Engineering Commons^™

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

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

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

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

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 …

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 …

Feasibility And Assessment Of Using Recycled Rubber For Infrastructure Applications, Ahmed A. Gheni

Doctoral Dissertations

“The United States needs to mine billions of tons of raw natural aggregate each year. At the same time, millions of scrap tires are stockpiled every year. Therefore, replacing natural aggregate with recycled crumb rubber aggregate will be beneficial to the construction industry and environment. This research aimed to investigate the feasibility of using recycled rubber in new construction applications. Based on size, recycled rubber was selected to match its natural counterpart. Different ratios of recycled crumb rubber were used as a fine aggregate replacement in concrete masonry units (CMUs) where the rubberized units showed a lower unit weight, higher …

Use Of Wicking Geotextile To Dehydrate Road Embankments, Chuang Lin

Doctoral Dissertations

“Excess water within a pavement structure is the major cause of pavement deteriorations. A roadway is often constructed with soils compacted at the optimum water contents to achieve the best performance. After construction, the soil water content variation is controlled by the ambient environment. The base course aggregate is very sensitive to water content variations. Unfortunately, conventional drainage system can only drain gravity water, but not capillary water, and it cannot work under unsaturated conditions. Consequently, no matter how well the road is constructed, the water content is expected to increase with time and the excess water will inevitably accelerate …

The Mechanics Of Precision Presplitting, Anthony Joseph Konya

Doctoral Dissertations

"Precision Presplitting is a widely used method of presplit blasting for the mining and construction industries. In recent years considerable effort has gone into the development of empirical equations based on field data to be able to better design the Precision Presplit for various rock types and structural environments. However, the most widely discussed theory about the mechanics of the presplit formation, that of shockwave collisions, does not appear to be applicable for this method of presplitting.

This research has disproven this theory based on insufficient magnitude of the shockwave from modeling with basic wave mechanics. Other authors have suggested …

Chemically-Bonded Enamel-Coated Steel Pipelines For Corrosion Protection And Flow Efficiency, Liang Fan

Doctoral Dissertations

"This study is to explore and develop chemically-bonded enamel coating (200-300 um) on steel pipes, when subjected to soil and thermal environments, in order to improve the corrosion protection and safety of hazardous liquid and natural gas pipelines while reducing pressure loss. Out of five types of enamels and their various mixtures, Tomatec slurry and GP2118 powder were selected for steel pipeline applications. They were applied at approximately 810 °C to the inside surface of steel pipes in wet and electrostatic processes, respectively. The thickness and surface roughness of the enamel coating were measured using a gauge and an optical …

Detection And Elimination Of Rock Face Vegetation From Terrestrial Lidar Data Using The Virtual Articulating Conical Probe Algorithm, Kenneth John Boyko

Doctoral Dissertations

"A common use of terrestrial lidar is to conduct studies involving change detection of natural or engineered surfaces. Change detection involves many technical steps beyond the initial data acquisition: data structuring, registration, and elimination of data artifacts such as parallax errors, near-field obstructions, and vegetation. Of these, vegetation detection and elimination with terrestrial lidar scanning (TLS) presents a completely different set of issues when compared to vegetation elimination from aerial lidar scanning (ALS). With ALS, the ground footprint of the lidar laser beam is very large, and the data acquisition hardware supports multi-return waveforms. Also, the underlying surface topography is …

Development Of Lidar Assisted Terrestrial Radar Interferometry For Rock Deformation Monitoring, Ricardo Javier Romero Ramirez

Doctoral Dissertations

"Rock and soil slope movements cost millions of dollars annually. During the past few decades, engineers have relied on traditional methods to detect slope movements. These tools are valuable for small spatial areas but, may not be adequate or cost effective for large spatial areas. Remote sensing methods such as terrestrial laser scanning (TLS) and terrestrial radar interferometry (TRI) provide excellent spatial coverage, and with adequate post-data-processing software, sub-millimetric scale deformation sensitivity can be achieved.

This work will present a comparative experimental study between TLS and TRI. The comparative experimental study will allow us to achieve the two main objectives …

Dynamic Impact Induced By Tornadoes Through Simulations Based On Two-Way Wind-Structure Interactions, Tiantian Li

Doctoral Dissertations

"Tornadoes have become a significant cause of property damage, injuries and life losses. Investigations of tornadoes indicate that most fatalities were caused by building failure. For example, in the Joplin, MO tornado of 22 May 2011, 161 people were killed, and 84% fatalities were related to building failure. Therefore, it is imperative to develop science-based tornado-resistant building codes, in order to provide a better level of occupant protection from tornadoes and to minimize the tornado-induced damage. This requires in-depth understanding of the wind characteristics of tornadoes and their wind effects on civil structures, based on which design tornadic wind loading …