Structural Engineering Commons^™

Structural Robustness Of Long-Span Cable-Supported Bridges, Qian Chen

Dissertations and Theses

As a critical part of the current infrastructure system, long-span bridges are directly exposed to adverse environments, such as floods, scours, hurricanes, etc., and dynamic loads such as earthquakes and vehicular impacts. Additionally, recent long-span cable-supported collapse examples show that many bridges suffered progressive collapse when local damage occurred, and they are highly vulnerable to severe damages in the event of a localized failure. However, the traditional design approaches are unable to provide explicit measures of residual safety of bridges, especially after an abnormal event. Currently available redundancy and robustness evaluation approaches, which were developed mainly for short-span bridges, are …

Alternate Load Paths And Retrofits For Long-Span Truss Bridges Under Sudden Member Loss And Blast Loads, Huihui Li

Dissertations and Theses

In current bridge design practices, due to the existence of alternate load paths (ALPs), continued stability and progressive collapse-resistance of long-span bridges following the initialed loss of a critical member can be attributed to “redundancy”. However, “redundancy”, also indicated as the post member failure behavior of long-span bridges is not well understood and is not explicitly considered, especially for long-span truss bridges. As one of the most famous collapse events that took place recently, collapse of the I-35W truss bridge has demonstrated the vulnerabilities of long-span truss bridges, and their societal and economic consequences under the abnormal events, such as …

Macro - And Microstructure Evaluation And Field Applications Of Concrete With Recycled Glass Pozzolan, Marija Krstic

Dissertations and Theses

Concrete is the most used material in the world, second only to water. Conventional concrete is produced with Portland cement (PC). The production of cement is an energy intensive operation that has raised significant environmental concerns, since one ton of cement generates an equal ton of CO₂. In the USA about 90 million tons of cement are used annually, with 3 million tons used in New York. Most contemporary concrete applications for buildings and infrastructure use high-performance concrete (HPC) mixtures which are produced by replacing a percentage of cement with supplementary cementitious materials (SCMs), consisting mainly of fly-ash …

Decision-Making In Reuse Of Highway Bridge Foundations, Ehssan Hoomaan

Dissertations and Theses

According to the 2019 National Bridge Inventory data from Federal Highway Administration, the average age of highway bridges in the U.S.A. is 45 years, with almost 43% of existing highway bridges being older than 50 years, and eight percent of all U.S. national highway bridges being in poor condition. Foundation and substructure of existing highway bridges (over land and water) may have significant functional values even after being under service for decades. Reusing an existing bridge foundation during the reconstruction of a bridge (e.g., major rehabilitation, retrofitting, replacement of superstructure and substructure, and addition/removal of a span) has the potential …

Slender Frp Elements As Discrete Reinforcement For Concrete, Yuan Tian

Dissertations and Theses

This dissertation presents a study that led to the development of slender elements that look like fibers used for reinforcing concrete but with a very different reinforcing mechanism. These elements, referred to as “Needles” are very rigid and strong; when intersected by growing cracks in concrete under heavy and increasing loads, they do not break and deform minimally. In the present work major steps were taken to understand the reinforcing mechanism of Needles. In addition, to investigate the influence of Needles on the mechanical performance of concrete incorporating Needles, at both material and structural levels, a series of laboratory experiments …

Computational Fluid Dynamics Simulation Of Rain-Wind-Induced Vibration Of Stay Cables, Hongfan Wang

Dissertations and Theses

Due to the large amplitude, frequent occurrence and severe consequences, the rain-wind induced vibration (RWIV) of stay cables in cable-stayed bridges has been investigated extensively by researchers around the world. However, the underlying excitation mechanism is still unclear. Recently, computational fluid dynamics (CFD) simulation has been widely applied in the research on structure vibrations due to dynamic wind loads, with great potential as an alternative tool for wind tunnel testing. It has also been adopted to investigate the RWIV, but only a few studies have been conducted so far. Furthermore, most of the CFD simulations reported in literatures are two-dimensional, …

Seismic Behavior Of Screen Grid Core Insulated Concrete Form Walls, Anwer Sabah Mohammed Mohammed

Dissertations and Theses

The use of the insulated concrete form (ICF) walls in residential buildings has increased over the past few decades. Much research has been conducted to evaluate the lateral strength of these walls by applying monotonic and cyclic loadings. In the current study, full-scale shake table experiments were employed to evaluate the in-plane behavior of four screen grid insulated concrete form (SGICF) walls. The first two wall specimens utilized dry fit insulated form blocks made from recycled expanded polystyrene granules that were bonded together with cement. When stacked, the cavities in the blocks formed a grid of cores that are evenly …

Development Of Electromagnetic Friction Dampers For Improving Seismic Performance Of Civil Structures, Mohsen Amjadian

Dissertations and Theses

Energy dissipation is critical to limiting damage to civil structures subjected to extreme natural events such as earthquakes. Friction is one of the most reliable mechanisms of energy dissipation that has been utilized extensively in friction dampers to improve seismic performance of civil structures. Friction dampers are well-known for having a highly nonlinear hysteretic behavior caused by stick-slip motion at low velocities, a phenomenon that is inherent in friction and increases the acceleration response of the structure under control unfavorably, in spite of the fact that the displacement is generally reduced because of the energy dissipation. This increase in acceleration …

Achieving Operational Seismic Performance Of Rc Bridge Bents Retrofitted With Buckling-Restrained Braces, Ramiro Andrés Gabriel Bazáez Gallardo

Dissertations and Theses

Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity …

Torsional Strengthening Of Reinforced Concrete Beams Using Cfrp Composites, Ranj Rafeeq

Dissertations and Theses

Few decades ago, there were no guidelines for torsion design of reinforced concrete (RC) beams. Hence, many existing beams in older buildings have a lack of adequate torsional strength since they were not properly designed for torsion. One way to regain/rehabilitate adequate torsional strength is through application of externally bonded carbon fiber reinforced polymers (CFRP). To date, American Concrete Institute (ACI) code, as well as other building codes, do not have recommendations or provisions for strengthening RC beams for torsion using fiber-reinforced polymer (FRP) composites due to the inexistence of conclusive experimental and analytical data. Of the very limited works …

Behavior Of Prestressed Concrete Beams With Cfrp Strands, Yasir Matloob Saeed

Dissertations and Theses

The high cost of repairing reinforced or prestressed concrete structures due to steel corrosion has driven engineers to look for solutions. Much research has been conducted over the last two decades to evaluate the use of Fiber Reinforced Polymers (FRPs) in concrete structures. Structural engineering researchers have been testing FRP to determine their usability instead of steel for strengthening existing reinforced concrete structures, reinforcing new concrete members, and for prestressed concrete applications. The high strength-to-weight ratio of FRP materials, especially Carbon FRP (CFRP), and their non-corrosive nature are probably the most attractive features of FRPs.

In this study, an experimental …

Experimental Investigation Of Fiber Reinforced Concrete Beams, Karrar Ali Al-Lami

Dissertations and Theses

Shear strength of fiber reinforced concrete beams was studied in this research project. Three types of fibers were examined: hooked-end steel fiber, crimped-steel fiber, and crimped-monofilament polypropylene fibers. The experimental program included five beam specimens. Two of the beams were control specimens in which one was reinforced with minimum shear reinforcement according to ACI 318, while the other one did not have any shear reinforcement. Each one of the other three specimens was reinforced with one of the above mentioned fibers by 1% volumetric ratio. In addition to the beam specimens, three prisms were also made for each type fiber …

Behavior Of Reinforced Concrete Beams Retrofitted In Flexure Using Cfrp-Nsm Technique, Salam Al-Obaidi

Dissertations and Theses

A variety of retrofitting methods are used to upgrade existing structures. For example, steel plates and Fiber Reinforced Polymer (FRP) jackets are externally bonded to members to increase their capacity in flexure and shear. However, due to the issue of corrosion these strengthening systems may lose their efficiency with time. FRP materials have been used to strengthen many structural components of different shapes and types. FRP jackets, FRP Strips, and FRP rods have commonly been used to rehabilitate existing structural components. The many advantages of using FRP as strengthening materials have made this material an attractive alternative: advantages such as …

Experimental Investigation Of Lateral Cyclic Behavior Of Wood-Based Screen-Grid Insulated Concrete Form Walls, John Stuart Garth

Dissertations and Theses

Insulated concrete forms (ICFs) are green building components that are primarily used for residential wall construction. Unlike most polystyrene based ICF variants, the Faswall ICFs used in these experiments were significantly denser because they were made from recycled wood particles and cement. The current design approach for structures constructed with this type of wall form only allows the designer to consider the contribution of the reinforced concrete cores. Previous research has shown that this approach may be conservative. This project experimentally evaluated the lateral structural response of these types of grid ICF walls under increasing amplitude of in-plane cyclic loading. …

Application Of Multi-Hazard Seismic-Blast Detailing For Highway Bridges, Dominique Morton Torres

Dissertations and Theses

The increase of worldwide terrorist attacks on public transportation has heightened our concerns of protecting the nation’s transportation infrastructure. Highway bridges are an attractive target for terrorist attacks due to ease of accessibility and their overall importance to society. The primary objective of this research is to investigate multi-hazard seismic-blast correlations of blast-induced bridge components through numerical simulations of a high-precision finite element model of a typical highway bridge in New York. Seismic-detailing for blast loading on bridges has been investigated to study the correlations between seismic design for blast load effects. High-precision 3D Finite Element models of bridges detailed …

An Empirical Study Of Particulate Matter Exposure For Transit Users At Bus Stop Shelters, Adam Moore

Dissertations and Theses

Congested traffic corridors in dense urban areas are key contributors to the degradation of urban air quality. While waiting at bus stops, transit patrons may be exposed to greater amounts of vehicle-based pollution, including particulate matter, due to their proximity to the roadway. Current guidelines for the location and design of bus stops do not take into account air quality or exposure considerations. This thesis provides a unique contribution to roadside air quality studies and presents an innovative method for the consideration of bus shelter placement. Exposure to roadside pollutants is estimated for transit riders waiting at three-sided bus stop …

Analytical And Experimental Stresses In Concrete Pavements And Unbonded Overlays, Ahmad Jaber

Dissertations and Theses

The principal objective of this study is to determine the accuracy of calculating stresses in concrete pavements and unbonded overlays under different loading conditions. The computed stresses for the single layer pavements are obtained based on Westergaard theory, the finite-element model (ILLI-SLAB), and the elastic layered model (ELSYM5). For the two-layer unbonded systems, stresses are estimated based on the finite-element theory and the Portland Cement Association design method. The experimental results for the comparison were available from a series of tests done on model scale concrete pavements and unbonded overlays. The results of present investigation show that the computed stresses …

A Study Of Single Angle Compression Members, James Robert Callaway

Dissertations and Theses

A study was undertaken to investigate the compressive capacity of a specific group of single angle members.

A review of existing literature and techniques was presented. Laboratory compression tests were performed on 22 angle members of four different sizes and two different lengths. Additional tests were performed to determine the yield strength of the material. The results, normalized with respect to the yield stress, were tabulated and discussed.

Two existing analytic models were used to attempt to predict the ultimate capacity of the test members. The first, an elastic method, was based upon the AISC combined stress equation. The second, …

Secondary Stresses In Bowstring Timber Trusses, John F. Bradford

Dissertations and Theses

This study was undertaken in order to determine analytically the magnitude of the secondary (i.e., joint deflection induced) moments in the continuous glued-laminated chords of bowstring timber trusses. Traditionally, these moments have been assumed to be small and therefore neglected. The American Institute of Timber Construction makes no mention of these moments in their recommended design procedure.

Experimental Determination Of Post-Buckling Performance Of Steel Angles, Rupasiri Purasinghe

Dissertations and Theses

An experimental testing program was conducted to determine the compression member performance in post-buckling region. These results are compared with an analytical computer program developed by Portland State University under Bonneville Power Administration Contract 79-80BP 24005. The paper presents the sensitivity of the performance of single angle compression members to various parameters such as length to radius of gyration ratio, eccentricity, end conditions and yield stress. The effect of local buckling on long member performance is also documented.

Response Of Orthotropic Bridge Decks To Highway Loadings, Harry Morris Rexin

Dissertations and Theses

This thesis documents the fabrication, testing techniques, and response of a plastic scale model of an orthotropic bridge deck. To economically investigate a two-lane steel bridge deck, plastic Acrylic^R was used as a modeling material. Welds were simulated with dichloromethane, a capillary action solvent, and PS-30, a polymerizable cement. Deflections were measured with laboratory dial guages while strains were monitored with strain guages mounted on the deck.

The response of the deck to AASHO vehicle axle loads was compared with a discrete element computer program used to analyze orthotropic bridge decks continuous over flexible supports. Results indicate good correlation …

Direct Design Of A Portal Frame, Angel Fajardo Ugaz

Dissertations and Theses

This investigation was undertaken to develop plastic design aids to be used in the direct design of optimum frames. It uses the concept of minimum weight of plastically designed steel frames, and the concept of linear programming to obtain general solutions. Among the special characteristics of this study are: A. The integration of both gravity and combined loading conditions into one linear programming problem. B. The application of the revised simplex method to the dual of a parametric original problem. C. The application of A and B above in the development of design aids for the optimum design of symmetrical …