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Your search for ETD Program Civil Engineering resulted in 15 match(es).

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Analysis and Design of MEMS Scan Mirrors Using Periodically Stiffened Silicon Nitride: Author: Lutzenberger, Bert Jeffrey; Date: 2006-05-15; Program: Civil Engineering; Abstract: This research presents a novel fabrication method combining surface and bulk micromachining techniques to deposit mechanically stiffened silicon nitride films for use in MEMS fabrication. The stiffened silicon nitride film consists of a thin (~1.5 um) top sheet with stiffening fins molded to the back of the film. In the final configuration, the fins extend between 15 um and 40 um vertically from the back of the film. The molded fins are arranged into periodic square and hexagonal cell configurations ranging in size from 10 um to 250 um. The periodic cells significantly increase the bending sti...; Download File | View full details

Concrete Bridge Deck Behavior Under Thermal Loads: Author: Johnson, Jeffrey Keith; Date: 2005-08-15; Program: Civil Engineering; Abstract: A major area of concern with concrete bridge decks is durability. The service life of bridge decks designed by traditional procedures is often shorter than desired. Typically, the decks crack under environmental loads, which lead to corrosion of the reinforcing steel and general deterioration of the concrete. In this investigation, the response of three different bridge decks was studied in the field under environmental loads. The decks, located within a mile of each other on the same road, differ in their steel reinforcement and the type of concrete used; otherwise, they are identical. Theref...; Download File | View full details

Empirical Velocity Predictions at Culvert Inlets: Author: Patton, Jesse Earl; Date: 2006-05-15; Program: Civil Engineering; Abstract: The velocity distribution at the entrance cross section of a culvert is typically diverse, reflecting the nuances of the bed material, debris and other hydraulic factors just upstream of the culvert. These diverse inlet velocity fields have been observed to perpetuate some distance into the culvert, impacting the ability of fish to travel upstream in the culvert barrel. It is important to be able to quantitatively describe the inlet velocity field, especially as this serves as a necessary boundary condition for three-dimensional modeling of fluid flow in culverts. While there are various theor...; Download File | View full details

Experimental Investigation of the Thermal Effects of Frost Susceptible Soils: Author: Newell, Zachary Allen; Date: 2005-12-15; Program: Civil Engineering; Abstract: Damages to Engineering structures attributed to frost action of subgrade soils amounts to millions of dollars annually. Theoretical research has been conducted to examine the details of the frost action phenomenon since the 1940's. However, a reliable and practical approach for evaluating the frost susceptibility of soils is nonetheless a goal that has eluded engineers and scientists alike. The research presented herein focuses on the procedures necessary to obtain a numerical model capable of predicting the thermal response of frost susceptible soils. A field facility was designed and constr...; Download File | View full details

Non-Destructive Soil Testing Using X-Ray Computed Tomography: Author: Nielsen, Brent Daniel; Date: 2004-12-15; Program: Civil Engineering; Abstract: The mechanical behavior of soils is highly dependent on the particle microstructure. Traditional geotechnical Engineering soil tests generally do not measure soil properties on a micro-scale; instead, macro scale properties are commonly used as estimates of microstructure properties in determining soil Engineering behavior. Additionally, traditional geotechnical Engineering soil tests are destructive in nature, and many test methods destroy the same soil properties they intend to measure. The goal of this research was to develop non-destructive soil test methods using x-ray computer-aided tomo...; Download File | View full details

Traffic Performance on Two-Lane, Two-Way Highways: Examination of New Analytical Approaches: Author: Durbin, Casey Thomas; Date: 2006-08-15; Program: Civil Engineering; Abstract: This project presents research on estimating traffic performance on two-lane, two-way highways. The main research objective is to examine two new approaches / methodologies in estimating the Percent-Time-Spent-Following (PTSF), a major indicator of performance on two-lane highways. The first new approach, named the weighted-average approach, is based on the weighted average of speeds for various vehicle types within the traffic stream. The second new approach, named the probabilistic approach, is concerned with using probabilities in estimating the PTSF. The need for this investigation has ari...; Download File | View full details

A Three Dimensional Finite Element Model of Biofilm Subjected to Fluid Flow and its Application to Predicting Detachment Potential: Author: Gammelgard, Peter Norman; Date: 2006-08-15; Program: Civil Engineering; Abstract: Microbial biofouling of wetted surfaces can adversely impact the hydrodynamic performance of pressurized conduits. These impacts are due, in part, to the viscoelastic material properties of biofilm. Of particular interest is the response of biofilm to changing hydrodynamic conditions and its effect on potential for biofilm removal. The goal of this research was two fold; 1) to develop a three dimensional numerical model, incorporating the viscoelastic material description of biofilm, to simulate the response of biofilm to varying hydrodynamic conditions and 2) use this model to identify behavi...; Download File | View full details

Feasability of Using a Gyratory Compactor to Determine Compaction Characteristics of Soil: Author: Browne, Michael John; Date: 2006-12-15; Program: Civil Engineering; Abstract: Proctor impact compaction tests represent the most commonly used laboratory method to determine the maximum dry unit weight and optimum moisture content of soils in the United States. Soil compaction methods in the field have changed dramatically over the last 50 years, though the Proctor tests have remained relatively unchanged. One shortcoming of the Proctor tests is that it uses impact loads to compact the soil in a stiff non-yielding mold. This technique may not accurately simulate modern field compaction methods, which rely on a combination of kneading, vibration, and increased normal pre...; Download File | View full details

Experimental Assessment of Aggregates: Author: Trimble, Nicholas Robert; Date: 2007-08-15; Program: Civil Engineering; Abstract: An extensive suite of geotechnical laboratory tests were conducted to quantify differences in Engineering properties of three crushed aggregates commonly used on Montana highway projects. The material types are identified in the Montana Supplemental Specifications as crushed base course (CBC, 1.5 to 2-inch maximum particle sizes) and crushed top surfacing (CTS, 0.75-inch maximum particle size). All aggregates were open-graded and contained relatively few fines. Results from R-value tests and direct shear (DS) tests performed on large samples (12-in by 12-in) indicate the CBC aggregates general...; Download File | View full details

Axial capacity of piles supported on intermediate geomaterials: Author: Brooks, Heather Margaret; Date: 2008-08-15; Program: Civil Engineering; Abstract: Pile foundations used to support bridges and other structures are designed and installed to sustain axial and lateral loads without failing in bearing capacity and without undergoing excessive movements. The axial load-carrying capacity of a driven pile is derived from friction or adhesion along the pile shaft and by compressive resistance at the pile tip. There are well established analytical methods for evaluating pile capacity and for predicting pile driving characteristics for cohesive soil, cohesionless soil, and rock. However, past experience indicates these methods may not be reliable f...; Download File | View full details

Estimating quality of traffic flow on two-lane highways: Author: Karjala, Sarah Renee; Date: 2008-08-15; Program: Civil Engineering; Abstract: Since the publication of the 2000 Highway Capacity Manual (HCM), there have been several studies that indicate that the HCM equations for Percent Time-Spent- Following (PTSF) on two-lane highways do not correspond to field-based measurements. This discrepancy was the motivation for this research project. The purpose of this project was two-fold. First, it aimed to find an alternative performance measure to PTSF that could be measured directly in the field and could adequately describe the quality of traffic flow. Secondly, the project aimed to investigate the inter-vehicular interaction betwee...; Download File | View full details

A conceptual precipitation-runoff modeling suite: model selection, calibration and predictive uncertainty assessment: Author: Smith, Tyler Jon; Date: 2008-12-15; Program: Civil Engineering; Abstract: In Montana and much of the Rocky Mountain West, the single most important parameter in forecasting the controls on regional water resources is snowpack. Despite the heightened importance of snowpack, few studies have considered the representation of uncertainty in coupled snowmelt/hydrologic conceptual models. Uncertainty estimation provides a direct interpretation of the risk associated with predictive modeling results. Bayesian inference, through the application of Markov chain Monte Carlo methods, provides a statistical means of approximating uncertainty associated with both the parameters ...; Download File | View full details

Slope scale modeling of snow surface temperature in topographically complex terrain: Author: Staples, James Mark; Date: 2008-12-15; Program: Civil Engineering; Abstract: In mountainous terrain, landscape can influences the thermal state of snow. Snow temperature and mass flux have been calculated using an energy balance model, Radtherm/RT, to account for the effects of topography and meteorological conditions. For a specific location, a terrain model is defined and contains a connected assemblage of elements or facets. Each element has a specified terrain type with assigned thermal properties. Meteorological data are applied, and a one dimensional energy balance is calculated for each element. This energy balance includes conduction, convection, radiation, and...; Download File | View full details

Development of a test protocol for cyclic pullout of geosynthetics in roadway base reinforcement: Author: Holley, Timothy Michael; Date: 2009-05-15; Program: Civil Engineering; Abstract: Geosynthetics, or manmade materials used in soils Engineering, have successfully been used as base reinforcement of pavements for over 40 years. Use of geosynthetics can result in cost savings by allowing the aggregate base layer to be reduced in thickness and/or the service life of the pavement to be extended. Design methods for this type of reinforcement have typically been developed by individual manufacturers for specific products. These methods are not widely used by state transportation agencies because 1) they are proprietary, 2) they are empirically based, and 3) they lack compatibilit...; Download File | View full details

Sensitivity of 1-D hydraulic models of fish passage in culverts to descriptions of fish swimming performance: Author: Nixon, Kyle Marshall; Date: 2009-08-15; Program: Civil Engineering; Abstract: One way culverts become barriers to the upstream movement of fish is by creating excessive velocities exceeding a fish's swimming ability. FishXing, a common tool for indirectly assessing fish passage, uses fish swimming ability information with one-dimensional culvert hydraulics to predict barrier status of culverts. However, since fish swimming ability data is scarce for many fish species, predictions of a culvert's barrier status can be inaccurate and overly conservative, possibly leading to misclassification or uneconomical design. Additional fish swimming ability research is necessary to ...; Download File | View full details

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