LIMITATIONS FOR THE DIRECT DESIGN METHOD

DIRECT DESIGN METHOD :-- Limitations :- Slab system designed by the direct design method shall fulfil the following conditions .(1) There shall be minimum of three continuous spans in each direction (2) The panels shall be rectangular and the ratio of the longer span to the shorter span with in a panel shall not be greater than 2.0 (3) It shall be permissible to offset Columns to a maximum of ten percent of the span in the direction of the offset not withstanding the provision made in number 2 .(4) The successive span lengths in each direction shall not differ by more than one third of the longer span .The end spans may be shorter but not longer than the interior spans ,and (5) The design live load shall not exceed three times the design load .The thickness of the flat slab shall be generally controlled by consideration of span to effective depth ratio and the minimum thickness of the slab shall be 125 mm .