Design rationale for stair slabs based on finite element analysis

Abstract

The results of a study of stair slabs by using finite element technique have been presented in this thesis. The behavior of both Dog-legged and Open-well type of stair have been analyzed. Both thick and thin shell finite elements have been used for this purpose and the results of the analyses by both of these elements compare well. Sensitivity study of the critical parameters of the stair slab has also been carried out to make the findings more generalized. The stair slabs, usually being supported on walls or beams at landing levels, derive significant rigidity from such supports. This reduces the magnitude of the moments that would have otherwise resulted. The leading codes of practice do not provide proper appreciation to this distinctive feature of stair slabs arising out of its supporting arrangements. The design moments for the stair slabs, under study, have been found to be considerably smaller than those commonly suggested by the Codes of Practice. Based on the findings of the present study, a new design rationale has been suggested, for both Dog-legged and Open-well type of stairs.