Elastic analysis of ground-floor slabs under multiple loads

The design of ground- floor slabs focuses mainly on single- load cases applied at the centre, edge and corner of the slab. The need for extending existing guidelines that allow for the effect of multiple loads, and for the effect of loads being at some distance from the three aforementioned locations, is fundamental for both safety and economy, and is increasingly recognised in the industry. Some elastic guidelines, which date back nearly a century ago, do exist but they are incomplete, cumbersome and generally little known. In the present paper, a new set of influence lines ( previous data really refer to certain stress contours) is proposed for both stresses and deflections owing to loads moving along the centrelines, edges and corner bisectors. These diagrams are based on linear finite element analysis ( LFEA), and thus allow the use of direct superposition to accommodate any number of applied loads. Non-linearities and/ or plastic methods are outside the scope of this paper.