Civil Engineering Commons^™

Surface Hydrologic Modeling And Analyzing Watershed Hydrologic Response To Landcover Change, Roshan Poudel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Urban flooding is the most frequently occurring disaster in rapidly urbanizing cities. Rapid urbanization in general, is characterized by an increase in the total impervious surface area, which means less soil cover for the stormwater to infiltrate and a greater volume of runoff from the area in case of a storm event. This increased volume of surface runoff, if not drained, results in urban flooding. Urban flooding can cause serious economic and environmental damages by disrupting transportation and spreading pollution. It is therefore, essential to understand the cause, behavior and effects of urban flooding so as to minimize the risks …

Cost Comparison Of Cement Concrete And Polymer Concrete Manholes In Sewer Systems, Sayan Sakhakarmi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cement concrete manholes are generally used in sewer networks in the United States. However, these concrete manholes are highly vulnerable to chemical corrosion and require frequent maintenance and replacement. Polymer concrete manholes as a substitute to the cement concrete manholes in water and wastewater pipelines have proved to have longer service life and more resistance to various chemical corrosions than normal concrete manholes. Despite the benefits that polymer concrete manholes offer, the higher initial installation cost has been a barrier to its wide application in public works. This study has been conducted to compare the cost of cement concrete manholes …

An Investigation Of Employment And Wage Distribution In The Construction Industry By Race/Ethnicity And Gender, Binit Kumar Shrestha

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the largest job providers in the U.S, is the construction industry, an industry that suffers from critical problems pertaining to a labor shortage. Yet the industry also struggles with insufficient interest and inconsistent participation from underrepresented demographic groups. To address the issue of workforce income inequality and bias, the industry must better understand the current situation regarding inequality; it needs to pinpoint some basic problems. To do so, analysts must scrutinize the following aspects: 1) the current differences within the construction workforce by race/ethnicity and gender with regards to the total employment and 2) the current disparity within …

Remote Sensing Of The Environmental Impacts Of Utility-Scale Solar Energy Plants, Mohammad Masih Edalat

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solar energy has many environmental benefits compared with fossil fuels but solar farming can have environmental impacts especially during construction and development. Thus, in order to enhance environmental sustainability, it is imperative to understand the environmental impacts of utility-scale solar energy (USSE) plants. During recent decades, remote sensing techniques and geographic information systems have become standard techniques in environmental applications. In this study, the environmental impacts of USSE plants are investigated by analyzing changes to land surface characteristics using remote sensing. The surface characteristics studied include land cover, land surface temperature, and hydrological response whereas changes are mapped by comparing …

Evaluation Of The Properties Of Rubberized Asphalt Binders And Mixtures, Kazem Jadidirendi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rubber modified binder samples are tested and evaluated based on SHRP requirements. Best rubber content is suggested for modifying binder. Rubber modified asphalt mixtures were manufactured and tested. Based on Hveem stability and volumetric properties of asphalt mixtures, optimum binder content is evaluated and reported. Performance properties of asphalt mixtures made with various rubber size and method were analyzed and compared. An ultrasound measurement performed on asphalt mixture samples and the results were analyzed. It is discovered that rubber improves asphalt viscosity and resistance to rutting deformation. Rubber also increases asphalt’s dynamic modulus.

Re-Evaluation Of Acceptance Testing Criteria For Structural Masonry Using The Prism Test Method, James Bristow

UNLV Theses, Dissertations, Professional Papers, and Capstones

The current acceptance criteria for structural masonry in accordance with International Building Code allows for the prism test method to be used. However, without a proper understanding of the effects of variable material properties such as individual masonry unit compressive strength and the various material moduli of elasticity, as well as the effect of field conditions on the unit’s performance, masonry prisms may “fail” to reach the design compressive strength (f’m).

By identifying causes of failure and evaluating the failure magnitude, it is concluded that when the masonry prism test method is utilized for acceptance testing of as-built masonry structures, …

Generalized Clusterwise Regression For Simultaneous Estimation Of Optimal Pavement Clusters And Performance Models, Mukesh Khadka

UNLV Theses, Dissertations, Professional Papers, and Capstones

The existing state-of-the-art approach of Clusterwise Regression (CR) to estimate pavement performance models (PPMs) pre-specifies explanatory variables without testing their significance; as an input, this approach requires the number of clusters for a given data set. Time-consuming ‘trial and error’ methods are required to determine the optimal number of clusters. A common objective function is the minimization of the total sum of squared errors (SSE). Given that SSE decreases monotonically as a function of the number of clusters, the optimal number of clusters with minimum SSE always is the total number of data points. Hence, the minimization of SSE is …

Calibration Of Microscopic Traffic Flow Models Enabling Simultaneous Selection Of Specific Links And Parameters, Kul Prasad Shrestha

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study proposes a methodology for the calibration of microscopic traffic flow simulation models by enabling simultaneous selection of traffic links and associated parameters. That is, any number and combination of links and model parameters can be selected for calibration. Most calibration approaches consider the entire network without enabling a specific selection of location and associated parameters. In practice, only a subset of links and parameters are used for calibration based on a number of factors such as expert local knowledge of the system. In this study, the calibration problem for the simultaneous selection of links and parameters was formulated …

Dynamic Risk Analysis Of Construction Delays Using Fuzzy-Failure Mode Effects Analysis, Mohammadsoroush Tafazzoli

UNLV Theses, Dissertations, Professional Papers, and Capstones

Considering the tremendous losses in the worldwide economy caused by construction delays, it is essential to invest in minimizing the risks of delays. In order to make this happen, two measures should be taken:

1) The roots and fundamental causes of delay should be identified and strategies to mitigate their risks be developed (General remedy).

2) The most significant potential causes of delay in each project should be identified and these causes should be given priority to control (Project-Specific Remedy).

The current research invests in both of the measures. To provide the general remedy, causes of delay in the construction …

High Early-Age Strength Concrete For Rapid Repair, Matthew O. Maler

UNLV Theses, Dissertations, Professional Papers, and Capstones

The aim of this research was to identify High Early-Age Strength (HES) concrete batch designs, and evaluate their suitability for use in the rapid repair of highways and bridge decks. To this end, two criteria needed to be met; a minimum compressive strength of 20.68 MPa (3000 psi) in no later than 12 hours, and a drying shrinkage of less than 0.06 % at 28 days after curing. The evaluations included both air-entrained, and non-air-entrained concretes.

The cement types chosen for this study included Type III and Type V Portland cement and “Rapid Set” − a Calcium Sulfoaluminate (CSA) cement. …

Sulfate Resistance Of Nanosilica Contained Portland Cement Mortars, Iani Batilov Batilov

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soils, sea water and ground water high in sulfates are commonly encountered hostile environments that can attack the structure of concrete via chemical and physical mechanisms which can lead to costly repairs or replacement. Sulfate attack is a slow acting deteriorative phenomenon that can result in cracking, spalling, expansion, increased permeability, paste-to-aggregate bond loss, paste softening, strength loss, and ultimately, progressive failure of concrete. In the presented research study, Portland cement (PC) mortars containing 1.5% to 6.0% nanosilica (nS) cement replacement by weight were tested for sulfate resistance through full submersion in sodium sulfate to simulate external sulfate attack. Mortars …

Causes And Impacts Of Geotechnical Problems On Bridge And Road Construction Projects, Krishna Prasad Neupane

UNLV Theses, Dissertations, Professional Papers, and Capstones

Changes during the construction phase generate cost growth, schedule delays, and claims in any project. However, the impact of geotechnical problems on construction costs, schedules, and claims in bridge and road projects had not been investigated in depth. The major objectives of this study were to determine the geotechnical-related causes of cost and schedule growth and claims as well as their impacts on the bridge and pavement projects’ performance. This study also identifies mitigation measures to avoid cost and schedule growth and claims in these projects.

A survey was conducted with 53 engineers from state Department of Transportations (DOTs) and …

Occurrence And Proliferation Of Antibiotics And Antibiotic Resistance In Wastewater Treatment Plants, Majid Neyestani

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solids retention time (SRT) is one of the most important factors in designing and operating activated sludge systems for biological wastewater treatment. Longer SRTs have been shown to alter the structure and function of microbial communities, thereby leading to improved treatment efficacy with respect to bulk and trace organics, nutrient removal, and membrane fouling. However, research has also shown that longer SRTs lead to increased prevalence of antibiotic resistant bacteria, perhaps due to increased exposure to antibiotics present in influent wastewater. The purpose of this study was to characterize changes in microbial community structure in a laboratory-scale activated sludge system …

Analyses Of Streamflow Change Patterns And Correlation Of These Changes With Sea-Surface Temperature Fluctuations, Kazi Ali Tamaddun

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents a comprehensive statistical analysis that determines the direction, rate, and interval of significant streamflow change patterns in the continental U.S. and correlates these changes with sea-surface temperature fluctuations. First, by using two non-parametric tests, namely, the Mann-Kendall trend test and the Pettitt’s test, the presence of long-term trends and abrupt shifts were determined at 10% significance level over continuously adjustable periods that stretched from 1903 to 2012. Modified versions of the tests were applied to account for the presence of persistence (autocorrelation) in data. Theil-Sen slope was determined to evaluate the rate of change across multiple temporal …

A Business Intelligence Framework For Network-Level Traffic Safety Analyses, Naveen Kumar Veeramisti

UNLV Theses, Dissertations, Professional Papers, and Capstones

Currently, there are both methodological and practical barriers that together preclude a substantial use of theoretically sound approaches, such as the ones recommended by the Highway Safety Manual (HSM), for traffic safety management. Although the state-of-the-art provides theoretically sound approaches such as the Empirical Bayes method, there are still various important capabilities missing. Methodological barriers include among others (i) lack of a theoretically sound approach for corridor-level network screening, (ii) lack of a comprehensive approach for estimation of Safety Performance Functions based on a simultaneous consideration of both crash patterns and associated explanatory variables, and (iii) lack of theoretically sound …

Alkali-Activated Natural Pozzolan/Slag Binder For Sustainable Concrete, Meysam Najimi

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study aimed to fully replace Portland cement (PC) with environmentally friendly binders capable of improving longevity of concrete. The new binders consisted of different proportions of natural Pozzolan and slag which were alkaline-activated with various combinations of sodium hydroxide and sodium silicate. A step-by-step research program was designed to (1) develop alkali-activated natural Pozzolan/slag pastes with adequate fresh and strength properties, (2) produce alkali-activated natural Pozzolan/slag mortars to assess the effects of dominant variables on their plastic and hardened properties, and (3) finally produce and assess fresh, mechanical, dimensional, transport and durability properties of alkali-activated natural Pozzolan/slag concretes. The …

Seismic Response Of An Older Bridge In Nevada Under Maximum Considered Earthquake, Ryan Thomas Isaac

UNLV Theses, Dissertations, Professional Papers, and Capstones

Given the aging infrastructure in the United States, a study was conducted on an older bridge in Nevada to determine its performance under the maximum considered earthquake. A suite of eight synthetic site-specific ground motions, including a spectrum-matched “RSP” record, were applied along both the longitudinal and transverse axes of Bridge G-953 in Las Vegas, Nevada. The supplementary materials contain the original drawings of Bridge G-953 for reference, including changes to the expansion joints and the addition of cable restrainers at the in-span hinges. A detailed model, including the effects of column nonlinearity, material degradation such as shear keys, abutment …

Effects Of Vertical Ground Motion On Seismic Performance Of Reinforced Concrete Flat-Plate Buildings, Sara Jean George

UNLV Theses, Dissertations, Professional Papers, and Capstones

Reinforced concrete flat plate is a type of structural system widely used for office and residential buildings in many areas including those with high seismic risk. In the regions of high seismicity, moment frames or shear walls are employed to resist lateral loading while the flat-plate system is designed to primarily resist gravity loading. Flat-plate structures must maintain lateral deformation capacity as well as resist gravity loading under seismic loads. The deformation capacity of a slab-column connection is a function of vertical shear transferred from slab to column. The effects of vertical loading become even more exaggerated when the flat-plate …

Solar Energy Storage In Molten Salt Shell Structures, Nathan David Tyrrell Loyd

UNLV Theses, Dissertations, Professional Papers, and Capstones

Molten salts (MS) in the 580°C range could be used to store excess energy from solar power stations and possibly from nuclear or coal. The energy can be stored up to a week in large containers at elevated temperature to generate eight hours of electricity to be used at night or during peak demand hours. This helps to reduce the fluctuation experienced at thermal solar power stations due to weather conditions. Our research supported by Office of Naval Research (ONR), presents a survey of salts to be used in molten salt technology and the design of large steel and hybrid …

Laboratory Evaluation Of Geogrid-Reinforced Flexible Pavements, Mohammadreza Sharbaf

UNLV Theses, Dissertations, Professional Papers, and Capstones

An experimental laboratory program to assess the effectiveness of biaxial and triaxial geogrid-reinforced flexible pavements to reduce roadway section was carried out. Six laboratory tests were conducted using a steel cylindrical mold with dimensions of 1.8 m (6 ft) in diameter and 2.1 m (7 ft) in height. The studied reinforced and unreinforced (without geogrid) sections consisted of a locally-obtained subgrade with a minimum thickness of 1.5 m (5 ft) and an asphaltic surface course of 7.6 cm (3 in). The base thickness of three tests was 30.5 cm (12 in) while for the other three tests used base thickness …

Perchlorate Bioremediation: Controlling Media Loss In Ex-Situ Fluidized Bed Reactors And In-Situ Biological Reduction By Slow-Release Electron Donor, Sichu Shrestha

UNLV Theses, Dissertations, Professional Papers, and Capstones

The main concern of perchlorate exposure through drinking water is its effects on the production of thyroid hormone, which is important for human metabolism and child’s brain development. The US Environmental Protection Agency (EPA) has listed perchlorate in the contaminant list as well as in the Unregulated Contaminant Monitoring rule.

The extent of perchlorate contamination can be categorized by the level of contamination into parts per million (ppm) levels, typically in locations where perchlorate was manufactured, and parts per billion (ppb) levels where perchlorate was used for various purposes. Ion-exchange is generally adopted for treating ppb levels of perchlorate while …

Framework Of Performance-Based Contracting For Chip Seal And Striping Maintenance Activities, Kishor Shrestha

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the United States, there are more than four million miles of road network and new roads are being constructed every year. Most of the road networks were constructed more than two decades ago. Therefore, the age of the majority of the pavement inventory has exceeded original design life. This results in increased work load for the maintenance division of the state Departments of Transportation (DOTs). To maintain the road system, state DOTs use In-House or outsource maintenance works to private contractors using Method Based Contracting (MBC), or Performance Based Contracting (PBC), or any combination of these three. Literature reviews …

Causes Of Change Orders And Its Impact On Road Maintenance Contracts, Kabindra Kumar Shrestha

UNLV Theses, Dissertations, Professional Papers, and Capstones

Change orders (CO) commonly generate cost-growth, schedule-growth or both, in construction as well as in maintenance contracts. Literature reviews revealed that the causes and impact of CO on new construction contracts had been comprehensively studied, but the causes and impact of CO in maintenance contracts remained neglected. This study collected CO data on road maintenance contracts to determine the amount of CO and the most frequent and high-risk road maintenance activities that had CO. A Delphi study was conducted with 33 maintenance engineers from the state Department of Transportation (DOT) to identify causes of CO and its impact on cost …

A Multi-~Procedural Approach To Evaluating Walkability And Pedestrian Safety, Peris Nyagah

UNLV Theses, Dissertations, Professional Papers, and Capstones

Walking has sound health benefits and tends to be a pleasurable experience requiring no fuel, fare, license, nor registration. Whilst walking is recommended as part of physical activity, it is necessary to provide a conducive and safe walking environment. In an effort to determine an optimum combination of infrastructure that would create walkable, transit-oriented neighborhoods eliminating unnecessary motorized trips; various approaches evaluating an assortment of features in the walking environment have been implemented. However, some factors such as crash risk which have an essential contribution to the suitability of the walking environment have yet to be considered. Therefore the objective …

Alkali-~Activated Fly Ash Binders: Feasibility As A Sustainable Alternative To Ordinary Portland Cement For Pre-~Cast Systems, Kimberly Sierra

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fresh, load-dependent, transport, and durability properties of alkali-activated fly ash mortars were studied. The influences of activator concentration, solution-to-binder ratio, curing condition, activator type, and sodium silicate-to-total solution ratio on the properties of the studied alkali-activated mortars were examined. This study was divided in two phases. The first phase dealt with the use of sodium hydroxide as the sole activator. The second phase of the study was divided into two parts, both of which used a combination of sodium hydroxide and sodium silicate as the activator solution. Part I of phase II used elevated temperature curing conditions, whereas part II …

Safety Analysis Of Freeway Segments With Unobserved Heterogeneity And Second Order Spatial Effects, Eneliko Mujuni Mulokozi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Safety analysis of freeway networks entails the quantification of crash frequency influencing factors which include roadway and traffic characteristics, environmental factors as well as human factors. This quantification can be used to detect locations with large impacts on the occurrence of crashes which in turn assist engineers and planners to improve safety levels of the network. Roadway characteristics are comprised of the physical elements of the road geometry such as section length, median and right shoulders, speed-exchange lanes, the number of main facility as well as geometry of the entrance from and exit to the main freeway facility. Traffic characteristics …

Fluoride And Phosphate Removal From Industrial And Domestic Wastewaters Using Cerium Chloride, John Michael Gonzales

UNLV Theses, Dissertations, Professional Papers, and Capstones

The use of cerium chloride (CeCl3) to remove fluoride and phosphate from waters is addressed in this study. High concentrations of fluoride exist in groundwater especially in developing countries. Consumption drinking water containing high levels of fluoride can lead to serious cases of dental and skeletal fluorosis. Current defluoridation technologies are limited, especially for high levels of fluoride, and are expensive. Industrial wastewaters contribute to the highest fluoride contamination in the world. With the increasing production of electronic materials, the global fluoride concentration and fluoride-contaminated waters have grown tremendously. Excessive discharge of phosphate into the environment promotes eutrophication of lakes …

Development Of A Decision Support Framework For The Planning Of Sustainable Transportation Systems, Pankaj Maheshwari

UNLV Theses, Dissertations, Professional Papers, and Capstones

With the rapid increase in economic development throughout the world, there is stress on the resources used to support global economy, including petroleum, coal, silver, and water. Currently, the world is consuming energy at an unprecedented rate never seen before. The finite nature of such non-renewable natural resources as petroleum and coal puts pressure on the environmental system, and ultimately reduces the availability of resources for future generations. Hence, it is critical to develop planning and operational strategies that seek to achieve a sustainable use of existing natural resources.

With this motivation, this dissertation focuses to develop a decision support …

Geotechnical Surrogates For Sediment Shear Behavior In Southern Nevada, Rinu Ann Samuel

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Nevada Department of Transportation design standards for deep foundations, particularly drilled shafts, in the Las Vegas Valley (LVV) may be overly conservative due to the challenges in characterizing strong but difficult-to-sample sediment strata, such as dense gravel, heavily cemented sediments, and mixed materials, which occur commonly in the LVV. Consequently, there is a need for investigating methods to assess the shear behavior of sediments that occur in the LVV in situ in working ranges of stress/strain, with the end goal of improving abilities to predict the capacity of drilled shafts in the LVV. To this end, global correlations of …

Bulbous Pier: Alternative To Bridge Pier Extensions, Amilcar Chavez

UNLV Theses, Dissertations, Professional Papers, and Capstones

Bridge deck splashing causes deterioration to the bridge structure and renders the bridge unsafe for motorist and pedestrians. The traditional countermeasure for bridge deck splashing is pier extension, the pier extension moves the pier wave away from the bridge deck, but retrofitting existing bridges with pier extensions is costly. This research proposes the bulbous pier concept as an alternative to pier extension.

The decrease in the pier wave produced by the bulb is due to energy subtracted by the bulb via two forces, the viscous resistance, and the wave-making resistance. The proposed mathematical model for the bulbous pier design follows …