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The Structural Engineer, Volume 64, Issue 15, 1986
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
The paper discusses movements in brick masonry caused by creep and considers its effect on prestress losses in post-tensioned brickwork. It follows almost 2 decades of research in which various specimens comprising brickwork walls, columns, and beams, with different types of brick and mortar, have been subjected to a sustained load at different stress levels. From the information obtained, a number of expressions are put forward for creep coefficients which can be fed into a simple theory for predicting prestress losses in post-tensioned brickwork members. A creep-time function was also obtained which was used in comparing experimental and theoretical creep strains in a loadbearing brickwork tower block, during its construction stage and later life. D. Lenczner
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.