Lateral Confinement Needed to Suppress Softening of Concrete in Compression
Publication: Journal of Engineering Mechanics
Volume 128, Issue 12
Abstract
Suppression of softening in the load-deflection diagram of concrete-filled tubular columns and spiral columns is proposed to serve as a design criterion helping to avoid the size effect and explosive brittle character of collapse. To this end, the recently developed “tube-squash” tests, in which a short concrete-filled steel tube is squashed to about a half of its original length and allowed to bulge, are conducted with tubes of different wall thicknesses. A finite-strain finite element computer code with a microplane constitutive model is used to simulate the tests. After its verification and calibration by tests, the code is used to analyze nonbuckling concrete-filled tubular columns and spirally reinforced columns. It is found that softening in the load-deflection diagram can be fully suppressed only if the reinforcement ratio (ratio of the tube volume or spiral volume to the total volume of column) exceeds about 14%. If mild softening is allowed, the reinforcement ratio must still exceed about 8%. These ratios are surprisingly high. If they are not used in design, one needs to pay attention to the localization of softening damage, accept the (deterministic) size effect engendered by it, and ensure safety margins appropriate for protecting against sudden explosive brittle collapse. This is of particular concern for the design of very large columns.
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References
ABAQUS Theory Manual. (1989). Hibbitt, Karlsson, and Sorensen, Pawtucket, R. I.
Bažant, Z. P.(1996). “Finite strain generalization of small-strain constitutive relations for any finite strain tensor and additive volumetric-deviatoric split.” Int. J. Solids Struct., 33(20–22), 2887–2897 (special issue in memory of Juan Simo).
Bažant, Z. P., Adley, M. D., Carol, I., Jirásek, M., Akers, S. A., Rohani, B., Cargile, J. D., and Caner, F. C.(2000a). “Large-strain generalization of microplane model for concrete and application.” J. Eng. Mech., 126(9), 971–980.
Bažant, Z. P., Caner, F. C., Carol, I., Adley, M. D., and Akers, S. A.(2000b). “Microplane model M4 for concrete. I: Formulation with work-conjugate deviatoric stress.” J. Eng. Mech., 126(9), 944–953.
Bažant, Z. P., and Cedolin, L. (1991). Stabilities of structures: Elastic, inelastic, fracture, and damage theories, Oxford University Press, New York.
Bažant, Z. P., Kim, J.-J. H., and Brocca, M.(1999). “Finite strain tube-squash test of concrete at high pressures and shear angles up to 70 degrees.” ACI Mater. J., 96(5), 580–592.
Bažant, Z. P., and Ožbolt, J.(1992). “Compression failure of quasibrittle material: Nonlocal microplane model.” J. Eng. Mech., 118(3), 540–556.
Bažant, Z. P., and Oh, B.-H. (1986). “Efficient numerical integration on the surface of a sphere.” Zeitschrift für angewandte mathematik und mechanik (ZAMM, Berlin), 66(1), 37–49.
Bažant, Z. P., and Planas, J. (1988). Fracture and size effect in concrete and other quasibrittle materials, CRC, Boca Raton, Fla.
Bažant, Z. P., Xiang, Y., and Prat, P. C.(1996). “Microplane model for concrete. I.: Stress-strain boundaries and finite strain.” J. Eng. Mech., 122(3), 245–254.
Bažant, Z. P., and Xiang, Yuyin. (1997). “Size effect in compression fracture: Splitting crack band propagation.” J. Eng. Mech., 123(2), 162–172.
Brocca, M., and Bažant, Z. P. (2001a). “Microplane finite element analysis of tube-squash test of concrete with shear angles up to 70°.” Int. J. Numer. Methods Eng., in press.
Brocca, M., and Bažant, Z. P.(2001b). “Size effect in concrete columns: Finite-element analysis with microplane model.” J. Struct. Eng., 127(12), 1382–1390.
Brocca, M., and Bažant, Z. P.(2001c). “Microplane constitutive model and metal plasticity.” Appl. Mech. Rev., 53(10), 265–281.
Caner, F. C., and Bažant, Z. P.(2000). “Microplane model M4 for concrete. II: Algorithm and calibration.” J. Eng. Mech., 126(9), 954–961.
Crisfield, M. A. (1997). Non-linear finite element analysis of solids and structures, Vol. 2, Advanced topics, Wiley, New York.
Furlong, R. W.(1967). “Strength of steel-encased concrete beam-columns.” J. Struct. Div., ASCE, 93(5), 113–124.
Gerard, G., and Becker, H. (1957). “Handbook of structural stability. Part I: Buckling of flat plates.” NACA Tech. Note No. 3781.
Ogden, R. W. (1984). Non-linear elastic deformations, Ellis Horwood, Chichester, U.K.
Roeder, C. W., Cameron, B., and Brown, C. B.(1999). “Composite ac-tion in concrete filled tubes.” J. Struct. Eng., 125(5), 477–484.
Schneider, S. P.(1998). “Axially loaded concrete-filled steel tubes.” J. Struct. Eng., 124(10), 1125–1138.
Stroud, A. H. (1971). Approximate calculation of multiple integrals, Prentice-Hall, Englewood Cliffs, N.J.
Taylor, G. I.(1938). “Plastic strain in metals.” J. Inst. Met., 62, 307–324.
van Mier, J. G. M.(1986). “Multiaxial strain-softening of concrete. Part I: Fracture, Part II: Load histories.” Mater. Struct., 111(19), 179–200.
Zienkiewicz, O. C., and Taylor, R. L. (1991). The finite element method, Vol. 2, Dynamics and non-linearity, McGraw-Hill, New York.
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Copyright © 2002 American Society of Civil Engineers.
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Received: Jun 5, 2001
Accepted: Jan 11, 2002
Published online: Nov 15, 2002
Published in print: Dec 2002
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