F. K. Kong MA, MSc, PhD, CEng, FICE, FIStructE, R. H. Evans CBE, DSc, D ès Sc, DTech, PhD, CEng, FICE, FIMechE, FIStructE (auth.)-Reinforced and Prestressed Concrete-Springer US (1987)

References 331
(a)
(b)
Problem8.5
reinforcement at the bottom face, giving a moment of resistance of M per
metre width for bending about an axis perpendicular to BC, and O.SM per
metre width for bending about an axis parallel to BC. Using the yield-line
method, determine the collapse value of q.
If the slab had been reinforced at the bottom face with two uniform skew
layers of reinforcement, in directions perpendicular respectively to AB
and CD, as shown in Fig. (b), explain briefly how the collapse load could
be determined.
Ans. 1st Part: q = 0.28M, for a collapse mode with two yield lines,
extending from Band C to the unsuported edge. (Worst layout of
yield-line pattern: each yield line has a projection of 1.80 m on BC.)
2nd Part: Use graphical method: see Example 8.5-3.
References
1 I.Struct.E/ICE Joint Committee. Manual for the Design of Reinforced
Concrete Building Structures. Institution of Structural Engineers, London,
1985.
2 Johansen, K. W. Yield-line Formulae for Slabs. Cement and Concrete
Associaton, London, 1972.
3 Hognestad, E. Yield-line theory for the ultimate flexural strength of reinforced
concrete slabs. Pro. ACI, 49, No. 7, March 1953, pp. 637-56.
4 Morley, C. T. Experiments on the yield criterion of isotropic reinforced
concrete slabs. Proc. ACI, 64, No. 1, Jan. 1967, pp. 40-5.
5 Baker, Sir John and Heyman, J. Plastic Design of Frames. 1: Fundamentals.
Cambridge University Press, 1968.
6 Kong, F. K. and Charlton, T. M. the fundamental theorems of the plastic
theory of structures. Proceedings of the M. R. Horne Conference on
Instability and Plastic Collapse of Steel Structures (Editor: L. J. Morris),
Manchester 1983. Granada Publishing, London, 1983, pp. 9-15.