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Showing 1-5 of 13 Abstracts search results

Document: 

SP155

Date: 

August 1, 1995

Author(s):

Editors: David J Stevens, Nemy Banthia, Vellore S. Gopalaratnam, and Peter C. Tatnall / Co-Sponsored by: ACI Committee 444 and ACI Committee 544

Publication:

Symposium Papers

Volume:

155

Abstract:

Fiber Reinforced Concrete (FRC) is a composite material that possesses many mechanical, physical, and chemical properties that are distinct from unreinforced concrete. Recent advances in testing techniques, instrumentation, and interpretation of test results for FRC are the subject of the papers included in this symposium volume. These papers were presented at two technical sessions on the Testing of Fiber Reinforced Concrete, held during the 1995 ACI Spring Convention in Salt Lake City, Utah. These sessions and this special volume were co-sponsored by Committees 544, Fiber Reinforced Concrete; and 444, Experimental Analysis of Concrete Structures. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP155

DOI:

10.14359/14195


Document: 

SP155-02

Date: 

August 1, 1995

Author(s):

D. Jamet

Publication:

Symposium Papers

Volume:

155

Abstract:

The toughness of fiber reinforced concretes (FRC) was characterized from notched beam tests. The tests were performed under CMOD control in a servo-hydraulic machine to obtain the stable response of both the unreinforced concrete and the FRC. Several toughness measures were defined in terms of the experimentally obtained load versus crack opening (CMOD) curves. They give a better indication of the fundamental behavior of the concrete, avoid the problems associated with the approach based on the deflection of unnotched beams, and are amenable to the incorporation of serviceability considerations (for example, crack widths). The effect of specimen size on toughness was found to be significant in both the matrix- and fiber-dominated regimes of the FRC behavior. In general, toughness increases with specimen size and needs to be accounted for in the characterization. The study was conducted on beams of a 70 MPa compressive strength silica fume concrete, with and without high-strength hooked steel fibers. It was found that the incorporation of a low volume fraction (one percent) of steel fibers is sufficient to significantly decrease the brittleness of high-strength concretes.

DOI:

10.14359/927


Document: 

SP155-11

Date: 

August 1, 1995

Author(s):

C. D. Hays and R. F. Zollo

Publication:

Symposium Papers

Volume:

155

Abstract:

Recent natural disasters involving high wind events have demonstrated the fact that building envelopes, including structural walls and roofs, can lose structural integrity as a result of penetration by missile objects. Because of this, there is heightened interest in the testing of components and cladding that are used as a part of building envelopes of habitable structures. A large missile impact test has been designed and is being evaluated in laboratories around the country. The test, discussed in this paper, is suitable for laboratory or field applications and is currently undergoing scrutiny by the ASTM Task Force of Committee E6, Performance of Buildings. Adoption of the test by the South Florida Building Code came in the wake of Hurricane Andrew in 1992. The test has been applied to numerous types of wall systems and building products, including a fiber reinforced cellular concrete panel which is designed to be used as an alternate to masonry infill construction, architectural precast, demising walls, and security fencing. Additional tests of the missile impact resistance of fiber reinforced cellular concrete involving the use of large caliber ballistics are also discussed. The high energy impact resistance of fiber reinforced systems is demonstrated and discussed.

DOI:

10.14359/936


Document: 

SP155-05

Date: 

August 1, 1995

Author(s):

B. Mobasher, C. Y. LI, and A. Arino

Publication:

Symposium Papers

Volume:

155

Abstract:

Procedures to obtain the experimental R-curves using a compliance calibration technique are revisited in this paper. R-curves provide a convenient means to study the process of fracture and the brittle-ductile transition in materials. Single edge notched beam specimens are tested under closed loop crack mouth opening control. The procedure to obtain the R-curves using loading/unloading compliance and the residual displacements are discussed. An elastically equivalent toughness K R as a function of crack extension is defined to compare the R-curves with the available data in the literature. The developed test method is applied to fiber reinforced concrete (FRC) composites with up to eight percent by volume of short, chopped alumina, carbon, and polypropylene (PP) fibers. Significant strengthening of the matrix due to the addition of short carbon and alumina fibers was observed. R-curves in these composites are characterized by an increase in the steady state fracture toughness. In PP-FRC composites, energy dissipation due to fiber pullout increases the ascending rate of the R-curve well after the main crack has formed. The work of fracture is computed from the cyclic loading/unloading tests and the results compared with the R-curves.

DOI:

10.14359/930


Document: 

SP155-04

Date: 

August 1, 1995

Author(s):

D. E. Nemegeer and P. C. Tatnall

Publication:

Symposium Papers

Volume:

155

Abstract:

Standard Test Method for Flexural Toughness and First- Crack Strength of Fiber-Reinforced Concrete (Using Beam With Third-Point Loading), was conceived to produce toughness parameters independent of the dimensions of the test specimen. This seems not to be true. Additionally, the toughness indices that are required to be reported are shown not to be sensitive to the type and amount of fibers used, thus not providing a usable value for characterizing flexural toughness. Furthermore, since the calculation of the toughness index values are directly related to the first-crack deflection measurements, a value which is difficult to determine, these values become dependent on the testing equipment used. Proposals for revision of ASTM C 1018 are presented in this paper to address these concerns.

DOI:

10.14359/929


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