Flexural Strength of Flat Slabs at Exterior Columns

The flexural strength of exterior panels of flat slab structures is investigated by use of Yield Line Theory. Six controlling, geometrically admissible, collapse mechanisms are identified, three of which involve local flexural failures around the columns. The loading is uniformly distributed, the columns are rectangular, and the reinforcement is arranged orthotropically. The coefficient of orthotropy and the ratio of negative to positive yield moment may vary arbitrarily. The governing equations for the six mechanisms are derived and presented in dimensionless form. Based on numerical solutions of four of the equations, a set of graphs is provided which covers practical ranges of the important physical and geometrical parameters. These graphs are useful for the analysis or design of the exterior slab panels. In addition, an equation is derived which gives an upper bound on the bending moment which the slab can transfer into the exterior column at collapse load through flexural action.