Is No-Tension Design of Concrete or Rock Structures Always Safe?—Fracture Analysis
Publication: Journal of Structural Engineering
Volume 122, Issue 1
Abstract
Plain concrete structures such as dams or retaining walls, as well as rock structures such as tunnels, caverns, excavations, and rock slopes, have commonly been designed by elastic–perfectly plastic analysis in which the tensile yield strength of the material is taken as zero. The paper analyzes the safety of this “no-tension” design in the light of the finiteness of the tensile strength of concrete or the tensile strength of rock between the joints. Through examples, it is demonstrated that: (1) the calculated length of cracks or cracking zones can correspond to an unstable state; (2) the uncracked ligament of the cross section, available for resisting horizontal shear loads, can be predicted much too large, compared to the fracture mechanics prediction; (3) the calculated load-deflection diagram can lie lower than that obtained by fracture mechanics; (4) the no-tension load capacity for a combination of crack face pressure and loads remote from the crack front, calculated by elastic analysis on the basis of allowable compressive stress, can be higher than that obtained by fracture mechanics; and (5) an increase in the tensile strength of the material can cause the load capacity of the structure to decrease. Due to the size effect, these facts are true not only for zero fracture toughness (no-toughness design) but also for finite fracture toughness provided that the structure size is large enough. Several previous studies on the safety of no-tension design, including the finite-element analysis of a gravity dam, are also reviewed. It is concluded that if the no-tension limit design is used, the safety factors of concrete or rock structures cannot be guaranteed to have the specified values. Fracture mechanics is required for that.
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References
1.
Bažant, Z. P.(1984). “Size effect in blunt fracture: rock, concrete, metal.”J. Engrg. Mech., ASCE, 110(4), 518–535.
2.
Bažant, Z. P.(1990). “A critical appraisal of `no-tension' dam design: a fracture mechanics viewpoint.”Dam Engrg., 1(4), 237–247.
3.
Bažant, Z. P. (1990). “Errata of `a critical appraisal of “no-tension” dam design: a fracture mechanics viewpoint.”' Dam Engrg., 2(2).
4.
Bažant, Z. P. (1994). “Recent advances in fracture mechanics, size effect and rate dependence of concrete: implication for dams.”Proc., Int. Workshop on Dam Fracture and Damage, A. A. Balkema, Rotterdam, The Netherlands, 41–54.
5.
Bažant, Z. P., and Cedolin, L. (1991). Stability of structures: elastic, inelastic, fracture and damage theories . Oxford University Press, New York, N.Y.
6.
Bažant, Z. P., and Kazemi, M. T.(1990). “Size effect in fracture of ceramics and its use to determine fracture energy and effective process zone length.”J. Am. Ceramic Soc., 73(7), 1841–1853.
7.
Bažant, Z. P., He, S., Plesha, M. E., and Rowlands, R. E. (1991). “Rate and size effect in concrete fracture: implications for dams.”Proc., Int. Conf. on Dam Fracture; Publ. 95-7491, V. Saouma, R. Dungar, and D. Morris, eds., Electric Power Res. Inst., Palo Alto, Calif., 413–425.
8.
Bourdarot, E., Mazars, J., and Saouma, V. E. (eds.). (1994). “Dam fracture and damage.”Proc. Int. Workshop on Dam Fracture and Damage, A. A. Balkema, Rotterdam, The Netherlands.
9.
Broek, D. (1986). Elementary engineering fracture mechanics, 4th Ed., Martinus Nijhoff Publishers, Dordrecht, The Netherlands.
10.
Brown, W. F., and Srawley, J. E. (1967). “Fracture toughness testing methods.”Fracture toughness testing and its applications; STP 381, ASTM, Philadelphia, Pa.
11.
Bureau of Reclamation (BuRec). (1987). Design of small dams, U.S. Dept. of the Interior, Denver, Colo.
12.
Dungar, R., Saouma, V. E., and Wittmann, F. H. (eds.). (1990). Workshop notes: research workshop on “Application of fracture mechanics to dam engineering .” Swiss Federal Inst. of Technol. (ETH), Zürich, Switzerland.
13.
Gioia, G., Bažant, Z. P., and Pohl, B.(1992). “Is no-tension dam design always safe?”Dam Engrg., 3(1), 23–34.
14.
Gioia, G., Bažant, Z. P., and Pohl, B. (1992). “Closure to `Is no-tension dam design always safe?”' Dam Engrg., 4(1), 59.
15.
Gross, B., and Srawley, J. E. (1964). “Stress intensity factors for a single-edge-notch tension specimen by boundary collocation of a stress function.”Rep. NASA TN D-2395.
16.
He, S., Plesha, M. E., Rowlands, R. E., and Bažant, Z. P.(1992). “Fracture energy tests of dam concrete with rate and size effects.”Dam Engrg., 3(2), 139–159.
17.
Hodge, P. G. (1959). Plastic analysis of structures, McGraw-Hill Book Co., Inc., New York, N.Y.
18.
Jansen, R. B. (1988). “Advanced dam engineering for design, construction and rehabilitation.” Rep., U.S. Dept. of Interior, Denver, Colo.
19.
Murakami, Y. (ed.) (1987). Stress intensity factors handbook; Vol. 1, Pergamon Press, Oxford, England.
20.
Ottosen, N. S.(1977). “A failure criterion for concrete.”J. Engrg. Mech., ASCE, 103(4), 527–535.
21.
Owen, D. R. J., and Hinton, E. (1980). Finite elements in plasticity, Pineridge Press, Swansea, Wales.
22.
Saouma, V. E., Dungar, R., and Morris, D. (eds.). (1991). “Dam fracture.”Proc., Int. Conf. on Dam Fracture; Publ. GS-7491, Electric Power Res. Inst., Palo Alto, Calif.
23.
Saouma, V. E., Brühwiler, E., and Boggs, H. L.(1990). “A review of fracture mechanics applied to concrete dams.”Dam Engrg., 1(1), 41–58.
24.
Tada, H., Paris, P. C., and Irwin, J. K. (1985). The stress analysis of cracks handbook, 2nd Ed., Paris Productions, Inc., St. Louis, Mo.
25.
Tardieu, B., and Londe, P.(1992). “Discussion of Bažant, Gioia and Pohl (1992).”Dam Engrg., 3(4), 301.
26.
Waterways Experiment Station (WES). (1983). “Design of gravity dams on rock foundations: sliding stability assessment by limit equilibrium and selection of shear strength parameters.”Tech. Rep. GL-83-13, U.S. Army Corps of Engrs., Vicksburg, Miss.
27.
Zienkiewicz, O. C. (1971). The finite element method in engineering science, McGraw-Hill Book Co., Inc., London, England.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 122 • Issue 1 • January 1996
Pages: 2 - 10
Copyright
Copyright © 1996 American Society of Civil Engineers.
History
Published online: Jan 1, 1996
Published in print: Jan 1996
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