Master of Science / Department of Civil Engineering / Asadollah Esmaeily / Realistic strength assessment of reinforced concrete structural elements, especially columns in bridges and tall buildings is a critical need not only at design time, but also when an accurate evaluation of the strength is needed for decisions such as retrofit or replacement of an existing structure. Assessment of the flexural strength of a column under a specific axial load level is usually done by constructing the axial force-bending moment interaction response curve of the section. This assessment can be done using the code procedure. However, the code does not consider the confinement effect, and is based on the “stress block” assumption for a pre-assumed failure strain for concrete. It has been shown by various experimental and analytical studies that the performance of a reinforced concrete section is affected by different factors such loading history and material behavior. A realistic performance assessment should consider not only proper models for the monotonic and cyclic response of the material, but also analytical methods and procedures that can capture the effects of loading pattern and provide realistic predictions of the section capacity. Accuracy of the analytical methods in strength assessment of reinforced concrete sections was explored in a comparative study. These methods were compared and validated against the existing experimental data. The factors considered in these analytical procedures, included the effect of confinement, and the method employed in assessment of the axial-force-bending moment interaction response of a column section. The experimental data were collected from tests conducted on circular and rectangular columns under a constant axial load. It has been shown that the axial force-bending moment interaction curve, constructed based on the moment-curvature response of a section using a more detailed analytical method such as fiber-model, considering the confining effect of the lateral reinforcement, represents the most realistic and optimal response of a cross section.

Master of Science / Department of Civil Engineering / Yacoub M. Najjar / Reliable and economical design of Portland Cement Concrete (PCC) pavement structural systems relies on various factors, among which is the proper characterization of the expected permeability response of the concrete mixes. Permeability is a highly important factor which strongly relates the durability of concrete structures and pavement systems to changing environmental conditions. One of the most common environmental attacks which cause the deterioration of concrete structures is the corrosion of reinforcing steel due to chloride penetration. On an annual basis, corrosion-related structural repairs typically cost millions of dollars. This durability problem has gotten widespread interest in recent years due to its incidence rate and the associated high repair costs. For this reason, material characterization is one of the best methods to reduce repair costs. To properly characterize the permeability response of PCC pavement structure, the Kansas Department of Transportation (KDOT) generally runs the Rapid Chloride Permeability test to determine the resistance of concrete to penetration of chloride ions as well as the Boil test to determine the percent voids in hardened concrete. Rapid Chloride test typically measures the number of coulombs passing through a concrete sample over a period of six hours at a concrete age of 7, 28, and 56 days. Boil Test measures the volume of permeable pore space of the concrete sample over a period of five hours at a concrete age of 7, 28, and 56 days. In this research, backpropagation Artificial Neural Network (ANN)-based and Regression-based permeability response prediction models for Rapid Chloride and Boil tests are developed by using the databases provided by KDOT in order to reduce or eliminate the duration of the testing period. Moreover, another set of ANN- and Regression-based permeability prediction models, based on mix-design parameters, are developed using datasets obtained from the literature. The backpropagation ANN learning technique proved to be an efficient methodology to produce a relatively accurate permeability response prediction models. Comparison of the prediction accuracy of the developed ANN models and regression models proved that ANN models have outperformed their counterpart regression-based models. Overall, it can be inferred that the developed ANN-Based permeability prediction models are effective and applicable in characterizing the permeability response of concrete mixes used in transportation applications.

Riprap is the most commonly employed countermeasure where bridge piers need to be protected against possible undermining by scour. An extensive review of available design techniques revealed a wide range of equations and proposed design procedures but no generally accepted method for riprap sizing and implementation. The aim of this study was to develop a design procedure for riprap protection at piers which can be used in most river environments. The failure mechanisms and stability of riprap layers around cylindrical and rectangular shaped piers were examined in a comprehensive experimental study. The study assessed the importance of various riprap, flow, sediment, and pier parameters. Parameters for investigation were determined by dimensional analysis and included riprap placement and arrangement. A riprap size prediction formula was developed based on an allowable maximum local scour depth of up to 20%. This equation has been incorporated in a design approach which was tested through a model study of the Hutt Estuary Bridge. The influence of various parameters on riprap stability are incorporated in the equation by way of adjustment factors. The adjustment factors, KY and KD, represent the effects of riprap placement and pier/sediment size ratio effects respectively. They were deemed the most important parameters in riprap layer performance and are therefore included in the riprap size prediction formula. Additional experiments using synthetic filters have shown their ability to eliminate local scour, however they are susceptible to failure under degrading bed conditions. Degrading bed conditions cause the riprap to subside as a layer with the downward movement of the surrounding bed. Subsidence allows the layer to withstand rapid short term degradation. However long term degradation will ultimately result in failure of the stone protection. A preliminary experimental study of the use of submerged vanes as a scour countermeasure was performed. Submerged vanes have been used previously in channel protection with much success. Results indicate that vanes with a length to height ratio greater than one can reduce the maximum local scour depth in live bed conditions by as much as 34%. Further testing is required to develop a complete design procedure.

Riprap is the most commonly employed countermeasure where bridge piers need to be protected against possible undermining by scour. An extensive review of available design techniques revealed a wide range of equations and proposed design procedures but no generally accepted method for riprap sizing and implementation. The aim of this study was to develop a design procedure for riprap protection at piers which can be used in most river environments. The failure mechanisms and stability of riprap layers around cylindrical and rectangular shaped piers were examined in a comprehensive experimental study. The study assessed the importance of various riprap, flow, sediment, and pier parameters. Parameters for investigation were determined by dimensional analysis and included riprap placement and arrangement. A riprap size prediction formula was developed based on an allowable maximum local scour depth of up to 20%. This equation has been incorporated in a design approach which was tested through a model study of the Hutt Estuary Bridge. The influence of various parameters on riprap stability are incorporated in the equation by way of adjustment factors. The adjustment factors, KY and KD, represent the effects of riprap placement and pier/sediment size ratio effects respectively. They were deemed the most important parameters in riprap layer performance and are therefore included in the riprap size prediction formula. Additional experiments using synthetic filters have shown their ability to eliminate local scour, however they are susceptible to failure under degrading bed conditions. Degrading bed conditions cause the riprap to subside as a layer with the downward movement of the surrounding bed. Subsidence allows the layer to withstand rapid short term degradation. However long term degradation will ultimately result in failure of the stone protection. A preliminary experimental study of the use of submerged vanes as a scour countermeasure was performed. Submerged vanes have been used previously in channel protection with much success. Results indicate that vanes with a length to height ratio greater than one can reduce the maximum local scour depth in live bed conditions by as much as 34%. Further testing is required to develop a complete design procedure.

Riprap is the most commonly employed countermeasure where bridge piers need to be protected against possible undermining by scour. An extensive review of available design techniques revealed a wide range of equations and proposed design procedures but no generally accepted method for riprap sizing and implementation. The aim of this study was to develop a design procedure for riprap protection at piers which can be used in most river environments. The failure mechanisms and stability of riprap layers around cylindrical and rectangular shaped piers were examined in a comprehensive experimental study. The study assessed the importance of various riprap, flow, sediment, and pier parameters. Parameters for investigation were determined by dimensional analysis and included riprap placement and arrangement. A riprap size prediction formula was developed based on an allowable maximum local scour depth of up to 20%. This equation has been incorporated in a design approach which was tested through a model study of the Hutt Estuary Bridge. The influence of various parameters on riprap stability are incorporated in the equation by way of adjustment factors. The adjustment factors, KY and KD, represent the effects of riprap placement and pier/sediment size ratio effects respectively. They were deemed the most important parameters in riprap layer performance and are therefore included in the riprap size prediction formula. Additional experiments using synthetic filters have shown their ability to eliminate local scour, however they are susceptible to failure under degrading bed conditions. Degrading bed conditions cause the riprap to subside as a layer with the downward movement of the surrounding bed. Subsidence allows the layer to withstand rapid short term degradation. However long term degradation will ultimately result in failure of the stone protection. A preliminary experimental study of the use of submerged vanes as a scour countermeasure was performed. Submerged vanes have been used previously in channel protection with much success. Results indicate that vanes with a length to height ratio greater than one can reduce the maximum local scour depth in live bed conditions by as much as 34%. Further testing is required to develop a complete design procedure.

Riprap is the most commonly employed countermeasure where bridge piers need to be protected against possible undermining by scour. An extensive review of available design techniques revealed a wide range of equations and proposed design procedures but no generally accepted method for riprap sizing and implementation. The aim of this study was to develop a design procedure for riprap protection at piers which can be used in most river environments. The failure mechanisms and stability of riprap layers around cylindrical and rectangular shaped piers were examined in a comprehensive experimental study. The study assessed the importance of various riprap, flow, sediment, and pier parameters. Parameters for investigation were determined by dimensional analysis and included riprap placement and arrangement. A riprap size prediction formula was developed based on an allowable maximum local scour depth of up to 20%. This equation has been incorporated in a design approach which was tested through a model study of the Hutt Estuary Bridge. The influence of various parameters on riprap stability are incorporated in the equation by way of adjustment factors. The adjustment factors, KY and KD, represent the effects of riprap placement and pier/sediment size ratio effects respectively. They were deemed the most important parameters in riprap layer performance and are therefore included in the riprap size prediction formula. Additional experiments using synthetic filters have shown their ability to eliminate local scour, however they are susceptible to failure under degrading bed conditions. Degrading bed conditions cause the riprap to subside as a layer with the downward movement of the surrounding bed. Subsidence allows the layer to withstand rapid short term degradation. However long term degradation will ultimately result in failure of the stone protection. A preliminary experimental study of the use of submerged vanes as a scour countermeasure was performed. Submerged vanes have been used previously in channel protection with much success. Results indicate that vanes with a length to height ratio greater than one can reduce the maximum local scour depth in live bed conditions by as much as 34%. Further testing is required to develop a complete design procedure.

Riprap is the most commonly employed countermeasure where bridge piers need to be protected against possible undermining by scour. An extensive review of available design techniques revealed a wide range of equations and proposed design procedures but no generally accepted method for riprap sizing and implementation. The aim of this study was to develop a design procedure for riprap protection at piers which can be used in most river environments. The failure mechanisms and stability of riprap layers around cylindrical and rectangular shaped piers were examined in a comprehensive experimental study. The study assessed the importance of various riprap, flow, sediment, and pier parameters. Parameters for investigation were determined by dimensional analysis and included riprap placement and arrangement. A riprap size prediction formula was developed based on an allowable maximum local scour depth of up to 20%. This equation has been incorporated in a design approach which was tested through a model study of the Hutt Estuary Bridge. The influence of various parameters on riprap stability are incorporated in the equation by way of adjustment factors. The adjustment factors, KY and KD, represent the effects of riprap placement and pier/sediment size ratio effects respectively. They were deemed the most important parameters in riprap layer performance and are therefore included in the riprap size prediction formula. Additional experiments using synthetic filters have shown their ability to eliminate local scour, however they are susceptible to failure under degrading bed conditions. Degrading bed conditions cause the riprap to subside as a layer with the downward movement of the surrounding bed. Subsidence allows the layer to withstand rapid short term degradation. However long term degradation will ultimately result in failure of the stone protection. A preliminary experimental study of the use of submerged vanes as a scour countermeasure was performed. Submerged vanes have been used previously in channel protection with much success. Results indicate that vanes with a length to height ratio greater than one can reduce the maximum local scour depth in live bed conditions by as much as 34%. Further testing is required to develop a complete design procedure.

Doctor of Philosophy / Department of Civil Engineering / Robert J. Peterman / Results of an extensive experimental program conducted to determine the material, bond characteristics, and time-dependent deformations of a proposed self-consolidating concrete (SCC) mixture for bridge girders are presented. This research program was completed in a three-step process. The first phase consisted of 15 full-scale, pretensioned SCC flexural specimens that were tested to evaluate their transfer and development lengths. These specimens included both single-strand and multiple-strand beams, as well as specimens designed to evaluate the so-called “top-strand" effect. The top-strand specimens, with more than 20 inches of concrete below the strand, were tested to evaluate the current American Association of State Highway Officials requirement of a 30% increase development length when the concrete below the strand is more than 12 inches. Strand end-slip measurements, used to estimate transfer lengths, indicated the proposed SCC mixture meets ACI and AASHTO requirements. In addition, flexural tests confirmed the proposed SCC mixture also meets current code requirements for development length. The second step was to evaluate the elastic shortening, creep, and shrinkage properties of the proposed SCC mixture for bridge girders. Four bridge girders with an inverted-T profile were used to measure these time-dependent deformations. In two of the specimens, the strands were tensioned to 75% of ultimate tensile strength (representing a girder that would be put into service). Strands of the other two specimens were left untensioned to evaluate shrinkage effect of the concrete alone. The shrinkage was then subtracted from the fully tensioned specimens and elastic shortening and creep were isolated after relaxation losses were calculated from code expressions. In addition, the fully tensioned specimens were used to determine transfer lengths of the prestressing strand. The final step in the program was to record strain measurements in actual bridge girders used in the field. Elastic shortening, creep, and shrinkage prestress loss results of the proposed SCC mixture were compared with current design equations. Instrumentation of seven pretensioned girders in a five-span bridge located in Cowley County, Kansas, was used to measure time-dependent deformations. Three of these girders utilized SCC, while the other four were cast with conventional concrete.

Doctor of Philosophy / Department of Civil Engineering / Robert J. Peterman / Possibly the most pressing need in highway construction today is the repair or replacement of existing bridges. Due to increased needs and growing traffic, in addition to aging and extensive use, more than 2000 bridges in Kansas alone need to be replaced during the next decade. The majority of these bridges has spans of 100 ft or less, and has relatively shallow profiles. It is becoming increasingly important to implement a standard method for replacement in which the process is expedited and accomplished in cost-effective manner. Requirements for design and construction of concrete bridges have drastically changed during recent years. A main change in design is live-load requirements. Nebraska inverted-T bridge system has gained increasing popularity for its lower weight compared to I-girder bridges. However, there are some limiting issues when using IT system in replacing existing CIP bridges. Implementation of a post-tensioned IT system, which is the focus of this research, is believed to be one excellent solution for the IT deficiencies. Post-tensioning is added by placing a draped, post-tensioning duct in the stems of the IT members. Post-tensioning will lead to a higher span-to-depth ratio than IT system, and will reduce the potential transverse cracks in the (CIP) deck. Finally, the undesired cambers of pretensioned beams will be reduced, because fewer initial prestressing will be needed. This study was intended to explore the behavior of the PT-IT system, identify major parameters that control and limit the design of this system, and investigate different construction scenarios. This was achieved by conducting an extensive parametric study. For that purpose, PT-IT analysis program was developed and written using C++ programming language. The program was used to analyze various post-tensioning procedures for the post-tensioned inverted-T system. A Visual Basic friendly interface was provided to simplify the data input process. The findings of this research included recommendation of construction scenario for PT-IT system, as well as examining different methods for estimating time-dependent restraining moments. Effect of different concrete strengths on the behavior of PT-IT system was also determined. Most importantly, the effect of timing on different construction stages was also evaluated and determined.

Master of Science / Department of Civil Engineering / Alok Bhandari / Antibiotics and pharmaceuticals are used to improve the quality of life worldwide. However, incomplete metabolism in humans has resulted in the release of large amounts of pharmaceutical drugs into municipal wastewater treatment plant. Past research has shown the release of antibiotic resistant organisms through wastewater effluents into streams and several studies have reported the occurrence of antibiotic resistant bacteria in major U.S. Rivers. Antibiotic resistant bacteria evolve and are selected by long-term environmental exposure to the low concentrations of antibiotics at the ng /L to g/L range. Infections caused by antibiotic resistant organisms are difficult to treat. The aim of this study was to analyze antibiotic resistance patterns in selected wastewater bacteria that include fecal coliforms, Escherichia coli and enterococci. Microorganisms in municipal wastewater treatment plant influent, secondary clarifier effluent and disinfected effluent were plated in the presence of predetermined concentrations of selected antibiotics. These antibiotics included ciprofloxacin, sulfamethoxazole/ trimethoprim and vancomycin. The diversity of enterococci was further investigated with PCR analysis. Fecal coliforms, E. coli and enterococci were found to be resistant or highly resistant to one or more target antibiotics in the influent and secondary clarifier (SC) effluent. Biological treatment reduced the number of overall and resistant bacteria in the SC effluent sample. UV disinfection was generally very effective and eliminated all fecal indicator organisms.