<p> The decision-making process used by construction foremen at a job site when the workflow is disrupted was investigated in this study. The foremen&rsquo;s decision-making process was mapped and then modeled to a heuristic model. This study focuses on cognitive decision or psychological heuristic models. The study shows that construction foremen use a heuristic decision model in their decision-making. The capability of heuristic to yield fast decision is very useful in construction because it is common for a construction foreman to experience several disruptions during the course of a single workday. With heuristic decision-making, a work-around decision can be rapidly and effectively made following a construction site disruption. Understanding the ability of heuristics to facilitate rapid and effective decision-making will help the construction industry to save time and increase productivity. </p><p> Research was conducted in order to map a decision process that foremen were using in their decision-making and to develop a model for a heuristic decision-making process. Interviews were conducted with 22 construction foremen in the electrical trade in 88 real disruption cases in order to understand how decisions were made after disruptions occurred. Interviews were subsequently conducted with 10 additional industry foremen in 10 real disruption cases to validate the data. Using this data, a heuristic decision-making model was developed. To validate this model, a survey was conducted with another 11 industry foremen. The findings indicate that construction foremen currently use a heuristic decision-making model known as &ldquo;determinant decision attribute&rdquo; (referred to as DDA) heuristics model. This DDA heuristic model was compared to the similar model with equal weighing and elimination by aspects (referred to as EW/EBA) to assess the performance of the heuristic. The DDA heuristic model correctly predicted, on average, 91% of the time what foremen&rsquo;s decisions were as to which decision task to choose to assign or re-assign to crew members. Whereas, the EW/EBA model correctly predicted, on average, 82% of the time, the foremen&rsquo;s decisions. A computer program was also developed for DDA heuristic model to help foremen expedite the process of their decision-making.</p>

<p>The objective of this research was to compare the condition of the asphalt and concrete sections of pavement on a section of US 35 for the West Virginia Division of Highways. In the process of completing this objective, existing procedures for pavement assessment were evaluated and an improved methodology for pavement condition evaluation, in terms of Pavement Surface Rating, PSR, was established. PSR uses observable surface distresses to quantify the condition of a pavement on a 0 to 100 scale. The PSR methodology includes surface distress data collection, a distress identification manual, and a PSR calculation procedure and spreadsheet. This process has been adopted by the WVDOH and is included in the special provision specification for pavements constructed using a warranted agreement. Data from the WVDOH Pavement Management System, PMS, were used to evaluate pavement condition but ultimately deemed ineffective in a relatively small scale analysis. The methodology used to collect and analyze the PMS data was not compatible with the PSR methodology. Deflection data gathered with a falling weight deflectometer were used to evaluate and compare the structural condition of the US 35 asphalt and concrete pavement sections. A screening of the deflection data on the concrete sections found the number of observations was an insufficient for meaningful analysis. The deflection data on the asphalt pavement sections were suitable for analysis. Since the WVDOH does not have an analysis methodology for deflection data, the research effort on this project focused on applying existing methodologies used for the analysis of deflection data. Due to the data problems, the analysis of the concrete sections was limited. The analysis of the asphalt sections was able to determine effective structural number for the asphalt sections. The analysis process is complex and several issues should be resolved to improve the ability of the WVDOH to use deflection analysis in a routine manner.

A Cast Modular Ductile Bracing System (CMDB) has been developed as an alternative to special concentrically braced frames. The CMDB system introduces cast components at the ends and center of the brace in an attempt to produce a system with reliable strength, stiffness, and deformation capacity. A cruciform cross-section has been chosen for the cast component geometry, which is specially detailed to enhance energy dissipation and increase low cycle fatigue life thereby reducing the likelihood of fracture. In this dissertation, capacity design parameters are established that describe the axial strength and flexural strength of the cast components relative to the main hollow structural section member. These parameters are varied in 2D finite element models to understand the nature of the system and identify the best performing designs. The cruciform shape of the casting is varied to produce better performance and self-centering enhancements are introduced. 3D FE models of the CMDB system and a typical special concentrically braced frame, in combination with fracture indices, are used to compare the expected low cycle fatigue life of the two systems. The dynamic performance of the system is assessed through nonlinear finite element anaylses and conclusions are drawn. The performance of the system is proved experimentally.

This report is concerned with the study of the effects of fine aggregate's surface texture on creep in asphaltic concrete mixtures. The "Time Index" method was applied to measure the degree of angularity and roughness of fine aggregates. The creep test method introduced by Shell Petroleum Company was studied and the review of literature appears to credit this method. A simple lever arm loading system was set up in a hot room with a temperature of 104 F. Variables of air void content, asphalt grade and content were studied in three different blends containing fine aggregates of low, medium and high surface texture indices. The creep test was easy to perform and during this study it showed to be a good reflectant of the influence of the effect of aggregate surface texture on plastic deformation of asphaltic concrete mixtures.

The effects of material nonlinearity and geometric instabilities of a bracing system of a dynamically loaded steel frame, as well as nonlinear soil-structure interaction are studied in this thesis. To investigate the response of a frame subjected to severe dynamic loads, a model of the force-displacement relationship of the bracing system is developed to account for the inelastic, post-buckling behavior of a brace subjected to strong compressive loads. This thesis also develops a model of the force-deformation relationship of the foundation-soil interface, confining the study only to the slide mode of failure. From these models, a softening behavior for the bracing system and a hyperbolic load-deformation behavior of the interface are proposed. It is shown that the structural response of a frame is significantly affected when the analysis includes both the effects of softening of the bracing system and soil-structure interaction.

This research focused on the color destruction of red dye-79 in aqueous solution. Red dye-79 is a typical pollutant in the textile industrial wastewater streams. A 50 parts per million (ppm) aqueous solution of this dye was used for all experiments. Although, there are many conventional techniques for the treatment, the research investigated a new methodology, which uses the synthetic ultraviolet radiation (254 nanometers) in combination with an undoped semi-conductor powder titanium dioxide (TiO₂) anatase for the photo-catalytic destruction of inorganics and organic moieties responsible for color in aqueous solution of red dye-79. Also, investigated were the effects of the oxidant hydrogen peroxide (H₂O₂) added externally to enhance the reaction kinetics for color destruction. Ultraviolet absorbance readings at 512 nanometers were employed to quantify the color destruction. The effects of reaction parameters catalyst (TiO₂), oxidant (H₂O₂), alkalinity and, dye concentrations as well as pH, on dye destruction kinetics were also quantified.

A model for the transformation of methane or vinyl chloride by methanotrophic bacteria in unsaturated sand columns was proposed. The model was based on Michaelis-Menten kinetics. The columns were successful in transforming methane and vinyl chloride at a remarkably high rate. Vinyl chloride was transformed only in the obligate presence of methane, as the two are in competition for the enzyme responsible for transformation. The model was highly sensitive to estimated methanotrophic biomass concentration. Water content was not inhibitory between 0.04 and 0.39 volumetric water content. Interphase mass transport limitation was not apparent at influent methane concentrations >> Km .

The combination of aqueous ozone, suspended titanium dioxide, and ultraviolet light with predominant wavelength of 254 nm was tested against other pairs of these three variables to determine if more radical species were produced. The addition of suspended and illuminated titanium dioxide did not affect the total or instantaneous transfer at the 95 percent confidence level measured in this research. Radical generation was suggested by the increased dissolved ozone decomposition with increased semiconductor concentration at pH 7.2 and the increase in ozone decomposition rate upon addition of 3.0 g/l TiO₂ to water pH 3.1. The presence of hydrogen peroxide in the suspensions may have assisted in the production of radicals by reacting with the semiconductor. The increased decomposition of glucose with 3.0 g/l TiO₂ also provided evidence that O₃/UV/TiO₂ led to the generation of more radical species.

This study investigates the feasibility of high-strength composite materials for strengthening of seismically deficient concrete columns. The concrete columns will be externally confined by wrapping thin straps of glass-fiber-reinforced or carbon-fiber-reinforced straps around the column. The confinement provided by the straps will increase the stress and strain of concrete at failure and will increase its ductility. Moreover, the composite strap will prevent spalling of the shell and will further increase the load carrying capacity of the column. Analytical models are developed for the analysis of circular and rectangular columns externally confined with high-strength composite straps. A parametric study is conducted to investigate the effectiveness of this technique for strengthening of concrete columns designed before the new seismic design provisions and codes were in place. The results indicate that external confinement provided by the composite straps significantly increases the strength and ductility of concrete columns.

Fractal dimensions of aggregates formed under natural and engineered fluid environments were investigated. Latex microsphere aggregates were generated under two separate hydrodynamic environments. Fractal dimensions were determined using power law relationships and relationships with slopes of aggregate size distributions. Aggregate properties were measured with a particle counter and an image analysis system. Aggregates generated in a paddle mixer and a rolling cylinder had D3 fractal dimensions of 1.92 ± 0.04 and 1.59 ± 0.16, respectively, indicating rolling cylinder aggregates are more fractal than paddle mixer aggregates. Fractal dimensions of marine snow aggregates were determined from image analysis of in-situ aggregate photographs at two different research facilities. Fractal dimensions from the two facilities were equal, indicating this analysis technique is independent of equipment and analyst. Fractal dimensions were determined for sloughed biofilm aggregates in trickling filter effluent aged under four different fluid environments. D1 and D2 fractal dimensions were 1.29 ± 0.03 and 1.71 ± 0.04, respectively, and remained unchanged.