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  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

Showing 1-5 of 487 Abstracts search results

Document: 

SP343

Date: 

November 3, 2020

Author(s):

fib and ACI

Publication:

Symposium Papers

Volume:

343

Abstract:

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. June 2018 Bruno Massicotte, Fausto Minelli, Barzin Mobasher, Giovanni Plizzari


Document: 

SP-343_09

Date: 

October 1, 2020

Author(s):

Ferrara, L.; Asensio, E.C.; Lo Monte, F.; Snoeck, D.; De Belie, N.

Publication:

Symposium Papers

Volume:

343

Abstract:

The design of building structures and infrastructures is mainly based on four concepts: safety, serviceability, durability and sustainability. The latter is becoming increasingly relevant in the field of civil engineering. Reinforced concrete structures are subjected to conditions that produce cracks which, if not repaired, can lead to a rapid deterioration and would result in increasing maintenance costs to guarantee the anticipated level of performance. Therefore, self-healing concrete can be very useful in any type of structure, as it allows to control and repair cracks as soon as they to occur. As a matter of fact, the synergy between fibre-reinforced cementitious composites and selfhealing techniques may result in promising solutions. Fibres improve the self-healing process due to their capacity to restrict crack widths and enable multiple crack formation. In particular, cracks smaller than 30-50 μm are able to heal completely. Moreover, in the case of High Performance Fibre Reinforced Cementitious Composites (HPFRCC), high content of cementitious/pozzolanic materials and low water-binder ratios are likely to make the composites naturally conducive to self-healing. In this framework the main goal of this paper is twofold. On the one hand, a state-of-the-art survey on self-healing of fibre-reinforced cementitious composites will be provided. This will be analysed with the goal of providing a “healable crack opening based” design concept which could pave the way for the incorporation of healing concepts into design approaches for FRC and also conventional R/C structures. On the other hand, the same state-of-the-art will be instrumental in identifying research needs, which still have to be addressed for the proper use of self-healing fibre-reinforced cementitious composites in the construction field.


Document: 

SP-343_39

Date: 

October 1, 2020

Author(s):

Zanotti, C.; Randl, N.; Gar, P.S.; Far, B.K.; Steiner, M.

Publication:

Symposium Papers

Volume:

343

Abstract:

Fiber Reinforced Concrete (FRC) is being increasingly applied in structural repair and retrofit of reinforced concrete structures. Not only fiber reinforcement improves the durability of reinforced concrete structures, but it also enhances compatibility of the repair material to the existing structure, further enhancing structural effectiveness and service life of the intervention. Furthermore, studies have shown that fiber reinforcement can significantly improve substrate-repair bond in both tension and shear. However, this benefit is not fully utilized in repair/retrofit design due to test uncertainties and lack of comprehensive data on correlations with other fundamental factors. In this study, the question of the appropriateness, reliability and sensitivity of current bond tests in case of FRC repairs is addressed. Several tension and shear bond tests on plain and fiber reinforced cement-based repairs are performed in parallel by two research teams at UBC (Canada) and CUAS (Austria), following a rigorous testing procedure to allow consistency among results from the two laboratories. The influence of repair strength and casting direction is also investigated. The effect of fiber reinforcement on bond is assessed while correlation, comparability, and sensitivity of different test set-ups and stress conditions are discussed.


Document: 

SP-343_14

Date: 

October 1, 2020

Author(s):

Winterberg, R.; Rodrìguez, L.M.; Cámara, R.J.; Abad, D.S

Publication:

Symposium Papers

Volume:

343

Abstract:

Fibre reinforced concrete (FRC) is becoming widely utilized in segmental linings due to the improved mechanical performance, robustness and durability of the segments. Further, significant cost savings can be achieved in segment production and by reduced repair rates during temporary loading conditions. The replacement of traditional rebar cages with fibres further allows changing a crack control governed design to a purely structural design with more freedom in detailing. Macro synthetic fibres (MSF) are non-corrosive and thus ideal for segmental linings in critical environments. Although fibre reinforcement for segments is relatively new, recent publications such as the ITAtech “Guidance for precast FRC segments – Volume 1: Design aspects” or the British PAS 8810 “Tunnel design – Design of concrete segmental tunnel linings – Code of practice” have now given more credibility to this reinforcement type and the basis for design. This paper presents and discusses the design methodology for precast tunnel segments and in particular the tasks associated with the use of MSF reinforcement. Temporary loadings as well as long term load behaviour will be addressed. A case history from the Santoña–Laredo General Interceptor Collector, currently under construction in northern Spain, will illustrate the specific benefits of MSF reinforcement for segmental linings.


Document: 

SP-341-06

Date: 

June 30, 2020

Author(s):

Mostafa Tazarv and M. Saiid Saiidi

Publication:

Symposium Papers

Volume:

341

Abstract:

Current seismic codes prevent bridge collapse under strong earthquakes. For conventional reinforced concrete (RC) bridges, this performance objective is usually achieved through confinement of ductile members such as columns. When an RC bridge column undergoes large displacements, its reinforcement yield and sometimes buckle, the cover concrete spalls, and the core concrete sometimes fail. Damage of reinforcement and core concrete is not easy to repair. Advanced materials and new technologies are emerging to enhance the seismic performance of RC bridge columns by reducing damage, increasing displacement capacities, and/or reducing permanent lateral displacements. Two types of advanced materials, shape memory alloy (SMA) bars and engineered cementitious composite (ECC), are the focus of the present study. SMA bars are viable reinforcement for concrete structures since they resist large stresses with minimal residual strains. Furthermore, ECC, which is a type of fiber-reinforced concrete, shows significant tensile strain capacities with minimal damage. SMA-reinforced ECC bridge columns are ductile with minimal damage and insignificant residual displacements under extreme events. A displacement-based design method for NiTi superelastic SMA-reinforced ECC bridge columns is proposed based on large-scale experimental and extensive analytical studies. A summary of the proposed guidelines, background information, and supporting studies are presented for this novel column type to facilitate field deployment. Finally, the details of the world first SMA-reinforced ECC bridge constructed in Seattle, USA, is discussed.


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