AN OVERVIEW OF PUNCHING SHEAR PHENOMENA IN REINFORCED CONCRETE FLAT SLABS
Abstract
Punching shear failure could occur in a flat slab column connection in cases of overloads of the slab or due to improper design of column-slab joints. Past incidents showed that accidents that happened due to punching shear failure of flat slabs had resulted in numerous casualties of building occupants. Over the years, many researchers have undertaken various research studies on the behaviour structures in response to punching shear phenomena in reinforced concrete flat slabs. In this Final Year research project paper, some data of the studies were be collected to identify any new developments on the design and analysis of punching shear strength of reinforced concrete flat slabs. In addition to that, published experimental data and results from the past researchers on punching shear strength of flat slabs are collated to compare the experimental punching shear strength to the predicted results by selected design code provisions (i.e. Eurocode 2, BS 8110 and ACI 318). Besides that, the current provisions in the international standards with regards to punching shear design of flat slabs are compared. It was found out that Eurocode 2 is the most accurate among the three codes to predict the punching shear strength of flat slabs without shear reinforcement. As for flat slabs with shear reinforcement, ACI 318 is most accurate and conservative compared to the other two codes. Partial replacement of cement in concrete using steel fibers can increase the punching shear strength and the ductility of the slab. As for the post tensioning reinforcement of flat slabs, it was concluded that in slabs that were reinforced with two strands of post tensioning strands, the post punching resistance was 78% of the punching shear capacity. In this paper, it is also shown that the method of using inclined bonded bars is effective in post reinforcement for flat slabs.
References
Ammash, H. K., Kadhim, M. J. and Ellk, D. S. (2012) ‘A New Punching Shear Equation of Normal and High Strength Reinforced Concrete Flat Slabs’, Journal of Engineering and Development, 16(4), pp. 47–65.
British Standards Institution BSI (1985) ‘Structural use of concrete’, Part 2: Code of practice for special circumstances
British Standards Institution BSI (2004) ‘Eurocode 2: Design of Concrete Structures – Part 1-1: General Rules and Rules for Buildings’, BS EN 1992-1-1:2004, 230p.
Dyrud, M. A. (2011) ‘AC 2011-32 : Familiarizing the Unknown : Three Unusual Engineering Cases’, 2011 Annual Conference & Exposition, p. 16.
Elstner, B. R. C. and Hognestadt, E. (1956) ‘Shearing Strength of Reinforced Concrete Slabs’, ACI Journal Proceedings, 53(2). doi: 10.14359/11501.
Inácio, M. M. G., Pinho Ramos, A. and Faria, D. M. V. (2012) ‘Strengthening of flat slabs with transverse reinforcement by introduction of steel bolts using different anchorage approaches’, Engineering Structures, 44, pp. 63–77.
Marzouk, H. and Hussein, A. (1991) ‘Punching shear analysis of reinforced high-strength concrete slabs’, ACI Structural Journal, 88(S72).
Metwally, I. M. (2013) ‘Prediction of punching shear capacities of two-way concrete slabs reinforced with FRP bars’, HBRC Journal. Housing and Building National Research Center, 9(2), pp. 125–133.
Narasimhan, N. (1971) ‘Shear reinforcement in reinforced concrete column heads’, (February).
Osman, M., Marzouk, H. and Helmy, S. (2000) ‘Behavior of high-strength lightweight concrete slabs under punching loads’, ACI Structural Journal, 97(3), pp. 492–498.
Park, T. W. (2018) ‘Inspection of collapse cause of Sampoong Department Store’, Forensic Science International. Elsevier Ireland Ltd, 217(1–3), pp. 119–126.
Regan, P. E. (2009) ‘Symmetric punching of reinforced concrete slabs’, Magazine of Concrete Research, 38(136), pp. 115–128.
Safiee, N. A. and Ashour, A. (2017) ‘Prediction of punching shear capacity of RC flat slabs using artificial neural network’, Asian Journal of Civil Engineering, 18(2), pp. 285–309.
Samad, S., Shah, A. and Limbachiya, M. C. (2018) Assessment of Punching Shear of Flat Slabs Using Ground Slag, ACI Materials Journal.
Subramanian, N. (2014) ‘Alternative punching shear reinforcement for RC flat slabs’, Indian Concrete Journal, pp. 33–44.
