Shear strength of end slabs of prestressed concrete reactor vessels

Many experimental investigations on PCRV end slabs have been conducted over the past decade. This information makes it possible to establish empirical formulae for the ultimate strength of PCRV end slabs. The basis and development of an empirical shear-flexure interaction expression is presented in this paper. A review of test data reported in the literature has shown that parametric studies conducted by the University of Illinois, Taylor Woodrow Construction, and the University of Sidney encompass the full range of credible design conditions for PCRV end slabs. The results of these tests were evaluated and an interaction equation was derived. The precedent for this approach has been established by numerous investigators of the punching shear strength of slabs. It was found that this approach offers a convenient and rational method of accounting for end slab geometry; material properties, the presence of bonded reinforcing steel; and the location, size, and level of stress of circumferential and longitudinal prestressing elements. Constants in the expression were determined statistically from the results of about seventy end slab tests. The application of the shear-flexure equation requires the determination of the flexural strength of the end slab as the first step in the interaction procedure. The development of the flexural analysis follows the classical yield-line theory. The mechanism of a flexural failure is formed by a series of wedge-shaped sections, each bounded by radial cracks. The relationship between the internal pressure and the resistance provided by the prestressing and reinforcing elements in the end slab is established by equilibrium consideration. The validity of the derived equation was verified by comparison with the results of PCRV scale model tests