Issue 16

The susceptibility of open sandwich beams (concrete/adhesive/steel) to static fracture by crack propagation along the adhesive layer is investigated, using linear elastic fracture mechanics. lt is found that beams constructed with a suitable adhesive should not be at risk from such failure, whether they are conventionally reinforced beams strengthened by an externally bonded plate or plain concrete beams rein forced solely by an external plate. A. Anandarajah and Professor A.E. Vardy

The paper presents a theoretical method for calculating the moment-curvature and thus the load-deflection relationships of post-tensioned brickwork beam. The theoretical method takes into account the various sources of non-linearity in brickwork behaviour, e.g. stress strain relationship, tensile cracking, and tension stiffening. A theoretical expression for predicting the crack width in terms of crack spacing and average strain at the level of crack is also described. R.F. Pedreschi and B.P. Sinha

This paper presents a method for the optimisation of stiffener sizes for ring stiffened cylinders under external pressure loading. The approach is based on rigid plastic mechanism formulations for local and general collapse modes. The criterion used for the optimisation process involves the determination of the stiffener geometry which produces concurrent collapse in the two modes. S.K. Tsang and Professor J.E. Harding

The paper describes the shear comb system of reinforcement used to increase the punching resistances of reinforced concrete flat slabs. Recommendations are made for the design and detailing of such reinforcement and are verified by reference to available test data for cases of symmetric punching. The application of shear combs in unsymmetric conditions is also discussed. P.E. Regan