Issue 5

A method for evaluating the central dip corresponding to an applied load for a simple flexible cable has been developed, based on the relationship between change in dip and change in applied load, and the known maximum permissible dip for the maximum applied load, with due attention to the other factors such as constructional elongation, thermal expansion and movement of end supports. S.B. Desai

Many civil engineering materials collapse by the initiation and the development of cracks. The detection of the source of these cracks and the manner in which they spread up to and including the stage of failure is of prime importance. In this paper an incremental finite element method is used to detect the origin of the initial crack and to trace the formation and the propagation of subsequent cracks up to failure. Two types of elements are employed. These are the simple constant stress (or strain) triangle and the eight noded isoparametric element. The theoretical validity of the proposed method is studied and illustrative examples are given. Comparisons are made with experimentalobservation on uniform soilcement samples with or without cylindrical cavities. K.I. Majid and K. Al-Hashimi

Light gauge steel folded plate structures are described in principle and the state of the art reviewed. Much of the previous research in this field has envisaged very stiff welded construction and the potentialadvantages of lighter construction using discrete fasteners have not previously been investigated. In this paper a complete theory for both the strength and stiffness of the elements of folded plate roofs is proposed. The theory is an extension of earlier work on shear diaphragms and is based on an assumed statically determinate internal force distribution which is a simplification of the highly indeterminate system existing in reality. J.M. Davies

In our April column we included a letter from Mr. D. T. Coates who wished to air what we consider are totally erroneous views about the role of learned societies in general and our Institution in particular. Mr. Coates is not one of our members and to this extent his misconception is possibly understandable. Mr. C. Billingham (TEng, CEI) has since written on an issue which reflects a similar misconception: The recent letter from Mr. P. E. Spriggs raises several points worthy of further comment both from the technician's point of view and that of the Institution. Verulam