Numerical Parametric Study on Structural Response of Drilled Shaft Footings Subjected to Concentric Axial Force
Publication: Journal of Structural Engineering
Volume 150, Issue 10
Abstract
This paper presents a numerical parametric study to examine the structural response of drilled shaft footings (pile caps) presenting different design characteristics, which have not been studied in depth in previous experimental studies. The numerical analyses were conducted with nonlinear finite element models representing typical designs and details of actual footings. The modeling scheme was validated using experimental data from large-scale drilled shaft footings. Key parameters of the numerical study included footing geometric properties, concrete strength, and reinforcement ratios. The results of the parametric studies were examined to identify key behavioral and design aspects to be considered when using 3D strut-and-tie models for the design of drilled shaft footings. The analysis results show that influences associated with footing and column aspect ratios were essentially negligible. However, it was estimated that an increase of the angle of inclination between the compression strut and the vertical axis led to significant reductions in footing stiffness and load capacity. The effect of shaft diameter was also examined in light of lateral concrete confining effects, and it was found that larger shaft diameters provide increased footing capacities. Analyses performed to estimate the influence of concrete compressive strength showed that splitting of the strut controlled the concrete-governed failure mechanism of footings. Finally, the models developed with different amounts of reinforcement revealed that increasing bottom mat reinforcement leads to increased ultimate loads; however, the rate of strength increase decreases with increasing reinforcement ratio. Providing a minimal amount of top mat and side face reinforcement was estimated to impact the structural responses of the footings positively; however, increasing the ratios of the top mat and side face reinforcing bars beyond this minimum did not significantly impact footing strength.
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
Some or all data, models, or code generated or used during the study are available from the corresponding author by request.
Acknowledgments
The authors would like to express their gratitude and sincere appreciation to the Texas Department of Transportation (TxDOT) for funding this study through Project 0-6953. The findings and suggestions reported in this paper are those of the authors and do not necessarily reflect the perspectives of TxDOT.
References
AASHTO. 2020. AASHTO LRFD bridge design specifications. 9th ed. Washington, DC: AASHTO.
ACI (American Concrete Institute). 2019. Building code requirements for structural concrete (ACI318-19): Commentary on building code requirements for structural concrete (ACI318R-19). ACI 318. Farmington Hills, MI: ACI.
Adebar, P., D. Kuchma, and M. P. Collins. 1990. “Strut-and-tie models for the design of pile caps: An experimental study.” ACI Struct. J. 87 (1): 81–92. https://doi.org/10.14359/2945.
Blevot, J., and R. Fremy. 1967. “Gewalles fur pieux.” Annales du Inistitute Technique du Betiment et des Travaux Publiccs 20 (2): 223–295.
CEN (European Commission for Standardization). 2004. Eurocode 2: Design of concrete structures. 1-1: General rules and rules for buildings. EN 1992-1-1. Brussels, Belgium: CEN.
Clarke, J. L. 1973. Behavior and design of pile caps with four piles. London: Cement and Concrete Association.
fib (Fédération International du Béton). 2013. fib model code for concrete structures 2010. 1st ed. Berlin: Ernst & Sohn.
Goh, C. Y. M., and T. D. Hrynyk. 2018. “Numerical investigation of the punching resistance of reinforced concrete flat plates.” J. Struct. Eng. 144 (10): 04018166. https://doi.org/10.1061/(ASCE)ST.1943-541X.0002142.
Goh, C. Y. M., and T. D. Hrynyk. 2020. “Nonlinear finite element analysis of reinforced concrete flat plate punching using a thick-shell modelling approach.” Eng. Struct. 224 (Dec): 111250. https://doi.org/10.1016/j.engstruct.2020.111250.
Kim, H., R. A. Boehm, Y. Yi, S. Mühlberg, Z. D. Webb, J. Choi, J. Murcia-Delso, T. D. Hrynyk, and O. Bayrak. 2023. “Effects of reinforcement details on behavior of drilled shaft footings.” ACI Struct. J. 120 (1): 285–301. https://doi.org/10.14359/51737145.
Klein, G. J. 2002. “Example 9: Pile cap.” In SP-208 examples for the design of structural concrete with strut-and-tie models, 213–224. Farmington Hills, MI: American Concrete Institute.
Michelle, D., M. P. Collins, S. B. Bhide, and B. G. Rabbat. 2004. AASHTO LRFD strut-and-tie model design examples. Skokie, IL: Portland Cement Association.
Miguel-Tortola, L., L. Pallarés, and P. F. Miguel. 2018. “Punching shear failure in three-pile caps: Influence of the shear span-depth ratio and secondary reinforcement.” Eng. Struct. 155 (Jan): 127–143. https://doi.org/10.1016/j.engstruct.2017.10.077.
Suzuki, K., and K. Otsuki. 2002. “Experimental study on corner shear failure of pile caps.” Trans. Jpn. Concr. Inst. 23: 303–310.
Suzuki, K., K. Otsuki, and T. Tsubata. 1998. “Influence of bar arrangement on ultimate strength of four-pile caps.” Trans. Jpn. Concr. Inst. 20 (Apr): 195–202.
Suzuki, K., K. Otsuki, and T. Tsubata. 1999. “Experimental study on four pile caps with taper.” Trans. Jpn. Concr. Inst. 21 (Feb): 327–334.
Suzuki, K., K. Otsuki, and T. Tsuchiya. 2000. “Influence of edge distance on failure mechanisms of pile caps.” Trans. Jpn. Concr. Inst. 22 (Feb): 361.
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-feld theory for reinforced concrete elements subjected to shear.” ACI J. Proc. 83 (2): 219–231. https://doi.org/10.14359/10416.
Widianto, and O. Bayrak. 2011. “Example 11: Deep pile cap with tension piles.” In SP-273 further examples for the design of structural concrete with strut-and-tie models, 169–188. Farmington Hills, MI: American Concrete Institute.
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.
Wong, P., F. J. Vecchio, and H. Trommels. 2013. VecTor2 & formworksuser’s manual. 2nd ed. Toronto: Univ. of Toronto.
Yi, Y., H. Kim, R. A. Boehm, Z. D. Webb, J. Choi, H. Wang, J. Murcia-Delso, T. D. Hrynyk, and O. Bayrak. 2021. 3D strut-and-tie modeling for design of drilled shaft footings. Austin, TX: Center for Transportation Research, Univ. of Texas at Austin.
Information & Authors
Information
Published In
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Aug 23, 2023
Accepted: May 6, 2024
Published online: Jul 26, 2024
Published in print: Oct 1, 2024
Discussion open until: Dec 26, 2024
ASCE Technical Topics:
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.