Description
The FRC-2014 Workshop, Fibre-reinforced concrete: From design to structural applications, was the first ever ACI-fib joint technical event. The workshop, held at Polytechnique Montreal, Canada, on July 24 and 25, 2014, was attended by 116 participants from 25 countries and four continents.
The first international FRC workshop was held in Bergamo, Italy, in 2004. At that time, the lack of specific building codes and standards was identified as the main inhibitor to the application of this technology in engineering practice. Ten years after Bergamo, many of the objectives identified at that time have been achieved. The use of fibre-reinforced concrete (FRC) for designing structural members in bending and shear has recently been addressed in the fib Model Code for Concrete Structures 2010. Steel-fibre-reinforced concrete (SFRC) has also been used structurally in several building and bridge projects in Europe and North America. SFRC has been widely used in segmental tunnel linings all over the world. Members of ACI 544 and fib TG 4.1 have been involved in writing code-based specifications for the design of FRC structural members.
Although fibres have been used by the construction industry for several decades, their use in structural applications is still very modest if one considers the gigantic potential of concrete structures around the world and the benefits expected of their mechanical behaviour and durability. However, recent technological developments and large scale applications have demonstrated that FRC has reached a level of maturity such that these innovative materials can be used by engineers with confidence. From that perspective, the aim of the FRC 2014 workshop was to provide the state-of-the-art on the recent progress attained in terms of specifications and actual applications. Presentations covered several design guidelines adopted worldwide illustrating the progress made in the last ten years, and also a wide spectrum of FRC applications such as beams, elevated floors, tunnel linings, slabs, pavements, precast elements, bridge elements, and many others.
More than fifty papers were presented at the workshop, from which 44 were selected for this joint ACI-fib publication. The papers are organised into six themes:
• design guidelines and specifications,
• material properties for design,
• behaviour and design of beams and columns,
• behaviour and design of slabs and other structures,
• behaviour and design of foundations and underground components, and finally,
• applications in structure and underground construction projects.
The papers cover a wide range of applications and illustrate the maturity of FRC as the choice material for improving the serviceability, sustainability, and performance of concrete structures. The workshop chairs would like to express their sincere recognition to all authors and reviewers who contributed to the quality of the document. Special thanks to both ACI and fib officers and staff who supported the organisation of the workshop, editorial support, and dissemination of the workshop proceeding as an ACI Symposium Publication and an fib Bulletin. While significant progress has been made in the introduction of FRC in codes and structures, the current accomplishment should be viewed as the beginning, and significant follow up work is still needed. Indeed, introducing new technologies and new materials in structural applications brings technical and scientific challenges and responsibilities. The necessity to achieve the objectives set worldwide for sustainable development requires that 21st century concrete structures meet higher performances than those of the previous one, a role that FRC can definitely help achieve. It is the responsibility of all actors to move forward in that direction.
The recently published codes and design guidelines, available worldwide, constitute a first step into the implementation of FRC in the construction industry. However, before the structural use of FRC becomes a common practice, several benchmarks need to be accomplished. The numerous factors that still inhibit the use of FRC in structural applications should be viewed as challenges that could only be solved through a joint effort of all key players. Professor Sidney Mindess, a pioneer of FRC research, indicated in his opening speech at the Montreal Workshop four challenges to increase the structural use of FRC: education and training, performance specifications, more appropriate testing methods, and comprehensive research programs focused on the combined use of FRC and continuous reinforcement. Without claiming to provide an exhaustive list of actions, the following presents some challenges that need to be addressed by the scientific community, fibre producers, structural design community, construction industry, and stakeholders to achieve the objective of building more durable concrete structures. These challenges are inspired by Professor Mindess’ remarks.
The scientific community should contribute to the elimination of artificial divisions between different types of FRC based on the compressive strength and type of fibres. They should put the emphasis on the benefits brought by fibres on the performance of concrete structures and present FRC as a continuum of materials with different characteristics and performances. Approaching research on FRC more holistically with the emphasis on applications is essential for the sound development of the scientific knowledge. Fibre producers would certainly be the first ones to benefit from a wider use of fibre concrete. Considering that about 1% of the concrete used worldwide contains fibres, they should combine their efforts for developing new applications and expanding the spectrum of the conventional uses, rather than working against each other for the same market.
Addressing the replacement of alternative reinforcement solutions should evolve toward adopting a strategy based on the vision that fibres should be used along with other types of reinforcement to make better constructions at both service and ultimate limit states. The structural design community has always adopted conservatism that is justified in many instances for safety and professional responsibility. The evidence of enhanced performances of FRC structures and the need to build more durable and safer structures only justifies a more extensive use of FRC. Being at the decision central point, designers should be more proactive in proposing the implementation of FRC in structures. They should contribute to the writing of design guidelines, they should ask to get appropriate training, and they should promote the improvement of the expertise level of the engineering profession.
Being driven by the necessity of profit, the construction industry has always been resistant to changes unless motivated by economic advantages. Problems associated with the use of FRC, especially at high dosages, have often and justifiably discouraged their broader use. Today's technological knowhow and availability of products are such that past technical problems have been overcome. Changing traditional ways of building with FRC will need some effort and modification of the current practice. However, members of the construction industry with the vision of tomorrow's concrete structures will make the appropriate changes because survival often requires evolution. A better and more modern image of the construction industry would certainly be beneficial to all.
Stakeholders with long-term vision will implement the needed change, as clear evidence of better, safer, and more durable structures with FRC is needed. Combined with the maturity of the scientific knowledge on FRC, stakeholders can now require a wider use of FRC. When only short-term economic considerations prevail, FRC is not always competitive. However, when better service performances, higher longevity and enhanced quality become important issues, FRC utilisation often becomes inevitable. Therefore, those who decide the quality of concrete should be able to defend their choice to those they represent. The onus is on them to justify not using FRC considering all benefits brought by their appropriate use in structures.
Not all challenges have been discussed here and several technical and scientific issues still have to be resolved. Adding fibres into a concrete mix is not magical and the challenges remain high. Despite the obstacles that need to be crossed and the long journey ahead, the path appears more clearly. It requires more research, open minds, visions and close collaboration between all actors. Forums such as the FRC workshops are essential events that bring together participants of various technical geographical origin. They are one component of the collaborative effort that is needed to achieve the objective of building better structures. FRC is a remarkable material, and so far we have only scratched the surface of the contributions it can make to structural concrete design. Although fibres themselves are relatively expensive, they lead to real economic benefits in the design of concrete structures, and can expand the range of structures that can be constructed using concrete. It is hoped that some of the suggestions presented above can lead to the more rapid introduction of this material into everyday engineering practice.
Table of Contents
Design guidelines and specifications
Structural design according to fib MC 2010: Comparison between RC and FRC elements
Marco di Prisco, Giovanni Plizzari, Lucie Vandewalle
Design based approaches for fibre-reinforced concrete: An overview of ACI
committee 544 activities
Barzin Mobasher
FRC design according to the draft Australian bridge code
Stephen Foster
An introduction to the Chinese guideline for fibre-reinforced concrete structures
Christopher K. Y. Leung
FRCC: Design and application in Japan
Yuichi Uchida, Minoru Kunieda, Keitetsu Rokugo
French recommendations and feedback on experience with ultra-high-performance
fibre-reinforced concrete (UHPFRC)
Jacques Resplendino
Steel-fibre-reinforced concrete (SFRC) in fire: Normative and pre-normative
requirements and code-type regulations
Frank Dehn, Annemarie Herrmann
Material properties for design
Translation of test results of small specimens of flowable fibre concrete to structural
behaviour: A discussion paper of fib Task Group 4.3
Steffen Grünewald, Luca Bartoli, Liberato Ferrara, Terje Kanstad, Frank Dehn
Fibre-reinforced cementitious composites with adapted rheology: From state-of-the-art
knowledge towards new boundaries for structural concrete applications
Liberato Ferrara
Study of rheological and mechanical performance of ultra-high-performance glass
concrete
Nancy Soliman, Arezki Tagnit-Hamou
Feasibility of using recycled steel fibres to enhance the behaviour of recycled aggregate
concrete
Khaleel H. Younis, Kypros Pilakoutas, Maurizio Guadagnini, Harris Angelakopoulos
Effect of steel fibres on the tensile behaviour of self-consolidating reinforced
concrete blocks
Romildo Dias Toledo Filho, Ederli Marangon, Flávio de Andrade Silva, Barzin Mobasher
Fracture behaviour of polyolefin fibre-reinforced self-compacting concrete
Marcos G. Alberti, Alejandro Enfedaque, Jaime C. Gálvez
Modelling early age drying in fibre-reinforced concretes
Tara Rahmani, Mehdi Bakhshi, Barzin Mobasher, Mohammad Shekarchi
Behaviour and design of beams and columns
Shear design of full-scale prestressed SFRC girders
Tim Soetens, Stijn Matthys
Numerical modelling of large scale steel-fibre-reinforced reinforced concrete
beams failing in shear
Ali Amin, Stephen J. Foster
Structural applicability of polypropylene fibres: Deep and wide-shallow beams
subjected to shear
Antonio Conforti, Andrea Tinini, Fausto Minelli, Giovanni Plizzari, Sandro Moro
The effect of fibres in UHPFRC beams with longitudinal steel reinforcement
Norbert Randl, Tamás Mészöly
Experimental and numerical study on the use of high-strength and ultra-highperformance
fibre-reinforced concrete in columns
Dario Redaelli, Ana Spasojevic, Aurelio Muttoni
Experimental and analytical behaviour of RC members strengthened by means of
a high-performance jacket
Serena Mostosi, Consuelo Beschi, Alberto Meda, Paolo Riva
Behaviour and design of slabs and other structures
The behaviour of SFRC flat slabs: The Limelette full-scale experiments to support
design model codes
Benoit Parmentier, Petra Van Itterbeeck, Audrey Skowron
Precast fibre-reinforced self-compacting concrete slabs
Luca Facconi, Fausto Minelli, Giovanni Plizzari, Andrea Pasetto
Precast plates made with lightweight fibre-reinforced concrete
Alessandro P. Fantilli, Andrea Gorino, Bernardino Chiaia
Mechanical behaviour of slabs made of strain-hardening cement-based composite
and steel reinforcement subject to uniaxial tensile loading
Eric Mündecke, Viktor Mechtcherine
Innovative precast HPFRC barriers for bridges
Jean-Philippe Charron, Matthew Namy, François Duchesneau, Bruno Massicotte
Effectiveness of fibres for structural elements in case of fire
György L. Balázs, Éva Lublóy, Olivér A. Czoboly
Steel-fibre reinforcement for large hydraulic concrete structures: Numerical
investigations on a semi-spiral case
Mahdi Ben Ftima, Bruno Massicotte, Sébastien Mousseau
Numerical models for designing steel-fibre-reinforced concrete structures: Why
and which ones?
Pierre Rossi, Jean-Louis Tailhan, Dominic Daviau-Desnoyers
Load-bearing capacities of SFRC elements accounting for tension stiffening with
modified moment-curvature relations
Peter Heek, Peter Mark
Behaviour and design of foundations and underground components
Design of glass-fibre-reinforced concrete floors according to the fib Model Code 2010
Bryan Barragán, Luca Facconi, Olivier Laurence, Giovanni Plizzari
A comprehensive methodology for the design of fibre-reinforced concrete pavements
Sunitha K. Nayar, Ravindra Gettu
Experimental and numerical study on the load-bearing behaviour of steel-fibrereinforced
concrete for precast tunnel lining segments under concentrated loads
Rolf Breitenbücher, Günther Meschke, Fanbing Song, Michael Hofmann, Yijian Zhan
Developments in design for fibre-reinforced concrete tunnel segments
Mehdi Bakhshi, Verya Nasri
Optimization of input parameters for material modelling of fibre-reinforced concrete
and application to the numerical simulation of tunnel lining
Tereza Sajdlová, Radomír Pukl
Steel-fibre reinforcement for precast lining in tunnels with different diameters
Alberto Meda, Zila Rinaldi
Numerical simulation of steel-fibre-reinforced concrete pipes using constitutive
equations based on the Barcelona test
Renata Monte, Albert de la Fuente, Antonio D. de Figueiredo, Antonio Aguado
Optimum fibre content for precast steel-fibre-reinforced concrete pipes
Nedal Mohamed, Ahmed Soliman, Moncef Nehdi
Applications in structure and underground construction projects
FRC structural applications according to the fib Model Code 2010: A unified approach
Marco di Prisco, Matteo Colombo, Pamela Bonalumi, Carlo Beltrami
Steel-fibre-reinforced concrete elevated suspended slabs: Design cases in Europe and
the USA
Xavier Destrée
Design and construction of SFRC bridge decks: Building on past experiences and recent
developments
Bruno Massicotte, Léa Faggio, Nicola Cordoni, Ali Nour, David Conciatori
Footbridge over the Ovejas ravine in Alicante: An economical alternative made only of
ultra-high-performance fibre-reinforced concrete (UHPFRC)
Pedro Serna, Juan Ángel López, Esteban Camacho, Hugo Coll, Juan Navarro-Gregori
Examples of bridge, tunnel lining and foundation design with steel-fibre-reinforced
concrete
Agnieszka Winkler, Carola Edvardsen, Thomas Kasper
Earthquake-resistant fibre-reinforced concrete coupling beams without diagonal bars
G.J. Parra-Montesinos, J. K. Wight, C. Kopczynski, R.D. Lequesne, M. Setkit, A. Conforti, J. Ferzli
Design of FRC tunnel segments considering the ductility requirements of the fib Model 471
Code 2010: Application to the Barcelona Metro Line 9
Albert de la Fuente, Liao Lin, Sergio Cavalaro, Antonio Aguado