fib Bulletin 57 is a collection of contributions from a workshop on "Recent developments on shear and punching shear in RC and FRC elements", held in Salò, Italy, in October 2010. Shear is one of a few areas of research into fundamentals of the behaviour of concrete structures where contention remains amongst researchers. There is a continuing debate between researchers from a structures perspective and those from a materials or fracture mechanics perspective about the mechanisms that enable the force flow through a concrete member and across cracks. In 2009, a Working Group was formed within fib Task Group 4.2 "Ultimate Limit State Models" to harmonise different ideas about design procedures for shear and punching. An important outcome of this work was the ensuing discussions between experts and practitioners regarding the shear and punching provisions of the draft fib Model Code, which led to the organization of the Salò workshop. Invited experts in the field of shear and FRC gave 18 lectures at the workshop that was attended by 72 participants from 12 countries in 3 different continents. The contributions from this conference as compiled in this bulletin are believed to represent the best of the current state of knowledge. They certainly are of general interest to fib members and especially helpful in the finalization of the 2010 fibModel Code. It is hoped that this publication will stimulate further research in the field, to refine and harmonize the available analytical models and tools for shear and punching design.
This book sheds light on the shear behavior of Fiber Reinforced Concrete (FRC) elements, presenting a thorough analysis of the most important studies in the field and highlighting their shortcomings and issues that have been neglected to date. Instead of proposing a new formula, which would add to an already long list, it instead focuses on existing design codes. Based on a comparison of experimental tests, it provides a thorough analysis of these codes, describing both their reliability and weaknesses. Among other issues, the book addresses the influence of flange size on shear, and the possible inclusion of the flange factor in design formulas. Moreover, it reports in detail on tests performed on beams made of concrete of different compressive strengths, and on fiber reinforcements to study the influence on shear, including size effects. Lastly, the book presents a thorough analysis of FRC hollow core slabs. In fact, although this is an area of great interest in the current research landscape, it remains largely unexplored due to the difficulties encountered in attempting to fit transverse reinforcement in these elements.
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.
The EURO-C conference series (Split 1984, Zell am See 1990, Innsbruck 1994, Badgastein 1998, St Johann im Pongau 2003, Mayrhofen 2006, Schladming 2010, St Anton am Alberg 2014) brings together researchers and practising engineers concerned with theoretical, algorithmic and validation aspects associated with computational simulations of concrete and concrete structures. The conference reviews and discusses research advancements and the applicability and robustness of methods and models for reliable analysis of complex concrete, reinforced concrete and pre-stressed concrete structures in engineering practice. Conference topics and invited papers cover both computational mechanics and computational modelling aspects of the analysis and design of concrete and concrete structures: * Constitutive and Multiscale Modelling of Concrete * Advances in Computational Modelling * Time Dependent and Multiphysics Problems * Performance of Concrete Structures The book is of special interest to researchers in computational concrete mechanics, as well as industry experts in complex nonlinear simulations of concrete structures.
Fibre-reinforced Concretes for High-performance Structures presents key information about the development, performance and design of fibre-reinforced concrete, ultra-high-performance fibre-reinforced concrete and geopolymer concrete, and critically analyses their key mechanical properties and durability characteristics.
Self-Compacting Concrete: Materials, Properties and Applications presents the latest research on various aspects of self-compacting concrete, including test methods, rheology, strength and durability properties, SCC properties at elevated temperature, SC manufacturing with the use of SCMs, recycled aggregates and industrial by-products. Written by an international group of contributors who are closely associated with the development of self-compacting concrete, the book explores the main differences between SCC and normal concrete in terms of raw materials, fresh properties and hardened properties. Other topics discussed include the structure and practical applications of fiber reinforced SCC. Researchers and experienced engineers will find this reference to be a systematic source to SCC with its accounting of the latest breakthroughs in the field and discussions of SCC constructability, structural integrity, improved flows into complex forms, and superior strength and durability. Offers a systematic and comprehensive source of information on the latest developments in SCC technology Includes mix design procedures, tests standards, rheology, strength and durability properties Explores the properties and practical applications of SCC
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.
