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Polymer Duct Systems For Internal Bonded Post Tensioning
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Author :fib Fédération internationale du béton Publisher :fib Fédération internationale du béton ISBN 13 :2883941157 Total Pages :183 pages Book Rating :4.8/5 (839 download)
Book Synopsis Polymer-duct systems for internal bonded post-tensioning by : fib Fédération internationale du béton
Download or read book Polymer-duct systems for internal bonded post-tensioning written by fib Fédération internationale du béton and published by fib Fédération internationale du béton. This book was released on 2014-12-01 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941475 Total Pages :116 pages Book Rating :4.8/5 (839 download)
Book Synopsis Acceptance of post-tensioning systems for cryogenic applications by : FIB – International Federation for Structural Concrete
Download or read book Acceptance of post-tensioning systems for cryogenic applications written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2021-04-01 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the Second World War the demand of energy has undergone an exponential growth that has led to a sharp annual increase in the use of natural gas in both, cities and thermal power stations. Nowadays, the strategic relevance of natural gas as a main source of energy is evident with a contribution of more than 20% of the total world consumption. This development in increasing demand of natural gas has led for a need of suitable storage and transportation infrastructure. Various gases, especially hydrocarbons, are preferably stored in liquid form for transportation and storage since the phase transformation from gas to liquid comes with a significant reduction of the volume (e.g. up to 600 times). Gases can be liquefied by raising the pressure or by cooling to their boiling point, which for most gases is below 0°C. This is known as cryogenic storage. The term cryogenic is derived from two Greek words, namely kryos meaning icy-cold and genes which can be translated as shape. These fib recommendations are concerned about post-tensioning systems used in cryogenic tanks and have been formulated on the basis of actual available knowledge with the aim to reflect the current state of the art. Consequently, these recommendations have included a classification of the different cryogenic tanks typologies used in the past and nowadays, the associated different tendon types depending on their exposure to low temperature (e.g. never, only accidentally or during normal tank operation) and the testing regime required for acceptance of the materials and the post-tensioning system according to this document. An international working group comprising more than 20 experts from administrative authorities, universities, laboratories, owners, structural designers, suppliers of prestressing steels and post-tensioning systems suppliers have actively contributed in order to develop these recommendations. This text has been written to cover best construction practices around the world, and to provide material specifications which are considered to be the most advanced available at the time of preparing this text. For ease of use (for Owner, Designer and Post-tensioning System Supplier), the content has been arranged systematically according to the system components into chapters focusing on performance characteristics, requirements and acceptance criteria.
Author :fib Fédération internationale du béton Publisher :FIB - Féd. Int. du Béton ISBN 13 :288394122X Total Pages :198 pages Book Rating :4.8/5 (839 download)
Book Synopsis Precast segmental bridges by : fib Fédération internationale du béton
Download or read book Precast segmental bridges written by fib Fédération internationale du béton and published by FIB - Féd. Int. du Béton. This book was released on 2017-08-01 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of precast segmental bridges is not new: the first application documented was from the mid-1940s, designed by Eugene Freyssinet and built over the river Marne near Luzancy in France, between 1944 and 1946. Although innovative, it also contained traditional wet concrete joints between the members. The impressive breakthrough came slightly later with the introduction of match-cast joints by Jean Muller, first for a bridge near Buffalo (USA) in 1952, and later for a bridge across the River Seine at Choisy le Roi near Paris in 1962. This opened the way for a large number of new developments in terms of design, production approaches and construction techniques, and precast prestressed concrete segmental construction became rapidly one of the most efficient and successful bridge construction methods all over the world. These developments are still evolving, but the interaction between design, production and construction is a critical factor for success: the interaction creates opportunities to optimise the scheme, but at the same time is crucial to ensure safety, especially during construction, when large weights are moved, placed and secured, frequently at substantial heights. Engineers of all disciplines involved should interact during the development and realisation of precast segmental bridge (PSB) schemes, to conclude the optimum method statement and consequently check all the intermediate steps of the method statement in terms of stress, stiffness, stability, production and constructability. With the ongoing development of the PSB concept, and consequently moving limits in terms of dimensions, it was concluded to be appropriate to develop a Guide to good practice for the PSB construction method. The present report was developed by an integrated team of engineers with roots in design, structural engineering, production and construction, and provides a valuable source of knowledge, experience, recommendations and examples, with particular emphasis on the fib Model Code for Concrete Structures 2010 and fib Bulletins 20, 33, 48 and 75. I would like to thank all the members of Task Group 1.7, all the individual contributors from outside Task Group 1.7, and the reviewers of the Technical Council of the fib for their contribution to this Guide to good practice. In particular, I would like to thank Gopal Srinivasan and Marcos Sanchez, who, apart from their own contributions, did the final editorial work for this bulletin.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941599 Total Pages :48 pages Book Rating :4.8/5 (839 download)
Book Synopsis 2022 fib Awards for Outstanding Concrete Structures by : FIB – International Federation for Structural Concrete
Download or read book 2022 fib Awards for Outstanding Concrete Structures written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2022-06-15 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fib has two major missions now. One is to work toward the publication of the Model Code 2020, and the other is to respond to the global movement toward carbon neutrality. While the former is steadily progressing toward completion, the latter will require significant efforts for generations to come. As we all know, cement, the primary material for concrete, is a sector that accounts for 8.5% of the world’s CO2 emissions. And the structural concrete that fib handles consume 60% of that. In other words, we need to know the reality that our structural concrete is emitting 5% of the world’s CO2. From now on, fib members, suppliers, designers, builders, owner’s engineers, and academic researchers will be asked how to solve this difficult problem. In general, most of the CO2 emissions in the life cycle of structural concrete come from the production stage of materials and the use stage after construction, i.e. A1 to A3 and B1 to B5 processes as defined in EN15978. Cement and steel sectors, which are the main materials for structural concrete, are expected to take various measures to achieve zero carbon in their respective sectors by 2050. Until then, we must deal with the transition with our low carbon technologies. Regarding the production stage, the fib has recently launched TG4.8 “Low carbon concrete”. And the latest low carbon technologies will be discussed there. On the other hand, in the use stage, there is very little data on the relationship between durability and intervention and maintenance so far. The data accumulation here is the work of the fib, a group of various experts on structural concrete. Through-life management using highly durable structures and precise monitoring will enable to realize minimum maintenance in the use stage and to minimize CO2 emissions. Furthermore, it is also possible to contribute to the reduction of CO2 emissions in the further stage after the first cycle by responding to the circular economy, that is, deconstruction (C), reuse, and recycle (D). However, the technology in this field is still in its infancy, and further research and development is expected in the future. As described above, structural concrete can be carbon neutral in all aspects of its conception, and it can make a significant contribution when it is realized. The fib will have to address these issues in the future. Of course, it will not be easy, and it will take time. However, if we do not continue our efforts as the only international academic society on structural concrete in the world to achieve carbon neutrality, the significance of our very existence may be questioned. Long before Portland cement was invented, Roman concrete, made of volcanic ash and other materials, was the ultimate low-carbon material, and is still in use 2’000 years later because of its non-reinforced structure and lack of deterioration factors. Reinforced concrete, which made it possible to apply concrete to structures other than arches and domes, is only 150 years old. Prestressed concrete is even younger, with only 80 years of history. Now that we think about it, we realize that Roman concrete, which is non-reinforced low carbon concrete, is one of the examples of problem solving that we are trying to achieve. We have new materials, such as coated reinforcement, FRP, and fiber reinforced concrete, which can be used in any structural form. To overcome this challenge with all our wisdom would be to live up to the feat the Romans accomplished 2’000 years ago. Realizing highly durable and elegant structures with low-carbon concrete is the key to meet the demands of the world in the future. I hope you will enjoy reading this AOS brochure showing the Outstanding Concrete Structures Awards at the fib 2022 Congress in Oslo. And I also hope you will find some clues for the challenges we are facing.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - Féd. Int. du Béton ISBN 13 :2883941297 Total Pages :126 pages Book Rating :4.8/5 (839 download)
Book Synopsis Acceptance of cable systems using prestressing steels by : FIB – International Federation for Structural Concrete
Download or read book Acceptance of cable systems using prestressing steels written by FIB – International Federation for Structural Concrete and published by FIB - Féd. Int. du Béton. This book was released on 2019-03-01 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 v 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
Author :fib Fédération internationale du béton Publisher :FIB - Féd. Int. du Béton ISBN 13 :2883941254 Total Pages :354 pages Book Rating :4.8/5 (839 download)
Book Synopsis Towards a rational understanding of shear in beams and slabs by : fib Fédération internationale du béton
Download or read book Towards a rational understanding of shear in beams and slabs written by fib Fédération internationale du béton and published by FIB - Féd. Int. du Béton. This book was released on 2018-05-01 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reliable performance of beams and slabs in shear is essential for the safety and also for the serviceability of reinforced concrete structures. A possible failure in shear is usually a brittle failure, which underlines the importance of the correct specification of the load carrying capacity in shear. The knowledge of performance in shear is steadily developing and it is now obvious that older structures were not always designed in accordance with contemporary requirements. The increasing load – mainly on bridges – requires the assessment of existing structures, often followed by their strengthening. An appropriate understanding of actual performance of concrete structures in shear is therefore of primary interest. The workshop which was held in Zürich in 2016 brought together a significant number of outstanding specialists working in the field of shear design, who had a chance to exchange their opinions and proposals for improving the current knowledge of shear behaviour in beams and slabs. The specialists came from different parts of the world, which made the workshop general and representative. The workshop was organised by fib Working Party 2.2.1 “Shear in Beams” (convened by O. Bayrak), which is a part of fib Commission 2 "Analysis and Design". Individual contributions mainly address shear in beams with low transversal reinforcement. It is crucial because many existing structures lack such reinforcement. Different theories, e.g. Critical Shear Crack Theory (CSCT), Modified Compression Field Theory (MCFT), Multi-Action Shear Model (MASM), etc. were presented and compared with procedures used in selected national codes or in the fib Model Code 2010. The models for shear design were often based to a great extent on empirical experience. The refined presented models tend to take into account the physical mechanisms in structures more effectively. A brittle behaviour in shear requires not only to check the equilibrium and failure load, but also to follow the progress of failure, including the crack development and propagation, stress redistribution, etc. The significance of the size effect – which causes the nominal strength of a large structure to be smaller than that of a small structure – was pointed out. Nowadays, the fibre reinforcement is used more than before since it allows significant labour costs savings in the construction industry. The contribution of fibres is suitable for shear transfer. It is very convenient that not only ordinary fibre reinforced elements were addressed but also the UHPFRC beams. The production of this new material is indeed growing, while the development of design recommendations has not been sufficiently fast. Fatigue resistance of structures with low shear reinforcement is also an important issue, which was also addressed in this bulletin. It cannot be neglected in prestressed bridges, which are exposed to dynamic loads. A comprehensive understanding of the shear behaviour is necessary. Although many laboratory experiments are carried out, they are suitable only to a limited extent. New testing methods are being developed and show promising results, e.g. digital image correlation. An actual structure performance should rather be tested on a large scale, ideally on real structures under realistic loading conditions.ii The papers presented in the bulletin are a basis for the discussion in view of the development of updated design rules for the new fib Model Code (MC2020), which is currently under preparation. fib Bulletins like this one, dealing with shear, help to transfer knowledge from research to design practice. The authors are convinced that it will lead to better new structures design of as well as to savings and to a safety increase in older existing structures, whose future is often decided now.
Book Synopsis Partial factor methods for existing concrete structures by : FIB - Féd. Int. du Béton
Download or read book Partial factor methods for existing concrete structures written by FIB - Féd. Int. du Béton and published by FIB - Féd. Int. du Béton. This book was released on 2016 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: For a large part of the existing buildings and infrastructure the design life has been reached or will be reached in the near future. These structures might need to be reassessed in order to investigate whether the safety requirements are met. Current practice on the assessment of existing concrete structures however needs a thorough evaluation from a risk and reliability point of view, as they are mostly verified using simplified procedures based on the partial factor method commonly applied in design of new structures. Such assessments are often conservative and may lead to expensive upgrades. Although the last decades reliability-based assessment of existing concrete structures has gained wide attention in the research field, a consistent reliability-based assessment framework and a practically applicable codified approach which is compatible with the Eurocodes and accessible for common structural engineering problems in everyday practice is currently missing. Such an approach however allows for a more uniform, more objective and probably more widely applied assessment approach for existing concrete structures. Hence, in this bulletin two different partial factor formats are elaborated, i.e. the Design Value Method (DVM) and the Adjusted Partial Factor Method (APFM), enabling the incorporation of specific reliability related aspects for existing structures. The DVM proposes a fundamental basis for evaluating partial factors whereas the APFM provides adjustment factors to be applied on the partial factors for new structures in EN 1990. In this bulletin both methods are elaborated and evaluated and a basis is provided for decision making regarding the target safety level of existing structures.
Author :fib Fédération internationale du béton Publisher :FIB - Féd. Int. du Béton ISBN 13 :2883941246 Total Pages :146 pages Book Rating :4.8/5 (839 download)
Book Synopsis Precast Insulated Sandwich Panels by : fib Fédération internationale du béton
Download or read book Precast Insulated Sandwich Panels written by fib Fédération internationale du béton and published by FIB - Féd. Int. du Béton. This book was released on 2017-12-01 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the mid-20th century, with the rise of industrial prefabrication, precast concrete sandwich panels started being used as cladding for buildings. Since then, society and construction industry have become increasingly aware of energy efficiency in all fields, including affordability and sustainability consciousness, while maintaining the buildings’ durability. As such, buildings have been subject to increasingly stringent requirements which has kept the technology of sandwich panels continually at the forefront of building envelope evolution. Nowadays, sandwich panels have reached the highest standards of functional performance and aesthetic appeal. In building construction, these sandwich panel attributes combine with the well-known advantages of prefabrication including structural efficiency, flexibility in use, speed of construction, quality consciousness, durability, and sustainability. Sandwich panels have gained more exposure, thus representing quite a significant application within the prefabrication industry and a vital component of the precast market. The fib Commission “Prefabrication” is eager to promote the development of all precast structural concrete products and to share the knowledge and experience gained, to aid with practical design and construction. By issuing this comprehensive overview, “Guide to Good Practice”, a better understanding of design considerations, structural analysis, building physics, use of materials, manufacturing methods, equipment usage and field performance will be provided. This document contains the latest information currently available worldwide. The Commission is particularly proud that this document is a result of close cooperation with PCI and that it is published by both the fib and PCI. This cooperation started six years ago, first with comparing the different approaches to several issues, then progressively integrating and producing common documents, like this one, that hasn’t yet been treated in a specific Guide by either body. This Guide is intended to be the reference document to all who are interested in utilising the advantages of Precast Sandwich wall panels. In conjunction with the previously published Planning and Design Handbook on Precast Building Structures, the designer will have significant resources to integrate sandwich wall panels into any applicable structure.
Author :fib Fédération internationale du béton Publisher :fib Fédération internationale du béton ISBN 13 :2883941165 Total Pages :205 pages Book Rating :4.8/5 (839 download)
Book Synopsis Benchmarking of deemed-to-satisfy provisions in standards by : fib Fédération internationale du béton
Download or read book Benchmarking of deemed-to-satisfy provisions in standards written by fib Fédération internationale du béton and published by fib Fédération internationale du béton. This book was released on 2015-05-01 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Punching shear of structural concrete slabs by : FIB - Féd. Int. du Béton
Download or read book Punching shear of structural concrete slabs written by FIB - Féd. Int. du Béton and published by FIB - Féd. Int. du Béton. This book was released on 2017 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: fib Bulletin 81 reports the latest information available to researchers and practitioners on the analysis, design and experimental evidence of punching shear of structural concrete slabs. It follows previous efforts by the International Federation for Structural Concrete (fib) and its predecessor the Euro-International Committee for Concrete (CEB), through CEB Bulletin 168, Punching Shear in Reinforced Concrete (1985) and fibBulletin 12, Punching of structural concrete slabs (2001), and an international symposium sponsored by the punching shear subcommittee of ACI Committee 445 (Shear and Torsion) and held in Kansas City, Mo., USA, in 2005. This bulletin contains 18 papers that were presented in three sessions as part of an international symposium held in Philadelphia, Pa., USA, on October 25, 2016. The symposium was co-organized by the punching shear sub-committee of ACI 445 and by fib Working Party 2.2.3 (Punching and Shear in Slabs) with the objectives of not only disseminating information on this important design subject but also promoting harmonization among the various design theories and treatment of key aspects of punching shear design. The papers are organized in the same order they were presented in the symposium. The symposium honored Professor Emeritus Neil M. Hawkins (University of Illinois at Urbana-Champaign, USA), whose contributions through the years in the field of punching shear of structural concrete slabs have been paramount. The papers cover key aspects related to punching shear of structural concrete slabs under different loading conditions, the study of size effect on punching capacity of slabs, the effect of slab reinforcement ratio on the response and failure mode of slabs, without and with shear reinforcement, and its implications for the design and formulation in codes of practice, an examination of different analytical tools to predict the punching shear response of slabs, the study of the post-punching response of concrete slabs, the evaluation of design provisions in modern codes based on recent experimental evidence and new punching shear theories, and an overview of the combined efforts undertaken jointly by ACI 445 and fib WP 2.2.3 to generate test result databanks for the evaluation and calibration of punching shear design recommendations in North American and international codes of practice.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941637 Total Pages :326 pages Book Rating :4.8/5 (839 download)
Book Synopsis Advances on bond in concrete by : FIB – International Federation for Structural Concrete
Download or read book Advances on bond in concrete written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2022-12-01 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural behavior of reinforced concrete elements strongly depends on the interaction between the reinforcing bars and the surrounding concrete, which is generally referred as “bond in concrete”. In service conditions, the reinforcement-to-concrete bond governs deformability through the tension stiffening of concrete surrounding the bar as well the crack development and crack width. At Ultimate Limit State, bond governs anchorage and lap splices behavior as well as structural ductility. When plain (smooth) bars were used, the steel-to-concrete bond was mainly associated with “chemical adhesion/friction” that is related to the surface roughness of the rebar. As steel strengths increased the need to enhance interaction between steel and the surrounding concrete was recognized, and square twisted rebars, indented rebars or, later on, ribbed rebars came into the market, the latter being the type of deformed bar most commonly adopted since the 1960/70s. When ribbed rebars became widely used, several research studies started worldwide for better understanding the interaction between ribs and the surrounding concrete. Researchers evidenced the development of micro-cracks (due to the wedge action of the ribs) towards the external face of the structural element. If confinement is provided by the concrete cover, by transverse reinforcement or by an external transverse pressure, the full-anchorage capacity is guaranteed and a pull-out failure occurs, with crushing of concrete between the ribs. On the contrary, with lesser confining action, a splitting failure of bond occurs; the latter may provoke a brittle failure of the lap splice or, in some cases, of anchorages. However, after many years of research studies on bond-related topics, there are still several open issues. In fact, new materials entered into the market, as concrete with recycled aggregates or fibre reinforced concrete; the latter, having a kind of distributed reinforcement into the matrix (the fibres), provides a better confinement to the wedge action of the ribs. In addition, concrete and steel strength continuously increased over the years, causing changes in the bond behavior due to differences in mechanical properties of materials but also to the different concrete composition at the interface with the steel rebar causing a different bond behavior. Moreover, the lower water/cement ratio of these high-strength concrete makes the bleeding phenomena less evident, changing the concrete porosity in the upper layers of the structural element and thus making the current casting position parameters no-longer reliable. Finally, concrete with recycled aggregates are becoming more important in a market that is looking forward to a circular economy. As such, all the experimental results and database that allowed the calibration of bond rules now present in building codes for conventional concrete, may be not be representative of these new types of materials nowadays adopted in practice. Furthermore, after more than 50 years of service life, structural elements may not satisfy the current safety requirements for several reasons, including material degradation (with particular reference to steel corrosion) or increased loads, by also considering the seismic actions that were non considered by building codes at the time of the original design. The structural assessment of existing structures requires proper conceptual models and new approaches for evaluating the reliability of existing structures by also considering the remaining expected service life. In addition, specific rules for older materials, as plain smooth bars, should be revised for a better assessment of old structures. Last, but not least, interventions in existing structures may require new technologies now available such as post-installed rebars. While many advances have been achieved, there remain areas where a better understanding of bond and its mechanisms are required, and where further work is required to incorporate this understanding into safe and economic rules to guide construction and maintenance of existing infrastructures. These aspects were widely discussed within the technical community, particularly in the fib Task Group 2.5 and in the ACI 408 Committee dealing with bond and anchorage issues. Furthermore, special opportunities for discussing bond developments were represented by the International Conferences on ‘Bond in Concrete’ held each decade since 1982 as well as by joint workshops organized by fib TG2.5 and ACI 408. Within this technical collaboration, this Bulletin was conceived, and, thus, it collects selected papers presented at the joint fib-ACI Convention Session on Bond in Concrete held in Detroit (USA) in 2017. The bulletin is based on four main Sections concerning: - General aspects of bond - Anchorages and laps of bars and prestressing tendons - Bond under severe conditions - Degradation of bond for corrosion - Bond in new types of concrete The main aim of the Bulletin is to shed some new lights on the advances in understanding and application of bond related issues achieved over the last few years, and identify the challenges and priorities to be addressed in the next years. Another important aspect of the bulletin is to provide practical information from research findings.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941459 Total Pages :118 pages Book Rating :4.8/5 (839 download)
Book Synopsis External Tendons for Bridges by : FIB – International Federation for Structural Concrete
Download or read book External Tendons for Bridges written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2020-12-01 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of post-tensioning has been recognized for over a century. Interestingly, early developments started with external tendons, but failed to be recognized as a major construction technique for two main reasons: - Low tensile performance of early steels in combination with a poor knowledge of concrete creep and shrinkage properties, - Lack of a durable corrosion protection. With the technological progress, external tendons became increasingly popular in the 1980’s, as a post-tensioning method enabling inspection and, if necessary, replacement of tendons without demolition of structural members. Towards the end of the last century, more than 50 bridges have been built with external tendons, first in France and soon gaining traction in other countries. FIP published a state-of the-art report in May 1996 to provide a review of the application of external tendons, describing specific material problems and methods for dealing with them. 25 years have passed and, while the engineering principles covered by the FIP report remain unchanged, the context has evolved: - External tendons and construction methods have kept evolving with better materials, ever longer spans, and tighter schedules. - Normalization frame in Europe changed, Severe durability issues have occurred in some countries from which the industry can extract good knowledge of the causes and how to avoid similar problems in the future. This new fib bulletin has been prepared with the aim to reflect the current state of the art and encompass the knowledge amassed in the last quarter of century with chapters covering from the design and approval of systems and materials to installation, quality control and monitoring. The last chapter is a compilation of structures worldwide covering all sorts of materials, typologies and construction methods, which might be a source of inspiration for owners and designers alike.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941416 Total Pages :555 pages Book Rating :4.8/5 (839 download)
Book Synopsis Fibre Reinforced Concrete: From Design to Structural Applications by : FIB – International Federation for Structural Concrete
Download or read book Fibre Reinforced Concrete: From Design to Structural Applications written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2020-08-01 with total page 555 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first international FRC workshop supported by RILEM and ACI was held in Bergamo (Italy) in 2004. At that time, a lack of specific building codes and standards was identified as the main inhibitor to the application of this technology in engineering practice. The workshop aim was placed on the identification of applications, guidelines, and research needs in order for this advanced technology to be transferred to professional practice. The second international FRC workshop, held in Montreal (Canada) in 2014, was the first ACI-fib joint technical event. Many of the objectives identified in 2004 had been achieved by various groups of researchers who shared a common interest in extending the application of FRC materials into the realm of structural engineering and design. The aim of the workshop was to provide the State-of-the-Art on the recent progress that had been made in term of specifications and actual applications for buildings, underground structures, and bridge projects worldwide. The rapid development of codes, the introduction of new materials and the growing interest of the construction industry suggested presenting this forum at closer intervals. In this context, the third international FRC workshop was held in Desenzano (Italy), four years after Montreal. In this first ACI-fib-RILEM joint technical event, the maturity gained through the recent technological developments and large-scale applications were used to show the acceptability of the concrete design using various fibre compositions. The growing interests of civil infrastructure owners in ultra-high-performance fibre-reinforced concrete (UHPFRC) and synthetic fibres in structural applications bring new challenges in terms of concrete technology and design recommendations. In such a short period of time, we have witnessed the proliferation of the use of fibres as structural reinforcement in various applications such as industrial floors, elevated slabs, precast tunnel lining sections, foundations, as well as bridge decks. We are now moving towards addressing many durability-based design requirements by the use of fibres, as well as the general serviceability-based design. However, the possibility of having a residual tensile strength after cracking of the concrete matrix requires a new conceptual approach for a proper design of FRC structural elements. With such a perspective in mind, the aim of FRC2018 workshop was to provide the State-of-the-Art on the recent progress in terms of specifications development, actual applications, and to expose users and researchers to the challenges in the design and construction of a wide variety of structural applications. Considering that at the time of the first workshop, in 2004, no structural codes were available on FRC, we have to recognize the enormous work done by researchers all over the world, who have presented at many FRC events, and convinced code bodies to include FRC among the reliable alternatives for structural applications. This will allow engineers to increasingly utilize FRC with confidence for designing safe and durable structures. Many presentations also clearly showed that FRC is a promising material for efficient rehabilitation of existing infrastructure in a broad spectrum of repair applications. These cases range from sustained gravity loads to harsh environmental conditions and seismic applications, which are some of the broadest ranges of applications in Civil Engineering. The workshop was attended by researchers, designers, owner and government representatives as well as participants from the construction and fibre industries. The presence of people with different expertise provided a unique opportunity to share knowledge and promote collaborative efforts. These interactions are essential for the common goal of making better and sustainable constructions in the near future. The workshop was attended by about 150 participants coming from 30 countries. Researchers from all the continents participated in the workshop, including 24 Ph.D. students, who brought their enthusiasm in FRC structural applications. For this reason, the workshop Co-chairs sincerely thank all the enterprises that sponsored this event. They also extend their appreciation for the support provided by the industry over the last 30 years which allowed research centers to study FRC materials and their properties, and develop applications to making its use more routine and accepted throughout the world. Their important contribution has been essential for moving the knowledge base forward. Finally, we appreciate the enormous support received from all three sponsoring organizations of ACI, fib and Rilem and look forward to paving the path for future collaborations in various areas of common interest so that the developmental work and implementation of new specifications and design procedures can be expedited internationally.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941572 Total Pages :338 pages Book Rating :4.8/5 (839 download)
Book Synopsis Guide for Strengthening of Concrete Structures by : FIB – International Federation for Structural Concrete
Download or read book Guide for Strengthening of Concrete Structures written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2022-05-01 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: The idea of preparing a technical document for the repairs and interventions upon concrete structures goes back to the former fib COM 5: Structural Service Life Aspects, being the goal of the then TG 5.9. After a long period of reduced activity, and taking into account the reorganization of fib commissions that meanwhile took place, on June 2017 a different approach was proposed to push forward the task of TG 8.1 (formerly TG 5.9). The (new) goal of TG 8.1 was to deliver a ‘how-to-do’ guide, gathering together protection, repair, and strengthening techniques for concrete structures. Chapters are intended to provide both guidelines and case-studies, serving as support to the application of fib MC 2020 pre-normative specifications. Each chapter was written by an editorial team comprising desirably at least a researcher, a designer and a contractor. Templates have been prepared in order to harmonize the contents and the presentation of the different methods. Following the writing process, chapters were reviewed by experts and, after amendments by the authors, they underwent a second review process by COM 8 and TG 3.4 members, as well as by different practitioners. For each protection, repair and strengthening method addressed in this guide, readers have a description of when to adopt it, which materials and systems are required, which techniques are available, and what kind of equipment is needed. It then presents a summary of stakeholders’ roles and qualifications, design guidelines referring to most relevant codes and references, the intervention procedure, quality control measures and monitoring and maintenance activities. Due to the extent of the guide, it was decided to publish it as bulletin 102, addressing protection and repair methods, and bulletin 103, addressing strengthening methods. We would like to thank the authors, reviewers and members of COM 8 and TG 3.4 for their work in developing this fib Bulletin, which we hope will be useful for professionals working in the field of existing concrete structures, especially those concerned with life-cycle management and conservation activities. As noted above, this Bulletin is also intended to act as a background and supporting document to the next edition of the fib Model Code for Concrete Structures, which is currently under development under the auspices of TG10.1 with the working title of ‘fib Model Code 2020’.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941610 Total Pages :461 pages Book Rating :4.8/5 (839 download)
Book Synopsis Fibre Reinforced Concrete by : FIB – International Federation for Structural Concrete
Download or read book Fibre Reinforced Concrete written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2022-11-01 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fibre Reinforced Concrete (FRC) is a composite material characterized by an enhanced post-cracking tensile residual strength, due to the capacity of fibres to bridge the crack faces by means of pull-out mechanism. Due to a better knowledge of FRC and the recent developments worldwide of guidelines for structural design, the fib Special Activity Group 5, who prepared the new fib Model Code, decided to introduce some sections on new materials and in particular on FRC structural design. At that time, working Groups TG 8.3 (“Fibre reinforced concrete”) and TG 8.6 (“Ultra high performance fibre reinforced concrete”) of fib prepared these sections of the new fib Model Code concerning FRC design rules for providing a guidance to engineers to properly and safely design FRC structural elements, both at serviceability and at ultimate limit states, based on the state-of-the-art knowledge. This bulletin was written with the aim to share the main framework used by the two groups to introduce these two sections and to describe the many aspects already known, but not yet introduced in the Model Code. Even though the basic principles introduced in the two sections are mainly obtained from research on steel fibre reinforced concrete, the Model Code is open to every type of fibres, following a performance-based design approach. The bulletin represents a wide effort made by the people of the Task Group 4.1 and 4.2 to trace the knowledge on FRC and aims to be helpful for structural designers when using this new material in the practice.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941351 Total Pages :219 pages Book Rating :4.8/5 (839 download)
Book Synopsis Serviceability Limit State of Concrete Structures by : FIB – International Federation for Structural Concrete
Download or read book Serviceability Limit State of Concrete Structures written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2019-09-01 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Serviceability limit states are essential for appropriate function and durability of concrete structures. The attention is paid especially to the stress limitation, crack width analysis and deflection analysis. The document provides supplementary information to the fib Model Code 2010 (MC2010), where a limited space did not allow for a detailed description of individual procedures. The principles used in MC2010 in chapter 7.6 are explained in detail within this document. The stress analysis is focused on stresses in concrete and steel including the stress redistribution due to the long-term load and cracking of reinforced concrete and prestressed concrete elements. Crack width analysis explains the mechanism of cracking under mechanical loading and due to deformation restraint. Cracks in prestressed concrete elements are also discussed. Deflection analyses with different levels of accuracy are described including the shear effects. Examples illustrate the practical application of rules defined in the MC2010 of individual serviceability limit states. Simplified and more general methods are used. An important part of the bulletin shows the development and extension of the serviceability limit states after publishing of the MC2010 and alternative approaches. Special attention is paid to deflections of prestressed concrete beams, shear effects on deflection, slenderness limits and influence of the concrete cover. The final part deals with an application of numerical simulations.
Author :FIB – International Federation for Structural Concrete Publisher :FIB - International Federation for Structural Concrete ISBN 13 :2883941556 Total Pages :313 pages Book Rating :4.8/5 (839 download)
Book Synopsis Guide for Protection and Repair of Concrete Structures by : FIB – International Federation for Structural Concrete
Download or read book Guide for Protection and Repair of Concrete Structures written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2022-03-01 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: The idea of preparing a technical document for the repairs and interventions upon concrete structures goes back to the former fib COM5: Structural Service Life Aspects, being the goal of the then TG5.9. After a long period of reduced activity, and taking into account the reorganization of fib commissions that meanwhile took place, on June 2017 a different approach was proposed to push forward the task of TG8.1 (formerly TG5.9). The (new) goal of TG 8.1 was to deliver a ‘how-to-do’ guide, gathering together protection, repair, and strengthening techniques for concrete structures. Chapters are intended to provide both guidelines and case-studies, serving as support to the application of fib MC2020 pre-normative specifications. Each chapter was written by an editorial team comprising desirably at least a researcher, a designer and a contractor. Templates have been prepared in order to harmonize the contents and the presentation of the different methods. Following the writing process, chapters were reviewed by experts and, after amendments by the authors, they underwent a second review process by COM8 and TG3.4 members, as well as by different practitioners. For each protection, repair and strengthening method addressed in this guide, readers have a description of when to adopt it, which materials and systems are required, which techniques are available, and what kind of equipment is needed. It then presents a summary of stakeholders’ roles and qualifications, design guidelines referring to most relevant codes and references, the intervention procedure, quality control measures and monitoring and maintenance activities. Due to the extent of the guide, it was decided to publish it as bulletin 102, addressing protection and repair methods, and bulletin 103, addressing strengthening methods. We would like to thank the authors, reviewers and members of COM8 and TG3.4 for their work in developing this fib Bulletin, which we hope will be useful for professionals working in the field of existing concrete structures, especially those concerned with life-cycle management and conservation activities. As noted above, this Bulletin is also intended to act as a background and supporting document to the next edition of the fib Model Code for Concrete Structures, which is currently under development under the auspices of TG10.1 with the working title of "fib Model Code 2020".
