concrete panels: 0.2% fibers with minimum ACI reinforcement, FRC 2, (iii) 0.3% fibers without...
Show moreThis investigation addresses the evaluation of the increase in structural integrity of concrete wall panels by the addition of polypropylene fibers. The test methodology used was the evaluation of flexural (simply-supported and cantilever), shear (in-plane and punching), and impact behavior. The concrete panels comprised sets with (i) regular reinforcement (ACI code based), (ii) Reinforced concrete panels: 0.2% fibers with minimum ACI reinforcement, FRC 2, (iii) 0.3% fibers without reinforcement, FRC 3, and (iv) plain beams without reinforcement. The instrumentation consisted of deflection and electrical strain gages, a slope indicator for slope testing, and an oscilloscope with a camera attachment for monitoring load and energy traces in impact testing. The normalized (adjusted for concrete strength variations) ultimate load and energy values were compared. The findings indicated enhancement of ductility and shear strength for the fiber reinforced specimens, which are very desirable for sudden and impact loading conditions associated with hurricane-type loading.
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Date Issued: 2000
PURL: http://purl.flvc.org/fcla/dt/12678
Subject Headings: Concrete walls--Design and construction, Reinforced concrete, Fiber
Format: Document (PDF)

Title: Strength and Durability of Rice Husk Ash-Modified Concrete in the Marine Environment.
Creator: Alvarez, Marcelina, Reddy, Dronnadula V., Florida Atlantic University
Abstract/Description: The purpose of this research project is to compare the strength and durability characteristics of rice husk ash-modified concrete with those of normal concrete in the marine environment. Specimens prepared from concrete mixes with watercementitious ratios of 0.40 and 0.55, and rice husk ash content of 0%, 10%, and 20% were tested. The rice husk ash used was obtained from Agrilectric, power plant located in Lake Charles, Louisiana. The grinding of the ash to particle size of 7-J..tm to 45-J....
Show moreThe purpose of this research project is to compare the strength and durability characteristics of rice husk ash-modified concrete with those of normal concrete in the marine environment. Specimens prepared from concrete mixes with watercementitious ratios of 0.40 and 0.55, and rice husk ash content of 0%, 10%, and 20% were tested. The rice husk ash used was obtained from Agrilectric, power plant located in Lake Charles, Louisiana. The grinding of the ash to particle size of 7-J..tm to 45-J..tm was done by Process Research ORTECH Inc., Ontario, Canada. Strength and durability tests were performed, following ASTM (American Society for Testing and Materials) Standards. The significant fmdings are that the properties and quality of the rice husk ash-modified concrete are as good, if not better than normal concrete.
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Date Issued: 2006
PURL: http://purl.flvc.org/fau/fd/FA00012502
Subject Headings: Seawater corrosion, Reinforced concrete--Environmental testing, Concrete--Additives, Rice hulls--Testing, Limekilns--Testing
Format: Document (PDF)

Title: Thermal modeling and field temperature measurement of segmental box girder bridges in Florida.
Creator: Basole, Milind Madhukar., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description: Temperature and thermal stress variations in a segmental box girder bridge arc studied. A finite element model using the general finite element software MARC is used to predict temperature and thermal stress variation, for segmental box girder bridges. The predictions are compared with actual measured temperature data of two segmental box girder bridges, instrumented with thermocouples and vibrating wire strain gages, in Davie, Florida. Continuous monitoring was carried out for two months in...
Show moreTemperature and thermal stress variations in a segmental box girder bridge arc studied. A finite element model using the general finite element software MARC is used to predict temperature and thermal stress variation, for segmental box girder bridges. The predictions are compared with actual measured temperature data of two segmental box girder bridges, instrumented with thermocouples and vibrating wire strain gages, in Davie, Florida. Continuous monitoring was carried out for two months in July-August, 1991, and for one month in January-February, 1992. Comparison are also made with the NCHRP suggested profiles. A Monte Carlo analysis is performed to accommodate the probabilistic variation of ambient temperature conditions.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/14840
Subject Headings: Bridges, Box girder, Bridges--Florida, Thermal stresses
Format: Document (PDF)

Title: Structural modification of Bascule bridges for noise mitigation.
Creator: Takkasila, Harinatha Reddy., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Noise mitigation and enhancement of skid resistance on Bascule bridge decks, including bridges, pose a considerable challenge. Typically measured noise levels that vary from 60 to 70 dB(A) need to be reduced to eliminate public concern. The objective of this investigation was to find possible modifications to the structure of the open grid decking to reduce the radiated noise from the bridges and at the same time to improve the skid resistance. This study was complementary to the acoustic...
Show moreNoise mitigation and enhancement of skid resistance on Bascule bridge decks, including bridges, pose a considerable challenge. Typically measured noise levels that vary from 60 to 70 dB(A) need to be reduced to eliminate public concern. The objective of this investigation was to find possible modifications to the structure of the open grid decking to reduce the radiated noise from the bridges and at the same time to improve the skid resistance. This study was complementary to the acoustic testing completed in September 1994 at Florida Atlantic University. Deck panels infilled with different types of lightweight infill material for noise mitigation, were tested for fatigue performance and abrasion characteristics. The computer software ANSYS was used to model the grid panel and analyzed for different depths of concrete infill to evaluate the composite action between the infill concrete and the grid panel. A typical case study on counterbalance dynamics of an infilled deck for the Sunrise Boulevard Bridge, included horsepower requirements, trunnion bearing and bending stresses, and flexural strength adequacies of the stringer and floor beams. Skid resistance values for twelve bridges from E-274 and G-analyst measurements were compared for dry and wet conditions, and accident statistics compiled for the period 1988-1992. The cost analysis of identified options was carried out.
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Date Issued: 1996
PURL: http://purl.flvc.org/fcla/dt/15284
Subject Headings: Bridges--Design and construction, Bridges, Iron and steel--Floors--Evaluation, Bridges--Noise, Tires, Traffic noise
Format: Document (PDF)

Title: An analytical and experimental investigation of a multicellular box beam bridge system using an acrylic model.
Creator: Ravichandran, T. V., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis presents an experimental investigation of a 1: 20 scale acrylic model to study the behavior of a multicellular box beam bridge system. The design of a 1: 2 scale concrete model is presented in the early part of the thesis. The acrylic model was tested under simulated AASHTO HS 20-44 loading. The load distribution characteristics of the bridge system was evaluated based on the strains and deflections at various points on the bridge model. The experimental results are presented by...
Show moreThis thesis presents an experimental investigation of a 1: 20 scale acrylic model to study the behavior of a multicellular box beam bridge system. The design of a 1: 2 scale concrete model is presented in the early part of the thesis. The acrylic model was tested under simulated AASHTO HS 20-44 loading. The load distribution characteristics of the bridge system was evaluated based on the strains and deflections at various points on the bridge model. The experimental results are presented by transverse distribution curves of strains and deflections for various load locations. Grillage analysis of the bridge system was performed and the results compared well with the experimental values.
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/14445
Subject Headings: Bridges, Box girder--Design and construction
Format: Document (PDF)

Title: Correlation of Chloride Diffusivity and Electrical Resistance for Cracked Concrete.
Creator: Merantus, Stanley W., Reddy, Dronnadula V., Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: The durability of Reinforced Concrete (RC) structures in the Marine environment is causing serious concern in the structural infrastructure. Reinforced concrete structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that causes degradation is Chloride Diffusion, due to shrinkage, atmospheric corrosion, and tide-induced wet and dry conditions at the air-water...
Show moreThe durability of Reinforced Concrete (RC) structures in the Marine environment is causing serious concern in the structural infrastructure. Reinforced concrete structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that causes degradation is Chloride Diffusion, due to shrinkage, atmospheric corrosion, and tide-induced wet and dry conditions at the air-water interfaces of coastal structures. Therefore, chloride diffusivity, which correlates with the electrical resistivity, has a significant impact on the durability of concrete. Concrete chloride diffusivity has been experimented by multiple agencies and researchers on sound concrete, but there is a considerable need for investigation of the durability of cracked concrete in the marine environment. The two test methods carried out are presented: Standardized American Society for Testing and Materials (ASTM) C1202 for Rapid Chloride Permeability (RCP) and ASTM D257 for Surface Resistivity (SR), and Nordtest (NT) Build 492 for Rapid Chloride Migration (RCM) and Bulk Resistivity (BR) for both sound (uncracked) and cracked (micro and macro) concrete. The limitations of the ASTM method, due to measurements before the steady-state migration is reached, does not account for leakage in cracked concrete, and the heating of the specimen due to higher current that increase the conductivity are indicated. The Rapid Chloride Migration test provides for the non-steady state of diffusion. Again, Bulk Resistivity, in contradistinction to Surface Resistivity is more accurate for cracked concrete. The correlation betweeen RCM-BR are plotted. Chloride Permeability/Migration is an important parameter that governs the Durability of Concrete. The principal contribution is the highlighting of the inadequacy of the current widely used standard ASTM C1202 for diffusivity testing, and the need for revision with further investigation.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00004942, http://purl.flvc.org/fau/fd/FA00004942
Subject Headings: Reinforced concrete--Construction--Corrosion., Reinforced concrete--Deterioration., Concrete--Corrosion., Concrete--Chemical resistance., Chlorides--Environmental aspects., Chlorides--Diffusion rate.
Format: Document (PDF)

Title: Fire resistance of corroded structural concrete.
Creator: Martinez, Fernando Jose, Reddy, Dronnadula V., Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: One of the major causes of structural repairs worldwide is the corrosion of reinforced concrete structures, such as residential buildings and piers, which are exposed to harsh marine environments. This investigation aims to provide experimental evidence of the fire resistance of corroded high strength reinforced concrete. For this, 14 reinforced concrete beams of three different concrete mix designs (different strengths) were prepared along with concrete cylinders for compression strength...
Show moreOne of the major causes of structural repairs worldwide is the corrosion of reinforced concrete structures, such as residential buildings and piers, which are exposed to harsh marine environments. This investigation aims to provide experimental evidence of the fire resistance of corroded high strength reinforced concrete. For this, 14 reinforced concrete beams of three different concrete mix designs (different strengths) were prepared along with concrete cylinders for compression strength testing (ASTM C39). After proper moist curing, all beams were corroded, in two phases, with impressed current, then “crack scored ”for corrosion evaluation, after which half were exposed to fire, also in two phases, following the ASTM E-119-12 time-temperature curve, using a gas kiln. The fire damage was evaluated and compared between phases by using Ultrasonic Pulse Velocity technology. Finally, all specimens were tested for flexural strength by using the third-point loading method (ASTM C78) and the effects of fire on the corroded beams were analyzed according to the level of corrosion.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004304, http://purl.flvc.org/fau/fd/FA00004304
Subject Headings: Concrete -- Effect of temperature on, Fire resistant materials, Reinforced concrete -- Corrosion, Thermodynamics
Format: Document (PDF)

Title: Acoustic emission investigation of marine corrosion-induced and external load-induced cracking of concrete.
Creator: Sailappan, R. N., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The acoustic emission investigations reported herein are divided into two experimental sets. In the first, the concrete specimens were stressed internally, and the resulting acoustic emissions were monitored. In the second, specimens were subjected to fracture mechanics tests and simultaneously studied for AE signals. For both sets, two kinds of concrete were studied--regular concrete and concrete containing fly ash. The specimens were stressed internally by subjecting them to an accelerated...
Show moreThe acoustic emission investigations reported herein are divided into two experimental sets. In the first, the concrete specimens were stressed internally, and the resulting acoustic emissions were monitored. In the second, specimens were subjected to fracture mechanics tests and simultaneously studied for AE signals. For both sets, two kinds of concrete were studied--regular concrete and concrete containing fly ash. The specimens were stressed internally by subjecting them to an accelerated state of corrosion in a marine environment. The corroded specimens were then tested for impact and flexural strengths to study the effect of fly ash replacement on rebar corrosion in a marine environment, and to ascertain any correlation between the monitored AE signals and residual strength. Furthermore, an attempt was made to predict the remaining life of the specimens. For the externally stressed specimens, AE was used to determine the load at initiation of unstable crack propagation terms of ultimate load. These tests have immediate and relevant applications to field problems.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14700
Subject Headings: Acoustic emission testing, Concrete--Corrosion, Concrete--Cracking
Format: Document (PDF)

Title: Rain-wind-induced cable vibrations in cable-stayed bridges.
Creator: Calle, Oscar F., Reddy, Dronnadula V., Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: This research is aimed at investigating and analyzing the rain-windinduced cable vibration phenomena experienced in cables of cable-stayed bridges and also the countermeasures employed by engineers to mitigate the large-amplitude vibration problem reported by various researchers around the world. In order to investigate the problem of the water rivulet creation at the top of the cable surface, a single-degree-of-freedom (SDOF) analytical model was developed and analyzed. This thesis studies...
Show moreThis research is aimed at investigating and analyzing the rain-windinduced cable vibration phenomena experienced in cables of cable-stayed bridges and also the countermeasures employed by engineers to mitigate the large-amplitude vibration problem reported by various researchers around the world. In order to investigate the problem of the water rivulet creation at the top of the cable surface, a single-degree-of-freedom (SDOF) analytical model was developed and analyzed. This thesis studies the aerodynamic instability of cables in cable-stayed bridges by doing literature review of a typical in-situ test, developing a single degree-of-freedom (SDOF) analytical model, and an ANSYS finite element model. Furthermore, a linear viscous damper that acts as a countermeasure to the large amplitudes of vibration is reported and analyzed. The suppression characteristics and damper effectiveness of such countermeasure are summarized.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004271, http://purl.flvc.org/fau/fd/FA00004271
Subject Headings: Bridges -- Aerodynamics, Bridges -- Vibration -- Prevention, Cable stayed bridges -- Maintenance and repair, Damping (Mechanics), Structural dynamics, Vibration -- Mathematical models, Wind resistant design
Format: Document (PDF)

Title: Analytical evaluation of marine concrete pile repairs.
Creator: Saleh, Zaher A. Abou., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: The purpose of the thesis is to determine and compare the performance characteristics of marine piles corroded by chloride diffusion and repaired by several different methods for both uncracked and cracked concrete and to determine their structural integrity. The long-term objective is the comparison of the analytical values with those from an on-going experimental evaluation. The time for chloride concentration reach the threshold value that initiates corrosion in the reinforcement has been...
Show moreThe purpose of the thesis is to determine and compare the performance characteristics of marine piles corroded by chloride diffusion and repaired by several different methods for both uncracked and cracked concrete and to determine their structural integrity. The long-term objective is the comparison of the analytical values with those from an on-going experimental evaluation. The time for chloride concentration reach the threshold value that initiates corrosion in the reinforcement has been determined by Fick's law, extended to 2-D and 3-D chloride diffusion, for (a) uncracked concrete, and (b) for cracked concrete with the Simplified Smeared Approach (SSA). The structural integrity of the concrete circular pile is compared before and alter repair, by (a) finite element modeling using ANSYS software with the maximum deflection, and (b) beam strength analysis to find the moment capacity for cracked and ultimate conditions. The overall findings indicate the adequacy of the repair procedures.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13062
Subject Headings: Concrete piling, Reinforced concrete--Corrosion, Seawater corrosion
Format: Document (PDF)

FAU Theses and Dissertations (33)	+ -
FAU Undergraduate Student Research (1)	+ -

Reinforced concrete--Corrosion (5)	+ -
Concrete--Cracking (3)	+ -
Fly ash (3)	+ -
Fiber reinforced plastics (2)	+ -
Fire resistant materials (2)	+ -

Fracture mechanics (2)	+ -
Pipe, Plastic--Testing (2)	+ -
Reinforced concrete--Environmental testing (2)	+ -
Retaining walls (2)	+ -
Seawater corrosion (2)	+ -
Soil stabilization (2)	+ -
Thermodynamics (2)	+ -
Acoustic emission testing (1)	+ -
Asphalt cement--Additives (1)	+ -
Breakwaters (1)	+ -
Bridges -- Aerodynamics (1)	+ -
Bridges -- Vibration -- Prevention (1)	+ -
Bridges, Box girder (1)	+ -
Bridges, Box girder--Design and construction (1)	+ -
Bridges, Concrete--Joints (1)	+ -
Bridges, Concrete--Models (1)	+ -
Bridges, Iron and steel--Floors--Evaluation (1)	+ -
Bridges--Design and construction (1)	+ -
Bridges--Florida (1)	+ -
Bridges--Noise (1)	+ -
Buildings--Repair and reconstruction (1)	+ -
Cable stayed bridges -- Maintenance and repair (1)	+ -
Chlorides--Diffusion rate. (1)	+ -
Chlorides--Environmental aspects. (1)	+ -
Coal ash (1)	+ -

Electronic Thesis or Dissertation (33)	+ -
poster (1)	+ -

Reddy, Dronnadula V. (34)	+ -
Florida Atlantic University (33)	+ -
College of Engineering and Computer Science (22)	+ -
Department of Ocean and Mechanical Engineering (16)	+ -
Department of Civil, Environmental and Geomatics Engineering (5)	+ -

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