Experimental and Numerical Assessment of Corbels Designed Based on Strut-and-Tie Provisions
Publication: Journal of Structural Engineering
Volume 144, Issue 9
Abstract
Reinforced concrete (RC) corbels are short cantilever members that are used to transfer eccentric loads into columns or walls. Due to discontinuity in load and geometry, RC corbels cannot be adequately designed using methods that are based on beam theory. AASHTO LRFD Bridge Design Specifications permit the use of the strut-and-tie method (STM) for designing corbels. However, these specifications also require that the reinforcement details satisfy the requirements of an empirical design method, which prevents the efficient use of STM for such members. Moreover, the crack-control reinforcement requirements in the current STM provisions of AASHTO LRFD have been developed based on studies on deep beams, and the suitability of these provisions for corbels has not been investigated. This paper evaluates the behavior of reinforced concrete corbels designed according to the STM provisions of AASHTO LRFD. To do so, first, the performances of three full-scale corbel specimens designed according to STM were experimentally evaluated. Then, a numerical study using experimentally validated nonlinear finite-element models was conducted to investigate the crack-control reinforcement requirements for RC corbels. The results from the experimental study indicate that the STM provisions of the AASHTO LRFD provide conservative estimates of the load-carrying capacity of RC corbels; however, examination of the smeared node near the corbel-column interface, a check not currently required in AASHTO LRFD, is highly recommended. The results from the numerical study suggest that a reduction in the amount of secondary reinforcement currently required by AASHTO LRFD may be feasible, depending on the reinforcement layout used.
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Acknowledgments
The experimental program presented in this paper was carried out as part of a course project for Structural Concrete Bridges at The University of Texas at Austin, during the Fall 2016 semester. The contributions of all graduate students in that class to the experimental program are acknowledged. The authors are also grateful to the staff at the Ferguson Structural Engineering Laboratory for assisting with the performance of the test program.
References
AASHTO. 1994. AASHTO LRFD bridge design specifications. Washington, DC: AASHTO.
AASHTO. 2017. AASHTO LRFD bridge design specifications. Washington, DC: AASHTO.
ACI (American Concrete Institute). 2001. Control of cracking in concrete structures. ACI 224R-01. Farmington Hills, MI: ACI.
ACI (American Concrete Institute). 2014. Building code requirements for structural concrete. ACI 318-14. Farmington Hills, MI: ACI.
ASCE-ACI Committee 445 on Shear and Torsion. 1998. “Recent approaches to shear design of structural concrete.” J. Struct. Eng. 124 (12): 1375–1417. https://doi.org/10.1061/(ASCE)0733-9445(1998)124:12(1375).
ASTM. 2011. Standard test method for splitting tensile strength of cylindrical concrete specimens, 1–5. ASTM C496/C496M. West Conshohocken, PA: ASTM.
ASTM. 2014. Standard test method for static modulus of elasticity and Poisson’s ratio of concrete in compression, 1–5. ASTM C469/C469M. West Conshohocken, PA: ASTM.
ASTM. 2016a. Standard test method for compressive strength of cylindrical concrete specimens, 1–7. ASTM C39. West Conshohocken, PA: ASTM.
ASTM. 2016b. Standard test methods and definitions for mechanical testing of steel products, 1–49. ASTM A370. West Conshohocken, PA: ASTM.
Birrcher, D., R. Tuchscherer, M. Huizinga, S. Wood, J. Jirsa, and O. Bayrak. 2009. Strength and serviceability design of reinforced concrete deep beams. Austin, TX: Center for Transportation Research, Univ. of Texas at Austin.
Campione, G. 2009. “Performance of steel fibrous reinforced concrete corbels subjected to vertical and horizontal loads.” J. Struct. Eng. 135 (5): 519–529. https://doi.org/10.1061/(ASCE)0733-9445(2009)135:5(519).
Fattuhi, N. I. 1990. “Strength of SFRC corbels subjected to vertical load.” J. Struct. Eng. 116 (3): 701–718. https://doi.org/10.1061/(ASCE)0733-9445(1990)116:3(701).
Fattuhi, N. I. 1994. “Reinforced corbels made with high-strength concrete and various secondary reinforcements.” ACI Struct. J. 91 (4): 376–383.
Fattuhi, N. I., and B. P. Hughes. 1989. “Ductility of reinforced concrete corbels containing either steel fibers or stirrups.” ACI Struct. J. 86 (6): 644–651.
Foster, S. J., R. E. Powell, and H. S. Selim. 1996. “Performance of high-strength concrete corbels.” ACI Struct. J. 93 (5): 555–563.
Halvorsen, G. T. 1987. “Code requirements for crack control.” In Concrete and concrete construction, 275–322. Farmington Hills, MI: ACI.
Kriz, L. B., and C. H. Raths. 1965. “Connections in precast concrete structures—Strength of corbels.” PCI J. 10 (1): 16–61. https://doi.org/10.15554/pcij.02011965.16.61.
Marti, P. 1985. “Basic tools of reinforced concrete beam design.” ACI J. 82 (1): 46–56. https://doi.org/10.14359/10314.
Mattock, A. H., K. C. Chen, and K. Soongswang. 1976. “The behavior of reinforced concrete corbels.” PCI J. 21 (2): 52–77. https://doi.org/10.15554/pcij.03011976.52.77.
Ritter, W. 1899. “Die Bauweise Hennebique [Hennebiques construction method].” Schweizerische Bauzeitung 33 (7): 59–61.
Schlaich, J., K. Schafer, and M. Jennewein. 1987. “Toward a consistent design of structural concrete.” PCI J. 32 (3): 74–150. https://doi.org/10.15554/pcij.05011987.74.150.
Vecchio, F. J. 2000. “Disturbed stress field model for reinforced concrete: Formulation.” J. Struct. Eng. 126 (9): 1070–1077. https://doi.org/10.1061/(ASCE)0733-9445(2000)126:9(1070).
Vecchio, F. J., and M. P. Collins. 1986. “The modified compression-field theory for reinforced concrete elements subjected to shear.” ACI J. 83 (2): 219–231.
Williams, C., D. Deschenes, and O. Bayrak. 2012. Strut-and-tie model design examples for bridges. Austin, TX: Center for Transportation Research, Univ. of Texas at Austin.
Wilson, H., H. Yousefpour, M. Brown, and O. Bayrak. 2018. “Investigation of corbels designed according to strut-and-tie and empirical methods.” ACI Struct. J. 115 (3): 813–824. https://doi.org/10.14359/51701282.
Wong, P. S., F. J. Vecchio, and H. Trommels. 2013. VecTor2 & Formworks user’s manual. 2nd ed. Toronto: Univ. of Toronto.
Yong, Y., and P. Baraguru. 1994. “Behavior of reinforced high-strength concrete corbels.” J. Struct. Eng. 120 (4): 1182–1201. https://doi.org/10.1061/(ASCE)0733-9445(1994)120:4(1182).
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©2018 American Society of Civil Engineers.
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Received: Oct 19, 2017
Accepted: Mar 6, 2018
Published online: Jun 22, 2018
Published in print: Sep 1, 2018
Discussion open until: Nov 22, 2018
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