Title: Load resistance and failure modes of hollow-core slabs with openings: A finite element analysis 
Date Published: July - August 2018 
Volume: 63 
Issue: 4 
Page Numbers: 25-40
Authors: Sameer K. S. Pachalla and S. Suriya Prakash
https://doi.org/10.15554/pcij63.4-03
 

Click here to view the full journal article 

Abstract

Hollow-core slabs are generally used as floor elements in buildings. Provision of openings and cutouts is common in slabs due to various structural or service requirements. In many situations, these openings are provided after the slab has been erected, based on the site requirements. Design engineers typically confirm the safety of prestressed hollow-core slabs with openings based on experience or by simple stress calculations, as no design guidelines exist at present for the design of these precast concrete slabs with openings. If the openings are planned in the design phase, their effects are generally lessened by providing additional prestressing strands in the adjacent webs. This paper evaluates the effects of openings on the behavior of hollow-core slabs by experimental and finite element method studies. Three-dimensional finite element models were developed and calibrated with the experimental data. Thereafter, the effects of the provision of additional strands in adjacent webs, the shear span–to–depth ratio, and opening size were studied. The provision of additional strands in webs adjacent to an opening could not completely restore the lost capacity of hollow-core slabs due to openings. The location and size of the openings plays an important role in the strength and failure mode of the hollow-core slabs.

References

Walraven, J. C., and W. P. M. Mercx. 1983. “The Bearing Capacity for Prestressed Hollow Core Slabs.” Heron 28 (3): 1–46.

Becker, R. J., and D. R. Buettner. 1985. “Shear Tests of Extruded Hollow-Core Slabs.” PCI Journal 30 (2): 40–54.

Pajari, M. 1998. “Shear Resistance of PHC Slabs Supported on Beams. II: Analysis.” Journal of Structural Engineering 124 (9): 1062–73. doi:10.1061/(ASCE)0733-9445(1998)124:9(1062).

Hawkins, N. M., and S. K. Ghosh. 2006. “Shear Strength of Hollow-Core Slabs.” PCI Journal 51 (1): 110–4.

Palmer, K. D., and A. E. Schultz. 2011. “Experimental Investigation of the Web-Shear Strength of Deep Hollow-Core Units.” PCI Journal 56 (4): 83–104.

Pachalla, S. K. S., and S. S. Prakash. 2017. “Load Resistance and Failure Modes of GFRP Composite Strengthened Hollow Core Slabs with Openings.” Materials and Structures 50 (1). doi: 10.1617/s11527-016-0883-8.

Pachalla, S. K. S., and S. S. Prakash. 2017. “Experimental Evaluation on Effect of Openings on Behavior of Prestressed Precast Hollow-Core Slabs.” ACI Structural Journal 114 (2): 427–436. doi:10.14359/51689155.

Pachalla, S. K. S., and S. S. Prakash. 2017. “Efficient Near Surface Mounting CFRP Strengthening of Pretensioned Hollowcore Slabs with Opening – An Experimental Study.” Composite Structures 162 (15): 28–38. doi:10.1016/j.compstruct.2016.11.072.

Kankeri, P., and S. S. Prakash. 2016. “Experimental Evaluation of Bonded Overlay and NSM GFRP Bar Strengthening on Flexural Behavior of Precast Prestressed Hollow Core Slabs.” Engineering Structures 120: 49–57. doi:10.1016/j.engstruct.2016.04.033.

Kankeri, P., and S. S. Prakash. 2017. “Efficient Hybrid Strengthening for Precast Hollow Core Slabs at Low and High Shear Span to Depth Ratios.” Composite Structures 170: 202–214. doi:10.1016/j.compstruct.2017.03.034.

Wang, X. 2007. “Study on the Shear Behavior of Prestressed Hollow Core Slabs by Nonlinear Finite Element Modelling.” Master’s degree thesis. University of Windsor, ON, Canada.

Barbosa, A. F., and G. O. Ribeiro. 1998. “Analysis of Reinforced Concrete Structures using Ansys Nonlinear Concrete Model.” In Computational Mechanics. New Trends and Applications, S. Idelsohn, E. Oñate, and E. Dvorkin (eds.), pp. 1–7. Barcelona, Spain: Centro Internacional de Métodos Numéricos en Ingeniería.

Hegger, J., T. Roggendorf, and F. Teworte. 2010. “FE Analyses of Shear-Loaded Hollow-Core Slabs On Different Supports.” Magazine of Concrete Research 62 (8): 531–541.

Brunesi, E., and R. Nascimbene. 2015. “Numerical Web-Shear Strength Assessment of Precast Prestressed Hollow Core Slab Units.” Engineering Structures 102: 13–30.

Gan, Y. 2000. “Bond Stress and Slip Modeling in Nonlinear Finite Element Analysis of Reinforced Concrete Structures.” Master’s degree thesis. University of Toronto, Canada.

Mondal, T. G., and S. S. Prakash. 2016. “Nonlinear Finite-Element Analysis of RC Bridge Columns under Torsion with and without Axial Compression.” Journal of Bridge Engineering 21 (2). doi:10.1061/(ASCE) BE.1943-5592.0000798.

Ganganagoudar, A., T. G. Mondal, and S. S. Prakash. 2016 “Analytical and Finite Element Studies on Behavior of FRP Strengthened RC Beams under Torsion.” Composite Structures 153: 876–885. doi:10.1016/j.compstruct. 2016.07.014.

Ganganagoudar, A., T. G. Mondal, and S. S. Prakash. 2016. “Improved Softened Membrane Model for Reinforced Concrete Circular Bridge Columns under Torsional Loading.” Journal of Bridge Engineering 21 (7): 1–13. doi: 10.1061/(ASCE)BE.1943-5592.0000907.

Kim, Y. J., J. M. Longworth, R. G. Wight, and M. F. Green. 2010. “Punching Shear of Two-way Slabs Retrofitted with Prestressed or Non-prestressed CFRP Sheets.” Journal of Reinforced Plastics and Composites 29 (8): 1206–23. doi:10.1177/0731684409103143.

ACI (American Concrete Institute) Committee 318. 2011. Building Code Requirements for Structural Concrete (ACI 318-11) and Commentary (ACI 318R-11). Farmington Hills, MI: ACI.

Hognestad, E. 1951. “Study of Combined Bending and Axial Load in Reinforced Concrete Members.” Bulletin 399. Engineering Experiment Station, University of Illinois at Urbana-Champaign.

Willam, K., and E. Warnke. 1975. “Constitutive Model for the Triaxial Behavior of Concrete International Association for Bridge and Structure Engineering.” In Proceedings, International Association for Bridge and Structure Engineering. Bergamo, Italy: International Association for Bridge and Structural Engineering.

Ramberg, W., and W. R. Osgood. 1943. “Description of Stress-Strain Curves by Three Parameters.” Technical Note 902. National Advisory Committee for Aeronautics.