Abstract
The paper presents some results of tests carried out on concrete confined in circular steel spirals subjected to monotonic compression. An equation is proposed for the stress-strain curves of such concrete. The parameters of the equation are determined and the curve given by the equation found to represent satisfactorily the test results of this investigation as well as those of an earlier study.
Résumé
On présente ici des résultats d'essai sur cylindre de béton confiné dans une hélice d'acier et soumis à une compression à gradient de contrainte constant. On propose une équation pour les courbes contrainte/déformation obtenues. Les paramètres qui ont été déterminés et la courbe résultant de l'équation représentent de façon satisfaisante les résultats d'essai de cette recherche comme ceux d'une étude antérieure.
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Abbreviations
- A, B, C, D :
-
parameters in the stress-strain equation
- C i :
-
confinement index=\(\left( {p_b - \bar p_b } \right){{f_y } \mathord{\left/ {\vphantom {{f_y } {f'_c }}} \right. \kern-\nulldelimiterspace} {f'_c }}\)
- E c :
-
initial slope of the stress-strain curve
- E′ c :
-
ratio\({{\bar f_c } \mathord{\left/ {\vphantom {{\bar f_c } {\bar \varepsilon }}} \right. \kern-\nulldelimiterspace} {\bar \varepsilon }}_c \)
- f, f c :
-
compressive stress
- f′ c :
-
ultimate strength of plain concrete specimen
- \(f_c ^\prime \) :
-
ultimate strength of a confined concrete speciment
- f y :
-
yield strength or 0.2% proof stress of steel spiral
- g 1(ε),g 2(ε):
-
functions of ε
- k :
-
constant
- P b :
-
volumetric ratio, i. e. ratio of the volume of spiral to the volume of confined concrete
- \(\bar p_b \) :
-
value ofp b when the pitch of spiral is equal to the least lateral dimension of the specimen
- β:
-
constant
- ε, εc :
-
compressive strain in concrete
- εc :
-
strain at the ultimate stress of a plain concrete specimen
- \(\bar \varepsilon _c \) :
-
strain at the ultimate stress of a confined concrete specimen
- \(\bar \varepsilon _{0.9} \left( {\bar \varepsilon _{0.85} } \right)\) :
-
strains at 0.9 (0.85) of the ultimate stress of a confined concrete specimen in the descending portion of the stress-strain curve.
References
Sundara Raja Iyengar K. T., Pakash Desayi, Nagi Reddy K.—Stress-strain characteristics of concrete confined in steel binders. Magazine of Concrete Research, Vol. 22, No. 72, September 1970, p. 173–184.
Sundara Raja Iyengar K. T., Prakash Desayi, Nagi Reddy K.—Flexure of reinforced concrete beams with confined compression zones.—Journal of the American Concrete Institute Proc., Vol. 68, No. 9, September 1971, p. 719–725.
Chan W. W. L.—The ultimate strength and deformation of plastic hinges in reinforced concrete frames. Magazine of Concrete Research, Vol. 7, No. 21, November 1955, p. 121–122.
Sargin M., Ghosh S. K., Handa V. K.—Effects of lateral reinforcement upon the strength and deformation properties of concrete. Magazine of Concrete Research, Vol. 23, No. 75-76, June–September 1971, p. 99–110.
Saenz L. P.—Discussion of the paperEquation for the stress-strain curve of concrete. Journal of the American Concrete Institute Proc., Vol. 61, No. 9, September 1964. p. 1229–1235.
Hognestad E.—A study of combined bending and axial load in reinforced concrete members. University of Illinois Engineering Experiment Station Bulletin. Series No. 399, 1951.
Nagi Reddy K.—Studies on the behaviour of confined concrete and its application in flexure of reinforced concrete structures. Ph. D. Thesis. Indian Institute of Science, Bangalore, 1969, 407 p.
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Desayi, P., Sundara Raja Iyengar, K.T. & Sanjeeva Reddy, T. Equation for stress-strain curve of concrete confined in circular steel spiral. Matériaux et Constructions 11, 339–345 (1978). https://doi.org/10.1007/BF02473875
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DOI: https://doi.org/10.1007/BF02473875