Engineering Commons^™

The Feasibility Of Using High Strength Stainless Steel In Pre-Stressing Applications, Rana Khaled Morsy

Theses and Dissertations

This paper evaluates the applicability of using a corrosion-resistant reinforcement high strength stainless steel strands (HSSS) Duplex 2205 in pre-stressing applications. HSSS-Duplex 2205 is a high performance steel which can be used as an alternative to the conventional carbon steel strands, for a better service life. The high strength and corrosion resistance of the material allows it to show its impressive performance in marine structural applications. Although the use of HSSS-Duplex 2205 could be initially costly; however, the improved durability and extended service life of the concrete structures using HSSS would require less life-cycle cost. Although there is a gap …

Enhancing The Performance Of Dowel Type Fasteners And A Case Study Of Timber Truss Failure, Lon A. Yeary

Theses and Dissertations

This document will outline the findings of three separate and independent studies: Study 1: In or around 1972, an experimental building was constructed. One of the intents of the construction project was to demonstrate advancements in wood building construction design. It was value-engineered throughout. That is, its materials and systems were intended to function at or near design capacity. In 2019, part of the roof of the structure collapsed. This case study investigates two potential factors that led to the failure: stress concentration in excess of the 12 allowable stress for 2 × 4 web members and insufficient plywood sheathing …

Strengthening Of Long Rc Columns Using Near Surface Mounted Gfrp Bars, Ahmed Romaih

Theses and Dissertations

Many of the existing reinforced concrete (RC) columns are deficient because of numerous reasons such as increase in service loads, deterioration due to environmental attacks, errors in the design and/or construction phase or in the worst case, accidents. These elements require strengthening or repair. Different methods have been developed over the years for solving different rehabilitation problems. Recently, advanced composites used for external bonding in the form of fabrics or laminates have become an accepted method. The use of Fibre-Reinforced Polymers (FRPs) in this process is a promising technology, especially that these materials are corrosion-free. One of the new techniques …

Flexural Strengthening Of Rc Slabs Using Near Surface Mounted Gfrp Bars, Sama Taha

Theses and Dissertations

Glass Fiber reinforced polymers (GFRPs) have been recently successfully used to increase reinforced concrete elements' strength. In general, FRPs have many advantages such as resistance to corrosion, and high strength-to-weight ratio. On the other hand, debonding from concrete may constitute a limitation to using GFRP bars; hence the increase in strength of RC elements strengthened using GFRP bars may be limited by this premature debonding failure mechanism.

This study aims to investigate the strengthening effect of GFRP bars on the capacity of RC slabs when subject to flexure loading. The work studies the use of different bonding lengths, diameters and …

Field Durability Test Of Clt Wall Envelope Using Physical Barriers Against Termites And Structural Performance Of Nailed Hold-Down Brackets Connected To Fungus-Exposed Clt Walls, Kamal Neupane

Theses and Dissertations

The effectiveness of using commercial polyethylene flashing and stainless-steel mesh in CLT wall systems as the termite barriers were evaluated in a short-term field test. American Wood Protection Association (AWPA) E21's visual ratings ranged from 10 to 9 in the specimens showing little damage when no physical barriers were used. Termites were able to crawl beyond the physical barriers in few specimens showing the necessity of further research on height and installation method of physical barriers. On the second part, the effect of decay caused due to Postia placenta, a brown-rot fungus, on the structural performance of hold-down brackets connected …

Effects Of Bonding Pressure And Lamina Thickness On Mechanical Properties Of Clt Composed Of Southern Yellow Pine, Cody S. Bates

Theses and Dissertations

This study produced cross-laminated timber panels at a range of four lamina thickness (5/8, 1, 1 1/8, and 1 1/4 inch) and three bonding pressures (50, 125, 200 psi), producing a total of 12 panels for mechanical testing. The goal of this study is to observe how the thickness and pressure trends affect the mechanical properties of CLT. Tests include flatwise bending, flatwise shear, internal-bond, and delamination. Results showed that bending MOE decreases as the panel thickness increases while bonding pressure had no significance. Bending MOR was less significant for the thickness and more significant for pressure compared to the …

Assessment Of Key Imperatives For Enhancing Precast Adoptability In Egypt, Mostafa Sameh

Theses and Dissertations

Precast Concrete’s modular application concept is a major construction method that has been used historically seen in various shapes, forms, and with a wide range of constituents. Examples include Ancient Egypt and China among several impressive structures in old civilizations. The major advantages of precast concrete lie in its adaptability, resilience, and versatility which makes precast concrete one of the most agile building materials. Precast concrete as we know it today has been introduced to our markets over the past several decades. Having similar advantages to that of old precast building methods, the road has been paved for wider use …

Methodology For Including Base Infrastructure In Conceptual System Analysis, Patrick J. Kelly Iv

Theses and Dissertations

The 2018 National Defense Strategy defines a transition to agile basing, where the logistics footprint of new conceptual systems can be distributed across a set of airfields, instead of one main operating base. Currently, there is no capability to assess early concepts using airfield data. This research develops a methodology and a tool that assesses system concepts using world-wide civil and military airfield infrastructure, such as runway parameters, parking, munitions, fuel and warehouse storage, and distance to areas of interest. Specifically, the focus of the thesis is on concepts for the Intelligence, Surveillance, and Reconnaissance (ISR) Strike mission. Four concepts …

Evaluating The Impact Of Different Types Of Stabilized Bases On The Overall Performance Of Flexible Pavements, Andrae Anthony Francois

Theses and Dissertations

This study was initiated with the aim of evaluating the impact of stabilized and untreated base layers on the performance (i.e., fatigue and rutting) of flexible pavements. Four field sections constructed using stabilized base layers (i.e., bituminous (asphalt emulsion), calcium chloride (CaCl-2), Portland cement, and geogrid stabilized base layers) and a control section constructed using untreated RAP aggregates were analyzed in this study. Falling Weight Deflectometer (FWD) tests were conducted on all the field sections and the collected data was used to backcalculate the elastic moduli for all layers. The influence of the stabilized bases and the untreated RAP base …

Structural Strength Evaluation And Retrofitting Of Hangar Q At Millville Airport, Harshdutta Indradutta Pandya

Theses and Dissertations

Hangar Q was built in Millville, New Jersey as a part of the Home Defense Program of World War II. The airport is now owned and operated by the Delaware River and Bay Authority (DRBA) as the Millville Airport. Hangar Q was a historic nine-bow truss hangar when it was first constructed, standing at 30 feet high, 130 feet wide, and 160 feet deep. It was originally constructed with no side walls and no back wall or front roll-up doors. It was later updated from a completely open design to a closed design. The objective of this study was to …

Relaxation In Bolted Assemblies, Samuel Augustus Moeller

Theses and Dissertations

The purposes of this investigation were to (a) extend previously developed elastic spring models for bolt assemblies to include simulating creep loss in the bolt and the threads and (b) to present an approach in which appropriate spring stiffness in the model are determined rationally. Previous efforts at modeling tension in bolts have been limited in that they were not readily applicable to analyses of realistic bolted connections. The simulated load distributions on the shank and the threads in a single-bolt assembly showed good comparison to the gathered experimental data as did the simulated, time dependent creep loss in the …

Design And Analysis Of Constrained Layer Damping Treatments For Bending And Torsion, Kimberly J. Balkema

Theses and Dissertations

In this dissertation, different aspects of constrained layer damping treatments on beams of various geometries are studied. First, the optimal length of a constrained layer damping treatment mounted on a surface in linear strain is identified as a function of the relative stiffnesses of the damping layers and the non-uniformity of the surface stain. The analysis extends previous work that considered the case of uniform surface strain. Sixth order sandwich beam theory is then modified for use with a rectangular beam covered with a segmented constrained layer damping treatment. Non-dimensional variables are used to simplify the form of the problem. …

Effects Of Thickness And Curvature On The Natural Frequencies Of Cylindrical Composite Shells, Jose L. Monteverde E.

Theses and Dissertations

An analytical study is performed to determine the dynamic response, natural frequencies and mode shapes, of deep composite cylindrical shells, including the effect of through the thickness shear strain. The DSHELL finite element program is used to predict the first four natural frequencies and the results are compared to a reference using the Galerkin technique. The program was extended to problems considering simply supported-free boundary conditions. As is well know, the free boundary is rather difficult to represent using the Galerkin technique approach. The mode shapes are created by plotting a surface-contour plot of the eigenvector output from DSHELL.

A …

Comparison Of The Dynamic Behavior Of Composite Plates And Shells Incorporating Green's Strain Terms With The Von Karman And Donnell Models, Arthur E. Forral

Theses and Dissertations

The dynamic collapse behavior of thin, composite cylindrical shells subjected to transverse point loads is considered. The dynamic behavior of the undamped cylindrical shells of varying radii is analyzed with a finite element formulation that incorporates all nonlinear Green's strain terms in the in-plane directions; transverse strains are linear and vary parabolically through the shell thickness. This formulation is denoted as the simplified large displacement/rotation (SLR) theory. Graphical representations are used extensively to examine dynamic behaviors not noted in similar research that utilized the DSHELL finite element code. Composite plate behavior is also explored. Comparison of the higher-order formulations to …

The Effect Of Cutout Dimensionality On The Collapse Characteristics Of Cylindrical Composite Shells Of Varying Thickness, John C. Del Barga

Theses and Dissertations

This study involved a numerical and experimental investigation of the (geometric instability of graphite/epoxy cylindrical panels with free vertical edges undergoing axial compression. Symmetric quasi-isotropic laminates with five different size centralized cutouts, were investigated for two axial lengths of panels and three thicknesses. The study compared experimental data to results from SHELL, a geometrically nonlinear finite-element program which incorporates a parabolic transverse shear strain distribution through the thickness. The research verified that the SHELL program will provide good predictions of the collapse characteristics of a panel with large cutouts of varying dimensions undergoing large displacements and rotations. The best correlation …