PRACTICAL RULES AND APPLICATION OF THE CODE FOR PRACTICE RELATED TO THE RC SLABS AND BEAMS

GENERAL DESIGN PRINCIPLES FOR RC SLABS AND BEAMS :-- The effective span of a simply supported beam or slab shall be taken as the clear span plus the effective depth of slab or beam ,or centre to centre of supports ,which ever is less and the effective depth is from top of the concrete to the centre of the tensile steel .In normal cases the overall depth of a beam or slab shall not be less than the following fraction of the effective span as per IS code .In case of beams up to ten meters span and simply supported it should be 1/20 of the span and in case of the continuous beams it should be 1/26 of the span and in case of cantilever it should be1/7 of span and for spans above ten meters the above values must be multiplied by 10/ span in meters. In case of slabs simply supported, spanning in one direction it should be 1/30 of span and in the case of simply supported spanning in two directions it should be 1/35 of the span and in case of continuous beams one direction it should be 1/ 35of the span and in case of two directions it should be 1/40 of the span and in the case of cantilever it should be 1/12 of the span. This will obviate deflection. In the cantilever beams and slabs ,the span may be taken as the effective overhang and in slabs spanning in the two directions ,the shorter of the two spans shall be taken to calculate the depth.The following minimum bearings on walls should be taken as the bearing on walls In case of solid slabs it is 10 cm ,in case of lintels it must be equal to depth of the lintels and 15 cm as the minimum and in the case of beams it should be 20 cm for spans up to 3.5 mts and 30 cm for spans up to 5.5 mts and 40 cm for spans upto 7.00 mts .The bearings of the ends of a beam on a wall beyond a certain distance does not strengthen the beam .