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International Concrete Abstracts Portal

Showing 1-5 of 45 Abstracts search results

Document: 

SP310-20

Date: 

March 17, 2017

Author(s):

Serena Mostosi; Consuelo Beschi; Alberto Meda; Paolo Riva

Publication:

Symposium Papers

Volume:

310

Abstract:

The strengthening of existing reinforced concrete (RC) structures, built according to the Italian construction practice of the ’60-‘70s, has become an important and urgent issue. The reasons for strengthening are the need for: increasing strength to withstand underestimated loads; increasing the load-carrying capacity; and fulfilling the seismic code requirements. A new technique to strengthen existing RC structures, based on the application of a thin highperformance fibre-reinforced jacket, is investigated herein. The application of this technique has been studied for the strengthening of beams, columns and beam-column joints by full scale experimental tests which results showed that the application of a high-performance fibrereinforced concrete (HPFRC) jacket leads to a significant increase in strength of the elements, also reaching an adequate level of ductility. Subsequently, the experimental results are compared with analytical evaluations of the load carrying capacity of the retrofitted elements, showing that the analytical formulations are consistent with the experimental evidence.


Document: 

SP310-02

Date: 

March 17, 2017

Author(s):

Barzin Mobasher

Publication:

Symposium Papers

Volume:

310

Abstract:

The ACI Committee 544 on fibre-reinforced concrete (FRC) has been involved in development and dissemination of technical information for nearly a half century. A key advantage in using FRC is the reduction in construction time compared to the traditional reinforcing bars or welded wire mesh. Application areas for FRC have extended to areas where high early strength and ductility are important and include pavement, shotcrete and structures such as bridge deck slabs, or rock slide stabilization. In these cases, the material properties must be measured using experimental test data obtained from an experimental program. Test results must be analysed in order to obtain effective stress strain responses that can be incorporated in analytical, or computer simulation. A list of examples including wall panels, hydraulic structures, airport pavements, and industrial floor overlays are described. To maintain integrity without collapse, such structural elements need to be designed with proper material models and analysis tools discussed.


Document: 

SP310-17

Date: 

March 17, 2017

Author(s):

Antonio Conforti; Andrea Tinini; Fausto Minelli; Giovanni Plizzari; Sandro Moro

Publication:

Symposium Papers

Volume:

310

Abstract:

In recent years important efforts have been devoted to develop new types of polypropylene (PP) macro fibres able to provide significant toughness and ductility to concrete. These PP fibres, which are now widely available in the market, present a series of advantages: a significantly number of fibres per unit volume that allows less variability of experimental results (hence, higher characteristic values for specific mean values); a higher number of fibres intercepting cracks and controlling their propagation (of outmost importance for early-age shrinkage cracking); last but not least, no corrosion stains at the concrete surface. However, even if several experiments available in literature showed that fibres, if provided in sufficient amount and with an adequate toughness, are significantly effective as shear reinforcement, just few of them focused on the shear behaviour of elements made of polypropylene-fibrereinforced concrete (PFRC). In this context, structural applicability of PP macro fibres, adopted as shear reinforcement, is investigated in this paper. Experimental results of full scale tests on fourteen wide-shallow beams (WSBs) and nineteen deep beams in reinforced concrete (RC) and PFRC are presented. These results show that, in both beam typologies, the addition of PP fibres significantly enhances both the shear bearing capacity and the ductility. PP fibres can completely replace and reduce the conventional shear reinforcement in WSBs and deep beams, respectively.


Document: 

SP310-03

Date: 

March 17, 2017

Author(s):

Stephen Foster

Publication:

Symposium Papers

Volume:

310

Abstract:

In January 2014 the Draft for Public Comment Australian Standard for the design of concrete bridges was released (DR AS5100.5); this is the first standard in Australia, and one of the few national standards in the world, to include design procedures for steel-fibrereinforced concrete in a comprehensive way. This presentation provides the background for the development of the design rules, including on determination of the mechanical properties of the materials, design models for strength and serviceability, considerations with regards to durability and on quality control measures. Validation of the mechanical models adopted for design is also presented.


Document: 

SP310-07

Date: 

March 17, 2017

Author(s):

Frank Dehn; Annemarie Herrmann

Publication:

Symposium Papers

Volume:

310

Abstract:

In recent years, because of developments in materials technology, by the understanding of fundamental relationships as well as due to experimentally and numerically driven modelling and design, the use of steel-fibre-reinforced concrete (SFRC) is steadily increasing. One major issue which needs to be taken particularly into account for most SFRC applications is the evidence of their structural safety under fire exposure. This paper gives an overview of nationally and internationally available normative and pre-normative requirements and codetype regulations to model and design both the material and structural behaviour of fireexposed SFRC. The paper will also illustrate that the fire behaviour of SFRC needs to be mandatorily considered both from a technical and legal perspective. Since an implied fire design approach is still pending, experimental verifications are still recommended on a material level but primarily on a structural level in order to provide technically and economically reasonable solutions which do not restrict innovative stages due to conservative assumptions.


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