NUMERICAL STUDIES ON FLAT SLAB STRCTURES SUPPORTED ON NON-RECTANGULAR GRIDS

Jayaprakash Narayana.S, Sreenivas Sarma.P

Abstract: Construction of flat slab structures has increased enormously in recent times. Well established procedures are available in the literature and codes for the analysis, design and detailing of flat slab structures supported on regular rectangular column grids. However, these structures pose a greater challenge to the designers, when they are supported on non-rectangular column grids. Use of non- rectangular column grids is often necessitated in the modern context, due to varied parking requirements, floor wise variation of building plans, site constraints etc. Besides, the seismic performance of flat slab structures has been the subject of interest for the researchers over the years. Though their works established the behavior of flat slabs supported on regular rectangular grids to a greater extent, the seismic behavior of flat slab structure supported on non-rectangular grids, still needs detailed investigations. Lack of adequate information in literature and non availability of standard specifications in codes on these types & structures indicate the immediate necessity for such investigations. This paper presents the inferences of extensive numerical investigations on a chosen flat slab structure for possible shifting, breaking and new formations of column strips with the variation in the position of an interior column, which makes the regular rectangular grids into non- rectangular. The sensitivity of the structure is explored by varying the position of an interior column. The variation of moments and shears in column strips in the flat slab under static and dynamic loads are observed and are also plotted. Further, a 10 storeyed flat slab structure is analysed and the results are studied to know the effect of staggering a column of a rectangular grid, on the moments in chosen (corner, side and interior) columns, under both static and dynamic loads. Results reveal that there is every need to consider the effect of non rectangularity column grids on the formation of column strips, moments and shears in column strips, the detailing of reinforcement in column strips and also the moments in the columns of such flat slab structures.

Keywords: Flat slab structures, Non- rectangular grids, shifting of column strips, seismic performance

DOI: https://doi.org/10.15623/ijret.2015.0413021