Ultimate-Load Analysis of Edge-Loaded Foundation Slabs

An informal discussion on ‘ What is the responsibility of the structural engineer? ’ replaces the open discussion on the Joint Institution/Concrete Society’s Report on Reinforced Concrete Detailing which appears in the sessional programme for 11 January. It is expected that the Reinforced Concrete Detailing Report will now be published within the next few weeks and the open discussion upon its recommendations will be held when members have had an opportunity of digesting them.

Firstly, the method of influence coefficients is applied to the analysis of any number of parallel arches, identical in their centre lines and having any number of transversals connected across them, with normal and tangential reactions occurring at each intersection. Next, it is proved that any loaded, symmetrical arch can be replaced by an equivalent straight beam with a certain modified loading. It is then explained how an interconnected encastre arch system can be solved by using this theory together with a quasi-slab analysis or by the ‘continuous-strip transversals’ method. Finally, results from this approach (most of which is already familiar to beam and slab bridge designers) are compared with those from influence coefficients and from experiments on a model arch system. E. Lightfoot and V.K. Datta

The increasing emphasis in building by-laws and regulations during the last two decades on the protection of structures against fire has obliged structural engineers to become at least acquainted with some general properties of materials of construction at high temperatures in order to comply with the minimum legal requirements. In the belief that a knowledge of the aims and methods of protecting structures is of value in design, while making Codes more intelligible, this paper has been prepared as a fairly detailed review of the subject. Most attention is given to fire resistance as measured by laboratory tests, the factors affecting this property of structures, and the data derived from tests for many forms of construction. The extent to which an analytical approach is feasible in solving fire resistance problems is examined. Although it is strictly outside the province of the structural engineer the importance of fire grading-assigning to buildings the appropriate level of fire precautions-cannot be overlooked. The application to buildings of the results of research and testing for fire resistance is therefore discussed briefly. L.A. Ashton