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International Concrete Abstracts Portal

Showing 1-5 of 96 Abstracts search results

Document: 

SP230-90

Date: 

October 1, 2005

Author(s):

T. Ozbakkaloglu and M. Saatcioglu

Publication:

Symposium Papers

Volume:

230

Abstract:

Fiber reinforced polymer (FRP) casings, in the form of stay-in-placeformwork, provide an attractive alternative to conventional confinement reinforcementfor concrete columns. These casings can fulfill multiple functions of; i) formwork, ii)confinement reinforcement, and iii) protective shell against corrosion, weathering andchemical attacks. This paper investigates the use of stay-in-place FRP formwork asconcrete confinement reinforcement for HSC columns with circular and square cross-sections. Large-scale specimens with 270 mm cross-sectional dimension and up to 90MPa concrete strength, were tested under combined axial compression andincrementally increasing lateral deformation reversals. FRP casings were manufacturedfrom carbon fiber sheets and epoxy resin. One of the square columns was providedwith internal FRP crossties, a new technique introduced by the authors, to provide well-distributed lateral restraints along the column face, thereby improving the mechanismof confinement. The results indicate that the deformation capacity of HSC columns canbe improved significantly by using FRP casings. The results further indicate that theconfinement effectiveness of casings of square columns is significantly affected by thecorner radius of casings. Confinement efficiency of these casings improves with the useof FRP crossties.

DOI:

10.14359/14911


Document: 

SP230-59

Date: 

October 1, 2005

Author(s):

Z. Yan, C.P. Pantelides, and L.D. Reaveley

Publication:

Symposium Papers

Volume:

230

Abstract:

To improve the confinement effectiveness of FRP composites for square andrectangular columns, shape modification is performed by using prefabricated FRP shellscombined with expansive cement concrete. Chemical post-tensioning using expansivecement concrete is used to change the FRP confinement from “passive” to “active”.Experimental results are presented demonstrating the effectiveness of this method. Ananalytical stress-strain model is developed for shape-modified FRP-confined columnswith expansive cement concrete which is based on the modified Willam-Warnkeplasticity model, the Popovics general stress-strain concrete model, and the dilatancybehavior obtained from the present study. This model is implemented by anincremental approach which accounts for the variable FRP confinement during theloading process. The analytical results show satisfactory agreement with theexperiments.

DOI:

10.14359/14880


Document: 

SP230-09

Date: 

October 1, 2005

Author(s):

D. Gremel, N. Galati, and J. Stull

Publication:

Symposium Papers

Volume:

230

Abstract:

A method for screening the durability of FRP bars under bending stress andimmersion in high pH solution at elevated temperature is described. Discussion of theneed for such a test, process variables affecting durability, determination of theappropriate bending radius and a description of the test method are shown. Testresults from a series of eight production runs varying only one of the processes relatedvariables, glass fiber supplier, are shown. Fiber sizing chemistry for the fiber/resin/production system is key to better durability of GFRP rebar. The bending stressdurability test method helps reveal FRP bar system performance for differentconstituent materials and offers a more practical method for evaluating alkalinedurability of GFRP bars. The method is intended as an indicator of durabilityperformance and not a definitive evaluation.

DOI:

10.14359/14830


Document: 

SP230-04

Date: 

October 1, 2005

Author(s):

M. Saiidi, R. Johnson, and E. Maragakis

Publication:

Symposium Papers

Volume:

230

Abstract:

Glass, carbon, and hybrid (glass/carbon) fabric reinforced polymer (FRP)restrainers were developed and tested as an alternative to steel restrainers to reducebridge hinge movement during earthquakes. The FRP bridge restrainers weredynamically tested on a representative in-span hinge, in the large-scale structureslaboratory at the University of Nevada, Reno (UNR). Work included: (1) Strain rate testson both FRP strips and FRP/concrete bond; (2) FRP restrainer development and testing;(3) Comparisons between FRP, steel, and shape memory alloy (SMA) restrainers; (4)Development and evaluation of a simple restrainer design method. Findings confirm thepotential use of FRP restrainers as a viable option to steel as a restraining device forbridges. Results include: (1) FRP strength is strain-rate insensitive; (2) FRP/concretebond strength is a function of concrete shear strength and is strain-rate sensitive; (3)FRP restrainers are easily constructed and installed; (4) A proposed restrainer designmethod that considers the bridge structure dynamic characteristics is demonstrated tobe both simple and realistic.

DOI:

10.14359/14825


Document: 

SP230-71

Date: 

October 1, 2005

Author(s):

V.K.R. Kodur, L.A. Bisby, M.F. Green, and E. Chowdhury

Publication:

Symposium Papers

Volume:

230

Abstract:

Increased use of fiber reinforced polymer (FRP) materials for strengtheningof concrete structures has raised concerns regarding the behavior of such FRP systemsin fire. Limited information is currently available on the fire endurance of FRP-strengthened concrete systems. This paper presents results from full-scale fireresistance experiments on two square reinforced concrete (RC) columns. A comparisonis made between the fire performance of a conventional RC column and that of an FRP-strengthened and insulated RC column. Data obtained during the experiments showthat the fire behavior of FRP-wrapped and insulated square concrete columns,protected using an appropriate fire protection system, is as good as that ofunstrengthened RC columns. Factors that significantly influence the fire resistance ofFRP-reinforced concrete columns are discussed. It is demonstrated that satisfactory fireresistance ratings for FRP-wrapped square concrete columns can be obtained throughcareful design and by incorporating appropriate fire protection measures into theoverall structural system.

DOI:

10.14359/14892


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