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Articles 1 - 17 of 17
Full-Text Articles in Engineering
Behavior Of Prestressed Concrete Bridges With Closure Pour Connections And Diaphragms, Gercelino Ramos
Behavior Of Prestressed Concrete Bridges With Closure Pour Connections And Diaphragms, Gercelino Ramos
Masters Theses
Accelerated Bridge Construction (ABC) has gained substantial popularity in new bridge construction and bridge deck replacement because it offers innovative construction techniques that result in time and cost savings when compared to traditional bridge construction practice. One technology commonly implemented in ABC to effectively execute its projects is the use of prefabricated bridge components (precast/prestressed bridge components). Precast/prestressed bridge components are fabricated offsite or near the site and then connected on-site using small volume closure pour connections. Diaphragms are also commonly used to strengthen the connection between certain prefabricated components used in ABC, such as beam elements. Bridges containing closure …
The Promise Of Vr Headsets: Validation Of A Virtual Reality Headset-Based Driving Simulator For Measuring Drivers’ Hazard Anticipation Performance, Ganesh Pai Mangalore
The Promise Of Vr Headsets: Validation Of A Virtual Reality Headset-Based Driving Simulator For Measuring Drivers’ Hazard Anticipation Performance, Ganesh Pai Mangalore
Masters Theses
The objective of the current study is to evaluate the use of virtual reality (VR) headsets to measure driving performance. This is desirable because they are several orders of magnitude less expensive and, if validated, could greatly extend the powers of simulation. Out of several possible measures of performance that could be considered for evaluating VR headsets, the current study specifically examines drivers’ latent hazard anticipation behavior both because it has been linked to crashes and because it has been shown to be significantly poorer in young drivers compared to their experienced counterparts in traditional driving simulators and in open …
Sustainable Travel Incentives Optimization In Multimodal Networks, Hossein Ghafourian
Sustainable Travel Incentives Optimization In Multimodal Networks, Hossein Ghafourian
Masters Theses
Tripod, an integrated bi-level transportation management system, is a smartphone application from the potential user’s point of view which would be instantly accessed prior to performing the trip. Since there are constantly several alternatives for any trip, Tripod considers a series and combination of various parameters, including departure time, mode and route, and rewards for each alternative with a number of redeemable points for goods and services called “Tokens”. The framework responsible for computing the optimized number of tokens awarded to the set of available alternatives in order to minimize the system-wide energy consumption under a constrained Token budget, is …
Finite Element Simulation Of Bonded And Mechanically Anchored Shear Interfaces Of Externally Applied Frp Sheets To Concrete And Wood-Concrete Composites, Alaa Al-Sammari
Finite Element Simulation Of Bonded And Mechanically Anchored Shear Interfaces Of Externally Applied Frp Sheets To Concrete And Wood-Concrete Composites, Alaa Al-Sammari
Doctoral Dissertations
Composite construction is prevalent in advanced structural systems where components of different materials are combined in the same structure to improve the performance of strong and economic structural sections. Maintaining continuity between the different structural components to produce monolithic structural behavior is challenging because of differences in the mechanical properties of these materials in terms of stiffness, strength, and ductility. The different components of the composite section are typically joined using adhesives and/or mechanical anchors to produce partial or full composite action. This dissertation discusses two types of shear interfaces intended to result in structural composite behavior. The first type …
Northeastern Species In Hybrid Cross Laminated Timber, Hamid Kaboli
Northeastern Species In Hybrid Cross Laminated Timber, Hamid Kaboli
Doctoral Dissertations
Known in the building industry throughout the world, Cross Laminated Timber (CLT) is a massive timber building material with outstanding structural, fire, and seismic properties. CLT is a cost-competitive, sustainable construction material is a good candidate as a substitute material for concrete, masonry, and steel, in mid-rise and high-rise buildings. CLT is perpendicular layers of dimensional lumbers usually laminated together and forming a massive structural panel. This dissertation explores the viability of utilizing Massachusetts grown Eastern Hemlock and Eastern White Pine in CLT panels as pure or in conjunction with other high-value wood products. 59% of Massachusetts’ lands are covered …
Evaluation Of The Effect Of Bottom Bar Splice Location On Performance Of Beams In Reinforced Concrete Perimeter Frames, Jorge Rivera Cruz
Evaluation Of The Effect Of Bottom Bar Splice Location On Performance Of Beams In Reinforced Concrete Perimeter Frames, Jorge Rivera Cruz
Doctoral Dissertations
The American Concrete Institute (ACI) Building Code Requirements for Structural Concrete and Commentary (ACI 318-14) indirectly accounts for resistance to progressive collapse by providing requirements for structural integrity in concrete structures. ACI 318-14 structural integrity requirements are intended to provide alternate load paths so that progressive collapse is avoided in the event of the unintended loss of an interior support. ACI 318-14 §9.7.7.5 requires that splices of structural integrity reinforcement be designed as Class B splices near mid-span for top reinforcement and near the support for bottom reinforcement. However, ACI 318-14 does not provide a clear definition for the support …
Laboratory Study Of The Geotechnical Properties Of Abraded Railway Ballast With Natural And Clay Mix Fouling, Andrew Rohrman
Laboratory Study Of The Geotechnical Properties Of Abraded Railway Ballast With Natural And Clay Mix Fouling, Andrew Rohrman
Doctoral Dissertations
With 140,000 miles of active track, railroad freight is the largest method of transporting goods in the United States. An important component of the railroad substructure is the gravel-size aggregate placed below the tracks, called ballast. The ballast is responsible for draining water away from the track, resisting forces from traffic loading, maintaining track position, and reducing loads to acceptable pressures for the subgrade. Ballast is typically selected to be highly angular and uniformly graded, but these characteristics are constantly changing under dynamic traffic loading. As the ballast is loaded, the particles abrade against each other, grinding off stone dust …
Mechanical Performance Of Structural Systems With Missing Members: From Buildings To Architected Materials, Panagiotis Pantidis
Mechanical Performance Of Structural Systems With Missing Members: From Buildings To Architected Materials, Panagiotis Pantidis
Doctoral Dissertations
Structural systems are potentially subjected to damage initiating scenarios throughout the course of their service time. Depending on the nature and extent of the damaging event, they may experience significant reduction or even complete loss of their mechanical performance. This dissertation delves into the mechanics of structural systems under the notion of missing members from their domain, investigating types of structural systems: a) multi-story steel framed buildings, and b) materials with a truss-lattice microstructure. Part I of the dissertation investigates the performance of multi-story steel framed buildings under a column removal scenario, developing an analytical framework for their quasi-static robustness …
Equity And Efficiency In Multi-Modal Transportation Systems, Nicholas M. Fournier
Equity And Efficiency In Multi-Modal Transportation Systems, Nicholas M. Fournier
Doctoral Dissertations
The land-use pattern for many cities is a central business district surrounded by sprawling suburbs. This pattern can lead to an inefficient and congestion-prone transportation system due to a reliance on automobiles, because high-capacity transit is not efficient in low-density areas where insufficient travelers can access transit. This also poses an equity concern as the monetary cost of faster and more expensive travel disproportionately burdens low income travelers. This dissertation presents a deterministic approximation of a discrete choice model for mixed access and mainline transportation modes, meaning that travelers may use different modes to access a mainline system, such as …
Modeling The Effect Of New Commuter Bus Service On Demand And The Impact On Ghg Emissions: Application To Greater Boston, Christopher Lyman
Modeling The Effect Of New Commuter Bus Service On Demand And The Impact On Ghg Emissions: Application To Greater Boston, Christopher Lyman
Masters Theses
The transportation sector is considered one of the major contributors to greenhouse gas (GHG) emissions in metropolitan areas, and any efforts to reduce these emissions requires strategic management of multiple transportation modes. This paper presents a method to identify opportunities to reduce GHG emissions by expanding commuter bus services and incentives to shift commuters from private cars to transit. The approach uses a nested multinomial logit model for mode choice in a region that includes driving alone, carpooling, walking, cycling, and using four possible transit modes (ferry, commuter rail, rapid transit and bus) by walk access or driving access. A …
Modeling And Optimizing Routing Decisions For Travelers And On-Demand Service Providers, Xinlian Yu
Modeling And Optimizing Routing Decisions For Travelers And On-Demand Service Providers, Xinlian Yu
Doctoral Dissertations
This thesis investigates the dynamic routing decisions for individual travelers and on-demand service providers (e.g., regular taxis, Uber, Lyft, etc). For individual travelers, this thesis models and predicts route choice at two time-scales: the day-to-day and within-day. For day-to-day route choice, methodological development and empirical evidences are presented to understand the roles of learning, inertia and real-time travel information on route choices in a highly disrupted network based on data from a laboratory competitive route choice game. The learning of routing policies instead of simple paths is modeled when real-time travel information is available, where a routing policy is defined …
A Multiline Anchor Concept For Floating Offshore Wind Turbines, Casey Fontana
A Multiline Anchor Concept For Floating Offshore Wind Turbines, Casey Fontana
Doctoral Dissertations
Floating offshore wind turbines (FOWTs) hold great potential for the renewable energy industry, but capital costs remain high. In efforts to increase FOWT substructure efficiency and reduce costs, this thesis investigates a novel multiline anchor concept in which FOWTs share anchors instead of being moored separately. The goal of this thesis is to evaluate the force dynamics, design, and potential cost reduction of the system. Anchor forces are simulated using the NREL 5 MW reference turbine and OC4-DeepCwind semisubmersible platform, and multiline anchor force is computed as the vector sum of the contributing mooring line tensions. The use of a …
Applications Of Machine Learning Methods In Macroscopic Crash Analysis For Transportation Safety Management, Somaye Garmroudi Dovirani
Applications Of Machine Learning Methods In Macroscopic Crash Analysis For Transportation Safety Management, Somaye Garmroudi Dovirani
Doctoral Dissertations
Transportation Safety Planning (TSP) is a statewide-scale tool and combines transportation planning processes with safety aims to increase safety and reduce transportation fatalities and injuries. Traffic safety, which continues to remain a critical issue worldwide, has led to a myriad of modeling techniques to improve analytical capabilities with respect to crash modeling and prediction. State and metropolitan transportation planning processes must be consistent with Strategic Highway Safety Plans. This research aims to identify models and methods to improve the ability to capture variables that have the most significant impact on traffic safety through crash prediction modeling. In order to achieve …
Application Of Ground Penetrating Radar For Use In Thermal Conductivity Site Investigations, Aaron J. Rubin
Application Of Ground Penetrating Radar For Use In Thermal Conductivity Site Investigations, Aaron J. Rubin
Doctoral Dissertations
Measurement of soil thermal conductivity in-situ is important for many practical geotechnical and civil engineering applications. However, for a variety of reasons it can be difficult to measure in-situ. A novel method to estimate the thermal conductivity of sands based on electrical relative permittivity (dielectric constant) measurements and GPR data is presented. First, an analytical model to estimate thermal conductivity of soils was developed and validated using a database of thermal conductivity measurements. The new thermal conductivity model was then compared to existing models using a larger database of new and pervious thermal conductivity measurements conducted on a wide range …
Analysis Of Adhesive Anchorage Systems Under Extreme In-Service Temperature Conditions, Rachel Wang
Analysis Of Adhesive Anchorage Systems Under Extreme In-Service Temperature Conditions, Rachel Wang
Masters Theses
Adhesive anchorage systems have found widespread use in structural applications, including bridge widening, concrete repair and rehabilitation, and barrier retrofitting. Because these applications typically require adhesive anchorage systems to be installed outdoors, the effects of climate conditions and day-to-day temperature fluctuations on adhesive behavior and performance should be considered. The purpose of this thesis is to simulate pullout tests of adhesive anchorage systems for threaded rod and reinforcing bars and to emulate effects under various temperature conditions through the use of finite element analysis. Results from the finite element simulation are then compared to the physical tests conducted at UMass …
Performance Of Concrete Tunnel Systems Subject To Fault Displacement, Michael Morano
Performance Of Concrete Tunnel Systems Subject To Fault Displacement, Michael Morano
Masters Theses
A Finite Element Analysis (FEA) investigation of concrete tunnel systems traversing seismic faults is carried out to determine how to effectively mitigate the stresses induced in the liner when subject to fault displacement. A parametric study of various fault parameters, both in the damage zone and competent rock, is carried out to determine the site conditions which induce the most stress on the tunnel liner system. Results indicate that friction angle, cohesion, and elastic modulus of fault zones have varying effects on the stresses induced on the liner. The width of damage zone and expected displacements are also investigated and …
High Fidelity Modeling Of Cold-Formed Steel Single Lap Shear Screw Fastened Connections, Rita Kalo
High Fidelity Modeling Of Cold-Formed Steel Single Lap Shear Screw Fastened Connections, Rita Kalo
Masters Theses
Cold-formed steel connections are commonly fastened using self-tapping self-drilling screws. The behavior of these connections can differ based on the screw manufacturer or the cold-formed steel product used, both of which have a large selection available for use in industry. Because of their popularity and the many possible variations of these connections, researchers have frequently tested screw connections to characterize their behavior. However, repeatedly conducting this type of experiment is time consuming and expensive. Therefore, the purpose of this work was to create finite element models that can successfully predict the behavior of single lap shear screw connections, a common …