Evaluation Of Strand To Grout Bond In Post Tensioned Tendons With Corrosion Inhibiting Penetrants
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Evaluation Of Strand To Grout Bond In Post Tensioned Tendons With Corrosion Inhibiting Penetrants
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Author : Kurt Kupselaitis
language : en
Publisher:
Release Date : 2019
Evaluation Of Strand To Grout Bond In Post Tensioned Tendons With Corrosion Inhibiting Penetrants written by Kurt Kupselaitis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Bridges categories.
Post tensioning bridges is an efficient way of construction where segments of a bridge are strung together using small diameter high strength strands. The steel strands are passed through internal and/or external ducts within the concrete segments, jacked to high levels of stress, anchored using steel wedges, and then filled with a corrosion inhibiting filler. A cementitious material called grout has been widely used for over 50 years as this filler. The Federal Highway Administration design and construction manual provides recommendations in the properly filling techniques to ensure the tendons are full of grout. Despite the level of detail the manual provides, several Florida bridges that used this construction technique have seen severe corrosion related failures due to poor grout quality. Oil based products have been developed for the express purpose of reducing the corrosion rate in previously grouted tendons. Utilizing the interstitial spaces in the steel strands, low viscosity fluid is pumped through the strand which can also penetrate the surrounding grout and fill unintentional voids. However, by doing so, there is the concern that the bond strength could be compromised and increase the risk of failure. This study presents the findings of small scale grouted mono-strand tendons which determined the bond effects of defective grout, evaluated the injection capabilities of various penetrants, and determined whether or not the penetrant adversely affects bond after impregnation. No appreciable variation in bond was found.
Factors Affecting Bond In Multi Strand Post Tensioning Tendons Including The Effect Of Emulsifiable Oils
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Author : Jeffrey Roger Diephuis
language : en
Publisher:
Release Date : 2004
Factors Affecting Bond In Multi Strand Post Tensioning Tendons Including The Effect Of Emulsifiable Oils written by Jeffrey Roger Diephuis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
Recent corrosion problems worldwide have brought increased attention to the issues of durability and corrosion resistance of post-tensioned tendons. While the overall experience in the United States has been good, there is a desire to implement further measures to ensure the adequate protection of post-tensioning systems. This thesis is part of a broad research program evaluating both temporary and long-term corrosion protection solutions. In particular, this thesis addresses the effect of emulsifiable oils used for temporary corrosion protection on bond in multi-strand post-tensioning tendons. The effect of duct type on bond behavior is also investigated. Overall findings indicate that while the force developed by oiled strands is satisfactory, the reduced adhesion between the steel and the grout results in excessive slip. Additionally, galvanized steel pipes tended to allow the grout to slip relative to the duct or the duct to slip relative to the concrete at significantly reduced loads. Corrugated ducts eliminated this slip. Of the corrugated ducts, galvanized metal ducts provided somewhat better bond performance than high density polyethylene ducts.
Evaluation Of Corrosion Protection Of Unbonded Tendons
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Author :
language : en
Publisher:
Release Date : 1978
Evaluation Of Corrosion Protection Of Unbonded Tendons written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1978 with Corrosion resistant materials categories.
Corrosion Forecasting And Failure Projection Of Post Tensioned Tendons In Deficient Cementitious Grout
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Author : William H. Hartt
language : en
Publisher:
Release Date : 2018
Corrosion Forecasting And Failure Projection Of Post Tensioned Tendons In Deficient Cementitious Grout written by William H. Hartt and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Post-tensioned prestressed concrete construction categories.
Post-tensioning has evolved to become the construction method of choice for many large structures, including bridges. However, instances of corrosion-induced fracture of wires and strands and resultant tendon failures have occurred as a consequence of either chemically or physically deficient grout (or a combination of these), where the former involves elevated levels of chlorides or free sulfates (or both) and the latter soft, chalky, separated, segregated grout with free water. In the extreme, there is the possibility of structure collapse. The present project builds on results from a recently completed in-house Federal Highway Administration study, termed “phase 1,” which determined the extent of localized wire and strand corrosion as a function of grout chloride concentration, presence of free sulfates, and physical deficiencies.(1) The objective of the present study was twofold: first, to present results from a phase 2 experimental study that extended what was accomplished in phase 1 and, second, to develop a methodology whereby the onset and subsequent rate of wire and strand fractures and tendon failures can be forecast given information regarding the extent of grout deficiency or deficiencies.(1) The former involved stressed, single-wire specimens that were exposed to deficient grouts. The latter was accomplished by relating occurrence of fractures and failures to the extent of localized wire corrosion and to the resultant rate of wire cross-section loss with time, as affected by the severity of a grout deficiency or deficiencies. Primary inputs to the model are the mean and standard deviation of, first, localized wire corrosion rate and, second, residual wire fracture strength. Results indicate an initiation period for fractures and failures during which corrosion progresses and that, once these commence, they do so initially at a progressively increasing rate up to a point beyond which this rate moderates. Other variables that were investigated include level of prestress, wire strength, number of tendons, tendon length, and fracture and failure rates subsequent to initial occurrence. Equations are presented whereby bridge engineers can forecast the onset of fractures and failures based on either localized wire corrosion wastage statistics or grout chloride concentration, and examples are provided.
Evaluation Of External Post Tensioned Tendons Using Vibration Signatures
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Author : Jun Ki Lee
language : en
Publisher:
Release Date : 2007
Evaluation Of External Post Tensioned Tendons Using Vibration Signatures written by Jun Ki Lee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Cables categories.
Recent findings regarding corrosion of post-tensioned bridges have highlighted the urgent need to develop reliable methods to predict the behavior of the structural system after damage has occurred and inspection techniques to assess the condition of the structure. Corrosion in strands is undesirable in that it often progresses without visual signs of distress, but may cause a brittle failure. To complicate the inspection, access to the strands for visual inspection is usually blocked by the concrete cross section. To date, significant efforts have been taken to improve the durability of the post-tensioned bridges. However, the behavior of the post-tensioned bridges with corrosion damage is not clearly understood and the currently available inspection techniques tend to provide only limited information about the nature and extent of the damage. The research project discussed in this dissertation was developed is to evaluate the feasibility of using the vibration technique to detect and estimate the extent of damage in an external tendon due to corrosion. To accomplish this goal, damage was induced in five specimens, which were monitored periodically to correlate the measured changes in the frequency response to the level of damage. The induced damage simulated the degradation of a post-tensioned structure from corrosion. This dissertation describes the experimental program and the numerical scheme used to estimate the condition of the specimens. Three types of specimens were tested during the experimental phase of the research: individual strands, cables specimens, and external tendons. A series of tension tests of individual strands were conducted to investigate changes in the uniaxial behavior after damage was induced. Simulated damage included uniform corrosion of the strand, mechanical wire cuts, and an initial defect in one wire. Three cable specimens and one tendon specimen were subjected to fatigue loading. The loading was selected to simulate the loss of cross-sectional area in the strands, and also caused grout damage. The frequency response of the specimens was recorded periodically during the fatigue tests and acoustic sensors were used to detect the occurrence of wire breaks. A second tendon specimen was exposed to an acid solution to simulate the hydrogen induced cracking in the strand at three different locations along the length of the specimen. A number of wires fractured during the exposure test and damage was inspected visually. Natural frequencies were also measured periodically. The residual prestressing force in of the specimens was extracted from the measured natural frequencies. The stiff string model was used to determine optimum values of tension and flexural stiffness from the frequency response. The numerical results from this optimization demonstrated the feasibility of using the vibration technique as a nondestructive testing method for external tendons.
Ageing Management Of Concrete Structures In Nuclear Power Plants
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Author : International Atomic Energy Agency
language : en
Publisher: IAEA Nuclear Energy
Release Date : 2016
Ageing Management Of Concrete Structures In Nuclear Power Plants written by International Atomic Energy Agency and has been published by IAEA Nuclear Energy this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Science categories.
This publication is one in a series of reports on the assessment and management of ageing of major nuclear power plant (NPP) components. Current practices for assessment of safety margins (fitness for service) and inspection, monitoring and mitigation of ageing related degradation of selected concrete structures related to NPPs are documented. Implications for and differences in new reactor designs are discussed. This information is intended to help all involved directly and indirectly in ensuring the safe operation of NPPs, and also to provide a common technical basis for dialogue between plant operators and regulators when dealing with age related licensing issues.
Twentieth Century Building Materials
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Author : Thomas C. Jester
language : en
Publisher: Getty Publications
Release Date : 2014-08-01
Twentieth Century Building Materials written by Thomas C. Jester and has been published by Getty Publications this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-08-01 with Architecture categories.
Over the concluding decades of the twentieth century, the historic preservation community increasingly turned its attention to modern buildings, including bungalows from the 1930s, gas stations and diners from the 1940s, and office buildings and architectural homes from the 1950s. Conservation efforts, however, were often hampered by a lack of technical information about the products used in these structures, and to fill this gap Twentieth-Century Building Materials was developed by the U.S. Department of the Interior’s National Park Service and first published in 1995. Now, this invaluable guide is being reissued—with a new preface by the book’s original editor. With more than 250 illustrations, including a full-color photographic essay, the volume remains an indispensable reference on the history and conservation of modern building materials. Thirty-seven essays written by leading experts offer insights into the history, manufacturing processes, and uses of a wide range of materials, including glass block, aluminum, plywood, linoleum, and gypsum board. Readers will also learn about how these materials perform over time and discover valuable conservation and repair techniques. Bibliographies and sources for further research complete the volume. The book is intended for a wide range of conservation professionals including architects, engineers, conservators, and material scientists engaged in the conservation of modern buildings, as well as scholars in related disciplines.
Construction Of Prestressed Concrete Structures
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Author : Ben C. Gerwick, Jr.
language : en
Publisher: John Wiley & Sons
Release Date : 1997-02-13
Construction Of Prestressed Concrete Structures written by Ben C. Gerwick, Jr. and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997-02-13 with Technology & Engineering categories.
Die zweite Auflage dieses Klassikers - jetzt als Paperback - bietet Profis auf diesem Gebiet eine aktuelle und kompetente Präsentation der Technologie der Vorbelastung von Stahlbeton. Grundlegende Techniken, Materialien und Systeme werden behandelt und vielfältige Anwendungen - Gebäude, Brücken, Bohrplattformen, Straßen, Rollbahnen, Rohrleitungen - erläutert.
Chemical Admixtures For Concrete
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Author : Sandra Senft
language : en
Publisher: CRC Press
Release Date : 1999-06-24
Chemical Admixtures For Concrete written by Sandra Senft and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999-06-24 with Architecture categories.
Chemical admixtures are used in concrete mixtures to produce particular engineering properties such as rapid hardening, water-proofing or resistance to cold. Chemical Admixtures for Concrete surveys recent developments in admixture technology, explaining the mechanisms by which admixtures produce their effects, the various types of admixtures avail
Lrfd Guide Specifications For The Design Of Pedestrian Bridges
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Author : American Association of State Highway and Transportation Officials
language : en
Publisher: AASHTO
Release Date : 2009
Lrfd Guide Specifications For The Design Of Pedestrian Bridges written by American Association of State Highway and Transportation Officials and has been published by AASHTO this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Bridges categories.