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Title: Characterization of steel cathodic polarization in seawater and its applications in offshore structure cathodic protection design.
Creator: Wang, Weiqing., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Laboratory experiments have been performed to characterize the effects of initial current density and selected variables (initial current density, temperature and surface treatment) upon the cathodic polarization behavior of API 2H Grade 42 steel in natural sea water. The procedure involved galvanic coupling of a cylindrical steel specimen to a larger diameter aluminum sacrificial anode ring through an external resistor, which offset the otherwise impractically small anode/cathode surface...
Show moreLaboratory experiments have been performed to characterize the effects of initial current density and selected variables (initial current density, temperature and surface treatment) upon the cathodic polarization behavior of API 2H Grade 42 steel in natural sea water. The procedure involved galvanic coupling of a cylindrical steel specimen to a larger diameter aluminum sacrificial anode ring through an external resistor, which offset the otherwise impractically small anode/cathode surface area ratio and permitted the desired initial current density to be realized. In the initial polarization stage the change in potential versus current density data with time was found to be linear with a slope equal to the product of the total circuit resistance and cathode surface area and with the vertical intercept corresponding to the anode open circuit potential. Lower temperature or increased flow resulted in reduced polarization and a relatively high current density, but data for experiments employing a particular resistance conformed to straight lines with the same slope R[ext] x A[c] (external resistance times cathode surface area). Some experiments exhibited concave behavior at longer test duration. An explanation for the linear interdependence of potential and current density and the following concave behavior is presented. The laboratory experiments were compared with offshore structure survey results. It is projected that the potential-current density behavior of galvanic cathodic protection (CP) systems of different geometries can be quantitatively interrelated through this slope parameter. Implications of the data are discussed within the context of cathodic protection design, rapid polarization and system performance for offshore structures.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/12362
Subject Headings: Steel--Cathodic protection, Seawater, Offshore structures
Format: Document (PDF)

Title: Effect of Polarization on Steel Embedded in Simulated Piling Specimens Evaluated by Critical Chloride Threshold.
Creator: Tanner, Russell, Hartt, William H., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Critical chloride threshold, CT values for initiation of reinforced steel corrosion m mortar typical of Florida coastal bridge substructures were determined in laboratory tests. Previous research has reported CT values that vary by more than an order-of-magnitude, making design life estimation for structures difficult. On this basis, experiments on piling type specimens focused on [Cl-] contamination in the splash zone and coupling of this steel to a large surface area submerged anode. The...
Show moreCritical chloride threshold, CT values for initiation of reinforced steel corrosion m mortar typical of Florida coastal bridge substructures were determined in laboratory tests. Previous research has reported CT values that vary by more than an order-of-magnitude, making design life estimation for structures difficult. On this basis, experiments on piling type specimens focused on [Cl-] contamination in the splash zone and coupling of this steel to a large surface area submerged anode. The lower portion of simulated piling was immersed and the region above the waterline periodically sprayed with NaCI solution. Corrosion potential with respect to height above the waterline was monitored. A temporary depolarization method for determining as to whether or not corrosion had initiated is proposed. Chloride distribution at the reinforcement-concrete interface was determined in piling using energy dispersive x-ray analysis and related to height with respect to the waterline. Chloride threshold was related to corrosion potential.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00012560
Subject Headings: Reinforced concrete construction, Steel, Structural--Corrosion, Chlorides, Corrosion and anti-corrosives, Seawater corrosion
Format: Document (PDF)

Title: Effects of High Alkalinity Cements on the Control of Alkali-Silica Reaction for Reinforced Concrete.
Creator: Suarez, Jorge Alejandro, Hartt, William H., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: In previous research, cements with high alkali content (EqA 1.0-1.2 percent) extended the corrosion initiation time of reinforcing steel in concrete. During this study, laboratory tests were performed to determine the suitability of high alkalinity cements to improve concrete durability without modifying physical properties and to control the risk of alkali-aggregate reaction (AAR). A mix design for the FOOT-Class V concrete served as base material for this study. On a cubic meter basis the...
Show moreIn previous research, cements with high alkali content (EqA 1.0-1.2 percent) extended the corrosion initiation time of reinforcing steel in concrete. During this study, laboratory tests were performed to determine the suitability of high alkalinity cements to improve concrete durability without modifying physical properties and to control the risk of alkali-aggregate reaction (AAR). A mix design for the FOOT-Class V concrete served as base material for this study. On a cubic meter basis the cementitious material in this concrete included 363 kg of Type l/ll Portland cement and 83 kg of Class F fly ash. The water-to-cementitious material ratio of the concrete was 0.40. The fine aggregate used in the experimental concretes was quartz sand from a Florida source with no history of alkali-silica reactivity (ASR) susceptibility. A number of cement alkali contents were prepared by different additions of sodium hydroxide to the concrete mix (3.42 - 4.57 kglm\ in some cases, and by using different cements in others. Thus, effects on concrete susceptibility to ASR, electrical resistivity, and strength were studied. Pore water alkalinity was measured by ex-situ leaching and pore water extraction methods. It was concluded that leaching procedures were not appropriate to determine concrete pore water alkalinity in the presence of fly ash. Results suggested that it is feasible to use high alkali cement without the risk of ASR or the loss of strength for two of the seven coarse aggregates studied, given that supplementary cementitious materials and lithium nitrate admixtures are utilized. Criteria for qualification of a concrete as being ASR resistant was based on dimensional stability (less than 0.01% average specimen length change) and the absence of cracking over the one and two year exposure periods according to ASTM Cl293. Based on the fundamentals of the electric double layer theory, the incidence of bivalent cations adjacent to the surface of cement hydrates and reactive silica particles was proposed to provide an explanation for the effects of alkali addition on the electrical resistivity of concrete and the source of the expansive nature of the ASR gel.
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Date Issued: 2006
PURL: http://purl.flvc.org/fau/fd/FA00012578
Subject Headings: Reinforced con crete construction, Concrete--Deterioration, Alkali-aggregate reactions, Silica
Format: Document (PDF)

Title: Design approaches for asymmetrical marine pipeline cathodic protection systems.
Creator: Qian, Haijun., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Marine pipeline cathodic protection systems for asymmetrical situation were systematically investigated by means of a newly proposed approach and Boundary Element Method (BEM). Potential attenuation profiles from BEM modeling indicate that far-field cathode potentials of different pipe sections approach identical values under different coating resistance and different electrolyte resistivity conditions provided anodes are separated by at least 10m and metallic resistance is negligible. A...
Show moreMarine pipeline cathodic protection systems for asymmetrical situation were systematically investigated by means of a newly proposed approach and Boundary Element Method (BEM). Potential attenuation profiles from BEM modeling indicate that far-field cathode potentials of different pipe sections approach identical values under different coating resistance and different electrolyte resistivity conditions provided anodes are separated by at least 10m and metallic resistance is negligible. A series of equations based on the Slope Parameter Method (SPM) has been modified for more extensive applicability. Several design examples have been analyzed and the results verified by BEM. Cathode potential and current demands projected by the new method are consistent with those of BEM. The inclusive equation for even anode spacing CP has been modified to include the cable parameters by combining cable resistance and the anode resistance. Current demand for existing pipelines can be determined by either of two methods. The first utilizes the inclusive equation and involves solving this for current demand based upon a known potential profile. The other is based on SPM.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13098
Subject Headings: Underwater pipelines, Pipelines--Cathodic protection, Boundary element methods
Format: Document (PDF)

Title: Discrete signal representation using triangular basis functions.
Creator: Nallur, Padmanabha., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis deals with the representation of discrete signals using triangular basis functions. Signals are usually represented by Fourier series expansions where the basis functions are cosine and sine functions which are all mutually orthogonal. The triangular basis functions used here are called TRIC (triangular cosine) and TRIS (triangular sine) functions. The TRIC and TRIS functions are like their cosine and sine function counterparts except that they are linear. The TRIC and TRIS...
Show moreThis thesis deals with the representation of discrete signals using triangular basis functions. Signals are usually represented by Fourier series expansions where the basis functions are cosine and sine functions which are all mutually orthogonal. The triangular basis functions used here are called TRIC (triangular cosine) and TRIS (triangular sine) functions. The TRIC and TRIS functions are like their cosine and sine function counterparts except that they are linear. The TRIC and TRIS functions are not all mutually orthogonal, though most of them are. A matrix method of representing discrete signals using TRIC and TRIS functions is presented. A discrete triangular transform matrix is developed and a method of deriving this matrix is presented. A Fortran program is written to derive the discrete triangular transform matrix and to prove the reconstruction of several basic functions like impulse, step, pulse and sinusoidal waveforms.
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/14451
Subject Headings: Signal processing--Mathematical models
Format: Document (PDF)

Title: CORROSION FATIGUE CRACK INITIATION BEHAVIOR OF SEVERAL HIGH STRENGTH STEELS IN SEAWATER (POTENTIAL, CATHODIC, POLARIZATION).
Creator: SLOAN, FORREST EUGENE., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: 'J 'ht' c· f feet of seawater ,_tnd potential on the fatigue crack initiation hehavior of several microalloyed and thermomPrhanically processed steels has been investigated. Five steels with yield strength in t~e range 500 to 750 MPa (73 to 108 ksi) were selected which included a range of processing histories from conventional quenching and tempering to precipitation hardening and direct quenching. These steels were chosen because of their potential utility as materials of construction for...
Show more'J 'ht' c· f feet of seawater ,_tnd potential on the fatigue crack initiation hehavior of several microalloyed and thermomPrhanically processed steels has been investigated. Five steels with yield strength in t~e range 500 to 750 MPa (73 to 108 ksi) were selected which included a range of processing histories from conventional quenching and tempering to precipitation hardening and direct quenching. These steels were chosen because of their potential utility as materials of construction for deep water compliant platform hull and riser systems. Blunt notch compact tension specimens were exposed to natural flowing seawater under constant load ampli tnrlc. conditions at both freely corroding and cathodically protected potentials. Cycles to crack initiation were characterized by cyclic stress intensity range normalized relative to the square root of notch radius. Test data are presented and compared with data from other tests and steels using appropriate stress analysis methods.
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Date Issued: 1986
PURL: http://purl.flvc.org/fcla/dt/14285
Subject Headings: Steel, High strength--Fatigue--Testing, Sea-water corrosion
Format: Document (PDF)

Title: Development of a multiple specimen test methodology for fatigue crack growth rate determination.
Creator: Deshayes, Frederic Rene., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A new experimental approach has been developed whereby fatigue crack growth rates are determined for multiple specimens tested in series. This involves a geometry whereby specimens respond to cyclic loading in a manner that is mutually independent. The classic compact-tension specimen geometry is inappropriate for this technique, since stress intensity factor range increases with increasing crack length (constant load amplitude or range); and this dictates load shedding according to the...
Show moreA new experimental approach has been developed whereby fatigue crack growth rates are determined for multiple specimens tested in series. This involves a geometry whereby specimens respond to cyclic loading in a manner that is mutually independent. The classic compact-tension specimen geometry is inappropriate for this technique, since stress intensity factor range increases with increasing crack length (constant load amplitude or range); and this dictates load shedding according to the specimen for which crack propagation is most rapid. Stress intensity factor range for the remaining specimens (smaller crack length) consequently decreases to low values and may even fall to below Delta KI, such that little or no information is obtained from them. To overcome this difficulty a new constant taper, side-grooved compact-tension specimen geometry for which stress intensity factor decreases with increasing crack length at constant load has been developed. Load shedding is, therefore, not necessarily required to reduce Delta KI during the test. A finite element analysis was performed to establish the stress intensity-crack length (constant load), compliance-crack length and DCPD (Direct Current Potential Drop)-crack length character of the specimen. An appropriate side-groove depth to avoid crack deviation from the intended plane was determined experimentally, and an analytical expression to account for reduced thickness in the crack plane was verified. Calibration curves between crack length and compliance and between crack length and potential drop were verified as well, and the stress intensity-crack length characteristics for the specimen were confirmed by comparison of da/dN-Delta KI curves with those for conventional C(T) specimens. A locally fabricated, five specimen fatigue testing frame was developed in conjunction with a 98 kN MTS actuator and interfaced with a commercially available control system, the hardware and software of which were modified to accommodate multiple specimen control and data acquisition. The utility of the proposed specimen and test procedure are discussed within the context of threshold and near-threshold crack growth rate determination where long test times are normally required for data development, particularly for low cyclic frequency applications such as nuclear and offshore.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/12272
Subject Headings: Materials--Fatigue
Format: Document (PDF)

Title: Modeling of bracelet anodes and anode arrays for pipeline CP systems.
Creator: Zhang, Xiaolin., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Two models for pipeline bracelet anodes depletion with time were analyzed: one with uniform corrosion and the other with localized corrosion. The potential of the pipeline was determined to become more positive with time due to corrosion of the anode. The pipeline protected by the anode with localized corrosion had more a positive potential than the one protected by the anode with uniform corrosion. A method based upon the equations of Sunde was developed for determining resistance of linear...
Show moreTwo models for pipeline bracelet anodes depletion with time were analyzed: one with uniform corrosion and the other with localized corrosion. The potential of the pipeline was determined to become more positive with time due to corrosion of the anode. The pipeline protected by the anode with localized corrosion had more a positive potential than the one protected by the anode with uniform corrosion. A method based upon the equations of Sunde was developed for determining resistance of linear and rectangular anode arrays. Accuracy of this approach was evaluated using Boundary Element Modeling (BEM). The difference between the two methods was defined as Error. A corrected function of Sunde's equation was developed in order to get a more accurate resistance of a 1 x N anode array. The influence on resistance of a M x N (M < N) anode array of anode size, separation distance and array number was analyzed. Error increased with increasing anode size and decreased with increasing number of anodes and separation distance. The application and limitations of commonly used anode resistance formulas are discussed.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13087
Subject Headings: Pipelines--Cathodic protection, Corrosion and anti-corrosives, Underwater pipelines, Anodes
Format: Document (PDF)

Title: Fatigue crack growth rate of short cracks for high strength steels in sea water.
Creator: Kim, Kijoon., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Experiments have been performed which determined the fatigue crack growth rate (FCGR) of short cracks (a > 0.1mm) for five high strength steels (yield stress 370-570 MPa) in air and in natural seawater with and without cathodic protection. Attention was focused upon Regions I and Il of the classical FCGR-stress intensity range(Delta K) curve with particular consideration of the near-threshold behavior for short cracks. Single edge notch (SEN) three-point bend specimens and a direct current...
Show moreExperiments have been performed which determined the fatigue crack growth rate (FCGR) of short cracks (a > 0.1mm) for five high strength steels (yield stress 370-570 MPa) in air and in natural seawater with and without cathodic protection. Attention was focused upon Regions I and Il of the classical FCGR-stress intensity range(Delta K) curve with particular consideration of the near-threshold behavior for short cracks. Single edge notch (SEN) three-point bend specimens and a direct current potential drop (DCPD) crack monitoring system were employed, and test parameters simulated offshore structure conditions. The results indicated enhanced FCGR for short cracks compared to macrocracks by 3-20 times in air and 2-6 in seawater free-corroding(FC). Also, the Delta Kth for short cracks was apparently lower than for long ones in both environments. The transition from short to long crack behavior occurred at constant $\Delta$K in each environment (15.6 MPa m in air and 10.0 MPa m in seawater(FC)) irrespective of initial Delta K (Delta K(0)). The transition crack length ranged from 0.25 to 1.6 mm and was inversely proportional to $\Delta$K(0). Scanning electron microscope fractography showed that the mechanism of enhanced crack growth rate was associated with secondary crack (SC) formation in air and SC or inter-granular cracking (or both) in seawater (FC). The enhanced FCGR for short cracks was minimized by polarization to -950 mV(SCE). Through an elastic-plastic fracture mechanics analysis using the J-integral parameter it was found that the influence of plastic deformation at the crack tip was approximately independent of crack length (short versus long), and the linear-elastic fracture mechanics analysis gave a realistic representation for fatigue behavior.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/12313
Subject Headings: Steel--Fatigue--Environmental aspects, Underwater acoustics, Seawater--Acoustic properties
Format: Document (PDF)

Title: Fatigue of high strength steels in sea water.
Creator: Sablok, Anil Kumar., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Fatigue response of selected high strength steels in seawater was investigated under conditions relevant to tension leg platform tendon applications. This involved both freely corroding and cathodically protected, displacement controlled experiments upon constant taper, bending specimens which were either notched or welded, ground and post weld heat treated. High stress range freely corroding results indicated enhanced life compared to structural steel, whereas at low stress range the...
Show moreFatigue response of selected high strength steels in seawater was investigated under conditions relevant to tension leg platform tendon applications. This involved both freely corroding and cathodically protected, displacement controlled experiments upon constant taper, bending specimens which were either notched or welded, ground and post weld heat treated. High stress range freely corroding results indicated enhanced life compared to structural steel, whereas at low stress range the opposite was true. Corrections made to the high strength steel and structural steel data to correspond to similar test conditions revealed no benefit of enhanced material strength on corrosion fatigue life. Fatigue life for all cathodically protected specimens exceeded that for the freely corroding ones, and with one exception testing was terminated prior to failure. The single cathodically protected specimen failure involved a stress range approximately one-third the value for other specimens which were run-outs. This suggests that an environmental cracking process may operate precipitously at relatively low stress amplitudes (alternately, high R values). Fatigue life for freely corroding notched specimens was less than for grounded PWHT specimens, the difference increasing with decreasing amplitude.
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/14463
Subject Headings: Steel--Fatigue, Steel, High strength
Format: Document (PDF)

Title: Evaluation of carbon fiber/polyetheretherketone composites exposed to marine microbial communities in laboratory media and natural seawater.
Creator: Sheetz, Andrew Douglas., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This research proposed to characterize any microbial induced degradation of carbon fiber/polyetheretherketone (PEEK) composites from acid-producing bacteria (APB) and sulfate-reducing bacteria (SRB). Electrochemical impedance spectroscopy (EIS) was used to provide a measure of degradation of the composite system as a function of exposure time. In addition, mechanical testing and microscopic evaluation of the specimens were utilized to determine if changes in the EIS spectra as a function of...
Show moreThis research proposed to characterize any microbial induced degradation of carbon fiber/polyetheretherketone (PEEK) composites from acid-producing bacteria (APB) and sulfate-reducing bacteria (SRB). Electrochemical impedance spectroscopy (EIS) was used to provide a measure of degradation of the composite system as a function of exposure time. In addition, mechanical testing and microscopic evaluation of the specimens were utilized to determine if changes in the EIS spectra as a function of exposure time correlated to changes in the mechanical properties. Results from most EIS scans were consistent with a well-consolidated and undamaged composite system. Changes in the EIS response of specimens exposed to the SRB environment were not matched by a reduction in the flexural strength. Mechanical testing also indicated no reduction in the flexural strength in any of the other exposure environments. Environmental scanning electron microscopy (ESEM)/energy dispersive x-ray spectroscopy (EDS) were inconclusive, though changes in the EDS spectra were seen. No definitive degradation was seen to occur in this composite system.
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Date Issued: 1998
PURL: http://purl.flvc.org/fcla/dt/15531
Subject Headings: Corrosion and anti-corrosives, Composite materials--Biodegradation
Format: Document (PDF)

Title: Environmental cracking of prestressing steel in calcium-hydroxide solutions.
Creator: Kumria, Chetan Chand., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Failure of prestressed steel tendon in concrete due to corrosion or environmental cracking (or both) has become a major technological concern because of increased utilization of this form of construction in corrosive exposure such as coastal bridge deck structures. At the same time cathodic protection has evolved as the most practical means for arresting corrosion of reinforcing steel in existing structures. This technology also applies to pretensioned tendons. However, concerns have been...
Show moreFailure of prestressed steel tendon in concrete due to corrosion or environmental cracking (or both) has become a major technological concern because of increased utilization of this form of construction in corrosive exposure such as coastal bridge deck structures. At the same time cathodic protection has evolved as the most practical means for arresting corrosion of reinforcing steel in existing structures. This technology also applies to pretensioned tendons. However, concerns have been raised that cathodic protection might cause embrittlement, since yield stress of these materials is relatively high. For the purpose of analyzing this embrittlement tendency a series of constant load and slow strain rate experiments were performed and the data evaluated. Influence of potential, chloride concentration, pH and precharging on the cracking susceptibility have been evaluated. The cracking process has been explained based on test results and SEM analysis.
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Date Issued: 1989
PURL: http://purl.flvc.org/fcla/dt/14531
Subject Headings: Steel, High strength--Brittleness
Format: Document (PDF)

Title: Environmental cracking of reinforcing steel in saturated calcium hydroxide solutions.
Creator: Mathew, Ivan., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Deterioration of reinforcing steel in concrete structures due to rebar corrosion is of national and international concern. Cathodic protection has evolved as the appropriate mitigating technique for existing structures. Another method which is being investigated is the electrochemical removal of chlorides from concrete. The current density used for this process leads to steel potentials at which hydrogen evolves. This raises concern regarding hydrogen embrittlement of reinforcing steel in...
Show moreDeterioration of reinforcing steel in concrete structures due to rebar corrosion is of national and international concern. Cathodic protection has evolved as the appropriate mitigating technique for existing structures. Another method which is being investigated is the electrochemical removal of chlorides from concrete. The current density used for this process leads to steel potentials at which hydrogen evolves. This raises concern regarding hydrogen embrittlement of reinforcing steel in concrete. For the purpose of analyzing this embrittlement tendency, a series of constant extension rate experiments was conducted in saturated calcium hydroxide solutions using notched and smooth specimens. While notched specimens did not show any effect of hydrogen embrittlement, the smooth specimens have revealed a reduction in ductility at high current densities. Experiments have shown that this loss in ductility is recoverable. Tests were also conducted on mortared smooth specimens which essentially exhibited the same trend observed as in the calcium hydroxide solution. The loss in ductility has been attributed to the enhanced void development in the presence of hydrogen during plastic deformation.
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Date Issued: 1990
PURL: http://purl.flvc.org/fcla/dt/14639
Subject Headings: Steel--Corrosion, Steel--Brittleness
Format: Document (PDF)

Title: INFLUENCE OF TEMPERATURE ON CALCAREOUS DEPOSIT DEPOSITION UPON CATHODICALLY POLARIZED STEEL IN SEA WATER.
Creator: KUNJAPUR, MADANA MOHAN., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Experiments have been performed where cylindrical 1018 steel specimens were polarized to -0.900 V.(SCE) in natural sea water at 24 and 3C and with rotation speeds of 0 and 0.83 Hz. The nature of the calcareous deposits which formed was characterized, first, by monitoring current density during the experiments and, second, by post-test SEM investigation of deposit morphology and thickness and by EEDS analysis of deposit composition. The dependence of cathodic current density and film...
Show moreExperiments have been performed where cylindrical 1018 steel specimens were polarized to -0.900 V.(SCE) in natural sea water at 24 and 3C and with rotation speeds of 0 and 0.83 Hz. The nature of the calcareous deposits which formed was characterized, first, by monitoring current density during the experiments and, second, by post-test SEM investigation of deposit morphology and thickness and by EEDS analysis of deposit composition. The dependence of cathodic current density and film composition upon temperature and exposure time has been established, and the observed trends have been interpreted in terms of (1) the temperature dependence of the solubility limit and relative nucleation and growth rates for Ca and Mg rich phases and (2) possible electrical conductive behavior on the part of Mg rich deposits.
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Date Issued: 1987
PURL: http://purl.flvc.org/fcla/dt/14377
Subject Headings: Steel--Cathodic protection, Calcium--Effect of temperature on, Seawater
Format: Document (PDF)

Title: AN INVESTIGATION OF POTENTIAL, PH AND CALCAREOUS DEPOSITS WITHIN SIMULATED FATIGUE CRACKS FOR CATHODICALLY POLARIZED STRUCTURAL STEEL IN SEA WATER.
Creator: MAO, WEI-YUN., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Electrochemical conditions within corrosion fatigue cracks are thought to exert an important influence upon propagation rate. For the case of cathodically polarized steel in sea water, it has been observed that pH of electrolyte adjacent to steel increased and calcareous material formed on the steel surface. As a consequence of the latter process the electrochemistry within cathodically polarized cracks may be unique compared to other electrolytes. The objective of this study has been to...
Show moreElectrochemical conditions within corrosion fatigue cracks are thought to exert an important influence upon propagation rate. For the case of cathodically polarized steel in sea water, it has been observed that pH of electrolyte adjacent to steel increased and calcareous material formed on the steel surface. As a consequence of the latter process the electrochemistry within cathodically polarized cracks may be unique compared to other electrolytes. The objective of this study has been to measure the potential and pH within simulated fatigue cracks of ABS DH 32 steel under cathodic protection. In addition, the calcareous deposits which formed within the simulated cracks were observed and analyzed. Based upon these data, potential, pH profiles and calcareous deposit thickness and composition were measured. This, in turn, permitted conditions within the simulated crack to be better understood.
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Date Issued: 1984
PURL: http://purl.flvc.org/fcla/dt/14208
Subject Headings: Steel, Structural--Testing, Cathodic protection, Electrolytic corrosion
Format: Document (PDF)

Title: Hydrogen embrittlement of cathodically protected prestressing steel.
Creator: Kliszowski, Stanislas Henri., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Cathodic protection is currently recognized as the most practical mean for arresting corrosion of reinforcing steel tendons in existing concrete structures, however, its appropriateness in the case of prestressed concrete is questioned because prestressing steels are relatively susceptible to environmental cracking (hydrogen embrittlement). For the purpose of studying embrittlement tendencies a series of experiments using the slow strain rate technique were performed. The susceptibility to...
Show moreCathodic protection is currently recognized as the most practical mean for arresting corrosion of reinforcing steel tendons in existing concrete structures, however, its appropriateness in the case of prestressed concrete is questioned because prestressing steels are relatively susceptible to environmental cracking (hydrogen embrittlement). For the purpose of studying embrittlement tendencies a series of experiments using the slow strain rate technique were performed. The susceptibility to environmental cracking was compared for different steels corresponding to ASTM grades 270 and 250 polarized at $-$900 and $-1300$ mV (SCE) in deaerated saturated Ca(OH)$\sb2$ solutions. The influence of different notch and pit geometries was studied to simulate the behavior of corroded tendons and investigate the transition between smooth and severely notched specimen behavior. Also evaluated was the evolution of the mechanical properties of tendons after excessive polarization. The different cracking processes are discussed based on test data, fractography and exposures conditions associated with concrete structures.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/14999
Subject Headings: Cathodic protection, Metals--Hydrogen embrittlement, Tendons (Prestressed concrete), Prestressed concrete--Deterioration, Prestressed steel construction
Format: Document (PDF)

Title: Performance of anodes in cathodic protection of reinforcing steel in concrete.
Creator: Venugopalan, Sivaraman., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Experiments were conducted on a simulated reinforced concrete bridge deck to test different anodes as part of a cathodic protection system. Both carbon based and titanium based anodes were tested. All the anodes were driven at predetermined current densities. Current off polarized potentials of steel and anode were monitored over six months. After this period, cores were extracted from slabs containing a part of anode and steel and then broken at the anode-concrete and steel-concrete...
Show moreExperiments were conducted on a simulated reinforced concrete bridge deck to test different anodes as part of a cathodic protection system. Both carbon based and titanium based anodes were tested. All the anodes were driven at predetermined current densities. Current off polarized potentials of steel and anode were monitored over six months. After this period, cores were extracted from slabs containing a part of anode and steel and then broken at the anode-concrete and steel-concrete interface to measure the pH at these interfaces. Differences in the pH values at the anode-concrete interface were compared to determine the performance of the different anodes. Carbon based anodes operated at a higher potential and produced anode corrosion products of lower pH when compared to titanium based anodes.
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Date Issued: 1990
PURL: http://purl.flvc.org/fcla/dt/14658
Subject Headings: Reinforcing bars--Cathodic protection, Reinforced concrete--Corrosion
Format: Document (PDF)

Title: Polyethylene duct cracking in post-tensioning tendons of Florida segmental bridges.
Creator: Suarez, Jorge Alejandro, Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: For the purpose of investigating the cause of duct cracking in post-tensioning tendons and improving the durability of this type of structure, a series of experiments was performed. These were divided in two groups, the first to simulate the state of stress inside the tendon ducts and the second to compare the properties of new materials approved according to new regulations on the subject and those used in the construction of the structures. A proposed mechanism of cracking was studied and...
Show moreFor the purpose of investigating the cause of duct cracking in post-tensioning tendons and improving the durability of this type of structure, a series of experiments was performed. These were divided in two groups, the first to simulate the state of stress inside the tendon ducts and the second to compare the properties of new materials approved according to new regulations on the subject and those used in the construction of the structures. A proposed mechanism of cracking was studied and its validity verified. According to simulations performed on specimens that were fabricated and others developed by the finite element method, new major factors were found to explain the duct failure. Finally, a comparison of mechanical properties indicated a difference between virgin and aged materials.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13071
Subject Headings: Post-tensioned prestressed concrete construction, Bridges--Florida, Polyethylene
Format: Document (PDF)

Title: STUDY OF ELECTROCHEMISTRY MODIFICATIONS WITHIN CATHODICALLY PROTECTED FATIGUE CREVICES IN 3% SODIUM-CHLORIDE - DISTILLED WATER SOLUTION AND SEAWATER.
Creator: RAJPATHAK, SHIRISH SHRIDHAR., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: It is well recognized that the electrochemistry modifications within cathodically protected fatigue crevices in seawater has pronounced effect on crack growth rate. This study focuses its attention on potential distribution within simulated fatigue crevice as a function of electrolyte velocity, fatigue frequency and cathodic protection potential. Results of salt water electrolyte and seawater electrolyte are compared to bring about the effect of calcareous deposits, Finally, a mathematical...
Show moreIt is well recognized that the electrochemistry modifications within cathodically protected fatigue crevices in seawater has pronounced effect on crack growth rate. This study focuses its attention on potential distribution within simulated fatigue crevice as a function of electrolyte velocity, fatigue frequency and cathodic protection potential. Results of salt water electrolyte and seawater electrolyte are compared to bring about the effect of calcareous deposits, Finally, a mathematical model based on mass transfer laws is developed to rationalise potential distribution trends within fatigue crevice and are compared with the observed behaviour.
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Date Issued: 1983
PURL: http://purl.flvc.org/fcla/dt/14151
Subject Headings: Cathodic protection, Metals--Corrosion fatigue, Sea-water corrosion
Format: Document (PDF)

Title: A STRESS CONCENTRATION ANALYSIS OF SELECTED WELDS FROM FATIGUE SPECIMENS USING THE FINITE-ELEMENT METHOD.
Creator: NEROLICH, SHAUN MICHAEL., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The stress concentration which exists at the toe of an AWS class 'c' weld has been investigated by means of the finite element method. This type of weld is representative of that specified to join tubular members for offshore structures. Welded fatigue specimens were sectioned and the weld profile described in terms of 1) the weld toe radius (R), 2) the reinforcement angle (e) and 3) the filler metal height QH). A statistical analysis was performed to determine the correlation between R, e...
Show moreThe stress concentration which exists at the toe of an AWS class 'c' weld has been investigated by means of the finite element method. This type of weld is representative of that specified to join tubular members for offshore structures. Welded fatigue specimens were sectioned and the weld profile described in terms of 1) the weld toe radius (R), 2) the reinforcement angle (e) and 3) the filler metal height QH). A statistical analysis was performed to determine the correlation between R, e and H from which it was found that they are independent of each other. By use of the finite element method, trends were established for the effect each parameter has on the stress concentration at the weld toe. Analysis of the effect of undercutting was also perfonned and the results used to offer an explanation why fatigue cracks propagate to failure in some cases and arrest in others.
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Date Issued: 1981
PURL: http://purl.flvc.org/fcla/dt/14069
Subject Headings: Offshore structures--Welding, Welded joints--Fatigue
Format: Document (PDF)

FAU Theses and Dissertations (80)	+ -
HBOI Faculty Contributions (1)	+ -
Florida Atlantic University Patents (1)	+ -

Steel--Corrosion (19)	+ -
Cathodic protection (15)	+ -
Steel--Fatigue (9)	+ -
Corrosion and anti-corrosives (8)	+ -
Reinforced concrete--Corrosion (8)	+ -

Chlorides (6)	+ -
Sea-water corrosion (6)	+ -
Seawater corrosion (6)	+ -
Offshore structures (4)	+ -
Pipelines--Cathodic protection (4)	+ -
Seawater (4)	+ -
Steel--Cathodic protection (4)	+ -
Underwater pipelines (4)	+ -
Aluminum--Corrosion (3)	+ -
Concrete--Corrosion (3)	+ -
Prestressed steel construction (3)	+ -
Reinforced concrete construction--Corrosion (3)	+ -
Reinforcing bars--Corrosion (3)	+ -
Steel, Structural--Fatigue (3)	+ -
Steel--Fracture (3)	+ -
Bridges--Florida (2)	+ -
Chlorides--Diffusion rate (2)	+ -
Composite reinforced concrete (2)	+ -
Concrete--Additives (2)	+ -
Concrete--Deterioration (2)	+ -
Marine steel (2)	+ -
Post-tensioned prestressed concrete construction (2)	+ -
Prestressed concrete--Corrosion (2)	+ -
Reinforced concrete (2)	+ -
Reinforced concrete construction (2)	+ -

Electronic Thesis or Dissertation (80)	+ -
article (1)	+ -
patent (1)	+ -

Hartt, William H. (82)	+ -
Florida Atlantic University (81)	+ -
College of Engineering and Computer Science (54)	+ -
Department of Ocean and Mechanical Engineering (54)	+ -
Clark, A. M. (2)	+ -

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