View All Items

Title: FEASIBILITY STUDY OF LIGHTWEIGHT HIGH-STRENGTH HOLLOW CORE BALSA-FRP COMPOSITE BEAMS UNDER FLEXURE.
Creator: O'Neill, Kevin, Mackie, Kevin, University of Central Florida
Abstract / Description: The United States of AmericaÃ‚Â's Military, more specifically the Army, has since the late 1990Ã‚Â's had a vested interest in the development of super-lightweight, portable, short-span composite bridge and decking components to replace aging heavy metal-alloy machine driven modular systems. The following study looks at the feasibility of using balsa wood as the structural core material in fiber reinforced polymer (FRP) wrapped hollow-core composites...
Show moreThe United States of AmericaÃ‚Â's Military, more specifically the Army, has since the late 1990Ã‚Â's had a vested interest in the development of super-lightweight, portable, short-span composite bridge and decking components to replace aging heavy metal-alloy machine driven modular systems. The following study looks at the feasibility of using balsa wood as the structural core material in fiber reinforced polymer (FRP) wrapped hollow-core composites in short-span bridge applications. The balsa provides shear resistance and the FRP the flexural resistance, resulting in extremely high strength-to-weight and strength-to-depth ratios. Several scaled short span specimens were constructed and tested using a variety of fibers and resins. In addition, a calibrated finite element model (FEM) was developed using data acquired through testing. Of the 3 FRP-matrices tested (carbon-polyurethane, glass-polyurethane, and carbon-epoxy-resin), the carbon-epoxy-resin had the stiffest cross-section and highest ultimate load achieved, although the fiber did not have the highest elastic modulus and ultimate rupture strength of the constituent materials. The carbon-polyurethane fiber had the largest elastic modulus and ultimate strength, but due to construction difficulties did not perform as well as expected. The glass-polyurethane fiber had the lowest elastic modulus and ultimate load with high strain values and performed accordingly during specimen testing. Given the constraints of self-weight, section geometry, and deflection set forth for lightweight short-span portable bridging solutions, this study demonstrates that the balsa-FRP composite systems are viable solutions; in particular, when carbon fabric is paired with balsa cores.
Show less
Date Issued: 2010
Identifier: CFE0002997, ucf:47931
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002997

Title: TRANSFER AND DEVELOPMENT LENGTH OF STRANDS IN POST-TENSIONED MEMBERS AFTER ANCHOR HEAD FAILURE.
Creator: El Zghayar, Elie, Mackie, Kevin, University of Central Florida
Abstract / Description: Post-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000 a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at...
Show morePost-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000 a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at the pier anchor location. Anchorage failure caused all PT force to transfer to the steel duct located within the pier segment that in turn slipped and caused the tendon to go completely slack. After the application of PT force, the anchorage assembly and steel pipes that house the tendon are filled with grout. These short grouted regions could, in the event of anchorage failure, provide a secondary anchorage mechanism preventing the scenario mentioned above from occurring. This paper presents the results of a full-scale experimental investigation on anchorage tendon pull-out and a finite element model to support the experimental results and interpretation. The study focuses on the length required to develop the in-service PT force within the pier segment grouted steel tube assembly. Seven, twelve, and nineteen 0.6Ã‚Â" diameter strand tendons with various development lengths were considered. Recommendations for pier section pipe detailing and design will be discussed.
Show less
Date Issued: 2010
Identifier: CFE0003363, ucf:48465
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003363

Title: COMPUTATIONAL HURRICANE HAZARD ANALYSIS-A PERFORMANCE BASED ENGINEERING VIEW.
Creator: Vanek, Christopher, Mackie, Kevin, University of Central Florida
Abstract / Description: Widespread structural damage to critical facilities such as levees, buildings, dams and bridges during hurricanes has exemplified the need to consider multiple hazards associated with hurricanes as well as the potential for unacceptable levels of performance even if failure is not observed. These inadequate standards warrant the use of more accurate methods to describe the anticipated structural response, and damage for extreme events often termed performance based engineering (PBE)....
Show moreWidespread structural damage to critical facilities such as levees, buildings, dams and bridges during hurricanes has exemplified the need to consider multiple hazards associated with hurricanes as well as the potential for unacceptable levels of performance even if failure is not observed. These inadequate standards warrant the use of more accurate methods to describe the anticipated structural response, and damage for extreme events often termed performance based engineering (PBE). Therefore PBE was extended into the field of hurricane engineering in this study. Application of performance-based principles involves collection of the numerous hazards data from sources such as historical records, laboratory experiments or stochastic simulations. However, the hazards associated with a hurricane typically include spatial and temporal variation therefore, more detailed collection of data from each hazard of this loading spectrum is required. At the same time, computational power and computer-aided design have advanced and potentially allows for collection of the structure-specific hazard data. This novel technique, known as computational fluid dynamics (CFD), was applied to the wind and wave hazards associated with hurricanes to accurately quantify the spectrum of dynamic loads in this study. Numerical simulation results are presented on verification of this technique with laboratory experimental studies and further application to a typical Florida building and bridge prototype. Both the time and frequency domain content of random process signals were analyzed and compared through basic properties including the spectral density, autocorrelation, and mean. Following quantification of the dynamic loads on each structure, a detailed structural FEM was constructed of each structure and response curves were created for various levels of hurricane categories. Results show that both the time and frequency content of the dynamic signal could be accurately captured through CFD simulations in a much more cost effective manner than laboratory experimentation. Structural FEM models showed the poor performance of two coastal structures designed using deterministic principles, as serviceability and strength limit states were exceeded. Additionally, the response curves created for the prototype structure could be further developed for multiple wind directions and wave periods. Thus CFD is a viable option to wind and wave laboratory studies and a key tool for the development of PBE in the field of hurricane engineering.
Show less
Date Issued: 2010
Identifier: CFE0003491, ucf:48963
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003491

Title: RESPONSE SENSITIVITY OF HIGHWAY BRIDGES TO RANDOM MULTI-COMPONENT EARTHQUAKE EXCITATION.
Creator: Cronin, Kyle, Mackie, Kevin, University of Central Florida
Abstract / Description: Highway bridges provide a critical lifeline during extreme seismic events and must maintain serviceability under a large range of earthquake intensities. Consequently, the advent of more computational power has allowed more advanced analysis approaches for predicting performance and vulnerability of highway bridges under these seismic loads. In traditional two-dimensional finite element analyses, it has been demonstrated that the incidence angle of the ground motion can play a significant...
Show moreHighway bridges provide a critical lifeline during extreme seismic events and must maintain serviceability under a large range of earthquake intensities. Consequently, the advent of more computational power has allowed more advanced analysis approaches for predicting performance and vulnerability of highway bridges under these seismic loads. In traditional two-dimensional finite element analyses, it has been demonstrated that the incidence angle of the ground motion can play a significant role in structural response. As three-dimensional nonlinear time history analyses are used more frequently in practice, ground motions are still usually applied along a single bridge axis. It is unknown how three orthogonal components of ground motion excitation should be applied to the structure to best represent the true response. In this study, the fundamental behavior of three-dimensional ground motion was studied using single-degree-of-freedom elastic spectra. Mean spectra computed from various orientation techniques were found indistinguishable when the orthogonal components were combined. The effect of incidence angle on the nonlinear structural response of highway bridges was then investigated through extensive statistical simulation. Three different bridge models were employed for this study implementing a suite of 180 multi-component ground motion records of various magnitude-distance-soil bins. Probabilistic seismic demand models for various response parameters are presented comparing the effects of random incidence angle to that of recorded directions. Although there are instances where the angle of incidence can significantly amplify response, results indicated that incidence angle had negligible effect on average ensemble response. This is consistent with results from the spectral analysis, although existing literature has emphasized incidence angle as a significant parameter of multi-component analysis.
Show less
Date Issued: 2009
Identifier: CFE0002933, ucf:47973
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002933

Title: ON THE USE OF POLYURETHANE MATRIX CARBON FIBER COMPOSITES FOR STRENGTHENING CONCRETE STRUCTURES.
Creator: Haber, Zachary, Mackie, Kevin, University of Central Florida
Abstract / Description: Fiber-reinforced polymer (FRP) composite materials have effectively been used in numerous reinforced concrete civil infrastructure strengthening projects. Although a significant body of knowledge has been established for epoxy matrix carbon FRPs and epoxy adhesives, there is still a need to investigate other matrices and adhesive types. One such matrix/adhesive type yet to be heavily researched for infrastructure application is polyurethane. This thesis investigates use of polyurethane matrix...
Show moreFiber-reinforced polymer (FRP) composite materials have effectively been used in numerous reinforced concrete civil infrastructure strengthening projects. Although a significant body of knowledge has been established for epoxy matrix carbon FRPs and epoxy adhesives, there is still a need to investigate other matrices and adhesive types. One such matrix/adhesive type yet to be heavily researched for infrastructure application is polyurethane. This thesis investigates use of polyurethane matrix carbon fiber composites for strengthening reinforced concrete civil infrastructure. Investigations on mirco- and macro-mechanical composite performance, strengthened member flexural performance, and bond durability under environmental conditioning will be presented. Results indicate that polyurethane carbon composites could potentially be a viable option for strengthening concrete structures.
Show less
Date Issued: 2010
Identifier: CFE0003073, ucf:48307
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003073

Title: FLEXURAL MECHANICAL DURABILITY OF CONCRETE BEAMS STRENGTHENED BY EXTERNALLY BONDED CARBON FIBER REINFORCED POLYMER SHEETS.
Creator: Olka, Michael, Mackie, Kevin, University of Central Florida
Abstract / Description: About 77,600 bridges throughout the United States in the Federal Highway Association (FHWA) bridge database are listed as structurally deficient. This has created a need to either replace or strengthen bridges quickly and efficiently. Due to high costs for total replacement of deficient bridges, strengthening of existing bridges is a more economical alternative. A technique that has been developing over the past two decades is the strengthening of bridges using carbon fiber reinforced polymer...
Show moreAbout 77,600 bridges throughout the United States in the Federal Highway Association (FHWA) bridge database are listed as structurally deficient. This has created a need to either replace or strengthen bridges quickly and efficiently. Due to high costs for total replacement of deficient bridges, strengthening of existing bridges is a more economical alternative. A technique that has been developing over the past two decades is the strengthening of bridges using carbon fiber reinforced polymer (CFRP) sheets. The CFRP sheets are attached to the bottom of the bridge girders using structural adhesives so that the CFRP becomes an integral part of the bridge and carries a portion of the flexural loading. The CFRP sheets allow for an increase in the capacity of the bridge with minimal increase in the weight of the structure due to CFRP having a low density. Because the CFRP is expected to be an integral component and carry some of the long-term loading it is important to understand the long-term durability of the composite section. This thesis is part of a larger project, in which the long-term durability of the CFRP composite on concrete beams is investigated experimentally. The CFRP strengthened beams are exposed to fatigue testing and thermal-humidity cycling followed by failure testing. The testing scheme for this experiment allows for the investigation of the individual effects of fatigue and thermal-humidity loading as well as to explore the effects from combined fatigue and thermal-humidity loading. The investigation of the combined effects is a unique aspect of this experiment that has not been performed in prior studies. Results indicate that a polyurethane-based adhesive could provide a more durable bond for the CFRP-concrete interface than possible with epoxy-based adhesives.
Show less
Date Issued: 2009
Identifier: CFE0002585, ucf:48252
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002585

Title: ULTRA-HIGH PERFORMANCE FIBER REINFORCED CONCRETE IN BRIDGE DECKAPPLICATIONS.
Creator: Xia, Jun, Mackie, Kevin, University of Central Florida
Abstract / Description: The research presented in this dissertation focuses on the material characterization of ultrahigh performance fiber reinforced concrete (UHP-FRC) at both the microscopic and macroscopic scales. The macroscopic mechanical properties of this material are highly related to the orientation of the steel fibers distributed within the matrix. However, the fiber orientation distribution has been confirmed to be anisotropic based on the flow-casting process. The orientation factor and probability...
Show moreThe research presented in this dissertation focuses on the material characterization of ultrahigh performance fiber reinforced concrete (UHP-FRC) at both the microscopic and macroscopic scales. The macroscopic mechanical properties of this material are highly related to the orientation of the steel fibers distributed within the matrix. However, the fiber orientation distribution has been confirmed to be anisotropic based on the flow-casting process. The orientation factor and probability density function (PDF) of the crossing fiber (fibers crossing a cutting plane) orientation was obtained based on theoretical derivations and numerical simulations with respect to different levels of anisotropy and cut planes oriented arbitrarily in space. The level of anisotropy can be calibrated based on image analysis on cut sections from hardened UHP-FRC prisms. Simplified equations provide a framework to predict the mechanical properties based on a single fiber-matrix interaction rule selected from existing theoretical models. Along with the investigation of the impacts from different curing methods and available post-cracking models, a versatile parameterized uniaxial stress-strain constitutive model was developed and calibrated. The constitutive model was implemented in a finite element analysis software program, and the program was utilized in the preliminary design of moveable bridge deck panels made of passively reinforced UHP-FRC. This deck system was among the several alternatives to replace the problematic steel grid decks currently in use. Based on experimental investigations of the deck panels, failure occurred largely in shear rather than flexure during bending tests. However, this shear failure is not abrupt and usually involves large deformation, large sectional rotation, and wide shear cracks before loss of load-carrying capacity. This particular shear failure mode observed was further investigated numerically and experimentally. Three-dimensional FEM models with the ability to reflect the interaction between rebar and concrete were created in a commercial FEM software to investigate the load transfer mechanism before and after bond failure. Small-scale passively reinforced prisms were tested to verify the conclusions drawn from simulation results. In an effort to improve the original design, several shear-strengthened deck panels were tested and evaluated for effectiveness. Finally, methods and equations to predict the ultimate shear capacity were calibrated. A two-dimensional frame element based complete moveable bridge finite element model was built for observation of bridge system performance. The model contained the option to substitute any available deck system based on a subset of pre-calibrated parameters specific to each deck type. These alternative deck systems include an aluminum bridge deck system and a glass fiber reinforced plastic (GFRP) deck system. All three alternatives and the original steel grid deck system were evaluated based on the global responses of the moveable bridge, and the advantages and disadvantages of adopting the UHP-FRC deck system are quantified.
Show less
Date Issued: 2011
Identifier: CFE0003721, ucf:48803
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003721

Title: IMPACT OF HURRICANES ON STRUCTURES Ã‚Â– A PERFORMANCE BASED ENGINEERING VIEW.
Creator: Mishra, Vijay, Mackie, Kevin, University of Central Florida
Abstract / Description: The magnitude of damage caused to the United States (US) coast due to hurricanes has increased significantly in the last decade. During the period 2004-2005, the US experienced seven of the costliest hurricanes in the countryÃ‚Â's history (NWS TPC-5, 2007) leading to an estimated loss of ~ $158 billion. The present method for predicting hurricane losses, HAZUS (HAZard US), is solely based on hurricane hazard and damage caused to building envelopes only and not to...
Show moreThe magnitude of damage caused to the United States (US) coast due to hurricanes has increased significantly in the last decade. During the period 2004-2005, the US experienced seven of the costliest hurricanes in the countryÃ‚Â's history (NWS TPC-5, 2007) leading to an estimated loss of ~ $158 billion. The present method for predicting hurricane losses, HAZUS (HAZard US), is solely based on hurricane hazard and damage caused to building envelopes only and not to structural systems (Vickery et al., 2006). This method does not take into account an intermediate step that allows for better damage estimates, which is structural response to the hazards that in turn can be mapped to the damage. The focus of this study was to quantify the uncertainty in response of structures to the hurricane hazards associated with hurricanes from performance based engineering perspective. The study enumerates hazards associated with hurricanes events. The hazards considered can be quantified using a variety of measures, such as wind speed intensities, wave and surge heights. These hazards are quantified in terms of structural loads and are then applied to a structural system. Following that, structural analysis was performed to estimate the response from the structural system for given loads. All the possible responses are measured and they are fitted with suitable probability distribution to estimate the probability of a response. The response measured then can be used to understand the performance of a given structure under the various hurricane loads. Dynamic vs. static analysis was performed and results were compared. This will answer a few questions like, if there is any need to do both static and dynamic analysis and how hurricane loads affect the structural material models. This being an exploratory study, available resources, research, and models were used. For generation of annual or extreme values of hazard, various available wind speed, storm surge, and wave height models were studied and evaluated. The wind field model by Batts et al. (1980) was selected for generation of annual wind speed data. For calculation of maximum storm surge height, the Sea, Lake Overland Surges from Hurricane (SLOSH, Jelesnianski et al., 1992) program was used. Wave data was acquired from a National Oceanic and Atmospheric Administration (NOAA) database. The (extreme or annual) wind speed, surge height, and wave height generated were then fitted by suitable probability distributions to find the realizations of hazards and their probabilities. The distribution properties were calculated, correlations between the data were established, and a joint probability distribution function (PDF) of the parameters (wind speed, wave height, and storm surge) was generated. Once the joint distribution of extreme loads was established, the next step was to measure the dynamic response of the structural system to these hazards. To measure the structural response, a finite element model of three-story concrete frame were constructed. Time histories of wind load were generated from wind net pressure coefficients recorded in a wind tunnel test (Main and Fritz, 2006). Wave load time histories were generated using laboratory basin test (HawkeÃ‚Â's et al., 1993) wave height time history data and were converted into wave loads using BernoulliÃ‚Â's equation. Surge height was treated as a hydrostatic load in this analysis. These load time histories were then applied to the finite element model and response was measured. Response of the structural system was measured in terms of the mean and maximum displacements recorded at specific nodes of model. Response was calculated for loads having constant mean wind speed and surge/wave and different time histories. The dominant frequency in the wind load time histories was closer to the natural frequency of the structural model used than the dominant frequency in the wave height time histories. Trends in the response for various combinations of mean wind speed, wave height, and surge heights were analyzed. It was observed that responses are amplified with increase in the mean wind speed. Less response was measured for change in mean surge/wave height as the tributary area for wave forces was less compared to wind force. No increase in dynamic amplification factor was observed for increase in force time histories case.
Show less
Date Issued: 2010
Identifier: CFE0003162, ucf:48612
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003162

Title: Ultra-High Performance Concrete for Precast Seismic Bridge Column Connection.
Creator: Chan, Titchenda, Mackie, Kevin, Catbas, Necati, Chopra, Manoj, Bai, Yuanli, University of Central Florida
Abstract / Description: Accelerated bridge construction (ABC) utilizes prefabricated bridge elements constructed off-site, delivered, and assembled on-site to expedite construction time and reduce traffic disruption. ABC has been increasingly used for super- and sub-structure elements in low seismic regions. However, its application in medium and high seismic regions remain limited, particularly for precast columns where connections typically coincide with plastic hinge (PH) regions. Ultra-high performance concrete ...
Show moreAccelerated bridge construction (ABC) utilizes prefabricated bridge elements constructed off-site, delivered, and assembled on-site to expedite construction time and reduce traffic disruption. ABC has been increasingly used for super- and sub-structure elements in low seismic regions. However, its application in medium and high seismic regions remain limited, particularly for precast columns where connections typically coincide with plastic hinge (PH) regions. Ultra-high performance concrete (UHPC), characterized by high compressive and tensile strength, and superior bond properties, is a potential material that can mitigate PH damage and enhance load transfer. This research proposes a new and simple damage tolerant precast column connection for use in medium and high seismic regions. The connection laps the column longitudinal reinforcement with footing dowels using a short splice length, a practical concrete cover, no shear reinforcement, and the shifted PH concept to prevent footing damage. Two 0.42-scale precast columns with different shear span ratios were tested under reversed cyclic loading to investigate the proposed connection relative to previously tested cast-in-place specimens. Results showed the connection performed well in shear, developed column longitudinal bars, shifted PH formation above the UHPC connection, and exhibited high lateral capacity and ductility. Twenty-seven pullout and lap splice beams were tested to study the bond of reinforcement in UHPC under different parameters and stress states. Results indicated significant bond strength improvement and splice length reduction compared with conventional concrete. The pullout specimens were simulated using the OpenSees framework to propose reinforcing steel in UHPC bond-slip models where existing studies in the literature were limited. The models were incorporated into the numerical modeling of the precast columns using one-dimensional fiber-section and two-dimensional plane stress nonlinear analyses. Results from the two modeling methods showed good agreement with the experiments, with the calibrated bond-slip models providing a good representation of load transfer in the connection.
Show less
Date Issued: 2019
Identifier: CFE0007610, ucf:52534
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007610

Title: experimental and numerical investigations on bond durability of cfrp strengthened concrete members subjected to environmental exposure.
Creator: Al-Jelawy, Haider, Mackie, Kevin, Gou, Jihua, Chopra, Manoj, University of Central Florida
Abstract / Description: Fiber reinforced polymer (FRP) composites have become an attractive alternative to conventional methods for external-strengthening of civil infrastructure, particularly as applied to flexural strengthening of reinforced concrete (RC) members. However, durability of the bond between FRP composite and concrete has shown degradation under some aggressive environments. Although numerous studies have been conducted on concrete members strengthened with FRP composites, most of those studies have...
Show moreFiber reinforced polymer (FRP) composites have become an attractive alternative to conventional methods for external-strengthening of civil infrastructure, particularly as applied to flexural strengthening of reinforced concrete (RC) members. However, durability of the bond between FRP composite and concrete has shown degradation under some aggressive environments. Although numerous studies have been conducted on concrete members strengthened with FRP composites, most of those studies have focused on the degradation of FRP material itself, relatively few on bond behavior under repeated mechanical and environmental loading.This thesis investigates bond durability under accelerated environmental conditioning of two FRP systems commonly employed in civil infrastructure strengthening: epoxy and polyurethane systems. Five environments were considered under three different conditioning durations (3 months, 6 months, and 1 year). For each conditioning environment and duration (including controls), the following were laboratory tested: concrete cylinders, FRP tensile coupons, and FRP-strengthened concrete flexural members. Numerical investigations were performed using MSC MARC finite element software package to support the outcomes of durability experimental tests. Precise numerical studies need an accurate model for the bond between FRP and concrete, a linear brittle model is proposed in this work that is calibrated based on nonlinear regression of existing experimental lap shear data.Results of tensile tests on FRP coupons indicate that both epoxy and polyurethane FRP systems do not degrade significantly under environmental exposure. However, flexural tests on the FRP strengthened concrete beams indicate that bond between FRP and concrete shows significant degradation, especially for aqueous exposure. Moreover, a protective coating suppresses the measured degradation. Also, experimental load-displacement curves for control beams show excellent agreement with numerical load-displacement curves obtained using the proposed bond model. Finally, a bond-slip model is predicted for concrete leachate conditioned beams by matching load-displacement curves for those beams with numerical load-displacement curves.
Show less
Date Issued: 2013
Identifier: CFE0004971, ucf:49589
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004971

Title: Failure Analysis of Impact-Damaged Metallic Poles Repaired With Fiber Reinforced Polymer Composites.
Creator: Slade, Robert, Mackie, Kevin, Yun, Hae-Bum, Gou, Jihua, University of Central Florida
Abstract / Description: Metallic utility poles, light poles, and mast arms are intermittently damaged by vehicle collision. In many cases the vehicular impact does not cause immediate failure of the structure, but induces localized damage that may result in failure under extreme service loadings or can promote degradation and corrosion within the damaged region. Replacement of these poles is costly and often involves prolonged lane closures, service interruption, and temporary loss of functionality. Therefore, an in...
Show moreMetallic utility poles, light poles, and mast arms are intermittently damaged by vehicle collision. In many cases the vehicular impact does not cause immediate failure of the structure, but induces localized damage that may result in failure under extreme service loadings or can promote degradation and corrosion within the damaged region. Replacement of these poles is costly and often involves prolonged lane closures, service interruption, and temporary loss of functionality. Therefore, an in situ repair of these structures is required.This thesis examines the failure modes of damaged metallic poles reinforced with externally-bonded fiber reinforced polymer (FRP) composites. Several FRP repair systems were selected for comparison, and a set of medium and full-scale tests were conducted to identify the critical failure modes. The material properties of each component of the repair were experimentally determined, and then combined into a numerical model capable of predicting global response.Four possible failure modes are discussed: yielding of the unreinforced substrate, tensile rupture of the FRP, compressive buckling of the FRP, and debonding of the FRP from the substrate. It was found that simple linear, bilinear, and trilinear stress-strain relationships accurately describe the response of the composite and substrate components, whereas a more complex bond-slip relationship is required to characterize debonding. These constitutive properties were then incorporated into MSC.Marc, a versatile nonlinear finite element program. The output of the FEM analysis showed good agreement with the results of the experimental bond-slip tests.
Show less
Date Issued: 2012
Identifier: CFE0004262, ucf:49514
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004262

Title: Resilience of Bridges Following Aftershocks.
Creator: Espinosa, Diego, Mackie, Kevin, Chopra, Manoj, Tatari, Mehmet, University of Central Florida
Abstract / Description: The ability to predict the reduction in capacity of a structure after an earthquake is vital in the process of assessing a structure after a main-shock or an after-shock. Main-shocks are normally followed by a few aftershocks in a short period of time. Researchers in the past have focused for the most part on the effects of main-shocks on buildings. Very little research has been performed on the ability to predict the reduction in capacity of bridges in aftershocks. This thesis focuses on...
Show moreThe ability to predict the reduction in capacity of a structure after an earthquake is vital in the process of assessing a structure after a main-shock or an after-shock. Main-shocks are normally followed by a few aftershocks in a short period of time. Researchers in the past have focused for the most part on the effects of main-shocks on buildings. Very little research has been performed on the ability to predict the reduction in capacity of bridges in aftershocks. This thesis focuses on providing a way of assessing the reduction in capacity for main-shocks as compared to aftershocks and the effects and importance of both in a bridge. The reduction in capacity was defined using three different ratios: ultimate force, stiffness, and strain energy ratio. The ratios were computed relative to an undamaged state following both the main-shock scenario and the main-shock combined with aftershock scenario. The force, stiffness, and strain energy quantities were obtained from lateral pushover analyses along the two lateral bridge axes. Probabilistic demand models describing the loss in capacity were formulated by pairing intensity measures, based on real ground motions obtained from previous earthquakes, for the main-shock and aftershock with the capacity ratios, obtained from nonlinear dynamic time history analysis. Additionally, the reduction in capacity was conditioned on residual displacement and intensity measure in an attempt to discover the reduction in capacity ratio due to the contribution of residual displacement and therefore separate contributions from geometrical and material nonlinearities. This thesis demonstrates that the usage of strain energy ratio provides a definition of capacity that ultimately provides the best correlation between capacity and intensity measure.
Show less
Date Issued: 2012
Identifier: CFE0004311, ucf:49494
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004311

Title: Performance of Mechanical and Non-mechanical Connections to GFRP Components.
Creator: Dike, Nnadozie, Mackie, Kevin, Gou, Jihua, Chopra, Manoj, University of Central Florida
Abstract / Description: There are presently many solutions to dealing with aging or deteriorated structures. Depending on the state of the structure, it may need to be completely over-hauled, demolished and replaced, or only specific components may need rehabilitation. In the case of bridges, rehabilitation and maintenance of the decks are critical needs for infrastructure management. Viable rehabilitation options include replacement of decks with aluminum extrusions, hybrid composite and sandwich systems, precast...
Show moreThere are presently many solutions to dealing with aging or deteriorated structures. Depending on the state of the structure, it may need to be completely over-hauled, demolished and replaced, or only specific components may need rehabilitation. In the case of bridges, rehabilitation and maintenance of the decks are critical needs for infrastructure management. Viable rehabilitation options include replacement of decks with aluminum extrusions, hybrid composite and sandwich systems, precast reinforced concrete systems, or the use of pultruded fiber-reinforced polymer (FRP) shapes. Previous research using pultruded glass fiber-reinforced polymer (GFRP) decks, focused on behaviour under various strength and serviceability loading conditions. Failure modes observed were specific to delamination of the flexural cross sections, local crushing under loading pads, web buckling and lip separation. However certain failure mechanisms observed from in-situ installations differ from these laboratory results, including behaviour of the connectors or system of connection, as well as the effect of cyclic and torsional loads on the connection.This thesis investigates the role of mechanical and non-mechanical connectors in the composite action and failure mechanisms in a pultruded GFRP deck system. There are many interfaces including top panel to I-beam, deck panel to girder, and panel to panel, but this work focuses on investigating the top panel connection. This is achieved through comparative component level shear, uplift, and flexure testing to characterize failure and determine connector capacity. Additionally, a connection of this GFRP deck system to a concrete girder is investigated during the system-level test. Results show that an epoxy non-mechanical connection may be better than mechanical options in ensuring composite behaviour of the system.
Show less
Date Issued: 2012
Identifier: CFE0004371, ucf:49413
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004371

Title: Cyclic and Impact Resistance of FRP Repaired Poles.
Creator: Mohsin, Zainab, Mackie, Kevin, Makris, Nicos, Nam, Boo Hyun, University of Central Florida
Abstract / Description: Sign and signal structures involved in vehicular accidents are often partially damaged, and it ispossible to repair them instead of replacing them, even when the extent and severity of the damageare substantial. The replacement of these poles is costly and involves interruption for pedestriansand traffic. Therefore, some trials were performed to retrofit these poles in-situ with low cost andshort time. Previous research has substantiated that the damage can decrease the strength of thethese...
Show moreSign and signal structures involved in vehicular accidents are often partially damaged, and it ispossible to repair them instead of replacing them, even when the extent and severity of the damageare substantial. The replacement of these poles is costly and involves interruption for pedestriansand traffic. Therefore, some trials were performed to retrofit these poles in-situ with low cost andshort time. Previous research has substantiated that the damage can decrease the strength of thethese structures with increasing the dent depth and the use of externally-bonded fiber-reinforcedpolymer (FRP) composites are beneficial to repair them. The composite systems were comprisedof glass or basalt fibers paired with epoxy or polyurethane matrices. The effectiveness of FRPin repairing the damaged poles was demonstrated in previous tests on dented poles using 3-point,4-point, and cantilever bending tests. The repair systems were able to develop the load carryingcapacity of the damaged poles, and their behaviors were controlled by various types of failuremodes like yielding of the metallic substrate, FRP tensile rupture, FRP compressive buckling, anddebonding of FRP from the substrate.This thesis investigates the resistance of repaired full-scale metallic poles retrieved from the fieldfor monotonic, cyclic, and impact loading. These poles, which have rounded and multi-sided crosssections with and without access ports, were dented in the field or dented mechanically in thelaboratory and repaired with the same repair systems mentioned previously. Six of these poleswere mounted horizontally in a cantilever configuration to test them monotonically, while three ofthem were tested cyclically. In both tests, the load was applied as a point load at 9 ft from the baseplate. Additionally, two poles were mounted vertically using a cantilever configuration to test themfor impact. This test was performed by hitting the poles using an impact pendulum with a 1100 kgmass.The results of static tests show that the repair systems failed because of the aforementioned failuremodes. However, most of the failure was located outside the dented region, which indicates theeffectiveness of these repair systems in restoring the capacity of the damaged area. During thefatigue tests, the repair experienced no damage before weld rupture in the original steel tube-baseplate connection. Moreover, the repair systems proved their effectiveness in resisting the impactload, because they were ruptured at the contact region between the pole and the impactor at thetime the poles were deformed at the free side of the poles, as well as the impact side, during thetest.In all these tests, the access ports affected the behavior of the repaired poles. Depending on thegeometry of the pole, metal substrate, and dent depth and location, FRP repair system recommendationswill be presented.
Show less
Date Issued: 2015
Identifier: CFE0005846, ucf:50936
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005846

Title: Development of a Chemical Kinetic Model for a Fluidized-bed Sewage Sludge Gasifier.
Creator: Champion, Wyatt, Cooper, Charles, Mackie, Kevin, Randall, Andrew, University of Central Florida
Abstract / Description: As the need for both sustainable energy production and waste minimization increases, the gasification of biomass becomes an increasingly important process. What would otherwise be considered waste can now be used as fuel, and the benefits of volume reduction through gasification are seen in the increased lifespan of landfills. Fluidized-bed gasification is a particularly robust technology, and allows for the conversion of most types of waste biomass.Within a fluidized-bed gasifier, thermal...
Show moreAs the need for both sustainable energy production and waste minimization increases, the gasification of biomass becomes an increasingly important process. What would otherwise be considered waste can now be used as fuel, and the benefits of volume reduction through gasification are seen in the increased lifespan of landfills. Fluidized-bed gasification is a particularly robust technology, and allows for the conversion of most types of waste biomass.Within a fluidized-bed gasifier, thermal medium (sand) is heated to operating temperature (around 1350(&)deg;F) and begins to fluidize due to the rapid expansion of air entering the bottom of the reactor. This fluidization allows for excellent heat transfer and contact between gases and solids, and prevents localized (")hot spots(") within the gasifier, thereby reducing the occurrence of ash agglomeration within the gasifier. Solids enter the middle of the gasifier and are rapidly dried and devolatilized, and the products of this step are subsequently oxidized and then reduced in the remainder of the gasifier. A syngas composed mainly of N2, H2O, CO2, CO, CH4, and H2 exits the top of the gasifier.A computer model was developed to predict the syngas composition and flow rate, as well as ash composition and mass flow rate from a fluidized-bed gasifier. A review of the literature was performed to determine the most appropriate modeling approach. A chemical kinetic model was chosen, and developed in MATLAB using the Newton-Raphson method to solve sets of 18 simultaneous equations. These equations account for mass and energy balances throughout the gasifier. The chemical kinetic rate expressions for these reactions were sourced from the literature, and some values modified to better fit the predicted gas composition to literature data.
Show less
Date Issued: 2013
Identifier: CFE0005089, ucf:50746
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005089

Title: Fiber-Reinforced Polymer (FRP) Composites in Retrofitting of Concrete Structures: Polyurethane Systems Versus Epoxy Systems.
Creator: El Zghayar, Elie, Mackie, Kevin, Catbas, Necati, Chopra, Manoj, University of Central Florida
Abstract / Description: Fiber reinforced polymer (FRP) composites have been of interest to the structural engineering society since the earliest days of FRP composites industry. The use of such systems has been implemented in both new construction and for repair and rehabilitation of existing structures. Since the 1980s, researchers have developed a significant body of knowledge to use FRP composites in infrastructure applications; however, most of this established knowledge was concentrated on the use of...
Show moreFiber reinforced polymer (FRP) composites have been of interest to the structural engineering society since the earliest days of FRP composites industry. The use of such systems has been implemented in both new construction and for repair and rehabilitation of existing structures. Since the 1980s, researchers have developed a significant body of knowledge to use FRP composites in infrastructure applications; however, most of this established knowledge was concentrated on the use of traditional epoxy (EP) systems (epoxy matrix FRPs and epoxy adhesives). FRP composites with polyurethane (PU) matrices and adhesives have recently attracted the attention of a few researchers due to their potential advantages in constructibility and mechanical properties. The deployment of these systems is currently limited by a lack of knowledge on mechanical and durability performance. The objective of this research is to quantify the mechanical behavior of PU composites utilized in externally-bonded repair of common flexural and flexural-axial reinforced concrete systems. In addition, the mechanical performance, strength, and failure modes are compared directly with an epoxy-based composite by subjecting reinforced concrete specimens utilizing each of the matrix types (EP and PU) to the same protocols. The study presented therefore allows an objective comparison (advantages and disadvantages) between the two composite system used for repair and rehabilitation of concrete infrastructure. An experimental research program was designed with different length scales. Small-scale experiments were utilized to characterize the component level properties of the materials and bond to concrete, which include the flexural behavior as well as the pure shear behavior. The results of these small scale experiments were used to calibrate analytical models of the interface behavior between FRP laminate and concrete, and paved the way for the next level of the research which studied the behavior of each composite system at larger scales. The large scale experiments included flexural retrofitting of reinforced concrete girders and retrofitting of circular columns using FRP laminates. The large-scale experimental specimens were mechanically damaged prior to FRP repair and testing, making the testing more appropriate compared to common practice of repairing undamaged specimens.
Show less
Date Issued: 2015
Identifier: CFE0005942, ucf:50820
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005942

Title: Effect of Load Path and Failure Modes on Seismic Response of Regular Bridges.
Creator: Darwash, Haider, Mackie, Kevin, Chopra, Manoj, Makris, Nicos, Bai, Yuanli, University of Central Florida
Abstract / Description: Bridges are essential infrastructure constituents that have been studied for centuries. Typically,seismic bridge design and assessment utilize simplified modeling and analysis techniques basedon one-dimensional spine elements and zero-length springs/hinges. The geometry of the elementsand calibration of parameters are based on assumptions for the lateral load path and failure modes,e.g., sacrificial backwall and shear keys, neglecting wing walls, and strength based on backfillalone. These...
Show moreBridges are essential infrastructure constituents that have been studied for centuries. Typically,seismic bridge design and assessment utilize simplified modeling and analysis techniques basedon one-dimensional spine elements and zero-length springs/hinges. The geometry of the elementsand calibration of parameters are based on assumptions for the lateral load path and failure modes,e.g., sacrificial backwall and shear keys, neglecting wing walls, and strength based on backfillalone. These assumptions have led to observations of underestimated resistance, overestimateddisplacement demands, and unpredicted damage and failure mode. The focus of the study is onordinary standard bridges with continuous reinforced concrete box girder superstructures and seattypeabutments.A bridge component calibration study was conducted first using simplified (spine models with 1Delements and springs) and three-dimensional nonlinear continuum finite element models (FEM).Model responses were compared with experimental results to identify the drawbacks in the simplifiedmodels and verify the adequacy of the material nonlinearities and analysis procedures. Thecomponents include a T-girder, abutment backfill, abutment shear key, elastomeric bearing pad,and a bridge pier. Results show the simplified models do not capture damage propagation andfailure mode in the shear key case, nonlinear behaviors in beams with high aspect ratios (or deepbeam action), and underestimate the strength and overestimate the stiffness for the backfill case.The component models (both simplified and continuum) were then used in studying the nonlinearstatic behaviors of key bridge lateral-load resisting substructures, namely abutments and bents.For the abutment subsystem, cases with and without backfill and several back wall constructionjoint configurations for the longitudinal direction, with monolithic shear key and shear key withconstruction joint for the transverse direction, and boundary conditions in the transverse direction were considered. Abutment subsystem results showed simplified models underestimate the resistanceby 10-60%, neglect back wall and wing wall structural contributions, and localize damagein the back fill relative to the continuum models. For the bent subsystem, a full bridge systemthat considers material nonlinearity and damage in the bent segment only was adopted to determinethe effect of the finite bent cap or superstructure-to-column connection. Inelastic behaviorand damage was included in the columns, bent cap, and a superstructure segment with a lengththat correspond to the dead load moment inflection point. The other superstructure segments andthe pile cap were modeled as elastic. Bent subsystem results showed simplified models overestimatethe stiffness, induce excessive flexibility and deformation in the cap beam, and overestimatecolumns' deformations.Due to the differences observed in the abutment subsystem, and the potential impact of the abutmentbehavior on the seismic response of the whole bridge system, dynamic studies on the bridgesystem were conducted using four abutment parameters: abutment stiffness and strength in eachof the longitudinal and transverse directions. Two models were developed to conduct nonlineartime history analysis: an equivalent single-degree-of-freedom (SDOF) model for each of the longitudinaland transverse directions, and a 3D spine bridge model. Constant ductility analyses wereconducted using the SDOF systems, while standard probabilistic seismic demand analysis wasused on the spine systems.Results revealed that, besides the columns yielding, the abutment has an early and significant contributionto the behavior. The SDOF system results showed that increasing the abutment stiffnessor strength reduces the system displacement demand and increases the system forces. The consequenceof such increase in the forces is mobilizing significant amount of force in the abutments,causing inelastic response. The full bridge study also confirmed the SDOF results and showedthat the abutment forces are more than 200% of the columns forces that would result in the sameaftereffect observed in the SDOF system.
Show less
Date Issued: 2017
Identifier: CFE0006869, ucf:51759
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006869

Title: Shifted Plastic Hinge Column Connections Using Grouted Sleeves for Accelerated Bridge Construction.
Creator: Al-Jelawy, Haider, Mackie, Kevin, Gou, Jihua, Chopra, Manoj, University of Central Florida
Abstract / Description: Accelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. ABC typically requires prefabricated elements joined with mechanical couplers. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast elements. However, previous research identified some performance issues with precast columns employing GS connections for seismic regions. Therefore, there is a need to develop improved connection details. This research...
Show moreAccelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. ABC typically requires prefabricated elements joined with mechanical couplers. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast elements. However, previous research identified some performance issues with precast columns employing GS connections for seismic regions. Therefore, there is a need to develop improved connection details. This research consists of three components; testing of six large-scale precast reinforced concrete column models, a series of individual component tests on GS bar splices, and analytical studies. Large-scale, precast column models were designed and experimentally tested using a shifted plastic hinge (SPH) concept to minimize the damage in the capacity-protected elements and retain the column ductility. The column testing matrix considered aspect ratio, moment gradient, and splicing details. Column models were tested in an upright cantilever configuration under quasi-static cyclic load. Results showed that SPH can be used for both flexural and flexural-shear columns. Two types of component tests were performed: tensile tests to quantify the tensile behavior of the splices, and strain penetration tests to quantify the slip at the sleeve ends. The tests were used to obtain constitutive models for the bond-slip behavior of the GS splices.Results showed that GS splices developed the full ultimate stress of the spliced bars and that the slip at sleeve ends can considerably influence the global behavior of the precast columns. The analytical models were developed in OpenSees using fiber-based beams models and they incorporated the calibrated bond-slip models of GS splices. The large-scale column tests were simulated and compared with respective experimental results. Analytical results showed that the developed models were able to mimic the column behavior and can be used for analysis of GS precast columns.
Show less
Date Issued: 2017
Identifier: CFE0006851, ucf:51739
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006851

Title: hydro-thermo-mechanical behavior of concrete at elevated temperatures.
Creator: Al Fadul, Manar, Mackie, Kevin, Makris, Nicos, Chopra, Manoj, Kar, Aravinda, University of Central Florida
Abstract / Description: In the light of recent tragic events, such as, natural disasters, arson and terrorism, studying the thermo mechanical behavior of concrete at elevated temperatures has become of special concern. In addition, the fact that concrete has been widely used as a structural material in many critical applications, such as high rise buildings, pressure vessels, and nuclear plants, enhances the potential risk of exposing concrete to high temperatures. Accordingly, the potential damage to large-scale...
Show moreIn the light of recent tragic events, such as, natural disasters, arson and terrorism, studying the thermo mechanical behavior of concrete at elevated temperatures has become of special concern. In addition, the fact that concrete has been widely used as a structural material in many critical applications, such as high rise buildings, pressure vessels, and nuclear plants, enhances the potential risk of exposing concrete to high temperatures. Accordingly, the potential damage to large-scale structures during the course of the fire, besides the possible loss of human life, emphasizes the necessity to better understand the thermo-structural behavior and failure mechanism of concrete exposed to elevated temperatures. In this study, a one-dimensional model that describes coupled heat and mass transfer phenomena in heated concrete was developed. The mathematical model is based on the fully implicit finite difference scheme. The control volume approach was employed in the formulation of the finite difference equations. The primary variables considered in the analysis are temperature, vapor density, and pore pressure of the gaseous mixture. Several phenomena have been taken into account, such as evaporation, condensation, and dehydration process. Temperature, pressure, and moisture dependent properties of both gaseous and solid phases were also considered. Moreover, the proposed model is capable of predicting pore pressure values with a sufficient accuracy, which could be significantly important for the prediction of spalling and fire resistance of concrete. The two dimensional coupled heat and mass transfer problem was then studied by extending the proposed one dimensional model so that it can be applicable in solving two-dimensional problems. Output from the numerical model showed that the maximum values of temperature, pressure, and moisture content occur in the corner zone of the concrete cross section, in which the pore pressure builds up right next to the moisture pocket towards the center. In addition, the model demonstrates the capability to solve the coupled problem in situations involving non symmetric boundary conditions, in which conducting a one dimensional analysis is of no use. The contour plots of the temperature, pressure, and moisture were also presented.Simulation results clearly indicate the capability of the proposed model to capture the complex behavior of the concrete exposed to elevated temperatures in two dimensional systems and to adequately predict the coupled heat and mass transfer phenomena of the heated concrete over the entire flow domain. In order to predict the structural behavior of reinforced concrete members exposed to elevated temperatures, a three-dimensional fiber beam model was developed in this study to compute the mechanical responses of reinforced concrete structures at elevated temperatures by using the well-known sectional analysis approach. The temperature distributions obtained from the two-dimensional coupled heat and mass transfer analysis were used as an input to the strength analysis. The model also accounts for the various strain components that might generate in concrete and steel due to the effect of high temperatures. The constitutive models that describe the structural behavior of concrete and steel at elevated temperatures were also presented. In order to establish the validity of the proposed fiber model, a sequentially coupled thermo mechanical analysis was implemented, in which the model predictions were compared against measured data from tests with good qualitative agreement. The developed model can be considered as an efficient and powerful tool to promptly assess the structural behavior and the integrity of the structure during emergency situations, such as fire events.
Show less
Date Issued: 2017
Identifier: CFE0006551, ucf:51340
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006551

Title: Role of Force Resultants Interaction on Fiber Reinforced Concrete.
Creator: Chan, Titchenda, Mackie, Kevin, Catbas, Necati, Makris, Nicos, University of Central Florida
Abstract / Description: Ultra-high performance concrete (UHPC) is a recently developed concrete gaining a lot of interest worldwide, and a lot research has been conducted to determine its material properties. UHPC is known for its very high strength and high durability. Association Francaise de Genie Civil (AFGC) has defined UHPC as a concrete exhibiting compressive strength greater than 150 MPa (22 ksi). To utilize the full compressive strength of UHPC, complementary tension reinforcement is required. A recent...
Show moreUltra-high performance concrete (UHPC) is a recently developed concrete gaining a lot of interest worldwide, and a lot research has been conducted to determine its material properties. UHPC is known for its very high strength and high durability. Association Francaise de Genie Civil (AFGC) has defined UHPC as a concrete exhibiting compressive strength greater than 150 MPa (22 ksi). To utilize the full compressive strength of UHPC, complementary tension reinforcement is required. A recent research study to find light weight yet high strength alternative deck systems for Florida movable bridges demonstrated that a composite UHPC and high strength steel (HSS) reinforcement deck system is a viable alternative. However, failure modes of the deck system observed during experimental testing were shear failures rather than flexural failures. Interestingly, the shear failures were ductile involving large deformations and large sectional rotations.The purpose of this research is to quantify the sensitivity of UHPC structural member mechanical response to different shear and normal stress demands, and investigate the underlying failure modes. An experimental investigation on small-scale prisms without reinforcement, prisms reinforced with ASTM Grade 60 steel, and prisms reinforced with high strength steel was carried out to capture load-deflection behavior as well as modes of failure of the UHPC specimens. Numerical analysis based on modified compression field theory (MCFT) was developed to verify experimental results at the section level, and further verification using continuum methods was performed using MCFT/DSFM (disturbed stress field method) based finite element analysis software (VecTor2).Results from the numerical analysis could reasonably predict the load-displacement as well as the failure modes of the experimental specimens. Obvious flexural failure was observed on unreinforced UHPC specimens where wide crack opening gradually widened at the bottom fiber of the concrete to the loading position. Whereas UHPC-Grade 60 steel specimens experienced ductile flexural failure with similar wide crack opening after the rebar yielded. On the other hand, UHPC-MMFX specimens largely failed in shear from a diagonal tension crack and crush of concrete top fiber.
Show less
Date Issued: 2014
Identifier: CFE0005471, ucf:50394
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005471

Bridges (4)	+ -
FRP (3)	+ -
bond (3)	+ -
composite (3)	+ -
Accelerated bridge construction (2)	+ -

Composites (2)	+ -
Structural Health Monitoring (2)	+ -
Structural Identification (2)	+ -
deck (2)	+ -
durability (2)	+ -
fatigue (2)	+ -
finite element (2)	+ -
shifted plastic hinge (2)	+ -
AERMOD (1)	+ -
Abutment components (1)	+ -
Active Traffic Management (1)	+ -
Advanced Traveler Information Systems (1)	+ -
Aftershocks (1)	+ -
Anchor head (1)	+ -
Anchorage (1)	+ -
Angle (1)	+ -
Blind Source Seperation (1)	+ -
Bond (1)	+ -
Bond-Slip (1)	+ -
Boudouard (1)	+ -
Bridge (1)	+ -
Buffering Distance (1)	+ -
C & D (1)	+ -
C and D (1)	+ -
CFD (1)	+ -

Mackie, Kevin (35)	+ -
University of Central Florida (35)	+ -
Chopra, Manoj (13)	+ -
Catbas, Necati (8)	+ -
Makris, Nicos (7)	+ -

Gou, Jihua (6)	+ -
Yun, Hae-Bum (5)	+ -
Nam, Boo Hyun (3)	+ -
Al-Jelawy, Haider (2)	+ -
Bai, Yuanli (2)	+ -
Catbas, Fikret (2)	+ -
Chan, Titchenda (2)	+ -
Cooper, Charles (2)	+ -
El Zghayar, Elie (2)	+ -
Kapat, Jayanta (2)	+ -
Kauffman, Jeffrey L. (2)	+ -
Randall, Andrew (2)	+ -
Tatari, Mehmet (2)	+ -
Abdel-Aty, Mohamed (1)	+ -
Aghagholizadeh, Mehrdad (1)	+ -
Ahmed, Mohamed (1)	+ -
Al Fadul, Manar (1)	+ -
Al Rumaithi, Ayad (1)	+ -
Al-Deek, Haitham (1)	+ -
Al-Labban, Salama (1)	+ -
Al-Lebban, Yasir (1)	+ -
Al-Ramahee, Munaf (1)	+ -
Behal, Aman (1)	+ -
Bolyard, Steven (1)	+ -
Canon, Ornan (1)	+ -

Search In

Pages

Pages

Sort Results By:

Narrow results by:

Topical Subject

Collection

Type of Resource

Language

Creator

Format

Owner