As general reporter of Commission X, 'Slabs', it seems to me appropriate to give a review of what has been done, and to mention our present and future programme of research.

You may remember that in that historical session in Monaco in January 1961, we added two more Commissions to the C.E.B. list: Commission X, 'Slabs', and Commission XI, 'Hyperstatic structures'. At that same session, it was understood that the scope of Commission X would be vast and really too large for one Commission to handle. Therefore, at the offset, the tasks were divided over two domains: the slabs proper and the flat plates (supported on columns). And even then, it seemed hard to come to results within a reasonable time as there are, for each of the two types of structures, so many important ranges of knowledge: the application of elasticity theory and the use of plasticity theory. Moreover, in addition to the research on the phenomenon of bending, attention should be directed to torsion, shear, and punching shear as well.

On the other hand, especially in building construction, about 50% of all reinforced concrete used goes into slabs and kindred constructions. Therefore, any knowledge or insight gained will have a widespread influence.

At the very beginning, it was agreed that the work of the Commission would not consist of a repetition of what has been done before, which means that large areas of applied elastic theory would be left as they had been developed.

In order to understand how slabs have been calculated and looked upon so far, a survey was made of the rules and regulations of many countries. This was extended to flat slabs as well and dealt with all aspects: rules for bending moments and shear calculation, min. thickness, min. reinforcement, slenderness ratios, one- and two-way slabs, etc. To that end, a letter was sent round and the results were classified by Mr. Brakel, Secretary of our group. Valuable assistance was received from Professor Franz, who had been working along similar lines (Bulletin No. 29).