Effect of zinc on prestressing steel

Effect of zinc on prestressing steel
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
Total Pages: 28
Release: 2012-06-01
Genre: Technology & Engineering
ISBN: 2883941041

Concerns have been raised regarding the durability of galvanized prestressing steels in contact with cementitious grout, and regarding the use of galvanized ducts for grouted tendons or galvanized inserts or components in contact with prestressing steel inside concrete. These concerns are mainly based on the assumption that the hydrogen formed on the zinc surface when exposed to the fresh cementitious grout for a short period of time represents a risk of hydrogen induced stress corrosion for the prestressing steel. Basic research has demonstrated that hydrogen induced stress corrosion may indeed occur with prestressing steels which are sensitive to hydrogen induced stress corrosion. The use of galvanizing for high strength steels exposed to atmosphere is less controversial. However, under certain conditions hydrogen may develop also and potentially damage the high strength steel. This report provides a summary and evaluation of the relevant parameters on the corrosion behaviour of high strength wires, strands and bars when in contact with zinc with and without the presence of fresh cementitious grout or concrete. Both, tendons made of prestressing steels used in structural concrete and cables under atmospheric conditions are considered. The main groups of applications discussed in the report are: A Zinc-coated high strength steel for applications in atmospheric corrosion conditions B Zinc-coated prestressing steel embedded in fresh cementitious grout or concrete C Bare prestressing steel (no zinc coating) embedded in fresh cementitious grout or concrete in direct contact with, or indirect contact in the immediate vicinity of galvanized components embedded in the grout or concrete (e.g. galvanized ducts, galvanized reinforcing steel, galvanized fastenings / dowels, etc).

Acceptance of stay cable systems using prestressing steels

Acceptance of stay cable systems using prestressing steels
Author: FIB – International Federation for Structural Concrete
Publisher: FIB - International Federation for Structural Concrete
Total Pages: 126
Release: 2019-03-01
Genre: Technology & Engineering
ISBN: 2883941300

Cable-stayed structures have become increasingly popular over the last 30 years and have been used in all parts of the world. Modern cable-stayed bridges have a history of over 50-years and have been constructed with span lengths ranging from 15 m to over 1000 m. Many long span cable-stayed bridges have been built for railway and highway traffic applications. Stay cables have also been used on pedestrian structures, many of which are architecturally striking and have become landmark structures. There is growing use in building structures, particularly for cable-supported roofs. Most of the cable supported structures have been in the form of cable-stayed bridges; but in recent years, extradosed bridges have seen increased popularity among the designers. Led by the experience in Japan, more than 200 extradosed bridges have been constructed worldwide in the past 15 years. The first edition of these fib recommendations was published as fib Bulletin 30 in 2005 and was the first specification published by fib for stay cable systems. This new bulletin has been updated based on Bulletin 30 with the aim to reflect the current state of the art and encompass the latest knowledge in cable systems. In addition, it has been the aspiration of Commission 5 and Task Group 5.5 to harmonize the guidance in this updated bulletin with other stay cable recommendations from around the world, including those from Europe, Japan and the USA. This new bulletin is intended to supersede and replace fib Bulletin 30. It is recommended that it be used in lieu of fib Bulletin 30 for all future cable supported applications. The updated bulletin introduces several significant enhancements to the specifications: These recommendations are applicable to both stay cable and extradosed cable applications. In the past, there has been some debate over the boundary between cable-stayed and extradosed bridges. This bulletin presents a new continuous approach valid for both. A completely new testing requirement to assess the performance of cable systems under bending fatigue, including both anchorages and saddles, if applicable, has been added. Testing requirements for saddle systems have been reformulated. In addition to the bending fatigue test noted above, new testing procedures for stay cable saddles with isolated tensile elements are introduced. This includes tests for saddle axial fatigue, friction and tensile testing, and determination of the effective saddle friction coefficient. Expanded system qualification, including requirements for both stay cable and extradosed applications. Includes new provisions for MTE qualification and additional load transferring connection devices. Minimum number of tests is specified for each. A new in-situ damping measurement test has been added to verify the actual damping ratio of the damping devices installed. By testing on site, selected cables may be excited to vibrate without and with the damping devices so that the observed vibration behaviour can be compared to the specified value. Other revisions have been made to reflect the current state of practice: Expanded quality control testing requirements Inclusion of epoxy-coated prestressing steel as a protection layer. Previous recommendations only considered zinc coatings. Specifications for epoxy coating material are given. Requirements for stainless steel components such as pipes, caps and plates Updated guidance for designing lightning protection systems Detailed recommendations for different levels of inspection of cable systems, including: initial, routine, detailed and exceptional inspections An updated list of references, relevant standards, and extended literature

Factory Applied Corrosion Protection of Prestressing Steel

Factory Applied Corrosion Protection of Prestressing Steel
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
Total Pages: 24
Release: 2001-01-01
Genre: Technology & Engineering
ISBN: 9782883940512

Without doubt, active corrosion protection of prestressing steels by cement grout can be one of the most economic and durable solutions, if properly executed. Numerous other corrosion protection systems which fulfill requirements such as controllability and exchangeability are available. This state-of-the-art report, prepared by a task group and approved by fib Commission 9 Reinforcing and prestressing materials and systems, concentrates exclusively on factory applied corrosion protection that can be produced in controlled processes which should assure a better quality than corrosion protection applied on site. The report is addressed to designers and installers (executing persons) attempting to inform them about the various possibilities for industrially applied corrosion protection and to provide the necessary knowledge for their application.

Polymer-duct systems for internal bonded post-tensioning

Polymer-duct systems for internal bonded post-tensioning
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
Total Pages: 183
Release: 2014-12-01
Genre: Technology & Engineering
ISBN: 2883941157

The purpose of this recommendation - fib Bulletin 75: Polymer-duct systems for internal bonded post-tensioning - is to update and amend fib Bulletin 7:Corrugated plastic ducts for internal bonded post-tensioning, a technical report published in 2000. fib Bulletin 75 is meant as a cornerstone for the technical approval of polymer (plastic) ducts for internal bonded post-tensioning and possibly for the test procedures of a future testing standard. The updated bulletin includes new information on the design and detailing of concrete structures containing tendons with polymer ducts. The recommendation provides detailed test specifications for polymer materials, duct components and duct systems. In addition, the report contains recommendations for approval testing and attestations of conformity for polymer-duct systems. Although the new generation of corrugated polymer ducts for bonded post-tensioning have now been around for approximately twenty years, products still differ in material properties, geometrical detail, installation procedures and on-site use. Unlike corrugated steel ducts or smooth polyethylene (PE) pipes, they have not yet become standardized. It is the opinion of fib Task Group 9.16 and Commission 9 that these plastic ducts should, therefore, still be subjected to a systems approval process. This recommendation offers information acquired from twenty years of experience as well as new specifications that will, hopefully, lead to the standardization of polymer-duct systems.

Effect of Zinc Coatings on the Endurance Properties of Steel (Classic Reprint)

Effect of Zinc Coatings on the Endurance Properties of Steel (Classic Reprint)
Author: W. H. Swanger
Publisher: Forgotten Books
Total Pages: 24
Release: 2018-09-10
Genre: Technology & Engineering
ISBN: 9781396093272

Excerpt from Effect of Zinc Coatings on the Endurance Properties of Steel The stresses applied to the acid pickled and the coated specimens were calculated on the diameter of the polished specimen before it was pickled or coated. The diameters were measured with a special micro meter capable of a precision of plus or minus inch. The change in diameter caused by either the acid treatment alone or the acid treatment and the application of the zinc coating was in all cases less than inch. The tensile strengths of the three materials were determined on standard inch diameter test bars, heat treated in the same way as the endurance specimens. Hardness determinations were made on the ends of the tensile and endurance test bars. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Report on Prestressing Steel

Report on Prestressing Steel
Author: Fédération internationale de la précontrainte. Commission on Prestressing Steels and Systems
Publisher:
Total Pages: 36
Release: 1980
Genre: Prestressed concrete
ISBN:

Corrosion protection of prestressing steels

Corrosion protection of prestressing steels
Author: FIB – International Federation for Structural Concrete
Publisher: FIB - International Federation for Structural Concrete
Total Pages: 52
Release: 1996-09-01
Genre: Technology & Engineering
ISBN: 1874266263

Benchmarking of deemed-to-satisfy provisions in standards

Benchmarking of deemed-to-satisfy provisions in standards
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
Total Pages: 205
Release: 2015-05-01
Genre: Technology & Engineering
ISBN: 2883941165

Standards for specifying and ensuring the durability of new concrete structures are commonly of the prescriptive kind. fib Bulletin 76: Benchmarking of deemed-to-satisfy provisions in standards - Durability of reinforced concrete structures exposed to chlorides presents the benchmarking of a number of rules for chloride-induced corrosion as given in national codes such as European, US and Australian standards. This new benchmark determines the reliability ranges in the chloride-induced depassivation of rebar if the deemed-to-satisfy rules of different countries are taken into consideration. It does not only involve (probabilistic) calculations using input mainly based on short-term and rapid laboratory-test data but also involves input based on an independent assessment of existing structures. The reliability analyses are carried out using the probabilistic design approach for chloride-induced corrosion presented in fib Bulletin 34: Model Code for Service Life Design (2006), fib Model Code for Concrete Structures 2010 and ISO 16204:2012. The work compares the calculated reliability ranges thus determined with the target reliabilities proposed by current specifications and, based on the comparison, offers a proposal for the improvement of deemed-to-satisfy rules and specifications. fib Bulletin 76 presents and discusses in detail the input data for the examined model parameters and offers an extensive annexe documenting the values of the individual parameters used in the analyses. It thus provides a reliable database for the performance-based probabilistic service-life design of concrete structures exposed to chlorides, be they in the form of salt fog, sea water or de-icing salts.

Durability of Post-tensioning Tendons

Durability of Post-tensioning Tendons
Author: fib Fédération internationale du béton
Publisher: fib Fédération internationale du béton
Total Pages: 279
Release: 2001-01-01
Genre: Technology & Engineering
ISBN: 288394055X

In some countries durability problems with post-tensioning tendons have in the past led to fairly restrictive regulations. Improvements to execution procedures have been developed since, and new or improved prestressing systems have been proposed, too. This development was, of course, subject of discussions in fib Commission 9 Reinforcing and Prestressing Materials and Sytems and in IABSE Working Commission 3 Concrete Structures. It was decided to organise a workshop with the aim to review the different aspects of the problems encountered and to discuss solutions available today. Keynote speakers from various countries were invited to contribute. Their papers are published in this bulletin, grouped together under the following themes: Inventory and condition (6 papers) Investigation and repair (5 papers) Technical progress (4 papers) Strategies for improvement (6 papers) Supported by the international federation for structural concrete fib, and the international association for bridge and structural engineering IABSE, the workshop took place on 15-16 November 2001 at Ghent University, celebrating the 75th anniversary of the Magnel Laboratory for Concrete Research, whose director also chaired the Scientific Committee and edited the bulletin. It needs to be emphasised that in the bulletin invited experts present their individual views. Although not yet discussed in any of the association's working bodies, the highly topical contents of the bulletin is believed to be of general interest to fib's members and to document a starting point for future work in this field. Therefore, the Council of fib agreed to exceptionally publish these papers within fib's series of Bulletins.