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The Structural Engineer, Volume 64, Issue 15, 1986
Buckling tests were carried out on 38 slender reinforced concrete deep beams having height:thickness ratios in the range 25 to 67. Observations were made on the ultimate loads and failure modes. The variables studied included the height:thickness ratio (h/b), the clear-shear-span:height ratio (x/h), and the load-eccentricity:thickness ratio (e/b). The observed behaviour and failure modes of the slender deep beams were described and compared with those of stocky deep beams as reported in the literature. The measured ultimate loads were compared with values predicted using CIRIA Guide no.2: The design of deep beams in reinforced concrete. These tests, which for the first time enabled the CIRIA buckling-load predictions to be checked against experimental values, have confirmed the CIRIA guide as a safe design document. For very slender deep beams, the CIRIA buckling predictions tend to be too conservative. Professor F.K. Kong, R.C. Garcia, J.M. Paine, H.H.A. Wong, C.W.J. Tang and M. Chemrouk
The results of 13 tests of post-tensioned I- and T-beams are presented. All but two of the beams contained inclined tendons and all but two failed in shear. The recommendations of the British and European Codes are reviewed and compared with the present and other test results. It is shown that the British Codes are unsatisfactory and that the CEB recommendations, while somewhat more logical, also leave much to be desired. A very simple approach to the subject is proposed, based on a truss model. The model is shown to give satisfactory agreement with experimental behaviour and ultimate strengths. H. Rezai-Jorabi and P.E. Regan
Professor R. P. Johnson (F) (University of Warwick): It is shown by numerical analysis in this paper that simply supported, open sandwich, steel reinforced concrete beams are not susceptible to failure by propagation of a crack along the adhesive layer. This is consistent with the results of a series of tests published in 1981, in respect of cracks that initiated within the length of the steel plate.