Shear Strength of Lightweight Reinforced Concrete Deep Beams with Web Openings

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Dr. W. B. Cranston : Professor Hendry has presented a large body of evidence related to clay brick masonry. The problem of lateral strength is relevant also to concrete block masonry. I should like to introduce work on this aspect carried out by the National Bureau of Standards in America, and also to mention work currently in progress at the Cement and Concrete Association.

When a thin steel plate with flat stiffeners is loaded either axially or in bending it will eventually undergo large deformations in either Mode I or Mode II, where for Mode I the free edges of the stiffeners have only tensile stresses and for Mode II these stresses are predominantly compressive. Thus Mode I is a plate buckle whereas Mode II is a stiffener buckle. Associated with each mode is a plastic mechanism the load-deflexion curve of which defines a panel’s post-buckling behaviour. These mechanisms are analysed theoretically and then a study is made of the effects of each parameter. Laboratory tests on large stiffened panels are briefly described. N.W. Murray