Engineering Commons^™

Development Of A Framework For The Calibration Of Rpas, A 3d Finite Element Analysis Tool For Rigid Pavements, Abbasali Taghavighalesari

Open Access Theses & Dissertations

The accurate analysis of rigid pavements requires a reliable modeling procedure based on integrating mechanistic analysis methods (i.e. closed-form solutions or numerical methods) and empirical observations (i.e. field measurements and laboratory test results). The use of the finite element method to model the response of rigid pavements has increased in recent decades due to its capability to incorporate the complexity of material behavior, traffic information, and environmental condition. Researchers from the University of Texas at El Paso developed the software Rigid Pavement Analysis System (RPAS) to comprehensively analyze the response of concrete pavements under different geometric configurations, foundation models, temperature …

Macro - And Microstructure Evaluation And Field Applications Of Concrete With Recycled Glass Pozzolan, Marija Krstic

Dissertations and Theses

Concrete is the most used material in the world, second only to water. Conventional concrete is produced with Portland cement (PC). The production of cement is an energy intensive operation that has raised significant environmental concerns, since one ton of cement generates an equal ton of CO₂. In the USA about 90 million tons of cement are used annually, with 3 million tons used in New York. Most contemporary concrete applications for buildings and infrastructure use high-performance concrete (HPC) mixtures which are produced by replacing a percentage of cement with supplementary cementitious materials (SCMs), consisting mainly of fly-ash …

Review Of Modern Nondestructive Testing Techniques For Civil Infrastructure, Shabnam Khanal

Graduate Theses, Dissertations, and Problem Reports

The repair and maintenance of aging infrastructures, in the United States alone, are estimated to have backlogs of trillions of dollars. This has posed widespread concerns about the existing and proposed infrastructures to adequately sustain the quality of life in the near future. Efficient and cost-effective approaches, such as nondestructive testing (NDT), are therefore required to better shape our future. Various NDT techniques have been developed over the past two decades with cutting-edge advances towards investigation and condition assessment of civil infrastructures. While the performance of NDT techniques has reached unparalleled heights, limitations remain. On one side, are the instrument …

Slender Frp Elements As Discrete Reinforcement For Concrete, Yuan Tian

Dissertations and Theses

This dissertation presents a study that led to the development of slender elements that look like fibers used for reinforcing concrete but with a very different reinforcing mechanism. These elements, referred to as “Needles” are very rigid and strong; when intersected by growing cracks in concrete under heavy and increasing loads, they do not break and deform minimally. In the present work major steps were taken to understand the reinforcing mechanism of Needles. In addition, to investigate the influence of Needles on the mechanical performance of concrete incorporating Needles, at both material and structural levels, a series of laboratory experiments …

Evaluation Of Tie-Bar Anchoring Methods: Non-Shrink Grout Vs. Epoxy, Wally Heyen, Lieska Halsey, Tim Krason, Brandon Varilek, David Hansen

Nebraska Department of Transportation: Research Reports

Tie bars are epoxy coated steel bars that connect the longitudinal joints in concrete pavement. Tie bars prevent faulting and joint separation between lanes Tie bars can be placed into the plastic concrete or inserted after curing by drilling and anchoring with epoxy or non-shrink grout. The specification for the tie bars requires the use of a No. 5 bar, 18 inches long and shall meet ASTM A775 / A775M [1], Section 1020.The Nebraska Department of Transportation “Standard Specifications for Highway Construction,” (Section 603.03) requires contractors to mechanically insert tie bars into the face of pavements during construction. Tie bars …

Development Of An Ndt Tool For In-Situ Assessment Of Prestress Loss, Bibo Zhong, Jinying Zhu, George Morcous

Nebraska Department of Transportation: Research Reports

The research objective is to develop a non-destructive testing (NDT) method to evaluate the prestress loss in prestressed concrete bridge girders using ultrasonic waves. The work principle is based on acoustoelastic effect - ultrasonic wave velocity varies with stress level in prestressed concrete. A self-reference test setup was proposed to measure wave velocity in two orthogonal directions (prestress and unstressed directions) in the girder. This setup will be able to reduce effects of material variation and temperature change.

The concept was first validated on small concrete specimens (cylinders and beams) in laboratory. A signal analysis algorithm was developed to reliably …

Bond Behavior Of Advanced Fiber Reinforced Composite-Concrete Joints, Xingxing Zou

Doctoral Dissertations

“Externally bonding advanced composite materials to concrete structures is an effective way to improve their strength, ductility, and durability. The interfacial bond behavior is fundamental to understand the overall structural performance of concrete structures strengthened with advanced composite materials. This study includes a comprehensive investigation of the bond behavior of composite-concrete joints with different fiber reinforced composite types. First, a direct approach to determine the bond-slip relationship for fiber reinforced cementitious matrix (FRCM)-concrete joints based on fiber strain measurements was proposed. Then, an analytical solution to predict the full-range response of FRCM-concrete joints was derived by assuming a trilinear bond-slip …