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Shear Strengthening Reinforced Concrete Bridge Girders Using Near Surface Mounted Titanium Alloy Bars
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Book Synopsis Shear Strengthening Reinforced Concrete Bridge Girders Using Near-surface Mounted Titanium Alloy Bars by : Jonathan Knudtsen
Download or read book Shear Strengthening Reinforced Concrete Bridge Girders Using Near-surface Mounted Titanium Alloy Bars written by Jonathan Knudtsen and published by . This book was released on 2016 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aging and deficient infrastructure has become a major problem throughout the world. This is particularly evident in the case of reinforced concrete (RC) bridges. The cost of replacing these bridges is often prohibitive, thus engineers must find ways to strengthen them. Many older RC bridges predate the modern understanding of shear behavior in girders, and were built with insufficient internal transverse reinforcement. These bridge girders often exhibit diagonal-tension cracks in the high-shear zones near the supports. One method commonly used to strengthen RC bridge girders is called near-surface mounting (NSM), which involves cutting vertical grooves into the concrete and adhesively bonding supplemental reinforcing. Although this method was first developed for use with steel bars, it is now most commonly implemented using carbon fiber rods, as steel bars near the concrete surface can corrode. The objective of this research was to investigate the use of titanium alloy bars as a viable alternative to steel and carbon fiber for NSM shear strengthening applications. The titanium alloy has several advantages over the other materials. It is insensitive to corrosion, it can be bent to provide mechanical anchorages at the ends, and it exhibits high strength and elongation on par with conventional reinforcing steel. These properties allow the use of small diameter bars, which can reduce installation costs. For the research program, seven realistically proportioned T-shaped reinforced concrete girders were constructed, and then strengthened with NSM titanium alloy bars. The specimens were tested to failure under four-point bending. Both positive and negative moment sections were investigated. Two commercially available epoxies were used to bond the titanium alloy bars. The test results showed that the titanium alloy bars yielded prior to failure. The hooks maintained the force in the bars even after the loss of bond along the length of the titanium alloy bars. Two specimens with different epoxies were subjected to simultaneously applied high-cycle fatigue and freeze-thaw cycles before being tested to failure. One of the specimens exhibited reduced strength, indicating the importance of proper selection of the epoxy used to bond the titanium alloy bars to the concrete. The experimental results were compared with code models, and it was determined that the present design specifications can conservatively be used to predict the strength of RC bridge girders strengthened for shear using NSM titanium alloy bars.
Book Synopsis Guide for Design and Construction of Near-surface Mounted Titanium Alloy Bars for Strengthening Concrete Structures by :
Download or read book Guide for Design and Construction of Near-surface Mounted Titanium Alloy Bars for Strengthening Concrete Structures written by and published by . This book was released on 2020 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: This guide provides design and construction recommendations for strengthening existing reinforced concrete structures with titanium alloy bars (TiABs), using the near-surface mounted (NSM) construction method. The overall approach and organization of the guide are based on those presented in ACI 440.2R. Design recommendations provided for shear and flexural strengthening are based on and adapted from the AASHTO LRFD Bridge Design Specifications. The recommendations are supported by experimental and analytical research, as well as field experiences that have demonstrated the application of TiABs for strengthening full-scale specimens typical of bridge girders. The available experimental evidence includes the influences of combined high-cycle fatigue and environmental durability on the structural performance of NSM-TiAB–strengthened girders.--AASHTO website
Book Synopsis Strength and Durability of Near-surface Mounted CFRP Bars for Shear Strengthening Reinforced Concrete Bridge Girders by : Jacob Hans Goebel
Download or read book Strength and Durability of Near-surface Mounted CFRP Bars for Shear Strengthening Reinforced Concrete Bridge Girders written by Jacob Hans Goebel and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candidates for shear strengthening to extend their useful life. Carbon fiber reinforced polymers (CFRP) are emerging as effective materials for strengthening and rehabilitating such bridges. Near surface mounting (NSM) is a newer technique for application of CFRP for retrofitting bridge members that provides advantages over other strengthening techniques. The technique is still new and uncertainties remain regarding strength, long-term durability, and design including the influence of member proportions, flexural reinforcing steel, and CFRP spacing. Bridge girders retrofitted with NSM-CFRP may be exposed to millions of load cycles and environmental conditions and the influence of these exposures on performance are not established. To address these issues, laboratory tests were performed on ten full-size reinforced concrete girders, representative of in-situ bridge members, to determine the performance of NSM-CFRP retrofitting for shear strengthening. One of the specimens was exposed to fatigue loading, two were subjected to environmental exposures, and one was subjected to combined environmental exposure and fatigue loading. Results indicated that NSM-CFRP retrofitting provided significant shear capacity increases, and the high-cycle fatigue and environmental exposures considered did not adversely affect the strength or behavior of the girders. Environmental exposures of some of the adhesives considered did show somewhat reduced performance; therefore, careful selection of materials is important to ensure performance over the expected lifetime. Recommendations for shear strength design with NSM-CFRP are made.
Book Synopsis Application of Titanium Alloy Bars for Strengthening Reinforced Concrete Bridge Girders in Flexure by : Eric Vavra
Download or read book Application of Titanium Alloy Bars for Strengthening Reinforced Concrete Bridge Girders in Flexure written by Eric Vavra and published by . This book was released on 2016 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structurally efficient and cost-effective solutions are needed to extend the service-life of deficient and aging highway infrastructure around the world. One critical need is to increase the flexural strength of older reinforced concrete (RC) structures to carry heavier and more frequent loads. Titanium alloy bars (TiAB) offer a new opportunity to strengthen such existing structures that has not previously been explored. Research on strengthening existing civil infrastructure using titanium alloy bars was undertaken in the laboratory through tests of full-scale RC bridge girders using two alternative strengthening techniques for flexure: near-surface mounting (NSM) and external unbonded reinforcement. The goals of this research were to determine fatigue effects and environmental durability of NSM TiABs and to investigate the behavior of RC girders strengthened with external unbonded TiAB reinforcement. The NSM retrofit technique involved cutting grooves into the concrete surface and bonding specially fabricated titanium alloy bars inside the grooves using structural epoxy. Original investigation of this novel technique was undertaken during previous research at Oregon State University and has since been installed on an existing bridge in the USA over a major interstate highway. However, the effects of long-term fatigue loading and environmental exposure on this technique are unknown and thus were investigated for this study by testing a similar retrofitted, full-scale RC girder as in the prior work but subjected to simultaneous fatigue and freeze-thaw cycles. It was determined that no significant changes in strength or stiffness were observed due to the combined fatigue and environmental effects compared to the companion specimen. The external unbonded reinforcement technique requires only drilling holes into the girder web. Smooth as-rolled TiABs with 90o hooks fabricated on the ends are not bonded along the length of the girder. To attach the bars to the girder, the hooks were anchored using one of two methods: epoxy bonded in the hook holes, or inserted entirely through the web and held in place with prestressing chucks. To investigate the effectiveness of the technique, two full-scale concrete girders were strengthened in the laboratory. Compared to a numerically modeled control specimen, strengthened girders exhibited significant increases in both ultimate strength and ductility with the prestressing chuck anchoring method showing considerable improvement over the epoxied hooks. However, due to the relatively low stiffness which results in large displacements and wide cracks, the technique is more suited for temporary strengthening necessitating rapid installation, such as after a seismic event, vehicle impact, or other such event.
Book Synopsis Strength and Durability of Near-surface Mounted CFRP Bars for Shear Strengthening Reinforced Concrete Bridge Girders by : Jacob Hans Goebel
Download or read book Strength and Durability of Near-surface Mounted CFRP Bars for Shear Strengthening Reinforced Concrete Bridge Girders written by Jacob Hans Goebel and published by . This book was released on 2012 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These aging bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candidates for shear strengthening to extend their useful life. Carbon fiber reinforced polymers (CFRP) are emerging as effective materials for strengthening and rehabilitating such bridges. Near surface mounting (NSM) is a newer technique for application of CFRP for retrofitting bridge members that provides advantages over other strengthening techniques. The technique is still new and uncertainties remain regarding strength, long-term durability, and design including the influence of member proportions, flexural reinforcing steel, and CFRP spacing. Bridge girders retrofitted with NSM-CFRP may be exposed to millions of load cycles and environmental conditions and the influence of these exposures on performance are not established. To address these issues, laboratory tests were performed on ten full-size reinforced concrete girders, representative of in-situ bridge members, to determine the performance of NSM-CFRP retrofitting for shear strengthening. One of the specimens was exposed to fatigue loading, two were subjected to environmental exposures, and one was subjected to combined environmental exposure and fatigue loading. Results indicated that NSM-CFRP retrofitting provided significant shear capacity increases, and the high-cycle fatigue and environmental exposures considered did not adversely affect the strength or behavior of the girders. Environmental exposures of some of the adhesives considered did show somewhat reduced performance; therefore, careful selection of materials is important to ensure performance over the expected lifetime. Recommendations for shear strength design with NSM-CFRP are made.
Book Synopsis Design and Environmental Performance of Near-surface Mounted Carbon Fiber Reinforced Polymer Strips for Shear Strengthening Reinforced Concrete Bridge Girders by : Jacob Hans Goebel
Download or read book Design and Environmental Performance of Near-surface Mounted Carbon Fiber Reinforced Polymer Strips for Shear Strengthening Reinforced Concrete Bridge Girders written by Jacob Hans Goebel and published by . This book was released on 2011 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the interstate expansion of the 1950s, many conventionally reinforced concrete deck girder bridges were built throughout the country. These now vintage bridges commonly exhibit diagonal cracking and rate inadequately for shear, thus they are candidates for shear strengthening to extend their useful life. Near-surface mounted (NSM) retrofitting is a promising new strengthening technique, but limited test data are available for carbon fiber reinforced polymer (CFRP) in shear strengthening making the long-term durability of NSM-CFRP unknown. This paper provides experimental results from realistic full-scale specimens strengthened with NSM-CFRP. Specimens were tested for shear strength and subjected to environmental exposures to assess long-term durability. Small cylinder specimens were tested to investigate relative performance of different adhesives on bond strength under different environmental exposures. Test results provide a better understanding of the NSM-CFRP shear behavior and strength. Recommendations for shear strength design with NSM-CFRP are made.
Book Synopsis Application of Titanium Alloy Bars for Strengthening Reinforced Concrete Bridge Girders (part B: Flexure) by : Eric Vavra
Download or read book Application of Titanium Alloy Bars for Strengthening Reinforced Concrete Bridge Girders (part B: Flexure) written by Eric Vavra and published by . This book was released on 2017 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Methods for Strengthening Reinforced Concrete Bridge Girders Containing Poorly Detailed Flexural Steel Using Near-surface Mounted Metallics by : Christopher C. Higgins
Download or read book Methods for Strengthening Reinforced Concrete Bridge Girders Containing Poorly Detailed Flexural Steel Using Near-surface Mounted Metallics written by Christopher C. Higgins and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Flexural Anchorage Performance and Strengthening on Negative Moment Regions Using Near-surface Mounted Retrofitting in Reinforced Concrete Bridge Girders by : Laura M. Barker
Download or read book Flexural Anchorage Performance and Strengthening on Negative Moment Regions Using Near-surface Mounted Retrofitting in Reinforced Concrete Bridge Girders written by Laura M. Barker and published by . This book was released on 2014 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large numbers of reinforced concrete deck girder (RCDG) bridges were built during the highway infrastructure boom of the 1950's. The advent of standardized deformed steel reinforcing bars during this time allowed for straight bar terminations in flexural tension regions. Designers of the time terminated reinforcing bars where they were no longer required by calculation and did not account for additional demands from the combination of shear and flexure. The design provisions of the time allowed higher shear stresses in the concrete than allowed in standards today which reduced the required quantity of transverse reinforcing steel. In addition, heavier trucks and higher traffic volumes on roadways today have greatly increased the service loading on these bridges. Engineers evaluating these older RCDG bridges often determine unsatisfactory load ratings due to flexural anchorage deficiencies in the girders, especially when the influence of shear is considered. These deficiencies result from inadequate capacity compared to current design standards due to poor cutoff details used in the initial design. Strengthening methods are necessary because comprehensive replacements of the large number of bridges are not economically feasible. Experimental research was conducted to evaluate the behavior of poorly detailed flexural anchorages and to develop methods to strengthen them. Realistic vintage girder specimens were constructed, retrofitted, instrumented, and tested to failure. The specimens reported in this thesis were full-scale inverted-T (IT) beams. Some of the specimens contained straight bar terminations crossing a preformed diagonal crack in the flexural tension region to investigate the influence of shear on the retrofit schemes. Instrumentation focused on measurement of the reinforcing steel stresses surrounding the diagonal crack and along the development length of the cutoff bars. Using results of past research to quantify the behavior of girders with straight-bar flexural anchorages in flexural tension regions, an innovative strengthening technique was developed using either near-surface mounted (NSM) stainless steel or titanium. Results from the NSM strengthening technique demonstrated the ability to delay or prevent flexural anchorage failures, with increased deformation capacities and increased strengths from 17% to 39% over baseline specimens. To show the success of this research and the immediate need for strengthened flexural anchorages, this research has already been implemented on a bridge in Mosier, Oregon. This groundbreaking research is described in detail in Appendix F.
Book Synopsis Methods for Strengthening Flexural Steel Details in Reinforced Concrete Bridge Girders Using a Near-surface Mounted Retrofitting Technique by : Deanna Amneus
Download or read book Methods for Strengthening Flexural Steel Details in Reinforced Concrete Bridge Girders Using a Near-surface Mounted Retrofitting Technique written by Deanna Amneus and published by . This book was released on 2014 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many older reinforced concrete deck girder (RCDG) bridges contain straight bar terminations of flexural reinforcement. Common bridge design practice of the 1950s did not consider the additional demands on the terminated bars from shear and flexure. Moreover, more stringent code specifications and heavier permit trucks contribute to the insufficient ratings and presence of diagonal cracks in RCDG bridges. Replacement of these bridges is not economically feasible and thus strengthening methods are necessary. The goal of this research was to investigate anchorage strengthening methods using full-scale vintage girder specimens. The specimens were constructed with a flexural anchorage deficiency by terminating two flexural bars that extended only one-third of their development length past a 45° preformed diagonal crack. A common flexural strengthening technique called near-surface mounting (NSM) was applied to T-specimens. Two metallic materials were selected for the NSM reinforcement: titanium and stainless steel. These materials were chosen because of their high strength, ductility, environmental durability, and ability to fabricate mechanical anchorages. This study found that the NSM strengthening technique with metallic materials increased the midspan displacement by at least 85%, and load capacity by at least 31% for each specimen. In addition, a case study was performed to simulate the positive moment anchorage strengthening of the Mosier Bridge in Oregon.
Download or read book ICSBE 2018 written by Ranjith Dissanayake and published by Springer. This book was released on 2019-08-06 with total page 635 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights current research and development in the area of sustainable built environments, currently one of the most important disciplines in civil engineering. It covers a range of topics, including sustainable construction and infrastructures, waste and wastewater management, enhanced sustainability, renewable and clean energy, sustainable materials and industrial ecology, building automation and virtual reality, and impact of climate change. As such it provides vital insights into responsible urbanization practices, and new tools and technologies in civil engineering that can mitigate the negative effects of the built environment.
Book Synopsis Building for the Future: Durable, Sustainable, Resilient by : Alper Ilki
Download or read book Building for the Future: Durable, Sustainable, Resilient written by Alper Ilki and published by Springer Nature. This book was released on 2023-07-04 with total page 1808 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the proceedings of the fib Symposium “Building for the future: Durable, Sustainable, Resilient”, held in Istanbul, Turkey, on 5–7 June 2023. The book covers topics such as concrete and innovative materials, structural performance and design, construction methods and management, and outstanding structures. fib (The International Federation for Structural Concrete) is a not-for-profit association whose mission is to develop at an international level the study of scientific and practical matters capable of advancing the technical, economic, aesthetic, and environmental performance of concrete construction.
Book Synopsis Shear Repair Methods for Conventionally Reinforced Concrete Girders and Deep Beams by :
Download or read book Shear Repair Methods for Conventionally Reinforced Concrete Girders and Deep Beams written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental and Numerical Evaluation of Rapid Post-tensioning of Damaged Reinforced Concrete Girders with Unbonded Near Surface Mounted Shape-memory Alloy Wires by : Arkabrata Sinha
Download or read book Experimental and Numerical Evaluation of Rapid Post-tensioning of Damaged Reinforced Concrete Girders with Unbonded Near Surface Mounted Shape-memory Alloy Wires written by Arkabrata Sinha and published by . This book was released on 2020 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: American Society of Civil Engineers (ASCE) classified 9.1% of the national bridges as structurally deficient in 2017. Several of the deficient concrete bridges have girder serviceability issues such as excessive cracking and deflection. Traditional external post-tensioning techniques involve high management of traffic costs and use of heavy construction equipment. To that end, a novel rapid post-tensioning technique using unbonded near-surface mounted shape-memory alloy (SMA) wires was herein evaluated. The suggested method relies on the intrinsic ability of the SMA to recover seemingly permanent deformation upon activation via heating. Mechanical characterization tests demonstrated that the SMA wires can generate 67 ksi of prestress. Within the range of SMA reinforcement ratios considered in this study (up to 0.17%), the structural-scale tests showed that post-tensioning of cracked reinforced concrete girders can reduce the crack width and residual midspan deflection by up to 370 ℗æm (74%) and 0.06 in. (49%), respectively, and increase the ultimate moment capacity up to 83 kip-ft (45%). Finite element model of post-tensioned girders was developed in a damage mechanics framework and was validated against experimental data - the predicted yield and ultimate moment of the strengthened girders were 14% less than those observed in the experiments. The difference was due to the cumulative effect of errors embedded in the model assumptions. The model was used to evaluate the service and ultimate behavior of strengthened girders over a range of variables such as the extent of cracking in concrete, SMA reinforcement ratio, interaction between SMA and concrete (unbonded vs. bonded), and effective prestress in SMA. The partial loss of prestress due to elastic shortening of concrete is insignificant (
Book Synopsis Shear Reinforcement Requirements for High-Strength Concrete Bridge Girders by : J.A. Ramirez
Download or read book Shear Reinforcement Requirements for High-Strength Concrete Bridge Girders written by J.A. Ramirez and published by . This book was released on 2005-07-15 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Sustainable Bridge Structures by : Khaled Mahmoud
Download or read book Sustainable Bridge Structures written by Khaled Mahmoud and published by CRC Press. This book was released on 2015-08-07 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ever-increasing traffic demands, coupled with deteriorating condition of bridge structures, present great challenges for maintaining a healthy transportation network. The challenges encompass a wide range of economic, environmental, and social constraints that go beyond the technical boundaries of bridge engineering. Those constraints compound
Book Synopsis Shear Repair Methods for Conventionally Reinforced Concrete Girders and Deep Beams by : Daniel A. Howell
Download or read book Shear Repair Methods for Conventionally Reinforced Concrete Girders and Deep Beams written by Daniel A. Howell and published by . This book was released on 2009 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many conventionally reinforced concrete deck girder bridges (RCDG) and their intermediate supporting bent caps were designed during the Eisenhower interstate era of the 1950's with the AASHO design equations at the time, which subsequently place higher demand on the concrete. The referenced components may exhibit diagonal cracking due to the initial design assumptions, increased traffic volume and truck weights, as well as temperature and shrinkage affects. Action is needed as these structures approach the end of their useful design life. Wholesale replacement is not economically feasible; therefore, repair may provide a more attractive alternative to maintain operational safety and freight mobility. The current research program builds on previous work at OSU, which focused on estimating unrepaired specimen capacity, to include various repair methods. The experimental program included full scale testing of specimens with vintage 1950s details, reinforcing steel, concrete strength/composition, and flexural cutoffs details. Repairs included externally applied steel stirrups, supplemental internal stirrups, externally applied carbon fiber reinforced plastic (CFRP), carbon fiber tape utilized in a near surface mount application, and longitudinal post tensioning (bent cap specimen only). All specimens were initially loaded under quasi-static force control to produce diagonal cracks in the specimen then repaired and tested to failure. Ultimate specimen capacity was compared against that predicted from those available in the literature (where applicable), international codes, sectional Modified Compression Field Theory (MCFT) analysis, Modified Zararis Mechanical Model (bent caps only), Strut-and-Tie methods (bent cap only), and nonlinear finite element analysis (NLFEM). Results indicate the repair methods increased the member strength and the predicted member strenths compare well to certain international codes, sectional MCFT analysis, and nonlinear FEM element analysis. Some repair techniques such as surface mounted CFRP produced disparate outcomes for different specimen types. The NSM repair technique requires additional research to draw general conclusions. Longitudinal post tensioning compared well with the Modified Zararis method. STM methods form a very conservative lower bound for design and are thus not suggested for base specimen capacity prediction in a retrofit analysis. Design recommendations for the deep beams are not provided, as there is not sufficient data to support general conclusions.
