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<title>Civil Engineering Masters Theses Collection</title>
<copyright>Copyright (c) 2013 University of Massachusetts - Amherst All rights reserved.</copyright>
<link>http://scholarworks.umass.edu/ce_theses</link>
<description>Recent documents in Civil Engineering Masters Theses Collection</description>
<language>en-us</language>
<lastBuildDate>Fri, 25 Jan 2013 18:18:45 PST</lastBuildDate>
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<title>Spatial and Temporal Correlations of Freeway Link Speeds: An Empirical Study</title>
<link>http://scholarworks.umass.edu/theses/940</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/940</guid>
<pubDate>Fri, 23 Nov 2012 07:36:52 PST</pubDate>
<description>
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	<p>Congestion on roadways and high level of uncertainty of traffic conditions are major considerations for trip planning. The purpose of this research is to investigate the characteristics and patterns of spatial and temporal correlations and also to detect other variables that affect correlation in a freeway setting. 5-minute speed aggregates from the Performance Measurement System (PeMS) database are obtained for two directions of an urban freeway – I-10 between Santa Monica and Los Angeles, California. Observations are for all non-holiday weekdays between January 1st and June 30th, 2010. Other variables include traffic flow, ramp locations, number of lanes and the level of congestion at each detector station. A weighted least squares multilinear regression model is fitted to the data; the dependent variable is Fisher Z transform of correlation coefficient.</p>
<p>Estimated coefficients of the general regression model indicate that increasing spatial and temporal distances reduces correlations. The positive parameters of spatial and temporal distance interaction term show that the reduction rate diminishes with spatial or temporal distance. Higher congestion tends to retain higher expected value of correlation; corrections to the model due to variations in road geometry tend to be minor. The general model provides a framework for building a family of more responsive and better-fitting models for a 6.5 mile segment of the freeway during three times of day: morning, midday, and afternoon.</p>
<p>Each model is cross-validated on two locations: the opposite direction of the freeway, and a different location on the direction used for estimation. Cross-validation results show that models are able to retain 75% or more of their original predictive capability on independent samples. Incorporation of predictor variables that describe road geometry and traffic conditions into the model works beneficially in capturing a significant portion of variance of the response. The developed regression models are thus transferrable and are apt to predict correlation on other freeway locations.</p>

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<author>Rachtan, Piotr J.</author>

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<title>An Optimal Adaptive Routing Algorithm for Large-scale Stochastic Time-Dependent Networks</title>
<link>http://scholarworks.umass.edu/theses/902</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/902</guid>
<pubDate>Fri, 23 Nov 2012 07:10:22 PST</pubDate>
<description>
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	<p>The objective of the research is to study optimal routing policy (ORP) problems and to develop an optimal adaptive routing algorithm practical for large-scale Stochastic Time-Dependent (STD) real-life networks, where a traveler could revise the route choice based upon en route information. The routing problems studied can be viewed as counterparts of shortest path problems in deterministic networks. A routing policy is defined as a decision rule that specifies what node to take next at each decision node based on realized link travel times and the current time. The existing routing policy algorithm is for explorative purpose and can only be applied to hypothetical simplified network. In this research, important changes have been made to make it practical in a large-scale real-life network. Important changes in the new algorithm include piece-wise linear travel time representation, turn-based, label-correcting, criterion of stochastic links, and dynamic blocked links. Complete dependency perfect online information (CDPI) variant is then studied in a real-life network (Pioneer Valley, Massachusetts). Link travel times are modeled as random variables with time-dependent distributions which are obtained by running Dynamic Traffic Assignment (DTA) using data provided by Pioneer Valley Planning Commission (PVPC). A comprehensive explanation of the changes by comparing the two algorithms and an in-depth discussion of the parameters that affects the runtime of the new algorithm is given. Computational tests on the runtime changing with different parameters are then carried out and the summary of its effectiveness are presented. To further and fully understand the applicability and efficiency, this algorithm is then tested in another large-scale network, Stockholm in Sweden, and in small random networks. This research is also a good starting point to investigate strategic route choice models and strategic route choice behavior in a real-life network. The major tasks are to acquire data, generate time-adaptive routing policies, and estimate the runtime of the algorithm by changing the parameters in two large-scale real-life networks, and to test the algorithm in small random networks. The research contributes to the knowledge base of ORP problems in stochastic time-dependent (STD) networks by developing an algorithm practical for large-scale networks that considers complete time-wise and link-wise stochastic dependency.</p>

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<author>Ding, Jing</author>

<source></source>

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<title>Evaluating and Modeling Traveler Response to Real-Time Information in the Pioneer Valley</title>
<link>http://scholarworks.umass.edu/theses/882</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/882</guid>
<pubDate>Thu, 23 Aug 2012 06:27:59 PDT</pubDate>
<description>
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	<p>This study used focus groups and surveys to provide a comprehensive evaluation of the Regional Traveler Information Center (RTIC) at UMass Amherst. The evaluation was completed by obtaining the awareness, usage, and perceived effectiveness of RTIC’s information by residents in the Pioneer Valley. It was found that awareness of RTIC is limited due to its lack of advertisement. Usage is focused primarily on its webcams and advisory information. Surveys showed that participants perceive RTIC to be useful, even though they may never have seen the information before (the survey provided a chance for them to become familiar with the service). Revealed preference data were collected regarding the travelers' most memorable instances where real-time traffic information was provided. A binary logit model of a traveler's switch decision (route, departure time, mode, destination, trip cancellation, or combinations of them) with real-time traffic information was specified and estimated. It was found that travelers have an increasing tendency to switch away from the original option when the resulting delay caused by congestion increases. Receiving congestion and crash information also provided a tendency to take an alternative travel method. It was found that males tend to switch more often than females, and young individuals switch less often.</p>

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<author>de Ruiter, Tyler</author>

<source></source>

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<title>Probabilistic Analysis of Offshore Wind Turbine Soil-Structure Interaction</title>
<link>http://scholarworks.umass.edu/theses/848</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/848</guid>
<pubDate>Thu, 23 Aug 2012 05:59:27 PDT</pubDate>
<description>
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	<p>A literature review of current design and analysis methods for offshore wind turbine (OWT) foundations is presented, focusing primarily on the monopile foundation. Laterally loaded monopile foundations are typically designed using the American Petroleum Institute (API) <em>p-y</em> method for offshore oil platforms, which presents several issues when extended to OWTs, mostly with respect to the large pile diameters required and the effect of cyclic loading from wind and waves. Although remedies have been proposed, none have been incorporated into current design standards. Foundations must be uniquely designed for each wind farm due to extreme dependence on site characteristics. The uncertainty in soil conditions as well as wind and wave loading is currently treated with a deterministic design procedure, though standards leave the door open for engineers to use a probability-based approach. This thesis uses probabilistic methods to examine the reliability of OWT pile foundations. A static two-dimensional analysis in MATLAB includes the nonlinearity of <em>p-y</em> soil spring stiffness, variation in soil properties, sensitivity to pile design parameters and loading conditions. Results are concluded with a natural frequency analysis.</p>

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<author>Carswell, Wystan</author>

<source></source>

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<title>User Equilibrium in a Disrupted Network with Real-Time Information and Heterogeneous Risk Attitude</title>
<link>http://scholarworks.umass.edu/theses/831</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/831</guid>
<pubDate>Thu, 23 Aug 2012 05:54:12 PDT</pubDate>
<description>
	<![CDATA[
	<p>The traffic network is subject to random disruptions, such as incidents, bad weather, or other drivers’ random behavior. A traveler’s route choice behavior in such a network is thus affected by the probabilities of such disruptions, his/her attitude towards risk, and real-time information on revealed traffic conditions that could potentially reduce the level of uncertainty due to the disruptions. As the road network’s performance is de-termined collectively by all travelers’ choices, it is also affected by these factors. This thesis features the development of a multi-class user equilibrium model based on hetero-geneous risk attitude distributions and a user equilibrium model based on various disrup-tion probabilities and information penetration rates that can be used to perform sensitivity analyses for a traffic network. The method of successive average (MSA) is used to solve for the equilibrium conditions. Laboratory experimental data are used to calibrate the risk attitude model. A sample sensitivity analysis is performed to show the disruption and in-formation penetration effects on network performance. Initial calibrations show promis-ing results for route flow predictions in a congested network with respect to heterogene-ous attitude. With respect to disruption probability and information access, having too v high information penetration will not improve the network’s performance, while having a small disruption probability can improve traffic conditions in the network</p>

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<author>Pothering, Ryan J.</author>

<source></source>

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<title>Automated Enforcement Using Dedicated Short Range Communication</title>
<link>http://scholarworks.umass.edu/theses/829</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/829</guid>
<pubDate>Thu, 23 Aug 2012 05:54:08 PDT</pubDate>
<description>
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	<p>This thesis presents a set of system algorithms and a feasibility analysis of an automated enforcement system that uses dedicated short-range communication with an emphasis on seatbelt and speed enforcement. The current seatbelt and speed enforcement limitations and disadvantages can be overcome because future vehicles will be equipped with devices that can be used to communicate with other vehicles or the traffic infrastructure.</p>
<p>One limitation of the current seatbelt enforcement system is that it relies only on human vision. Today’s automated photo speed enforcement also has the following major limitations and disadvantages: fixed position enforcement, system installation and maintenance costs, enforcement based only on spot speed, sensitivity to lighting conditions, and vulnerability to sprays and obstructions that might block the license plates. This thesis proposes an automated enforcement system that uses wireless communication (IEEE 802.11p protocol), which can resolve all of the above-mentioned problems and is also more efficient, accurate, and cost effective.</p>

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<author>Kim, Gilbert</author>

<source></source>

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<title>Evaluation of Live-Load Distribution Factors (LLDFs) of NEXT Beam Bridges</title>
<link>http://scholarworks.umass.edu/theses/816</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/816</guid>
<pubDate>Thu, 23 Aug 2012 05:44:34 PDT</pubDate>
<description>
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	<p>A new precast-prestressed cross section was recently developed by a consortium of engineers from the six New England states, New York and members of the northeast region of PCI. The northeast extreme Tee (NEXT) beam is efficient for medium Bridge spans (50 to 80 ft long). Field formwork savings are introduced by having a flange cast integrally during fabrication of the beams at the precasting plant. Job safety is increased because a working platform is created. The flange width of the NEXT Beams can be adjusted during fabrication to accommodate roadways of different widths and skew angles. Because the section is new with complexity in its shape, the present design guidance cannot be used to evaluate LLDFs for NEXT beams within the context of the AASHTO LRFD. In particular, the use of live-load distribution factors (LLDFs) equations in LRFD for NEXT beams is not straightforward. The distance between the beam webs is variable depending on whether it is measured within a beam module or between adjacent modules. In absence of detailed information a PCI technical committee evaluated LLDFs (through AASHTO 2010 Bridge specification) for the NEXT beams used in the Brimfield Bridge by two different approaches and found one of them conservative. The conservative approach was single stem which uses the average spacing (between webs ([S1+S3]/2)) for use in the LLDF equations.. The committee expressed concerns about whether trends of LLDFs would be similar for other parametric sets, and would like to standardize the methodology for the Bridge projects in Massachusetts with NEXT beam as the girder. To verify the conservativeness of single stem methodology (for the evaluation of LLDFs) for other parameters this research project was initiated. LLDFs are evaluated based on the two approaches and compared with the LLDFs obtained through finite element modeling.</p>
<p>The results of 40-3D finite element models have been used to compare the LLDFs obtained from AASHTO 2010 Bridge design specification. The results were also used to compare different parameters that affect LLDFs of NEXT beams including span, skew angle, and beam end fixity. The finite element models were created using a Bridge prototype that is being instrumented for future field verification of the analyses. The models were created using frame elements for the beams and shell elements for the cast in place deck. The integral abutment and foundation of the Bridges was included in the models in which piles are created using frame elements and abutments are created using shell elements. The results indicate that the approach taken for the design of NEXT beams is in general conservative for interior girders of the Bridge. On the contrary such the adopted approach was not yielding the higher value of LLDFs. The variation in strains due to losses are compared by two methods (strains variation obtained from field data and strain variation obtained based on AASHTO equation of losses) to verify the AASHTO equation of losses.</p>

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<author>Singh, Abhijeet Kumar</author>

<source></source>

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<title>Material Characterization and Computational Simulation of Steel Foam for Use in Structural Applications</title>
<link>http://scholarworks.umass.edu/theses/813</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/813</guid>
<pubDate>Thu, 23 Aug 2012 05:44:27 PDT</pubDate>
<description>
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	<p>Cellular metals made from aluminum, titanium, or other metals are becoming increasingly popular for use in structural components of automobiles, aircraft, and orthopaedic implants. Civil engineering applications remain largely absent, primarily due to poor understanding of the material and its structural properties. However, the material features a high stiffness to weight ratio, excellent energy dissipation, and low thermal conductivity, suggesting that it could become a highly valuable new material in structural engineering. Previous attempts to characterize the mechanical properties of steel foam have focused almost exclusively upon uniaxial compression tests, both in experimental research and in computational simulations. Further, computational simulations have rarely taken the randomness of the material’s microstructure into account and have instead simplified the material to a regular structure. Experimental tests have therefore been performed upon both hollow spheres and PCM steel foams to determine compressive, tensile, and shear properties. Computational simulations which accurately represent the randomness within the microstructure have been validated against these experimental results and then used to simulate other material scale tests. Simulated test matrices have determined macroscopic system sensitivity to various material and geometrical parameters.</p>

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<author>Smith, Brooks H.</author>

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<title>Driver Dynamics and the Longitudinal Control Model</title>
<link>http://scholarworks.umass.edu/theses/792</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/792</guid>
<pubDate>Thu, 23 Aug 2012 05:26:04 PDT</pubDate>
<description>
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	<p>Driver psychology is one of the most difficult phenomena to model in the realm of traffic flow theory because mathematics often cannot capture the human factors involved with driving a car. Over the past several decades, many models have attempted to model driver aggressiveness with varied results. The recently proposed Longitudinal Control Model (LCM) makes such an attempt, and this paper offers evidence of the LCM's usefulness in modeling road dynamics by analyzing deceleration rates that are commonly associated with various levels of aggression displayed by drivers. The paper is roughly divided into three sections, one outlining the LCM's ability to quantify forces between passive and aggressive drivers on a microscopic level, one describing the LCM's ability to measure aggressiveness of platoons of drivers, and the last explaining the meaning of the model’s derivative. The paper references some attempts to capture driver aggressiveness made by classic car-following models, and endeavors to offer some new ideas in study of driver characteristics and traffic flow theory.</p>

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<author>Leiner, Gabriel G.</author>

<source></source>

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<title>New Technologies in Short Span Bridges: A Study of Three Innovative Systems</title>
<link>http://scholarworks.umass.edu/theses/790</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/theses/790</guid>
<pubDate>Thu, 23 Aug 2012 05:26:01 PDT</pubDate>
<description>
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	<p>Short span bridges are commonly used throughout the United States to span small waterways and highway overpasses. New technologies in the civil engineering industry have aided in the creation of many unique designs of these short span highway bridges in efforts to decrease construction cost, decrease maintenance costs, increase efficiency, increase constructability, and increase safety. Three innovative systems, the Integral Abutment Bridge, “Bridge-in-a-Backpack”, and the Folded Plate Girder bridge will be analyzed to study how the bridges behave under various types of loading.</p>
<p>Detailed finite element models were created for integral abutment bridges of varying geometry. These models are used to study how the live load distribution transversely across the bridge is effected by varying geometric properties and varying modeling techniques. These models will also be used to determine live load distribution factors for the integral abutment bridges and compare them to current American Association of State Highway and Transportation Officials specifications.</p>
<p>The “Bridge-in-a-Backpack” and the Folded Plate Girder bridges were each constructed with a variety of instruments to measure the bridge movements. Readings from these instruments are used to determine the bridge response under various loading conditions. Bridges were analyzed during their construction process, during static live load testing, and during long term seasonal changes. The results from these studies will aid in the refinement of these innovative designs.</p>

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<author>Lahovich, Andrew</author>

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