Engineering Commons^™

Condition Factor Calibration For Load And Resistance Factor Rating Of Steel Girder Bridges, Pranav M. Shakya

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The Load and Resistance Factor Rating (LRFR) is a reliability-based rating procedure complementary to the Load and Resistance Factor Design (LRFD). The intent of LRFR is to provide consistent reliability for all bridges regardless of in-situ condition. The primary difference between design and rating is the uncertain severity and location of deterioration, including the potential future loss of strength for an element already evidencing deterioration. Ostensibly, these uncertainties are accounted for by applying an additional strength reduction factor: the condition factor, ϕ_c. Currently, condition factors are nominally correlated to the condition of the member, which can be Good, …

Cfd Study Of Decay Function Of Wall Shear Stress With Scour Around Complex-Shape Bridge Pier, Chen Li

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Pier scour problem is close related to the safety of bridges. The Federal Highway Administration of the United State also has a great interest in studying the relation between hydraulic loadings and scour depth. The current technological problem of directly measuring hydraulic loadings on a dynamic bed using physical experiments and the weak capacity to simulate the real scour processes with CFD methods inspired the development of a hybrid approach by combining them to study pier scour.

This research specifically focuses on the CFD part of the hybrid method. A series of three-dimensional (3-D) CFD models were developed with unsteady …

An Investigation Of Motor Vehicle Driver Inattention And Its Effects At Highway-Rail Grade Crossings, Shanshan Zhao

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The relationship between accident injury severity and drivers’ inattentive behavior requires an in-depth investigation – this is especially needed in the case of motor vehicle drivers at highway-rail grade crossings (HRGCs). The relationship between drivers’ personality/ socioeconomic characteristics and inattentive behavior at HRGCs is another topic requiring research. Past educational programs about safe driving at HRGCs have often not been designed to target people who may be in urgent need of such information, which may limit the effectiveness of those programs.

This dissertation thus focuses on the following four objectives: to investigate the association between motor vehicle inattentive driving and …

Development Of A Transition Between An Energy-Absorbing Concrete Barrier And A Rigid Concrete Buttress, Tyler Schmidt

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress.

The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed …

Water And Energy Use Of Antimicrobial Interventions In A Mid-Size Beef Packing Plant, Rami M. M. Ziara, Shaobin Li, Bruce I. Dvorak, Jeyamkondan Subbiah

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Data regarding the water and energy usage of current antimicrobial interventions in beef packing plants is scarce. The objective of this study was to collect representative water and energy usage data in a beef packing plant, with emphasis on antimicrobial interventions, to provide baseline data for comparison of new intervention technologies developed by researchers. Permanent and portable water flow meters were installed on the plant’s plumbing system to collect water flow data from March 2014 to March 2015. A local utility company was hired to meter electricity at the different subsystems using portable data loggers. The natural gas used in …

Microbial Degradation Of Sulfonamide Antibiotics, Rachel Levine

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Certain microbes can transform antibiotics in the environment. However, little is known about the identity of these microbes and their antibiotic biotransformation processes. The objectives of this study were to (1) isolate bacterial strains capable of transforming antibiotics, (2) determine the biotransformation kinetics of antibiotics, (3) characterize the effects of background carbons on the biotransformation kinetics, and (4) identify biotransformation products under various environmental conditions. Sulfadiazine (SDZ) was used as the model antibiotic in this study due to its frequent occurrence in livestock wastes. Surface soil from a cattle feedlot was collected to enrich potential SDZ degrading bacteria. A mixed …

The Influence Of Sediment Characteristics On The Fate Of Steroidogenic Compounds In Aquatic Systems And The Effects On Progesterone Bioavailability In A Target Organism, Jodi L. Sangster

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

There is growing concern about the biologic effects stemming from steroids in impacted waterways. In aquatic systems, interaction between steroids and sediment influence both contaminant fate as well as subsequent bioavailability to aquatic organisms. The focus of this dissertation research was to gain a better understanding of steroid behavior in aquatic systems based on the physiochemical properties of sediment and to use this knowledge to better understand the biological effects stemming from sediment-associated progesterone exposure. Two natural aquatic sediments, a sand and a silty loam, were selected to represent marked differences in sediments properties. Initially, sorption of 17β-estradiol, estrone, progesterone, …

Volume-Change Restraining Effects In Continuous Precast/Prestressed Bridge Girders, Athul Alex

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

A variety of design and construction practices are feasible when building precast concrete continuous bridges with long spans. Precast, prestressed concrete continuous bridges have been implemented by countries around the world. Although these bridges have been in service for many years, there has been limited verification of the ability of connection to provide the predicted continuity. Subsequently many states in the United States design the girders as simple spans for both dead and live loads without considering any moments developed by the connection. The effect of thermal expansion and contraction is hardly considered in the analysis, even though it is …

Performance Assessment Of Deteriorated And Retrofitted Steel Hp Piles, Steven T. Stauffer

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Deterioration of aging bridges can be attributed to an assortment of mechanisms throughout the structure, with remediation policies also varying. This study focused on assessing the validity of the Nebraska Department of Roads’ (NDOR) reinforced concrete encasement retrofit for corroded steel HP piles. Experiments were designed and conducted to test the capacity of the NDOR retrofit and evaluate failure limit states. Two pile locations were considered: abutment and pile bent. For each location there was a non-deteriorated, deteriorated, and retrofitted case. These cases represented the pile at key stages during its life. NDOR’s concrete encasement retrofit provided the required stability …

Improved Methodologies In Modeling And Predicting Failure In Aashto M-180 Guardrail Steel Using Finite Element Analysis - Phase I, Brandt M. Humphrey

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Steel guardrail systems have historic and widespread applications throughout the nation’s highways and roadways. However, catastrophic system failure can occur if the guardrail element ruptures, thus allowing an errant vehicle to pass uncontrolled through the system and potentially allow fractured ends to pierce the occupant compartment. To aid in the analysis and design of guardrail systems, further efforts are needed to develop and implement more reliable material failure criteria to predict and model guardrail steel rupture under all vehicle impact loading scenarios within impact simulation finite element method (FEM) software, such as LS-DYNA.

This Phase I study accomplished a number …

Optimizing Chemical & Rheological Properties Of Rejuvenated Bitumen, Dominic Nguyen, Hamzeh Haghshenas Fatmehsari, Santosh Kommidi, Yong-Rak Kim

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Bitumen has long been a material used in the construction of roadways, yet new pavement only consists of low fractions of recycled materials due to poor compatibility of aged bitumen and new materials. Thus, rejuvenators, chemical additives, have been used in an attempt to re-balance the chemical composition and restore the physical properties of aged bitumen back to its virgin state. A fundamental understanding of how one particular rejuvenator, soybean oil, revitalizes bitumen was investigated using a multi-scale approach.

Fourier-transform infrared spectroscopy (FTIR) was used to determine the changes in chemical properties of pure and rejuvenated virgin and aged samples. …

Multiscale Research Toward Resilient Civil Infrastructure, Hamzeh Haghshenas Fatmehsari, Keyvan Zare Rami, Mahdieh Khedmati, Kommidi Santosh, Farshad Fallah, Yong-Rak Kim

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Infrastructure materials are generally composite in nature and consist of different phases. Despite their widespread use, the mechanisms behind their behavior are often not fully understood. The aim of this research is to develop the capability to predict the performance of infrastructure based on its components, thus eliminating the need for costly experimental tests. Such an objective requires thorough understanding of material properties at various length-scales and investigation of the linkage between each scale. This approach can lead to more optimized designs, sustainable performance and maximized public benefit