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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 415 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_22

Date: 

October 1, 2020

Author(s):

Zani, G.; Colombo, M.; Failla, C.; di Prisco, M.

Publication:

Symposium Papers

Volume:

343

Abstract:

A new partially prefabricated elevated slab has been recently introduced in two different industrial buildings, to propose a viable alternative to the classical double tee deck with the addition of an in-situ RC topping. The solution is characterized by an adjustable spacing in the orthogonal direction, 40 mm thick FRC plates used as predalles and a cast-in-place FRC finishing, designed according to a continuous slab resting on the simply-supported beams. The proposed deck is a structural solution that tries to fit different issues like construction speed, transport and cost reduction, structural optimization, high fire resistance (R120) and quality performance. All elements are made of SFRC, characterized by different mix designs. This paper presents a design investigation on this kind of floor element, aimed at optimizing the global structural solution by minimizing the whole floor weight. Longitudinal and transverse bending, as well as vibration limit state, were considered in the design. The optimization strategy will be here presented, through the discussion of the parameters considered in the design, the variables taken into account and the constraints adopted within the procedure. A Model Code 2010 design approach was followed.


Document: 

SP-343_17

Date: 

October 1, 2020

Author(s):

Juhasz, K.P.; Schaul, P.

Publication:

Symposium Papers

Volume:

343

Abstract:

In the past decade macro synthetic fibre reinforcement has become widely used for concrete track slabs including tramlines. By using macro synthetic fibres as a reinforcement in concrete slabs both the casting time and manual work will decrease, while the concrete’s ductility will increase. In addition the durability will be higher with using synthetic fibres, and the carbon footprint will be lower compared to steel mesh or fibre reinforcement. In most cases the steel reinforcement can be omitted entirely from the structures using macro synthetic fibres. The uniformly distributed fibres in the concrete can increase the residual flexural strength of the concrete independently from the location. This makes it possible to use the fibres in both cast in situ and precast elements used for tramlines. The calculation process for these structures always has to comprise of both the static load, the dynamic load and the effect of cyclic loading, i.e. fatigue. These load calculations can be handled using advanced finite element analysis software, which is specialized for concrete and fibre reinforced concrete structures. The paper will present the opportunities for using macro synthetic fibres together with the process of designing fibre reinforced concrete tramlines.


Document: 

SP-343_50

Date: 

October 1, 2020

Author(s):

Charron, J.P.; Desmettre, C.; Cantin Bellemare, E.

Publication:

Symposium Papers

Volume:

343

Abstract:

A cast-in-place reinforced concrete footbridge built in 1967 suffering from extensive concrete spalling and rebar corrosion needed to be replaced. The use of a steel Pony-Warren truss combined with thin precast UHPFRC slabs linked by short UHPFRC field-cast joints was selected to build an innovative, durable and aesthetic footbridge minimizing impact on traffic during construction. Material rationalization allowed respective reductions of 64 % and 91 % of concrete and rebar volumes in the slab in comparison to a conventional reinforced concrete slab. The design process was completed with non-linear finite element calculations to obtain an adequate behaviour of the UHPFRC slabs and joints at service and ultimate limit states. A full-size proof specimen was then tested under positive bending moment and confirmed being adequate and fulfilling all the design specifications. Construction of the precast slab was successful and required less time than a conventional slab. The long-term performance provided by the UHPFRC slab will be followed up in the next decades.


Document: 

SP-343_19

Date: 

October 1, 2020

Author(s):

Conforti, A.; Trabucchi, I.; Tiberti, G.; Plizzari, G.A.; Caratelli, A; Meda, A.; Moro, S.; Hunger, M.

Publication:

Symposium Papers

Volume:

343

Abstract:

There is a growing interest in the scientific community on the structural applicability of polypropylene macrofibers without or in combination with conventional reinforcement as spread reinforcement for precast tunnel segmental linings. Polypropylene macrofibers could be used in precast tunnel segments as shear reinforcement and for withstanding splitting and spalling tensile stresses which occur under and between Tunnel Boring Machine (TBM) rams, respectively. Fibers could also simplify and speed up the tunnel element production process. In this context, the present study investigates the possibility of using polypropylene macrofiber reinforcement in precast tunnel segments for both hydraulic and metro tunnel linings. Four full-scale segments (two counter-key segments of a hydraulic tunnel and two trapezoidal shaped segments of a metro tunnel) were experimentally evaluated under point load test. The latter simulate the TBM actions on segments during the excavation process (TBM thrust jack phase), which is generally the most critical temporary loading condition for segments. Two reinforcement solutions were studied: a typical conventional reinforcement (reference samples) and a combination of polypropylene macrofibers and conventional reinforcement (hybrid solution). Polypropylene macrofibers were observed to be very effective in combination with conventional reinforcement, underlining the fibers ability in controlling both splitting and spalling phenomena.


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