Prediction of Punching Shear Capacity of Biaxial Voided Slab

Radha Sagadevan, BN Rao


Biaxial voided slab systems are advantageous due to their reduced self-weight, up to 50 % in comparison with the conventional reinforced concrete solid slab. The reduction in the concrete cross sectional area reduces the shear capacity up to about 40 %. The prediction of punching shear capacity in voided slab is not direct unlike in solid slab. This is because the presence of voids alters the critical failure section and hence the punching load. In the present study, the applicability of conventional method (adopted for solid slabs) in the Indian design standard IS 456: 2000 is explored for predicting the punching shear capacity of the voided slab. In addition, three full-scale specimens were tested with sphere shaped voids. Finally, experimental results of present study and test data collected from literature (23 specimens) are compared with theoretical predictions. The estimation of punching shear capacity of biaxial voided slab by existing provisions for solid slabs in IS 456 do not lead to satisfactory results. Hence, the presence of voids is considered by adopting an effective concrete area available to resist punching shear at the critical section. It is found that the estimated capacity based on IS 456 with effective concrete area is in good agreement with experimentally observed capacity.


Reinforced concrete slab, voided slab, punching shear, two-way shear, effective concrete area


BubbleDeck Technology. BubbleDeck Voided Flat Slab Solutions - Technical Manual & Documents. UK: 2008.

Cobiax Technologies. Cobiax Engineering Manual. Switzerland: 2010.

Daliform Group. U-Boot Beton® System Study: Lightened Concrete Slab by using U-Boot Beton®. Italy: 2014.

Sagadevan R, Nageswara Rao B. Numerical Study on Flexural Capacity of Biaxial Hollow Slab. In: Rao ARM, Ramanjaneyulu K, editors. Recent Adv. Struct. Eng. Vol. 1. Sel. Proc. SEC 2016, Singapore: Springer; 2019, p. 97–105. doi:10.1007/978-981-13-0362-3_8.

Björnson G. BubbleDeck - Two-way Hollow slab. Denmark: 2003.

Harding P. BubbleDeckTM–Advanced Structure Engineering. BubbleDeck Artic 2004:15–6.

Sagadevan R, Rao B N. Experimental and Analytical Investigations on Two-way Flexural Capacity of Biaxial Voided Slab. Proceedings, Natl Conf Adv Struct Technol 2019:635–48.

Fall D, Shu J, Rempling R, Lundgren K, Zandi K. Two-way Slabs: Experimental Investigation of Load Redistributions in Steel Fibre Reinforced Concrete. Eng Struct 2014;80:61–74. doi:10.1016/j.engstruct.2014.08.033.

Chung JH, Bae B Il, Choi HK, Jung HS, Choi CS. Evaluation of Punching Shear Strength of Voided Slabs Considering the Effect of the Ratio b0/d. Eng Struct 2018;164:70–81. doi:10.1016/j.engstruct.2018.02.085.

Schnellenbach Held M, Pfeffer K. Punching Behavior of Biaxial Hollow Slabs. Cem Concr Compos 2002;24:551–6. doi:10.1016/S0958-9465(01)00071-3.

Valivonis J, Skuturna T, Daugevičius M, Šneideris A. Punching Shear Strength of Reinforced Concrete Slabs with Plastic Void Formers. Constr Build Mater 2017;145:518–27. doi:10.1016/j.conbuildmat.2017.04.057.

Valivonis J, Šneideris A, Šalna R, Popov V, Daugevičius M, Jonaitis B. Punching Strength of Biaxial Voided Slabs. ACI Struct J 2017;114:1373–83. doi:10.14359/51700912.

Chung JH, Choi HK, Lee SC, Choi CS. Punching Shear Strength of Biaxial Hollow Slab with Donut Type Hollow Sphere. Key Eng Mater 2011;452–453:777–80. doi:10.4028/

Sagadevan R, Rao BN. Numerical Study on Punching Shear Capacity of Biaxial Hollow Slabs. Proceedings, 5th Int. Congr. Comput. Mech. Simul., Singapore: Research Publishing Services; 2014, p. 1881–90. doi:10.3850/978-981-09-1139-3_217.

Oukaili NKA, Husain LF. Punching Shear in Reinforced Concrete Bubbled Slabs: Experimental Investigation. Smart Monit. Assess. Rehabil. Civ. Struct., Zurich, Switzerland: 2017.

Han SW, Lee CS. Evaluation of Punching Shear Strength of Voided Transfer Slabs. Mag Concr Res 2014;66:1116–28. doi:10.1680/macr.14.00080.

IS 456. Plain and Reinforced Concrete - Code of Practice. Bureau of Indian Standards, New Delhi: 2000.



  • There are currently no refbacks.