Skip to main content
Log in

Square Beam–Slab Systems: Resolving a Design Controversy Related to Collapse Mechanism

  • Original Contribution
  • Published:
Journal of The Institution of Engineers (India): Series A Aims and scope Submit manuscript

Abstract

This paper attempts to take a fresh look at the behaviour of simple reinforced concrete beam–slab systems, subject to gravity loading. The simplest case of a square slab, integrally connected to edge beams and supported on pillars or columns at the four corners, is considered. It is shown that the usual design procedure of separating the slab analysis and design, from that of the edge beams (proportioned to be adequately stiff), is irrational in terms of expected behaviour at collapse. The expected diagonal yield line formation in the slab is kinematically incompatible with the expected plastic hinge formation in the edge beams. This paper attempts to resolve this dispute in design by showing how the mode of failure depends on a relative beam–slab strength parameter. The yield line theory, which considers the alternative possibility of combined beam–slab failure, is validated by experimental results reported in the literature. It is established that the prevailing design practice, assuming diagonal yield line formation in the slab, turns out to be not only irrational but also uneconomical. The combined beam–slab failure mechanism is more likely to occur in practice, and it would be rational and economical to aim for such a design.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

Similar content being viewed by others

References

  1. S.P. Timoshenko, S. Woinowsky-Krieger, Theory of Plates and Shells (McGraw-Hill, New York, 1959)

    MATH  Google Scholar 

  2. K.W. Johansen, Yield-Line Formulae for Slabs (Cement and Concrete Association, London, 1962)

    Google Scholar 

  3. U. Pillai, D. Menon, Reinforced Concrete Design, 3rd edn. (Tata McGraw Hill Publication Co., Ltd., New Delhi, 2015)

    Google Scholar 

  4. B. Hayes, Allowing for membrane action in the plastic analysis of rectangular reinforced concrete slabs. Mag. Concr. Res. 20(65), 205–212 (1968)

    Article  Google Scholar 

  5. S.J. Foster, C.G. Bailey, I.W. Burgess, R.J. Plank, Experimental behaviour of concrete floor slabs at large displacements. Eng. Struct. 26(9), 1231–1247 (2004)

    Article  Google Scholar 

  6. C.G. Bailey, W.S. Toh, B.M. Chan, Simplified and advanced analysis of membrane action of concrete slabs. ACI Struct. J. 105(1), 30–40 (2008)

    Google Scholar 

  7. J. Yu, K.H. Tan, Structural behavior of RC beam–column subassemblages under a middle column removal scenario. J. Struct. Eng. 139(2), 233–250 (2013)

    Article  Google Scholar 

  8. P.X. Dat, K.H. Tan, Experimental response of beam–slab substructures subject to penultimate-external column removal. J. Struct. Eng. 141(7), 04014170 (2015)

    Article  Google Scholar 

  9. P.E. Regan, C.W. Yu, Limit State Design of Structural Concrete (Chatto and Windus, London, 1973)

    Google Scholar 

  10. B. Hayes, R. Taylor, Some tests on reinforced concrete beam–slab panels. Mag. Concr. Res. 21(67), 113–120 (1969)

    Article  Google Scholar 

  11. B. Balakrishnan, Yield line analysis of rectangular reinforced concrete beam–slab systems. Ph.D. thesis, Indian Institute of Technology Madras, Chennai, India (2017)

  12. A. Pachenari, A. Keramati, Progressive collapsed zone extent estimation in two-way slab floors by yield line analysis. Mag. Concr. Res. 66(13), 685–696 (2014)

    Article  Google Scholar 

  13. B. Balakrishnan, D. Menon, Collapse load estimation of rectangular reinforced concrete beam–slab systems—new insights. ACI Struct. J. 115(5), 1279–1294 (2018)

    Article  Google Scholar 

  14. B. Balakrishnan, D. Menon, Yield line analysis of RC grid slab systems, in Proceedings of the 11th FIB International Ph.D. Symposium in Civil Engineering, The University of Tokyo, Tokyo, Japan, August 29 to 31, pp. 601–607 (2016)

  15. B. Balakrishnan, D. Menon, Yield line analysis and testing of reinforced concrete rectangular slabs with primary and secondary beams. ACI Struct. J. 116(5), 187–200 (2019)

    Article  Google Scholar 

  16. Indian standard code of practice for plain and reinforced concrete for general building construction, IS 456: 2000, Bureau of Indian Standards, New Delhi

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Bijily Balakrishnan.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Balakrishnan, B., Menon, D. Square Beam–Slab Systems: Resolving a Design Controversy Related to Collapse Mechanism. J. Inst. Eng. India Ser. A 101, 361–370 (2020). https://doi.org/10.1007/s40030-020-00433-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s40030-020-00433-9

Keywords

Navigation