ABSTRACT
The general recommendations in BS8110 for the design of slabs spanning in two directions apply to slabs of all shapes and with all types of loading and support fixity. BS8110 tabulates empirical bending-moment coefficients for solid slabs that are uniformly loaded and span in two directions at right angles. The design of typical beams supporting the panels of the two-way roof slabs is given on Drawing 9 and Calculation Sheets 11 and 12. Rectangular slabs carrying partial loads can be analysed elastically fairly simply by Pigeaud’s method. The bending-moment coefficients given in BS8110 for a uniformly loaded rectangular panel, freely supported on all sides and with the corners not reinforced to resist torsion or to prevent lifting, have been obtained by application of the Grashof and Rankine analysis. Although the analysis and design are for the ultimate limit-state, it is important to estimate accurately an appropriate effective depth before carrying through the entire design calculations in too much detail.
