Distribution of elastic moments in flat slabs with particular reference to lift-slab structures.

A generalised theoretical analysis is developed for the determination of bending moments in a uniformly loaded infinite flat plate structure, rigidly clamped in rectangular-shaped columns, spaced at regular intervals to form the rectangular panels of the slab. The same analysis is also being applied for solving Lift Slab structures in which the collar corresponds very closely to the column capital of a flat plate structure. The method of complex variable in connection with conformal mapping has been used for the solution of the problem. A series of tests on models has been carried out with the aid of the Moire apparatus to determine bending moments and deflections in flat plate and Lift Slab structures under various loading combinations. The first two series relate to the flat plate structures, the rest four series being on lift slabs. The close agreement between the compared theoretical and experimental results indicates that the analysis yields reliable results. The results are also compared with the recommended design moments as laid down in the Code of Practice, CP 114