Master of Science / Department of Architectural Engineering and Construction Science / Sutton F. Stephens / Cold-formed steel has become a preferred building material for structural farming in many different types of structures, commonly for repetitive members such as floor joists, roof rafters, roof trusses and wall studs. For wood framed structures with repetitive members, a repetitive member factor increases the allowable bending stress from 1.00 to 1.50 times the reference design value, depending on both the type of material and the type of load. Currently, however, the bending strength of cold-formed steel repetitive members is not permitted to be increased, even though the method of framing is quite similar to that of wood except for the material properties. Typical light-frame wood construction consists of floor, roof, and wall systems, each with repetitive members connected by sheathing. A repetitive system is one of at least three members that are spaced not farther apart than 24-inches. These members must also be joined by a load distributing element adequate to support the design load. The behavior of the individual members, then, is affected by inclusion into this system. Additionally, the connected sheathing increases the bending capacity of bending members due to both composite action and load sharing. Composite action is a result of T-beam-like action between the repetitive member and connected sheathing, but is limited by nail slippage in the connection. Secondly, due to differential deflection between the members, sheathing is also able to distribute loads from weaker, more flexible members to the more rigid and stronger members. This effect is known as load-sharing. The same general principles of repetitive use should apply to cold-formed steel due to its similarity to wood construction. Accordingly, this paper conducts a preliminary study of the effects of both composite action and load-sharing in cold-formed steel assemblies and subsequently recommends using a repetitive member factor for cold-formed steel members.

Master of Science / Department of Civil Engineering / Eugene R. Russell / Pedestrian signals, particularly at signalized, mid-block crossing can cause delay to drivers after pedestrians’ have successfully crossed, which is termed “unnecessary delay” in this study. In many cases at a mid-block signal, a pedestrian pushes the button and then quickly crosses the street as soon as the walk signal appears and drivers still face several seconds of solid red ball and by law must remain stopped. On a busy street, a queue of vehicles waiting after all pedestrians have crossed can amount to hundreds of hours of unnecessary delay per year. The ‘Pedestrian Hybrid Beacon’ (Initially named a HAWK (High Intensity Activated Crosswalk)) Beacon was proven to be effective in decreasing this unnecessary delay when compared to standard signalized mid-blocks. The City of Lawrence, Kansas was interested in experimenting (as a HAWK beacon was considered experimental when they were installed) with a pedestrian hybrid beacon and they installed their first pedestrian hybrid beacon at a mid-block crossing on 11th street and a second pedestrian hybrid beacon at mid-block crossing on New Hampshire street, Lawrence, Kansas, which were the sites of interest for this research. A study was conducted at these sites to determine the effectiveness of the pedestrian hybrid beacon in decreasing the unnecessary delay to drivers by comparing it to a signalized mid-block crossing on Massachusetts Ave in Lawrence, Kansas. Apart from the delay measurements for these two sites, other parameters such as driver compliance rate to the signal, pedestrian compliance rate, and other driver and pedestrian characteristics were also studied. Video cameras were used to capture video at these sites and the effectiveness of the pedestrian hybrid beacon was analyzed from the video. The HAWK, now in the MUTCD as a Pedestrian Hybrid Beacon, proved to be effective in decreasing the unnecessary delay for drivers in this study. The City of Lawrence had a total of six pedestrian hybrid beacons in operation as per the information received in March 2010.

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.

The Distinct Element Method (DEM) and Discontinuous Deformation Analysis (DDA) are the two most commonly used discrete element methods in rock mechanics. Discrete element approaches are computationally expensive as they involve the interaction of multiple discrete bodies with continuously changing contacts. Therefore, it is very important to ensure that the method selected for the analysis is computationally efficient. In this research, a general assessment of DDA and DEM is performed from a computational efficiency perspective, and relevant enhancements to DDA are developed. The computational speed of DDA is observed to be considerably slower than DEM. In order to identify reasons affecting the computational efficiency of DDA, fundamental aspects of DDA and DEM are compared which suggests that they mainly differ in the contact mechanics, and the time integration scheme used. An in-depth evaluation of these aspects revealed that the openclose iterative procedure used in DDA which exhibits highly nonlinear behavior is one of the main reasons causing DDA to slow down. In order to improve the computational efficiency of DDA, an alternative approach based on a more realistic rock joint behavior is developed in this research. In this approach, contacts are assumed to be deformable, i.e., interpenetrations of the blocks in contact are permitted. This eliminated the computationally expensive open-close iterative procedure adopted in DDA-Shi and enhanced its speed up to four times. In order to consider deformability of the blocks in DDA, several approaches are reported. The hybrid DDA-FEM approach is one of them, although this approach captures the block deformability quite effectively, it becomes computationally expensive for large-scale problems. An alternative simplified uncoupled DDA-FEM approach is developed in this research. The main idea of this approach is to model rigid body movement and the block internal deformation separately. Efficiency and simplicity of this approach lie in keeping the DDA and the FEM algorithms separate and solving FEM equations individually for each block. Based on a number of numerical examples presented in this dissertation, it is concluded that from a computational efficiency standpoint, the implicit solution scheme may not be appropriate for discrete element modelling. Although for quasi-static problems where inertia effects are insignificant, implicit schemes have been successfully used for linear analyses, they do not prove to be advantageous for contact-type problems even in quasi-static mode due to the highly nonlinear behavior of contacts.

Since 2008, more than half of the world population lives in cities. To cope with this rapid urbanization in a sustainable manner, transit systems all around the world are likely to grow. By studying 33 networks in the world, this thesis identifies the properties and effects of metro network designs by using a graph theory approach. After the literature review, a new methodology was introduced to translate networks into graphs; it notably accounts for various transit specificities (e.g., presence of lines). Metro networks were then characterised according to their State, Form, and Structure; where State relates to the development phase of metros; Form investigates the link between metros and the built environment; Structure examines the intrinsic properties of metros, by notably looking at their connectivity. Subsequently, the complexity and robustness of metros were studied; metros were found to possess scale-free and small-world features although showing atypical topologies; robustness emphasizes on the presence of alternative paths. Three network design indicators (coverage, directness and connectivity) were then related to ridership (annual boardings per capita), and positive relations were observed, which suggests that network design plays an important role in their success. Finally, these concepts were applied to the Toronto metro plans announced by the Toronto regional transportation authority, Metrolinx; it was found that the grid-pattern nature of the plans could hinder the success of the metro; seven possible improvements were suggested. Overall, the topology of metro networks can play a key role in their success. The concepts presented here can particularly be useful to transit planners; they should also be used along with conventional planning techniques. New transit projects could benefit greatly from an analysis of their network designs, which in turn may play a relevant role in the global endeavour for sustainability.

In this thesis, a load path caused by arching action in reinforced concrete slabs is described and validated using a three-dimensional model. Currently, the CHBDC enforces a 4 meter girder spacing requirement in the design of deck slabs. The aim of this thesis is to investigate the load path induced by arching action in deck slabs with a wide range of girder spacing. To do this, a two-dimensional model was developed to examine the path of horizontal stress and was validated using a FEM. A parametric study showed that girder spacing does not affect the development of restraining stress while cantilever width does. As well, cracking of the slab is necessary for arching action to occur. These results help with future development of a rational model to be used by bridge designers.

Master of Science / Department of Civil Engineering / Hani Melhem / Researchers have been compiling lists of key factors the presence or absence of which have determined the success or failure of projects. Early researches of critical success factors were largely theory based; subsequent researches employed the use of statistics and continuously refined methods like neural network and the analytical hierarchy process. Over the passage of time, the focus has narrowed down from broad generalization of ‘projects’ to ‘project classes’. The thesis can be broadly divided into three components. First Component: The first component (Chapter 1, 2, and 3) leads an insight into the basic concept of success factor studies, and the empirical frameworks adopted for identification of critical success factors. The second and the third component, comprises literature review and original research, respectively. These components pertain to success factor studies of construction projects, and are introduced as below. Second Component: The second component (Chapter 4: Review Component) sets out to choose from among a treasure of resources on construction projects, three such state of the art works that can best explain the progress in search of success factors over a period of the foregoing 25 years. After discussing each work in detail, the reader’s attention is drawn to a collective discussion, and summary towards the end of the Review Component. The review includes the following works: (1) Pinto and Covin, 1989, (2) Ashley et al., 1987, and (3) Kog and Loh, 2011. Pinto and Covin (1989) endeavored to set aside the convenient research trend of treating all project types (Manufacturing, R&D, Construction etc.) as similar. It was felt that management practitioners considered the generalized project management prescriptions offered by researchers as mostly inapplicable to the unique situations posed by their respective classes of projects. Stepwise regression analysis was employed to seek separate sets of CSFs for construction and R&D projects. The choice of these two project types was made as they apparently lied on opposite ends of the spectrum of characteristics. The phases of project lifecycle considered for determining CSFs were conceptualization, planning, execution, and termination. It was concluded that though identification of a set of general critical success factors has some benefits for both academics and practitioners, strict adherence to them would not necessarily ensure project success. It was proved that every project type offers its own set of problems, and that these vary over a project’s lifecycle. The review briefly touches upon the work of Ashley et al. (1987) so as to lead an insight into yet another methodology adopted by CSF researchers. This study views project success from the project managers’ perspective for the owner and contractor organizations they works for, and does not take into consideration the view point of other professionals working for owner, contractor and consultant organizations. Hypothesis testing was employed to find those factors that exhibited strong statistical difference while going from average to outstanding projects. Kog and Loh (2011) studied a possible dissimilarity between CSFs pertaining to different components of construction projects: (1) civil works, (2) architectural works, and (3) mechanical and electrical works. Using the Analytical Hierarchy Process the CSFs were compared separately for the objectives of budget, schedule, quality, and overall performance. They concluded that, on the whole, markedly distinct sets of factors were perceived as crucial by professionals associated with these three components. Apart from their varying job descriptions, the divergence in views of professionals was interpreted to be an outcome of the different frames of time that they mostly work in. While a major portion of civil and structural works would be undertaken in early project-life, mechanical and electrical works, and architectural works would be initiated later in the project’s life. For the three components of construction projects (C&S: civil & structural, M&E: mechanical & electrical, and architectural works), the highest correlation of views was seen to exist between the C&S and M&E, while the lowest was always that between the M&E and the architect. This trend remained the same whether the goal of overall performance or any of the three objectives were taken into consideration. Third Component: The thesis terminates with the original work (Research Component: Chapter 5) conducted by the author in the light of Chua et al. (1999) that had attempted, though very briefly, to distinguish between CSFs for different organizations involved in construction projects. Because the survey sample of Chua et al. (1999) was quite small, the researchers referred to their findings regarding organization-based CSFs as inconclusive. It was suggested that further research be conducted in this regard. Addressing these recommendations, the ‘Research Component’ has differentiated the CSFs based on organizational backgrounds of project participants: consultants, contractors, and project management organizations. Spearman’s test on overall rankings of 40 significant factors results in a highest level of correlation between the managers and contractor personnel (rs=0.54), followed by that between the managers and the consultants (rs=0.50), and a least correlation between the contractor personnel and the consultants (rs=0.19). Managers not only maintain a significant presence on the site with the contractors, but also coordinate with the consultants regarding any design-construction issues that arise more than often during project execution: No wonder why their pivotal position helps the managers to establish a higher understanding with both contractor personnel and consultants. The lowest correlation of views between the contractor personnel and the consultants arise from the spot on difference between their workspace environments. Whereas the contractor personnel operate in the field, the consultants are mostly restricted to their design offices.

Master of Science / Department of Civil Engineering / Mustaque Hossain / Because of recent rises in asphalt binder prices, state agencies and contractors are now willing to use higher volumes of reclaimed asphalt pavement (RAP). In this project, the effects of increasing RAP percentage and using fractionated RAP (FRAP) in hot-mix asphalt (HMA) mixtures have been studied. Fractionation involved processing and separating of RAP materials into at least two sizes, typically a coarse fraction and a fine fraction. This study evaluated the effects of increasing the proportions of RAP and FRAP on moisture resistance, rutting, and fatigue cracking of Superpave mixtures. Furthermore, the effect of using different sources of RAP in the mix has been investigated. HMA mixtures with five varying RAP and FRAP contents (20, 30, and 40% RAP, and 30 and 40% FRAP) were studied. The Hamburg wheel-tracking device (HWTD) test (TEX-242-F), the Kansas standard test method no. 56 (KT-56), or modified Lottman test, and the dynamic modulus test (AASHTO TP: 62-03) were used to predict moisture damage, rutting potential, and fatigue cracking resistance of the mixes. HMA specimens were made based on Superpave HMA mix design criteria for 12.5-mm (1/2-inch) nominal maximum aggregate size (NMAS) and compacted using the Superpave gyratory compactor. For the first source of RAP, results of this study showed that although mixture performance declined as the percentage of RAP increased, mixtures with even 40% RAP met minimum performance requirements. The second source of RAP, however, almost failed to meet minimum requirements even at 20% RAP. Results proved the maximum percentage of RAP allowed in the mix is highly influenced by its source. Although some improvements have been observed, especially for the second source of RAP, when RAP is compared to FRAP, FRAP does not seem to considerably affect performance of the HMA mixture.

Master of Science / Department of Civil Engineering / Robert J. Peterman / An experimental testing program was conducted at Kansas State University (KSU) to test the bond characteristics of various 5.32-mm-diameter steel wires and smaller diameter (less than 0.5 in.) strands used in prestressed concrete railroad ties. A total of 13 wires and six strands produced by seven different steel manufacturers were used during this testing. Since no wire bond pullout test currently exists, one was developed and its validity tested. This un-tensioned pullout test could serve as a quality control test similar to the standard test for strand bond (ASTM A1081) that has been developed for pretensioned strands. This strand test is currently not verified for strands less than 0.5-in. in diameter, so the procedure was also scrutinized using strands common in the concrete railroad tie industry. Some of the wires and strands contained surface indentations. It is generally accepted that indentations in the reinforcements improve the bond between the steel and concrete. To further complicate the issue, reinforcements with different surface conditions (rust, oils, lubricants) are allowed to be used in the concrete ties which further affects the bond quality of the reinforcements. However, no standardized indentation patterns (shape, size, depth of indent, etc.) or surface conditions (degree of rusting, amount of surface lubricants, etc.) are utilized by all wire and strand manufacturers. Thus, the corresponding bond behavior of these different reinforcements when placed in various concrete mixtures, in terms of average transfer lengths and typical variations, is essentially unknown. The purpose of this testing program was to develop (in the case of wires) or verify/develop (in the case of strands) a pullout testing procedure predictive of the reinforcement’s bond performance in a prestressed application. The test should be relatively inexpensive, demonstrably repeatable, and easily reproducible. Results from the un-tensioned pullout tests were compared to transfer length measurements from accompanying pretensioned concrete prisms in the lab. Additionally, pullout tests and transfer length measurements were obtained at an actual concrete railroad tie manufacturing plant. The obtained data was compared to the lab data and analyzed to further understand the relationship between un-tensioned pullout tests and pretensioned concrete members.