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International Concrete Abstracts Portal

Showing 1-5 of 93 Abstracts search results

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: 

SP326-74

Date: 

August 10, 2018

Author(s):

Lijie Wang, Robby Caspeele, and Luc Taerwe

Publication:

Symposium Papers

Volume:

326

Abstract:

Fire has an important influence on concrete structures. It does not only affect the strength of concrete, but also the structural stiffness and stability. A concrete column has most often to cope with vertical forces and bending moments from slabs and beams. Consequently, it is essential to find a reliable and practical way to establish interaction curves for concrete columns subjected to fire.

As a first step, the current situation on the fire resistance of reinforced concrete columns is explained and a cross-sectional calculation tool is proposed taking into account the thermal properties as well as the temperature-dependent material properties provided in Eurocode 2. Further, second-order effects are considered based on cross-sectional calculations. The temperature distributions of a chosen cross-section as well as the load capacity of the columns exposed to an ISO834 standard fire are shown and compared with the rules incorporated in Eurocode 2 and experimental data respectively. It is observed that the results obtained with the numerical tool are in good agreements with the experiments. Finally, the effect of several parameters (i.e. fire duration, exposure faces, dimensions, reinforcement ratio, axial load, eccentricity, concrete cover thickness and the slenderness ratio) is investigated and discussed.


Document: 

SP326-62

Date: 

August 10, 2018

Author(s):

Valeriy Dorf, Rostislav Krasnovskiy, Dmitriy Kapustin, Patimat Sultygova, and Nina Umnyakova

Publication:

Symposium Papers

Volume:

326

Abstract:

The results of an experimental campaign on the thermal conductivity of a mortar (cement + sand) containing various amounts of steel fibers are presented in this study. Increasing the amount of steel fibers (from 0 to 6% by volume) is shown to reduce the thermal conductivity of SFRC, by the extra porosity induced by the fibers and contact thermal resistance. To show the possible benefits coming from the use of SFRC, the case of SFRC formworks is presented, as these formworks may be used in the fire protection of R/C members, as expendable permanent formworks. To this purpose, the finite-element analysis of an R/C member protected by a SFRC formwork is presented, to assess the effectiveness of this kind of fire protection


Document: 

SP322-04

Date: 

June 18, 2018

Author(s):

Cristian Maluk, Luke Bisby, and Giovanni P. Terrasi

Publication:

Symposium Papers

Volume:

322

Abstract:

Results are presented from a comprehensive experimental study to assess the occurrence of heat-induced longitudinal splitting cracks in concrete specimens reinforced with CFRP or steel when exposed to severe heating from one side, as would likely occur in a fire in a building. Tests were performed on large- and medium-scale precast CFRP reinforced or prestressed specimens. Large-scale specimens were tested in a standard fire resistance test, while medium-scale specimens were tested using a novel Heat-Transfer Rate Inducing System (H-TRIS) which controls thermal exposure by imposing a time-history of incident heat flux at a specimen’s exposed surface. The formation of thermally-induced longitudinal splitting cracks and failure of the concrete cover to provide sufficient confining action, and thus sufficient bond strength, is shown to be more likely for FRP reinforced or prestressed concrete elements than for those reinforced or prestressed with steel. This appears to be at least partly due to thermo-mechanical incompatibility between CFRP reinforcement and concrete; formation of heat-induced longitudinal splitting cracks is related to rapid thermal expansion of CFRP tendons relative to the surrounding concrete. Many aspects of bond performance at elevated temperature remain poorly understood, and these require additional investigation before FRP reinforced or prestressed elements can be used in fire-rated applications with confidence.


Document: 

SP321-12

Date: 

September 29, 2017

Author(s):

David A. Fanella, Mustafa Mahamid, and Michael Mota

Publication:

Symposium Papers

Volume:

321

Abstract:

Voided concrete flat plate slab systems, which have been used for many years in Europe and other parts of the world, are becoming increasingly popular in the U.S. because of many inherent benefits. This paper presents information on these benefits as well as requirements for serviceability, flexure, and shear. Also included are discussions on vibration and fire resistance.


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