The paper sets out by examining methods that have been suggested for designing reinforced concrete columns in a fire, together with their drawbacks. The main part of the paper dicusses the theoretical background of a recently developed computer program SAFE-RCC (Structural Analysis of Fire Exposed Reinforced Concrete Columns) which takes account of the change in loadcarrying capacity and stiffness of a column during a fire, together with the change in stiffness of the framingsystem at each end of the column. Following the presentation of results from some proving tests, the results from an exploratory series of runs are presented in which it becomes very clear that the flexural stiffness of the restraint system plays a large part in determining the fire response. J.A. Purkiss and N.J. Weeks
The work described forms part of a comprehensive research programme concerned with an investigation of the causes of ‘shear’ failure of rein forced concrete beams. It is shown by experiment that the shear resistance of T-beams with shear span-to-depth ratios greater than 2.5 is provided by the flange and not, as widely considered, by the web. Such behaviour is in compliance with the concept that shear capacity is associated with the strength of the region of the path along which the compressive force is transmitted to the supports, with the region of the beam below the neutral axis making an insignificant contribution. The high loadcarrying capacity of the compressive zone appears to be related with the triaxial stress conditions that exist there. It is found that, in spite of their conservative nature, Code provisions may lead to unsafe design solutions since the obtained results indicate that shear failure usually occurs outside the regions considered as critical by Code provisions. It is demonstrated that there is already available an empirical design formula which is in compliance with the concept of the ‘Compressive force path’ and, unlike the formulae recommended in Codes of Practice, provides realistic predictions of both shear capacity and location of shear failure. M. D. Kotsovos, J. Bobrowski and Prof. J. Eibl
Results of an experimental investigation into environmental thermal strains and stresses in concrete members are reported, of relevance to temperature gradients in bridge decks. M. Richardson and A.R. Selby
An experimental and analytical investiagation of the punching shear capacity and moment transfer characteristics of reinforced concrete flat slabs at the edge column location is presented. In all, 12 models with carefully controlled boundary conditions were tested. Six of these were used to investigate the effect of column aspect ratio and size on the punching shear capacity. The remaining models were further reinforced using shearhead reinforcement, the main variable being the length and type of shearhead. From the results of the investigation a method for predicting the punching shear capacity has been proposed, based on the shear criterion of failure and designed to cover the use of shearhead reinforcement. Comparison with the British and American Codes of Practice reveals it to give consistently more accurate and reliable estimates of the punching shear capacity than either of those methods. S.G. Gilbert and C. Glass