High-Bond Bars in NSC and HPC: Study on Size Effect and on the Local Bond Stress-Slip Law
Publication: Journal of Structural Engineering
Volume 133, Issue 2
Abstract
Size effect is studied here with reference to the bonding of short, deformed bars, embedded in normal-strength concrete (NSC) and high-performance concrete (HPC). Tests on 48 cylindrical specimens reinforced with a single bar and subjected to a pull-out or push-in force show that bond exhibits a strong size effect, which is well described by Bazant’s general-type size-effect law. Four diameters are considered ( , 12, 18, and ), with bonded length-to-bar diameter ratios equal to 3.5 (HPC) and 5 (NSC). All specimens are highly confined by means of a steel jacket to prevent or control cover splitting and to investigate bond behavior in highly confined conditions. Test results on short, anchored bars were instrumental in working out the local bond stress-slip law, taking into account size effect, which appears in the formulation of the maximum bond stress through the bar diameter. Short embedments also prevented bar yielding. The proposed local bond stress-slip law (1) is formulated as an extension of the law suggested in European Model Code MC90, also including some later proposals; (2) fits quite well with the available test data on short, well-confined anchored bars; (3) introduces the favorable effects that the confining reinforcement (generally consisting of stirrups and longitudinal bars) has on bond strength; and (4) may be easily introduced into a design code.
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Acknowledgments
The writers are grateful to the Italian Ministry of the University and Research—MIUR, for funding this project, through the National Cooperative Research Project “Mechanical Deterioration and Durability of Normal and High-Performance Concrete Structures” (2000–2002). The suggestions by Dr. Dario Coronelli and the support given by MS Engineer Lorenzo Lelli in carrying out the tests are gratefully acknowledged.
References
Bamonte, P., Coronelli, D., and Gambarova, P. G. (2002). “Size effect in high-bond bars.” Proc., 3rd Int. Symp. on Bond in Concrete: From Research to Standards, G. L. Balazs, P. J. M. Bartos, J. Cairns, and A. Borosnyoi, eds., Univ. of Technology and Economics, Budapest, Hungary, 43–52.
Bamonte, P., Coronelli, D., and Gambarova, P. G. (2003). “Smooth anchored bars in NSC and HPC: A study on size effect.” J. Adv. Concrete Technol., 1(1), 42–53.
Bamonte, P., Coronelli, D., and Gambarova, P. G. (2004). “Local bond stress-slip law and size effect in high-bond bars.” Proc., 5th Int. Conf. on Fracture Mechanics of Concrete and Concrete Structures (FraMCoS-5), Vol. 2, V. C. Li, C. K. Y. Leung, K. J. Willam, and S. L. Billington, eds., ACI, Farmington Hills, Mich., 869–876.
Bazant, Z. P., and Desmorat, R. (1994). “Size effect in fiber or bar pullout with interface softening slip.” J. Eng. Mech., 120(9), 1945–1962.
Bazant, Z. P., Li, Z., and Thoma, M. (1995). “Identification of stress–slip law for bar or fiber pullout by size effect tests.” J. Eng. Mech., 121(5), 620–625.
Bazant, Z. P., and Sener, S. (1988). “Size effect in pullout tests.” ACI Mater. J., 85(5), 347–351.
Cattaneo, S., Mola, F., Rosati, G. P., and Giussani, F. (2004). “Bond and size effect in self-compacting concrete.” Proc., 23rd National Conf. of the Italian Society of R/C and P/C Structures—AICAP, E. F. Radogna, ed., Patron Editore, Bologna, Italy, 95–100.
Comité Euro-International du Béton (CEB-FIB). (1993). “CEB-FIP model code 1990—Design code.” Thomas Telford, London.
de Larrard, F., Schaller, I., and Fuchs, J. (1993). “Effect of bar diameter on the bond strength of passive reinforcement in HPC.” ACI Mater. J., 90(4), 333–339.
Elfgren, L., Noghabai, K., Ohlsson, U., and Olofsson, T. (1995). “Application of fracture mechanics to anchors and bond.” Proc., 2nd Int. Conf. on Fracture Mechanics of Concrete and Concrete Structures (FraMCoS-2), Vol. 3, F. H. Wittmann, ed., Aedificatio, Freiburg, Germany, 1685–1694.
Eligehausen, R., Popov, E. P., and Bertero, V. V. (1983). “Local bond stress-slip relationships of deformed bars under generalized excitations.” Rep. No. UCB/EERC 83-23, Univ. of California at Berkeley, Berkeley, Calif.
Esfahani, M. R., and Rangan, B. V. (1998). “Local bond strength of reinforcing bars in normal-strength and high-strength concrete (HSC).” ACI Struct. J., 95(2), 96–106.
Fédération Internationale du Béton (FIB). (2000). “Bond of reinforcement in concrete.” Bulletin No. 10, State-of-Art Rep. T.G. 4/2 Bond Models, FIB, Lausanne, Switzerland.
Giuriani, E. (1981). “Experimental investigation on the bond–slip law of deformed bars in concrete.” Proc., IABSE Colloquium Delft on Advanced Mechanics of Reinforced Concrete, IABSE-AIPC-IVBH, Zurich, Switzerland, 121–142.
Huang, Z., Engström, B., and Magnusson, J. (1996). “Experimental and analytical studies of the bond behavior of deformed bars in high-strength concrete.” Proc., 4th Int. Symp. on the Utilization of HSC/HPC, Vol. 3, F. de Larrard and R. Lacroix, eds., ENPC, Paris, 1115–1124.
Lorrain, M., and Hamouine, A. (1996). “Bond performance of high-strength concrete.” Proc. 4th Int. Symp. on the Utilization of HSC/HPC, Vol. 3, F. de Larrard and R. Lacroix, eds., ENPC, Paris, 1195–1200.
Morita, S., Fujii, S., and Kondo, G. (1994). “Experimental study on size effect in concrete structures.” Size effect in concrete structures, H. Mihashi, H. Okamura, and Z. P. Bazant, eds., E & FN Spon, London, 27–46.
Soroushian, P., and Choi, K. B. (1989). “Local bond of deformed bars with different diameters in confined concrete.” ACI Struct. J., 86(2), 217–222.
Stang, H., Li, Z., and Shah, S. P. (1990). “Pullout problem: Stress versus fracture mechanical approach.” J. Eng. Mech., 116(10), 2136–2150.
Yerlici, V. A., and Ozturan, T. (2000). “Factors affecting anchorageb ond strength in high-performance concrete.” ACI Struct. J., 97(3), 499–507.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 133 • Issue 2 • February 2007
Pages: 225 - 234
Copyright
© 2007 ASCE.
History
Received: Nov 9, 2004
Accepted: Dec 16, 2005
Published online: Feb 1, 2007
Published in print: Feb 2007
Notes
Note. Associate Editor: Dat Duthinh
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