Issue 15

The paper presents a design philosophy for large storage tank roofs which makes use of finite element analysis to asess and develop simplified structural mathematical models of the roof components. The aim is to provide the designer with an optimked structural layout, and suitable section sizes, which both satisfies structural standards and is cost effective. The approach is illustrated with reference to two different types of domed roof which are widely used in practice. G. Thomson, G.K. Schleyer and Professor A.S. Tooth

Dr. P. S. Chana (Cement & Concrete Association): It is encouraging to see a paper which aims to clarify the fundamental behaviour of reinforced concrete T-beams in shear. Owing to the difficult nature of the problem, research in this area has been largely restricted to empirical studies. I would like to make some comments regarding some of the basic assumptions and the significance of the results on present design methods.

A mathematical model, based on the physical properties of nominally ‘pinned’ column-bases and intended to describe the moment-rotation characteristics for given eccentricity of axial load, is presented. The model uses three main parameters to describe the characteristic: elastic stiffness, strain hardening stiffness, and plastic moment capacity. In addition, an empirically determined ‘shape’ factor allows for the transition from elastic to inelastic behaviour. K.K. Hon and Professor R.E. Melchers