Civil and Environmental Engineering Commons^™

Mitigation Of Impact Vibrations Using Impedance Mismatch In Cylindrical Structures, Sachiko Sueki

UNLV Theses, Dissertations, Professional Papers, and Capstones

The focus of this work is to study the phenomenon of material impedance mismatch to determine its effect on the mitigation of high frequency accelerations in projectile and long bar structures within linear ranges of materials. In this study, the acceleration responses of structures with various materials and material combinations were studied experimentally, numerically and by the Finite Element Analysis (FEA). Air-gun tests conducted by the US Army Research Laboratory were modeled using FEA to simulate the acceleration pulse and shock waves experienced by artillery components during a launch. After the prototype of projectile was selected, further studies were conducted …

Parametric Study Of Stimulus-Response Behavior Incorporating Vehicle Heterogeneity In Car-Following Models, Saidi Siuhi

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of this study was to develop a family of car-following models that address the shortcomings of car-following models developed by General Motors (GM) in the 1950s. The developed models consist of separate models for acceleration, deceleration, and steady-state responses for congested freeway traffic conditions. The study calibrated the models using individual vehicle trajectory data collected on a segment of Interstate 101 in Los Angeles, California. Furthermore, the study validated the models using individual vehicle trajectory data collected on a segment of Interstate 80 in Emeryville, California. The study used nonlinear regression with robust standard errors to estimate the …

Analysis Of A Caliche Stiffened Pile Foundation, Richard C. Stone Jr.

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cemented carbonate deposits (known locally as "caliche") in Las Vegas have been used to support shallow and deep foundations with relatively high bearing pressures compared to soil. Most high rise structures in Las Vegas are founded on either a large mat or a long pile foundation. Recently, a new foundation type consisting of a short pile system bonded to shallow cemented layers was utilized for a large high rise building in Las Vegas and settlements during construction were recorded. The bonding of caliche layers together with short piles forms a caliche stiffened pile (CSP) foundation. The CSP foundation is unique …

Quantity-Based Cost Forecasting System For Street Construction Projects, Nipesh Pradhananga

UNLV Theses, Dissertations, Professional Papers, and Capstones

Construction projects typically are not withdrawn after going into the competitive bidding process. The decision of contracting authorities regarding which projects will proceed to the bidding stage depends, in part, upon the early estimates of probable cost. Efforts are made to make this estimate as realistic as possible. Irrespective of the estimate of probable cost, the actual project cost is established by the amount of the winning bid.

This study analyzed historical bid data of street construction projects undertaken by the Public Works Department, Clark County, Nevada, from 1991 through 2006. The focus of this study was on utilizing statistical …

Impact Of Watershed Delineation Detail On Hydrologic Process Modeling In Low Slope Areas, Jason Alexander Braud

LSU Master's Theses

Ascension Parish, located along the Mississippi River in southern Louisiana, is a low-lying, low slope landscape that primarily drains into the tidally-influenced Lake Maurepas. The predominant method of drainage within the parish is gravity drainage. Ascension Parish is currently one of the fastest growing areas in the United States. New developments have changed the area’s hydrology along with its landscape. Proper watershed delineation within the parish is critical for the management of and future improvements to the parish’s drainage infrastructure. Most of the recent drainage modeling in the parish has been performed using a light detection and ranging (LIDAR) digital …

Freeway Crash And Lane Compliance Under Truck Lane Restriction And Differential Speed Limit, Murat Korkut

LSU Master's Theses

In the last decade, several fatal truck related crashes occurred on the elevated freeway over the Atchafalaya Basin. In an attempt to reduce the crash rates, the Louisiana Department of Transportation and Development implemented two policies to regulate the truck traffic on this rural divided freeway that has two lanes in each direction of flow. These policies restricted truck traffic to the right lane and reduced the maximum truck speed limit to 55-mph. On the other hand, maximum car speed limit was kept at 60-mph. The changes took place in 2003. While the policies were in effect, crash and traffic …

Soil Moisture And Water Stage Estimation Using Precipitation Radar, Sumit Puri

UNLV Theses, Dissertations, Professional Papers, and Capstones

In south-western United States, soil moisture data is important for drought studies in the region which is experiencing a drought for many years, whereas in South Florida, water stage data is required by hydrologists to monitor the hydrological flow in wetlands. Soil moisture data and water stage data are not sufficiently available due to sparse monitoring stations. Installation of dense measuring stations over an extended area is costly and labor intensive. Therefore, there is a need to develop an alternative method of measuring soil moisture and water stage. Microwave remote sensing has proven to be a useful tool in the …

Slab-On-Girder Prestressed Concrete Bridges: Linear And Nonlinear Finite Element Analysis And Experimental Load Tests, Marcio Costa Araujo

LSU Doctoral Dissertations

“A diaphragm is a transverse stiffener, which is placed between girders in order to maintain section geometry”, (AASHTO, 2002). Intermediate diaphragms, usually placed at the midspan or third points of a bridge, are thought to contribute to the overall distribution of live loads in bridges. Cast-in-place concrete intermediate diaphragms were investigated in this study in order to assess their load distribution effectiveness in prestressed concrete I-girder bridges. Finite element packages (Ansys and GT STRUDL) were used to perform the analyses for multiple bridge configurations, including a parametric study of span length, girder spacing, and concrete strength. It was found that …

Copula-Based Multivariate Hydrologic Frequency Analysis, Hemant Chowdhary

LSU Doctoral Dissertations

Multivariate frequency distributions are being increasingly recognized for their role in hydrological design and risk management. The conventional multivariate distributions are severely limited in that all constituent marginals have to be from the same distribution family. The copula method is a newly emerging approach for deriving multivariate distributions which overcomes this limitation. Use of copula method in hydrological applications has begun only recently and ascertaining the applicability of different copulas for combinations of various hydrological variables is currently an area of active research. Since there exists a variety of copulas capable of characterizing a broad range of dependence, the selection …

Granular Activated Carbon Sorption As A Load Equalization Mechanism In Operation Of Air Pollution Control Devices, Marilou Montevirgen Nabatilan

LSU Doctoral Dissertations

Transient periods of unsteady loading pose a challenge in design and operation of bioreactors for air pollution control. As a potential means of overcoming some of these challenges, a systematic study of granular activated carbon (GAC) sorption was conducted to further evaluate its potential as a load equalization mechanism for unsteady loading of volatile organic carbons (VOCs). GAC columns were experimentally tested under dynamic loading conditions involving variations in contaminant concentrations, gas flow rates, and relative humidity. Toluene was used as model VOC, and BPL 4x6 mesh GAC was used as a model adsorbent. The research was divided into four …

The Fate And Transport Of Light Petroleum Hydrocarbons In The Lower Mississippi River Delta, Samantha Nicole Danchuk

LSU Doctoral Dissertations

Important processes governing the fate and transport of light petroleum hydrocarbons in the Lower Mississippi River and other river delta systems are not adequately represented in existing oil spill models. In response, three methods were introduced to include the effects of dynamic annual discharges and variation of shoreline type on shoreline retention and re-floatation and the potential of oil- mineral aggregate formation based contributing environmental factors. Parcel tracking was used, in conjunction with detailed shoreline types correlated to flow rate, to evaluate the benefits of using multiple shoreline re-floatation half lives correlated to shoreline type instead of a single half …

An Uncertainty-Based Approach To The Total Maximum Daily Load Development, Abhijit Patil

LSU Doctoral Dissertations

A Bayesian-updating approach is developed to the estimation of the total uncertainty-based Margin of Safety (MOS) for Total Maximum Daily Load calculations using the watershed modeling tool HSPF. In order to determine the prior, likelihood, and posterior distributions of uncertainties involved in Bayesian approach, various probability density functions are derived. The temperature measurement induced uncertainty in dissolved oxygen simulation is found to be normally distributed. The temporal scale uncertainty in weather data decreases with decreasing temporal resolution. The temporal-scale uncertainties in the rainfall and temperature data follow a Weibull and general extreme value distributions, respectively. The spatial-resolution uncertainty in simulated …

Micro Characterization Of Deformations In Granular Materials During Shear, Alsidqi Hasan

LSU Doctoral Dissertations

One of the greatest challenges in studying the engineering behavior of granular materials is the lack of tools for an unobstructed view of a large quantity of microscopic particles. This dissertation presents a thorough characterization of deformations in sheared granular materials. The investigation involves experimental programs, utilization of computed tomography (CT) techniques, and application of Distinct Element Method (DEM). The investigation was conducted at multi-scale (macroscopic, mesoscopic, and microscopic) to better understand the physical properties and constitutive behavior of granular materials during shear. The experiments include conducting a series of axisymmetric triaxial, miniature axisymmetric triaxial, and biaxial experiments. They were …

Bacterial Characterization Of Louisiana Groundwater Contaminated By Dnapl-Containing Chloroethanes And Other Solvents, Kimberly Bowman

LSU Doctoral Dissertations

In support of an effort to determine the feasibility of using an in-situ bioremediation strategy for cleanup of groundwater in an area containing chlorinated solvents present as a dense non-aqueous phase liquid (DNAPL), the bacterial population in the groundwater at a Superfund site located near Baton Rouge, Louisiana was characterized. More than 3¡Á107 cells/mL in the groundwater were observed via microscopy. Universal bacterial and ¡°Dehalococcoides¡±-specific 16S rRNA gene libraries were constructed and analyzed. Universal clones grouped into 18 operational taxonomic units (OTUs), as defined by sequence similarity ¡Ý97.0%, which included several as yet undescribed organisms. Multiple unique sequences closely related …

Nanoidentation Behavior Of Clay Minerals And Clay-Based Nonstructured Multilayers, Zhongxin Wei

LSU Doctoral Dissertations

Clay minerals, ubiquitous in the geosphere, are hydrous layered silicates or phyllosilicates that are made of nanometer-thick 2:1 or 1:1 layers. Understanding their mechanical properties of clay minerals is of vital importance to a variety of disciplines, such as geomechanics, geophysics, mineral physics, and nanocomposites. Owing to their complex crystal structure and size, however, accurate determination of their mechanical properties is a significant challenge. This dissertation presents the first research effort to study systematically the fundamental mechanical properties along the c-axis (e.g., elastic modulus, hardness) of a wide range of phyllosilicates with varying crystal structure and chemical compositions. To explore …

The Study Of Sediment Dynamics In A Shallow Estuary Using Integrated Numerical Modeling And Satellite Remote Sensing, Haihong Zhao

LSU Doctoral Dissertations

The primary objective of the study is to develop an effective tool to investigate the resuspension, deposition and transport of mixed cohesive and non-cohesive sediments in an estuary. The research has integrated 1) statistical analyses of the primary forcing, 2) numerical models for hydrodynamics, surface waves and sediment transport, and 3) the MODIS (Moderate Imaging Spectroradiometer) remotely sensed imagery, to investigate hydrodynamics and sediment dynamics in Mobile Bay, Alabama. First, based on long-term meteorological and tidal observations, statistical analyses have been conducted to predict extreme values of winds and water levels at different return periods in the estuary. Application of …

Residential Building Damage From Hurricane Storm Surge: Proposed Methodologies To Describe, Assess And Model Building Damage, Carol J. Friedland

LSU Doctoral Dissertations

Although hydrodynamic models are used extensively to quantify the physical hazard of hurricane storm surge, the connection between the physical hazard and its effects on the built environment has not been well addressed. The focus of this dissertation research is the improvement of our understanding of the interaction of hurricane storm surge with the built environment. This is accomplished through proposed methodologies to describe, assess and model residential building damage from hurricane storm surge. Current methods to describe damage from hurricane events rely on the initiating mechanism. To describe hurricane damage to residential buildings, a combined wind and flood damage …

Stability Of Articulated Revetments Against Wave Attack On Shallow Soft Soil Slopes, Edmond Joseph Russo

LSU Doctoral Dissertations

Continuously-connected, articulated revetment systems have potential to decrease the weight of armor cover in resisting wave attack, compared to traditional designs. Modes of instability for sloping revetments include uplift, sliding, and toe roll-up. Design methods are summarized by McDonnell (1998), Pilarczyk (1998), and Herbich (1999). Russo (2003) conducted a field prototype scale investigation on performance of Articulated Concrete Mattresses (ACMs) in coastal Louisiana, which demonstrated this structure’s ability to resist a range of wave loading conditions, and inspired scoping of further research to quantify structure performance beyond known limits. Present research expanded earlier works by examining fundamental physical processes of …

Anchorage And Bond Characteristics Of Externally Bonded Frp Laminates Used For Shear Strengthening Of Rc And Pc Girders, Carlos Andres Ortega Ordonez

Masters Theses

"In the last three decades, the use of fiber reinforced polymer (FRP) materials to strengthen structures externally has emerged as one of the most promising technologies in materials and structural engineering, and these materials have been gaining popularity in the civil engineering community. Externally bonded FRP sheets and laminates have been used successfully to increase flexural and shear capacity. The overall performance of the strengthened system depends heavily on the quality of the bond between the concrete and the FRP laminate. Low bond strength can cause delamination at the fiber-matrix interface and at the FRP laminate-concrete interface. As a result, …

An Evolutionary Algorithm Approach To Actuated Signal Timing Optimization Under Lane-By-Lane Detection Condition, Eric G. Strack

Masters Theses

"Motivated by the need to reduce congestion on the nation's roadway network, this research seeks to determine when a new detection scheme at actuated signalized intersections may help. This new detection scheme is called lane-by-lane detection. It "looks" at traffic in all lanes individually to determine the traffic volume on the roadway. Specifically, the problems addressed are investigating alternate signal timings and investigating the traffic volume's effect on performance of the detection scheme. For the alternate signal timings, an Evolutionary Algorithm (EA) was employed to identify the optimal signal timing. This algorithm creates signal timings and tests them in the …

Het-Cam For The Identification Of Ocular Irritancy In Seawater/Salt Water Sources, Alexander Clovis Winters

Masters Theses

"The Hens Egg Test on the Chorionallantoic Membrane (HET-CAM) is an ocular irritation test proposed to replace tradition ocular investigations such as the Draize eye test that has been criticized because of its use of animals. In this study, the ocular irritation potential of seawater and saltwater sources dosed with different disinfectants has been evaluated using the HET-CAM. The seawater and salt water tested was taken from the main show pools from three aquatic theme parks (San Diego, San Antonio, and Orlando). The three disinfectants considered were sodium hypochlorite (NaOCl), calcium hypochlorite (Ca(OCl)₂), and ozone (O₃).

Three different HET-CAM methods …

Pore-Scale Analysis Of Dnapl Dissolution And Biomass Distribution, Keegan L. Roberts

LSU Doctoral Dissertations

A comparison of equilibrium and non-equilibrium dissolution of tetrachloroethylene (PCE) was conducted to ascertain how PCE saturation, individual blob properties (volume, surface area, sphericity), and PCE occupied pores are affected by two distinct dissolution regimes. One-dimensional columns were imaged at various dissolution stages using high resolution (~10 um) synchrotron x-ray tomography (XT) and image subvolumes were analyzed using a series of grain, pore network structure, and blob analysis algorithms. An analysis of algorithm-generated data was conducted to determine grain and pore statistics, PCE saturation and individual blob properties, and correlations between PCE blobs and pore network structure. Grain and pore …

Seismic Behavior Of Circular Reinforced Concrete Bridge Columns Under Combined Loading Including Torsion, Suriya Prakash Shanmugam

Doctoral Dissertations

"Reinforced concrete (RC) columns of skewed and curved bridges with unequal spans and column heights can be subjected to combined loading including axial, flexure, shear, and torsion loads during earthquakes. The combination of axial loads, shear force, and flexural and torsional moments can result in complex failure modes of RC bridge columns. This study carried out experimental and analytical studies to investigate the seismic performance of circular RC columns under combined loading including torsion. The main variables considered here were (i) the ratio of torsion-to-bending moment (T/M), (ii) the ratio of bending moment-to-shear (M/V) or shear span (H/D), and (iii) …

Time-Weighted Average Solid-Phase Microextraction (Twa-Spme) For In-Planta Detection Of Chlorinated Solvents, Emily Moore Sheehan

Masters Theses

"Recent interest in the use of phyto-mapping for plume delineation at contaminated sites has promoted a need for new and innovative sampling techniques. Solid-phase micro-extraction (SPME) methods have been developed as a chemical analysis tool offering fast, simple, non-invasive sampling without the use of solvents. In this study SPME devices were tested for applicability for in-planta detection of chlorinated solvents. To evaluate the use of SPME for VOCs in-planta a number of integrated studies were undertaken. Uptake profiles were developed for nine chlorinated solvents in a liquid polydimethylsiloxane (PDMS) matrix with 100 µm Carboxene SPME fibers. Timeweighted average (TWA) sampling …

Comparison Of In-Planta Sampling Methods For Delineating Groundwater Contaminants, Kendra Marie Waltermire

Masters Theses

"Plants directly interact with surrounding water, air, and soil, collecting and storing chemicals and elements from the surrounding environment. Two new and innovative sampling methods have been developed in which this valuable data can be accessed to replace as well as supplement contaminated-site investigations. When determining the extent of the plume on a contaminated site, groundwater sampling may be limited due to time, site access, and expense. Using new techniques that place sampling devices in trees on site, we can sample trees naturally occurring on a contaminated site or those planted in phytoremediation or redevelopment efforts. Using these sampling devices, …