The shear resistance of castellated joints between large, precast concrete panels is investigated experimentally. A total of 23 specimens, with various configurations of castellation and joint properties, were tested. Results obtained are compared with available theoretical methods as well as design provkions given in CP1lO and the ACI Code. A prediction model is proposed, taking into consideration the combined effect of dowel action of the reinforcing bars and the shear resistance offered by the castellation. The model gave good agreement with experimental results as a reasonable lower-bound solution with a factor of safety of 1.08. It is concluded that the width of the joint and the width of the key have no effect on the shear resistance of the joint, whereas the depth and number of keys have a direct effect on the shear capacity. Hashim M.S. Abdul-Wahab
Tests were carried out to investigate the behaviour of two tall, narrow diaphragm walls under varying levels of prestrm and subject to varying magnitudes of lateral loading. The main and primary objective was to evaluate the massive increase in lateral load resistance of such walls, of well over a 100 times, compared to traditional walls of similar cross-sectional area. A number of secondary objectives such as creep, elastic contraction, princbal tensile strength, shear lag, and the general behaviour of full-scale plain diaphragm walls, were also examined. It was found that prestressing not only immensely increases brickwork’s bending strength; it also increases the stiffness of elements and changes brickwork behaviour from brittle to ductile. It may not be an exaggeration to state that it is a ’new’ structural material and bears no comparison, structurally, with traditional brickwork. W.G. Curtin
Eleven bamboo-reinforced concrete two-way slabs with simply supported boundaries have been subjected to concentrated central loading. Concrete strength, span/depth ratio, bamboo percentage, and the treatment given to the bamboo reinforcement, were varied. Punching failure always followed the full development of the flexural collapse mechanism, and the punching load was always greater than the yieldline theory load. From a consideration of the results, methods of predicting both the cracking load and the punching load of a bamboo reinforced slab are suggested. J.A. Kankam, M. Ben-George and Professor S.H. Perry
Dr. 0. Vilnay (University College, Cardiff): For a long time, the stability of masonry arches has been confused with the problem of equilibrium and strength. It was generally assumed that, where it is possible to establish a thrust line lying wholly within the arch, the arch is stablec. However, this situation indicates only that the load is sustained by internal compression and does not indicate anything about the stability of the arch.
In structural testing, it is important to ensure that the loading that is applied to the test piece is that which is intended. If unintended constraints or instabilities arise, these will often lead to errors. The paper proposes a method of assessing the kinematic state of a test setup and enables suitable systems to be designed. R.C. Corless and Professor P.B. Morice