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The finite difference method and the finite element method are the most commonly used mathematical tools to numerically characterize the mechanical behavior of window glass. The finite element method is increasingly popular due to its flexibility in analyzing bodies with complex geometries and the option to solve mechanics problems without use of the governing partial differential equations. These advantages allow the analyses of various glass applications, such as point- supported glass and insulating glass units, using the same finite element routine. A two-dimensional, four-node, nonlinear quadrilateral finite element formu- lation is advanced incorporating the Von Karman assumptions into the Reissner- Mindlin plate theory to analyze monolithic and laminated glass lites undergoing large deflections due to applied lateral loads. The assumed transverse shear strain fields method is employed to mitigate shear locking, and the shear stiffness terms are fully integrated. The finite element formulation is benchmarked against ex- perimental test results for laminated glass subjected to an applied uniform load. The numerical and test results are found to be in good agreement. The finite element formulation and a modified glass failure prediction model are applied to determine the load resistance of point-supported glass. Numerical results show that the load resistance of point-supported glass vary as a function of glass lite geometry and hole location. Furthermore, the tensile stress concen- trations at the exterior surface of the lite are the primary driver controlling the load resistance of point-supported glass. The finite element formulation is further applied to analyze insulating glass units simply supported along two parallel sides and three sides subjected to applied uniform lateral loads. The spacer separating the glass lites apart is assumed to behave as an Euler beam along the unsupported edges. Numerical results show that the load sharing and mechanical behavior of partially supported insulating glass units vary as a function of spacer flexural rigidity and/or aspect ratio. As the spacer flexural rigidity is increased, the behavior of partially supported insulating glass units tends towards that of units simply supported along four sides.

The 1-day, 100-year depth-duration-frequency (DDF) for Texas is investigated by comparing historical estimates dating back to the early 1900s. For the first time ever, we define these historical estimates veracity using a variety of statistical application that ultimately demonstrates their magnitudes are not significantly different from one another, and for application purposes are inseparable. We develop a new regionalization approach for estimating 1-day, 100-year DDF at Texas county centroids with a spatial analysis process called geographically-weighted-regression. The intent of this new regionalization approach is to simplify the computational rigor that has been introduced by newer DDF regionalization methodologies while still providing reliable 1-day, 100-year DDF estimates. As a “proof of concept” the new method is applied to various statistical methods, which collectively show a reduction in error when compared to the historical estimates. Therefore, the proposed workflow has the potential of not only being more computationally efficient, but also more reliable than past methodologies. A “special topics” discussion of Hurricane Harvey’s maximum daily rainfall totals within Harris county, Texas is presented. Hurricane Harvey’s rainfall is investigated using similar approach to the newly proposed regionalization method concluding local DDF estimates for Harris County, Texas are likely to substantially increase after including Hurricane Harvey’s rainfall. The investigation of Hurricane Harvey concludes that its maximum rainfall totals exceeded 1,000-year frequencies throughout the county. Collectively, this research was conducted to demonstrate: Where we were, where we are, and where are we going with DDF analysis.

Hydraulic fracturing is a hydrocarbon reservoir stimulation technique with a wide range of application that extends from low permeability hard rocks to unconsolidated oil sands. Conventional models of hydraulic fracturing are tailored to hard rocks, and there is overwhelming evidence that the assumptions of the conventional models are not applicable in rocks that deviate from linear elastic behavior. Previous studies on the influence of inelastic rock behavior during fracturing have been limited by the type of constitutive rock model used and by how fluid and solid behavior are coupled. Here I offer a new approach to model hydraulic fracturing. It considers rate independent elastoplasticity in the most general sense. It also fully integrates viscous fluid flow with solid deformation. After validation against an existing linear elastic analytical solution, sensitivity analyses determined the extent of plasticity during hydraulic fracture propagation. A case study involving a field example shows that the proposed model agrees with the observed data. Furthermore, it shows that plasticity dramatically changes the geometry of the fracture.

This dissertation presents a predictive approach to evaluate the maintainability of a Commercial Off-the-Shelf (COTS)-based system by analyzing the complexity of the deployment of the system. The approach integrates architectural dependencies and the system’s concept of operations to derive a network-based representation of the software system. A greater understanding of the deployment complexity is gained by using a Design Structure Matrix to determine the number of architectural dependencies on a COTS product, or in-degree, for each COTS product in the system. The arithmetic mean of the in-degree for all nodes in the system can then be compared with the perceived effort to maintain the system. The resultant measure is useful in evaluating the maintainability of the operational system while the system is being designed and throughout its lifetime. Architects can use the approach to assist in COTS product selection and to make product trades to optimize the maintainability of the system. Integrators can use the approach to optimize product deployment and to determine the upgrade strategy for deployment. Finally, maintenance engineers can use the approach to estimate the effort required to maintain the system and to identify areas in which extensive product expertise is required. Because the approach requires only basic information about the system, it can be applied early in the design process and used until the system is decommissioned.

Propagation pattern of hydraulic fractures in the complicated reservoirs such as shale is not well understood yet. Analytical models are only useful for solving problems with simple geometry, and only the fracture propagation mode I can be predicted by these models. Therefore, a numerical model is needed to solve this complicated problems. A Few numerical simulators are capable of predicting non-planar propagation of hydraulic fractures. Thus, a robust fracture simulator is desirable to study the complexities. In this thesis, analytical and numerical methods are studied to analyze the geomechanical effects of a fracturing treatment on the rock system. These analyses are performed on the commonly used hydraulic fracturing models. Stress and displacement changes in the neighborhood of elliptical fractures are calculated. As the result, a 2D fully coupled numerical simulator called “TechFrac” is developed using displacement discontinuity method for studying the non-planar fracture propagation. The finite difference method is also used for solving fluid flow equations inside the fracture. The rock is considered as an elastic medium and the effect of leak off is ignored. Also, pressure distribution inside fracture is assumed to be constant in the first step, then a constant injection rate is assumed. The simulator results are verified successfully by analytical and experimental results, and several common hydraulic fracturing problems are studied. Propagation of a pressurized fracture, propagation of clusters, overlapping zone of two propagation fracture and Modified Zipper Frac are among this fracturing problems under the study in this work. The injected fluid is assumed to be Newtonian and maximum hoop stress criterion is used for predicting the direction and mode of the fracture propagation. The results of the fluid solver and geomechanical solver are coupled together in order to make the simulator more accurate. Major parameters that affect hydraulic fracturing behavior are studied. Mode I and II stress intensity factors calculated with error of less than 5%. Also, mixed mode fracture propagation path based on maximum hoop stress criterion is calculated. The result showed that any increase in the far field stress anisotropy or decrease in the pressure inside fracture results in faster fracture reorientation into maximum horizontal stress direction. It was observed that stress shadowing between two propagating fracture affect their propagation path. An optimization is required to achieve the desirable geometry. In the Modified Zipper Crack, desirable result may not be obtained if non-symmetric case happens. Also, the effect of injection rate and viscosity on the propagation path of the hydraulic fractures were investigated. It has been observed that higher injection rate or higher fluid viscosity will yield a larger reorientation radius into the direction of maximum horizontal stress. Moreover, the result of pressure distribution inside the fracture showed that the constant pressure assumption should not be used for study of proppant transform and leakoff. However, it gives similar results to those in constant injection assumption for propagation path, displacement and stress calculations.

Corrosion of the steel compression members used as bridge piles reduces the axial load carrying capacity significantly. To combat this, the Texas Department of Transportation (TxDOT) initiated a research project to develop cost-effective, yet reliable methods to repair/strengthen the corrosion-damaged bridge steel piles. This study was performed as part of the TxDOT project with focus on the development of finite element (FE) models that can be used to predict the behavior of un-damaged, damaged, and repaired steel piles. Many potential repair methods were proposed in the TxDOT project. Among them, this study focused on a method which uses a fiber reinforced polymer (FRP) jacket to surround the damaged area and is then grouted into place. A series of FE models were created to duplicate existing laboratory test specimens. The analysis results of the FE models were then compared to the experimental results to evaluate the performance of the developed FE models. The performance evaluation showed that the FE models could predict the failure loads with the error ranging from 1% to 27%. Based on the knowledge built on the performance evaluation of the developed FE models, a series of FE models were developed and analyzed to make recommendations to the design of laboratory test specimens (60 in.-long W4X14 sections) of the on-going TxDOT project, which include the location and size of corrosion damage, and the strengthening details such as the number of FRP layers and size of the FRP jackets. The FE models developed in this study assumed that there is the 'perfect bond' between the steel members and grout. Although the FE models have shown good agreement with the experimental results, it is recommended using a shear stress - slip model to simulate the steel-grout interface behavior to further improve the accuracy of the developed FE models.

Bond length is one of factors which are important with regards to the effective technique of improving the shear capacity of a concrete member by externally bonding fiber reinforcement polymer laminates. A number of models have been proposed by various researchers over the years but there is not a single model that can definitely predict the effective bond length (effective bond length). The models proposed show a disparity between the analytical and experimental values. This study takes a holistic approach to rationalize all the influencing factors. FEA is done of the existing experimental test results by calibrating for measured failure load and effective bond length values. A sensitivity study is undertaken to understand the influence of the affecting parameters on shear stress and effective bond length.

In a market economy, prices are derived from supply and demand. However, in the market economy for cotton which varies in its quality attributes, implicit or hedonic prices can and are determined for each of its quality attributes. These implicit prices contain a relationship with the quality attributes that are theoretically and qualitatively recognized by the industry. This study conceptually derives a general pr1cequality relationship for cotton from the supply and demand sides of the market. It also theoretically evaluates this price-quality relationship for each and all recognized characteristics of cotton. These pricequality relationships were then analytically tested and determined through two functional form models for the Texas and Oklahoma markets. The findings of this study determined the optimal or "best" statistically determined functional form hedonic model structures for daily cotton market price reporting. The two structures were found to estimate prices, premiums, and discounts for the grading systems used before August 1, 1993, in which the grade code consisted of trash and color, and after August 1, 1993, in which the grade code will represent only color; trash and its sub-categories of bark and grass will be separately identified. The post-1993/94 model was found to contain no residual bias across attribute levels for all attributes and determined to be the "best" functional form to represent the price structures for the upcoming grading system.

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