Abstract
A safety assessment of various methods for designing RC (reinforced concrete) pile caps, consisting of the traditional and strut-and-tie methods (STMs) available in the international concrete codes of practice and state-of-the-art literature, was conducted using a probabilistic approach and is presented in this paper. The uncertainties in load effects and member strengths, including variability in material properties, dimensions and modeling error were considered as random variables. The safety index used as an indication of level of safety was analyzed utilizing Monte Carlo simulation with a wide range of live-to-dead load ratios and a usual range of normal strength concrete. It was found that the traditional method of American concrete code (ACI 318-14) and the shear design using British code (BS 8110) provided a lower level of safety than the STM approaches. Finally, for each pile cap design method, reliability-based understrength factors are proposed to satisfy the target safety index by more than 3.5.
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References
AASHTO (2012). AASHTO LRFD Bridge design specifications, AASHTO, Washington, D.C., USA.
ACI 318 (2014). Building code requirements for structural concrete (ACI 318-14) and commentary, ACI 318–14, American Concrete Institute, FarmingtonHills, MI, USA.
Adebar, P., Kuchma, D., and Collins, M. P. (1990). “Strut-and-tie models for the design of pile caps: An experimental study.” ACI Structural Journal, Vol. 87, No. 1, pp. 81–92, DOI: https://doi.org/10.14359/2945.
Adebar, P. and Zhou, Z. (1996). “Design of deep pile caps by strut-and-tie models.” ACI Structural Journal, Vol. 93, No. 4, pp. 1–12, DOI: https://doi.org/10.14359/9703.
Ahmad, S., Shah, A., and Zaman, S. (2009). “Evaluation of the shear strength of four pile cap using strut and tie model (STM).” Journal of the Chinese Institute of Engineers, Vol. 32, No. 2, pp. 243–249, DOI: https://doi.org/10.1080/02533839.2009.9671501.
Araújo, J. M. (2016). “Design of rigid pile caps through an iterative strut-and-tie model.” Journal of Advanced Concrete Technology, Vol. 14, No. 8, pp. 397–407, DOI: https://doi.org/10.3151/jact.14.397.
ASCE 7–10 (2010). Minimum design loads for buildings and other structures, ASCE 7–10, American Society of Civil Engineers, Washington, D.C., USA.
Bhatt, P., Macginley, T. J., and Choo, B. S. (2006). Reinforced concrete: Design theory and examples. CRC Press, New York, NY, USA.
Blévot, J. L. and Frémy, R (1967). “Semelles sur pieux.” Institute Technique du Bâtiment et des Travaux Publics, Vol. 20, No. 230, pp. 223–295 (in French).
BS (1997). Structural use of concrete, part 1: code of practice for design and construction, BS 8110–1, British Standards Institution, London, UK.
Cavers, W. and Fenton, G. A. (2004). “An evaluation of pile cap design methods in accordance with the Canadian design standard.” Canadian Journal of Civil Engineering, Vol. 31, No. 1, pp. 109–119, DOI: https://doi.org/10.1139/l03-075.
Chan, T. K. and Poh, C. K. (2000). “Behaviour of precast reinforced concrete pile caps.” Construction and Building Materials, Vol. 14, pp. 73–78, DOI: https://doi.org/10.1016/S0950-0618(00)00006-4.
Chetchotisak, P., Teerawong, J., Yindeesuk, S., and Song, J. (2014). “New strut-and-tie-models for shear strength prediction and design of RC deep beams.” Computers and Concrete, Vol. 14, No. 1, pp. 19–40, DOI: https://doi.org/10.12989/cac.2014.14.1.019.
Chetchotisak, P., Yindeesuk, S., and Teerawong, J. (2017). “Interactive strut-and-tie-model for shear strength prediction of RC pile caps.” Computers and Concrete, Vol. 20, No. 3, pp. 339–348, DOI: https://doi.org/10.12989/cac.2017.20.3.329.
Chetchotisak, P., Ruengpim, P., Chetchotsak, D., and Yindeesuk, S. (2018). “Punching shear strengths of RC slab-column connections: Prediction and reliability.” KSCE Journal of Civil Engineering, Vol. 22, No. 8, pp. 3066–3076, DOI: https://doi.org/10.1007/s12205-017-0456-6.
Clarke, J. L. (1973). Behavior and design of pile caps with four piles, Technical Report No. 42.489, Cement and Concrete Association, Wexham Springs, Berkshire, UK.
CSA A23.3 (2004). CAN/CSA A23.3 Design of Concrete Structures, CAN/CSA A23.3, Canadian Standards Association (CSA), Rexdale, Ontario, Canada.
Ellingwood, B. and Galambos, T. V. (1982). “Probability-based criteria for structural design.” Structural Safety, Vol. 1, No. 1, pp. 15–26, DOI: https://doi.org/10.1016/0167-4730(82)90012-1.
Eurocode 2 (CEN) (2004). Design of concrete structures-Part 1.1: general rules and rules for buildings, Eurocode 2, European Committee for Standardization, Brussels, Belgium.
Guo, H. (2015). “Evaluation of column load for generally uniform grid-reinforced pile cap failing in punching.” ACI Structural Journal, Vol. 112, No. 2, pp. 123–134, DOI: https://doi.org/10.14359/51687420.
Hwang, S., Lu, W., and Lee, H. (2000). “Shear strength prediction for deep beams.” ACI Structural Journal, Vol. 97, No. 3, pp. 367–376, DOI: https://doi.org/10.14359/9624.
Jensen, U. G. and Hoang, L. C. (2012). “Collapse mechanisms and strength prediction of reinforced concrete pile caps.” Engineering Structures, Vol. 35, pp. 203–214, DOI: https://doi.org/10.1016/j.engstruct.2011.11.006.
Ju, M., Park, C., Hwang, E. S., and Sim, J. (2015). “Predictability evaluation of the existing punching shear formulas using failure test and probability-based approach.” KSCE Journal of Civil Engineering, Vol. 19, No. 5, pp. 1420–1430, DOI: https://doi.org/10.1007/s12205-015-0040-x.
Kim, D., Chung, M., and Kwak, K. (2011). “Resistance factor calculations for LRFD of axially loaded driven piles in sands.” KSCE Journal of Civil Engineering, KSCE, Vol. 15, No. 7, pp. 1185–1196, DOI: https://doi.org/10.1007/s12205-011-1254-1.
Kim, H. and Mission, J. L. (2011). “Probabilistic evaluation of economical factor of safety for the geotechnical design of pile axial load capacity.” KSCE Journal of Civil Engineering, Vol. 15, No. 7, pp. 1167–1176, DOI: https://doi.org/10.1007/s12205-011-0948-8.
Kupfer, H. and Gerstle, K. H. (1973). “Behavior of concrete under biaxial stress.” Journal of the Engineering Mechanics Division, ASCE, Vol. 99, No. 4, pp. 853–866.
Nowak, A. S., Rakoczy, A. M., and Szeliga, E. (2011). “Revised statistical resistance models for R/C structural components.” ACI Special Publication, DOI: https://doi.org/10.14359/51683801.
Nowak, A. S. and Collins, K. R. (2000). Reliability of structures, McGraw Hill, New York, NY, USA.
Park, J. W., Kuchma, D., and Souza, R. (2008). “Strength predictions of pile caps by a strut-and-tie model approach.” Canadian Journal of Civil Engineering, Vol. 35, Vol. 12, pp. 1399–1413, DOI: https://doi.org/10.1139/L08-062.
Rakoczy, A. M. and Nowak, A. S. (2013). “Resistance model of lightweight concrete members.” ACI Material Journal, Vol. 110, No. 1, pp. 99–108, DOI: https://doi.org/10.14359/51684370.
Rakoczy, A. M. and Nowak, A. S. (2014). “Resistance factors for lightweight concrete members.” ACI Structural Journal, Vol. 111, No. 1, pp. 103–111, DOI: https://doi.org/10.14359/51686435.
Reineck, K. H., Kuchma, D. A., Sim, K. S., and Marx, S. (2003). “Shear database for reinforced concrete members without shear reinforcement.” ACI Structural Journal, Vol. 100, No. 2, pp. 240–249, DOI: https://doi.org/10.14359/12488.
Sabnis, G. M. and Gogate, A. B. (1984). “Investigation of thick slab (pile cap) behaviour.” ACI Journal, Vol. 81, No. 5, pp. 35–39, DOI: https://doi.org/10.14359/10638.
Souza, R., Kuchma, D., Park, J., and Bittencourt, T. (2009). “Adaptable strut-and-tie model for design and verification of four-pile caps.” ACI Structural Journal, Vol. 106, No. 2, pp. 142–150, DOI: https://doi.org/10.14359/56352.
Stewart, M. G., Foster, S., Ahammed, M., and Sirivivatnanon, V. (2016). “Calibration of Australian Standard AS3600 concrete structures part II: reliability indices and changes to capacity reduction factors.” Australian Journal of Structural Engineering, Vol. 17, No. 4, pp. 254–266, DOI: https://doi.org/10.1080/13287982.2016.1246215.
Suzuki, K., Otsuki, K., and Tsubata T. (1998). “Influence of bar arrangement on ultimate strength of four-pile caps.” Transactions of the Japan Concrete Institute, Vol. 20, pp. 195–202.
Suzuki, K., Otsuki, K., and Tsubata, T. (1999). “Experimental study on four-pile caps with taper.” Transactions of the Japan Concrete Institute, Vol. 21, pp. 327–334.
Suzuki, K., Otsuki, K., and Tsuhiya, T. (2000). “Influence of edge distance on failure mechanism of pile caps.” Transactions of the Japan Concrete Institute, Vol. 22, pp. 361–367.
Suzuki, K. and Otsuki, K. (2002). “Experimental study on corner shear failure of pile caps.” Transactions of the Japan Concrete Institute, Vol. 23, pp. 303–310.
Szerszen, M. M. and Nowak, A. S. (2003). “Calibration of design code for buildings (ACI 318), part 2—reliability analysis and resistance factors.” ACI Structural Journal, Vol. 100, No. 3, pp. 383–391, DOI: https://doi.org/10.14359/12614.
Yang, Z. and Wang, W. (2016). “Experimental and numerical investigation on the behaviour of prestressed high strength concrete pile-to-pile cap connections.” KSCE Journal of Civil Engineering, Vol. 20, No. 5, pp. 1903–1912, DOI: https://doi.org/10.1007/s12205-015-0658-8.
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The authors would like to acknowledge gratefully the support and funding of Rajamangala University of Technology Isan (RMUTI), Thailand.
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Chetchotisak, P., Teerawong, J. Reliability-based Assessment of RC Pile Cap Design Methods and Proposals for their Strength Resistance Factors. KSCE J Civ Eng 23, 3372–3382 (2019). https://doi.org/10.1007/s12205-019-0079-1
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DOI: https://doi.org/10.1007/s12205-019-0079-1