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Articles 601 - 630 of 699

Full-Text Articles in Civil and Environmental Engineering

Evaluation Of Project Delivery Methods For Trenchless Construction, Sahar W. Hasan Jan 2010

Evaluation Of Project Delivery Methods For Trenchless Construction, Sahar W. Hasan

Civil Engineering Theses - Archive

The need of today's construction whether it be residential, commercial or infrastructure is to cut costs while maintaining schedule, scope, and delivering the expected quality. This realization has brought to light the importance of project delivery methods. Project delivery methods are no longer seen only as procedures to follow for a construction project; they have become instruments that are being used to save money, deliver projects ahead of schedule and come up with innovative design solutions by utilizing the contractor's expertise. This thesis evaluates the pros and cons of project delivery methods with respect to trenchless construction. Trenchless technology methods …

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Performance-Based Plastic Design Of Earthquake Resistant Steel Structures: Concentrically Braced Frames, Tall Moment Frames, Plate Shear Wall Frames, Mohammad Reza Bayat Jan 2010

Performance-Based Plastic Design Of Earthquake Resistant Steel Structures: Concentrically Braced Frames, Tall Moment Frames, Plate Shear Wall Frames, Mohammad Reza Bayat

Civil Engineering Dissertations - Archive

It is well known that structures designed by current codes experience large inelastic deformations during major earthquakes. However, current seismic design practice in the U.S. is based on elastic structural behavior and accounts for inelastic behavior only in an indirect manner through certain modification factors such as R, I, and Cd. Under moderate to severe earthquakes, inelastic activity, including severe yielding and buckling of structural members can be unevenly distributed in the structure which may result in global collapse or costly repair work. Recently, a new design method has been developed and referred to as Performance-Based Plastic Design (PBPD). This …

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A Refined True Triaxial Apparatus For Testing Unsaturated Soils Under Suction-Controlled Stress Paths, Diego D. Perez-Ruiz Jan 2009

A Refined True Triaxial Apparatus For Testing Unsaturated Soils Under Suction-Controlled Stress Paths, Diego D. Perez-Ruiz

Civil Engineering Dissertations - Archive

A novel, computer-driven, true triaxial (cubical) apparatus has been developed to test unsaturated soil specimens under suction-controlled multi-axial stress paths that are not achievable in a conventional cylindrical apparatus. The cubical cell implemented in this research work is a considerably refined version of those previously reported by Hoyos (1998) and Laikram (2007). The refined version is a servo-controlled, mixed boundary type of cell that allows for full control and real time measurements of matric suction, net principal stresses and soil deformations along a wide range of simple-to-complex stress paths induced on cubical specimens of unsaturated soil. The specimen seats on …

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Performance Of Large Scale Steel Fiber Reinforced Concrete Deep Beam With Single Opening Under Monotonic Loading, Carlos Flores Jan 2009

Performance Of Large Scale Steel Fiber Reinforced Concrete Deep Beam With Single Opening Under Monotonic Loading, Carlos Flores

Civil Engineering Theses - Archive

The design of complex, discontinuous stress trajectory regions (D-regions) is complex in natureand cumbersome to design. The performance of a large scale steel fiber reinforced concrete (SFRC)deep beam with single opening under monotonic loading was tested under controlled conditions. Themain objective of this study was to see if Steel Fiber Reinforced Concrete (SFRC), used as a bettermaterial than reinforced concrete (RC) offered an alternate to the cumbersome and iterative stepsinvolved in strut-and-tie (STM) methodology. Additionally, a similar reinforced concrete (RC) specimenwas tested under the same controlled condition designed with classical strut-and-tie model designmethodology reinforced using conventional steel bars.Material testing was …

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Theoretical Feasibility Study For A Conceptual Approach To Trenchless Replacement Of Culverts, Diego R. Calderon Jan 2009

Theoretical Feasibility Study For A Conceptual Approach To Trenchless Replacement Of Culverts, Diego R. Calderon

Civil Engineering Theses - Archive

Culvert damage and collapses and their renewal alternatives are a raising concern in today's infrastructure topics. In most cases damages are irreversible; however, in many cases opportunities exist to correct and renew. While conventional open-cut construction brings inconvenience to the public, trenchless technology brings a greener, reliable and more socially acceptable alternative to renew culverts. Considering the strong dependency on highway transportation by the American lifestyle, collapses of culverts in major roads may produce chaotic traffic redirections. To reduce this risk, this research sets a path for a construction and feasibility study on a new culvert replacement method based on …

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Use Of Electrical Resistivity And Multichannel Analysis Of Surface Wave Geophysical Tomography In Geotechnical Site Characterization Of Dam, Joshua Lee Hubbard Jan 2009

Use Of Electrical Resistivity And Multichannel Analysis Of Surface Wave Geophysical Tomography In Geotechnical Site Characterization Of Dam, Joshua Lee Hubbard

Civil Engineering Theses - Archive

Performance of geotechnical site characterization is a primary function of geotechnical engineers. Generalizations required to extrapolate conventional geotechnical boring data can limit the effectiveness of site assessments. Advancements in geophysical technology have simplified means of data acquisition and interpretation of electrical and seismic testing, allowing a broader audience of practitioners to utilize methods for various engineering and environmental applications. In this study, electrical resistivity and multichannel analysis of surface waves (MASW) seismic geophysical methods are used to expound upon previous geotechnical sampling and in situ testing conducted at an earthen dam site in East Texas. Findings from this study show: …

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A New Paradigm In User Equilibrium - Application In Managed Lane Pricing, Asapol Sinprasertkool Jan 2009

A New Paradigm In User Equilibrium - Application In Managed Lane Pricing, Asapol Sinprasertkool

Civil Engineering Dissertations - Archive

Ineffective use of the High-Occupancy-Vehicle (HOV) lanes has the potential to decrease the overall roadway capacity during peak periods. Excess capacity in HOV lanes during peak periods can be made available to other types of vehicles, including single occupancy vehicles (SOV) for a price (toll). Such dual use lanes are known as "Managed Lanes." The main purpose of this research is to propose a new paradigm in user equilibrium to predict the travel demand for determining the optimal fare policy for managed lane facilities. Depending on their value of time, motorists may choose to travel on Managed Lanes (ML) or …

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Durability Studies On Stabilization Effectiveness Of Soils Containing Different Fractions Of Montmorillonite, Aravind Pedarla Jan 2009

Durability Studies On Stabilization Effectiveness Of Soils Containing Different Fractions Of Montmorillonite, Aravind Pedarla

Civil Engineering Theses - Archive

Stabilization of clays with additives like lime and cement has been practiced for several years and worked well in improving the subgrades. Though this practice is used widely, there were cases where the treated subgrades exhibited premature failures. Many departments of transportation (DOT) agencies in the United States have had subgrade failures even after stabilization with chemical additives due to loss of stabilizer over a time period, or a stabilizer being ineffective in some soils. The design based on PI and gradation of soil followed by many DOTs is quite misleading due to the lack of inclusion of basic soil …

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Failure Analysis Of A Mechanically Stabilized Earth (Mse) Wall Using Finite Element Program Plaxis, Tahsina Mahmood Jan 2009

Failure Analysis Of A Mechanically Stabilized Earth (Mse) Wall Using Finite Element Program Plaxis, Tahsina Mahmood

Civil Engineering Theses - Archive

Mechanically Stabilized Earth (MSE) retaining walls have been increasingly used in many federal, state and private projects over the last 20 years. MSE walls are reliable, constructible, and cost effective. However, failure of MSE wall has become a problem for all agencies using them. This study presents the failure analysis of a segmental block, MSE retaining wall located in Rockville, Maryland. The top of MSE wall moved about 12 inches to 18 inches. An extensive geotechnical investigation program was undertaken to investigate the MSE wall failure. This study presents the results of investigations to determine the causes of failure. The …

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Development And Benefits Of A Leed Project Management Database, Teri Schmig Jan 2009

Development And Benefits Of A Leed Project Management Database, Teri Schmig

Civil Engineering Theses - Archive

The U.S. Green Building Council is a non-profit community of industry leaders working to make green buildings available to everyone. The documentation process for achieving Leadership in Energy and Environmental Design (LEED® ) certification is highly complex and more time-consuming than necessary with currently employed systems. This thesis explains the need for development of a relational database as a means to increase the efficiency of the documentation process to meet LEED® requirements. This database will provide the construction project team a relational platform that guides the user through the LEED® administration and certification process. By developing a LEED® specific project …

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Development Of Brownfield Database Using Gis, Jubair Hossain Jan 2009

Development Of Brownfield Database Using Gis, Jubair Hossain

Civil Engineering Theses - Archive

Brownfields are abandoned, idled or underutilized industrial or commercial sites where expansion or redevelopment is complicated by actual or perceived environmental contamination. Brownfields may be as small as a vacant city lot or as large as an abandoned manufacturing facility occupying several hundred acres. The extent of contamination encountered at brownfield sites may range from minor surface debris to extensive, dangerous soil and ground-water contamination. Concerning the communities in which brownfields are located, redevelopment may improve community appearance and image, relieve associated health and environmental concerns and produce a beneficial economic effect through increased property values and employment opportunities.The overall …

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A Comprehensive Study Of Recycled Concrete Aggregates As A Drainable Base Layer For Pavements, Juan Bosquez Jan 2009

A Comprehensive Study Of Recycled Concrete Aggregates As A Drainable Base Layer For Pavements, Juan Bosquez

Civil Engineering Dissertations - Archive

The use of recycled materials in construction is becoming increasingly popular due to the shortage of raw materials. Coupled with the environmental concerns surrounding the quarrying of natural minerals, waste materials are being considered as viable replacement sources. By recycling waste materials, available landfill space is increased and costs of transportation are reduced. This dissertation study was conducted to evaluate the use of recycled concrete aggregates as flexible base as per the requirements of the Texas Department of Transportation (2004). Two sources of recycled aggregates and one source of natural limestone aggregate were collected from the Dallas/Fort Worth Area and …

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Nonlinear Dynamic Analysis Of Hybrid Frames, Dobrinka Radulova Jan 2009

Nonlinear Dynamic Analysis Of Hybrid Frames, Dobrinka Radulova

Civil Engineering Theses - Archive

This study proposes a hybrid frame system consisting of rigid and semi-rigid connections subjected to a dynamic loading. Two building geometries are chosen to represent low-rise and high-rise buildings. Multiple locations for placement of semi-rigid connections are proposed, and the hybrid systems with the most efficient energy dissipation are identified. During this analysis, five earthquake records are used to provide a spectrum of frequencies. Five practical semi-rigid connection types and one connection with analytical parameters are also modeled into the selected hybrid combinations by applying zero-length springs at the ends of beams, in which their nonlinear constitutive relation is defined …

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Non-Linear Finite Element Dynamic Analysis Of The Effect Of Compaction On Underground Conduits, Anupong Kararam Jan 2009

Non-Linear Finite Element Dynamic Analysis Of The Effect Of Compaction On Underground Conduits, Anupong Kararam

Civil Engineering Dissertations - Archive

Construction loads are an important but often overlooked factor in underground pipe design and installation. Common compaction equipments used in pipeline construction can be a major contributor to pipe damage. To reduce load concentrations in excess of the design loads, construction equipment should be kept at a safe distance above the pipe location.This study investigates the behavior of a reinforced concrete pipeline system under a compaction process. The full-scale experimental test was conducted using a Type-2 standard trench installations soil and minimum compaction requirement. Using a compaction machine "hoe pack" and including the weight of a backhoe, a maximum dynamic …

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Applications Of Gis For Mapping And Tracking Underground Infrastructure, Anurag Babu Bhogenahally Lakshminarayanappa Jan 2009

Applications Of Gis For Mapping And Tracking Underground Infrastructure, Anurag Babu Bhogenahally Lakshminarayanappa

Civil Engineering Theses - Archive

The main objective of this research is to apply Geographic Information Systems (GIS) for construction and renewal of underground infrastructures. As a first step, a suitability analysis to determine location of existing underground infrastructure is performed. Next, a GIS template is developed using a digital elevation model (DEM) to get a three dimensional visualization of the underground infrastructure. Creating a Google Map using ArcGIS is one of the key features of this research, which provides an exact location of the existing site and distances from the nearby reference points. Once the GIS data is exported to Google Map and Google …

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Long Term Durability Studies On Chemically Treated Reclaimed Asphalt Pavement (Rap) Materials, Vijay Krishna Ganne Jan 2009

Long Term Durability Studies On Chemically Treated Reclaimed Asphalt Pavement (Rap) Materials, Vijay Krishna Ganne

Civil Engineering Theses - Archive

Reclaimed Asphalt Pavement (RAP) is a well known construction material which has been used in Hot Mix Asphalt (HMA) to reduce material costs and stabilizing the pavements for several years. It has been reported that out of 45 million tons of RAP produced every year in US, only 33% is being used in HMA. It is clear that a large amount of RAP produced is disposed off as a waste material in landfills. Hence, in order to utilize the maximum percentage of RAP and reduce the disposal rate, stabilized RAP can be effectively used as a base layer instead of …

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Managed Lanes Weaving And Access Guideliness, Chulsu Yang Jan 2009

Managed Lanes Weaving And Access Guideliness, Chulsu Yang

Civil Engineering Dissertations - Archive

To maximize the potential for successful managed lanes (MLs) operations, there are critical design issues that require special attention. Adequate ML access spacing and length of the ML access opening are required for the preservation of freeway capacity, level of service, and safety. The traffic weaving from an entrance ramp to the general purpose lanes across to a ML access point and vice versa are effectively modeled as a two-sided Type C weave. The 2000 Highway Capacity Manual (HCM) methodology was calibrated for the major weave without lane balance or merging (standard Type C weave) but not for the two-sided …

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Comparative Damage Of Different Truck Configurations On Jointed Plain Concrete Pavement, Tito P. Nyamuhokya Jan 2009

Comparative Damage Of Different Truck Configurations On Jointed Plain Concrete Pavement, Tito P. Nyamuhokya

Civil Engineering Theses - Archive

This study estimated the damage done by trucks with 35 different configurations on a typical structure of a Jointed Plain Concrete Pavement. The configurations were proposed by New York Department of Transportation, the sponsor of this study. The generalized three dimensional finite element program Abaqus was used to calculate the response of linear elastic rigid pavement structure under truck loading. The loads for each truck case were placed at critical locations on the surface of the pavement to obtain the maximum tensile stresses at the bottom of concrete slab. The computed tensile stresses were used in Darter fatigue model (1977) …

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Operations-Oriented Performance Measures For Freeway Management Systems: Final Report, Robert E. Brydia, Stephen P. Mattingly, Melanie L. Sattler, Auttawit Upayokin Dec 2008

Operations-Oriented Performance Measures For Freeway Management Systems: Final Report, Robert E. Brydia, Stephen P. Mattingly, Melanie L. Sattler, Auttawit Upayokin

Civil Engineering Faculty Publications - Archive

This report describes the second and final year activities of the project titled “Using Operations-Oriented Performance Measures to Support Freeway Management Systems.” Work activities included developing a prototype system architecture for testing the use of performance measures in real-time. Outputs from this effort included operator’s screens, a prototype database, and a concept of operations for using the real-time measures. Additional work showcased the application of a multi-criterion screening approach to the selection of competing performance measures.

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Empirical Two-Point Α-Mixing Model For Calibrating The Ech2o Ec-5 Soil Moisture Sensor In Sands, Toshihiro Sakaki, Anuchit Limsuwat, Kathleen M. Smits, Tissa H. Illangasekare Nov 2008

Empirical Two-Point Α-Mixing Model For Calibrating The Ech2o Ec-5 Soil Moisture Sensor In Sands, Toshihiro Sakaki, Anuchit Limsuwat, Kathleen M. Smits, Tissa H. Illangasekare

Civil Engineering Faculty Publications - Archive

Recently improved ECH2O soil moisture sensors have received significant attention in many field and laboratory applications. Focusing on the EC-5 sensor, a simple and robust calibration method is proposed. The sensor-to-sensor variability in the readings (analog-to-digital converter (ADC) counts) among 30 EC-5 sensors was relatively small but not negligible. A large number of ADC counts were taken under various volumetric water contents (?) using four test sands. The proposed two-point a-mixing model, as well as linear and quadratic models, was fitted to the ADC – ? data. Unlike for conventional TDR measurements, the effect of sensor characteristics is lumped into …

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Development Of A Freeway Incident Rating System, Jose Javier Lopez Aug 2008

Development Of A Freeway Incident Rating System, Jose Javier Lopez

Civil Engineering Theses - Archive

A freeway incident rating system is proposed to classify incidents in terms of their disruptive potential to cause delays, fuel wastage, secondary accidents, and other adverse operational impacts. A two-dimensional rating scale is used which classifies incidents in terms of their severity and the number of agencies required to respond and clear incidents. Variables used in characterizing the severity include number of vehicles involved, number of lanes and shoulders blocked, time of incident occurrence, duration of incident until full clearance, and weather conditions at the time of the incident. The objective behind the development of such a rating system is …

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Studies On Volume Change Movements In High Pi Clays For Better Design Of Low Volume Pavements, Thammanoon Manosuthikij Aug 2008

Studies On Volume Change Movements In High Pi Clays For Better Design Of Low Volume Pavements, Thammanoon Manosuthikij

Civil Engineering Dissertations - Archive

Numerous low- to medium-volume roads such as Farm Market (FM) roads constructed on expansive clay subgrades, especially in the eastern and central Texas, encounter severe pavement cracking and premature loss of serviceability. The maintenance costs, in some cases, are greater than the initial construction costs. The roads built on problematic expansive soils often become distressed due to volume changes associated with seasonal moisture content fluctuations. This dissertation research was attempted to evaluate models that predict volume changes movements of the expansive or highly plastic soils and also develop new models that could provide better prediction of volume change movements in …

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Building Pressure Tests Of Fiber-Reinforced Foam-Based Lightweight Concrete Precast Wall Panels, Francheska Enid Seijo Aug 2008

Building Pressure Tests Of Fiber-Reinforced Foam-Based Lightweight Concrete Precast Wall Panels, Francheska Enid Seijo

Civil Engineering Theses - Archive

Instrumentation and procedures for building pressure tests were designed as a means of providing new wind pressure test methods for full-scale building models. Fiber-reinforced foam-based lightweight concrete precast wall panels were studied in this investigation. Three (3) full-scale prototype buildings were tested for this purpose. To determine the material properties and design parameters for this targeted 90 pcf (1,446 kg/m3) cellular lightweight concrete and to gain overall knowledge of its behavior, some tests such as compressive strength test, pull-out strength test, and flexural strength test were performed. The wind pressure tests performed provided results for strength, maximum wind pressure the …

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Subsurface Investigations Using High Resolution Resistivity, Dharmateja Maganti Aug 2008

Subsurface Investigations Using High Resolution Resistivity, Dharmateja Maganti

Civil Engineering Theses - Archive

Electrical resistivity imaging has been proved to be well suited to produce images of subsurface conditionsbecause of the ability of the technique for detecting resistive features and discriminating subtle resistivity variations in the soil media. Electrical resistivity imaging survey was performed at E. Center Development in Duncanville, Texas. The survey was conducted using SuperSting R8/IP Multi-channel Resistivity Imaging System to image the subsurface structure. Both 2-D and 3-D electrical resistivity imaging tests were conducted using dipole-dipole array at 2 feet, 5 feet and 20 feet electrode spacing. Earth Imager 2D and Earth Imager 3D software's were then used to invert …

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Life Cycle Assessment Of Bio-Material Stabilized Expansive Soils, Ranjith Samuel Rosenberk Aug 2008

Life Cycle Assessment Of Bio-Material Stabilized Expansive Soils, Ranjith Samuel Rosenberk

Civil Engineering Dissertations - Archive

Pavement cracking is one of the major maintenance works that requires millions of dollars in repair costs annually. Pavement cracks are formed due to moisture and temperature fluctuations in the soil. Stabilization of pavement shoulder subsoil with the addition of compost material was studied for preventing pavement cracks. Eight different compost materials with three major feed stock sources such as biosolids, wood waste, and animal manure were investigated in this research. Compost treatment studies were performed at four different test sites located in various regions of the state of Texas. Laboratory experiments were conducted completed compost manufactured topsoil's (CMTs) to …

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Effects Of Calcium-Based Treatment On Organic Soil Behavior, Srujan Rao Chikyala Aug 2008

Effects Of Calcium-Based Treatment On Organic Soil Behavior, Srujan Rao Chikyala

Civil Engineering Theses - Archive

Organic soils are found in many places around the world. Organic soils undergo large secondary settlements depending on the amount of organic matter present in the soil Organic soil is a mixture of finely divided particles of organic matter, in some instances visible fragments of partly decayed vegetable matter and shells are also present in the organic matter. In order to reduce the secondary settlements caused by organic matter, soil is treated with different stabilizing agents. The difficulties associated with organic soils arise when they are treated with cement or lime stabilizers, as organic matter inhibits cementitious reactions responsible for …

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Impact Of Lateral Swell Pressure On Retaining Structure Design Using Expansive Cohesive Backfill, Mark G. Thomas Apr 2008

Impact Of Lateral Swell Pressure On Retaining Structure Design Using Expansive Cohesive Backfill, Mark G. Thomas

Civil Engineering Theses - Archive

Since cohesive soils are difficult to drain once becoming saturated, in order to reduce lateral earth pressures exerted by saturated cohesive soils on retaining structures, retaining wall designs most always specify use of drainable granular backfill. However, costs for the importation of granular backfill materials continues to increase due to depletion of these materials in certain areas, and to the ever-increasing costs for material transportation, largely related to increased labor and fuel prices. These factors, together with the costs of removing replaced cohesive materials, and coupled with resource and environmental conservation concerns, are driving efforts to develop reasonable and prudent …

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Non-Linear Finite Element Dynamic Analysis Of Tapered Hollow Steel Poles For Passive Base Isolation, Tri Le Apr 2008

Non-Linear Finite Element Dynamic Analysis Of Tapered Hollow Steel Poles For Passive Base Isolation, Tri Le

Civil Engineering Dissertations - Archive

Long tapered poles are commonly used to support Closed Circuit Television (CCTV) Cameras for security and traffic monitoring. Images received from CCTV are normally distorted depending on the wind induced vibration characteristics of the forcing function. To reduce image distortion, three approaches are integrated to optimize the process, which are: (1) development of equations for pole's frequency of vibration in terms of its geometric variables; (2) development of a mechanical damping device to isolate the pole's vibration from that of the camera; and (3) development of an electrical image processing device for image corrections. The identification of a pole's natural …

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Dynamic Properties Of Compacted Soils Using Resonant Column With Self-Contained Bender Elements, Roshnara Mohammad Apr 2008

Dynamic Properties Of Compacted Soils Using Resonant Column With Self-Contained Bender Elements, Roshnara Mohammad

Civil Engineering Theses - Archive

A comprehensive series of resonant column and bender elements tests were simultaneously performed in the developed RC/BE apparatus. RC/BE tests were conducted on compacted specimens of poorly graded sand (SP) and high plasticity clay (CH) prepared at different moisture contents (17.7, 22.1, 25.5, 30.2% by weight for clay, and 5, 10, 15, 20% by weight for sand) and under different confining pressures (0, 2.5, 5.0, and 10.0 psi, or 0, 17.2, 34.4, 69.0 kPa) in order to assess the influence of key environmental factors, such as compaction induced suction and confining pressure, on small-strain stiffness properties of unsaturated soils, such …

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Clay Mineralogy Effects On Long-Term Performance Of Chemically Treated Expansive Clays, Bhaskar Chandra Srinivas Chittoori Jan 2008

Clay Mineralogy Effects On Long-Term Performance Of Chemically Treated Expansive Clays, Bhaskar Chandra Srinivas Chittoori

Civil Engineering Dissertations - Archive

Stabilization of expansive soils using chemical additives such as cement and lime had been in use for several decades and these treatments provide riding comforts to travelers. However, many state Departments of Transportation (DOTs) in the United States have had problems with subgrade failure even after stabilization with chemical additives due to a loss of stabilizer over time, or a stabilizer being ineffective in some soils while other soils with the same index properties respond well to that stabilizer. These problems are attributed to the limitations of the current procedures of stabilization for pavement subsoil layers. One such limitation is …

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