ABSTRACT
In the past three decades, much of the research on the ultimate load behaviour of reinforced concrete beams has been concentrated on their bearing, flexural and shear strengths (Albritton, 1965; C & CA, 1969; CIRIA, 1977, Kong, 1986a). At a recent lecture given at Ove Arup and Partners, (Kong, 1986b; Whittle, 1986), it became clear that deep beam buckling is a failure criterion that needs to be considered in design. Indeed, with the expected advances in materials technology (ACI Committee 363, 1984; Clarke and Pomeroy, 1985; Kong et al, 1983) deep beam designers will find it possible to use much smaller cross sections in the future. This would clearly allow more slender deep beams. As with other thin-walled and slender members such as thin plates and slender columns, stability rather than strength requirements will probably dictate the design of slender deep beams. Of the four main deep beam design documents, namely, the Canadian Building Code CAN3-A23.3-M84 (CSA, 1984), the American Building Code ACI 318– 83 (1983), the CEB-FIP Model Code (1978) and the CIRIA Guide No. 2 (1977), the only one that gives direct recommendations on the buckling strength of concrete deep beams is the CIRIA Guide. However, because of the lack of experimental data, the CIRIA’s buckling recommendations had to be based on theoretical studies and engineering judgement; at the end of the CIRIA Guide’s Appendix C: Buckling strength of deep beams, it is pointed out that ‘there is no experimental evidence to substantiate these procedures’ (CIRIA, 1977).
