FLAT SLAB TWO WAY SHEAR CHECK AS PER BNBC

 

    

SLAB THICKNESS                                       = 6.5 inch = 0.542 ft

EFFECTIVE DEPTH                                     = 6.5 – 0.75= 5.75 inch

FLOOR FINISH                                             = 25 psf

SELF-WEIGHT OF SLAB                            = 0.542 x150 pcf = 81.3 psf

TOTAL DEAD LOAD                                   = 106.3 psf

LIVE LOAD                                                   = 42 psf

FACTORED LOAD (1.4DL+1.7LL)            = (1.4 x 106.3 + 1.7 x 42) = 220.22 psf

 

STEP- 1: DETERMINATION OF PUNCHING LOAD

           

            Total Area                                           = 19 ft 11 inch X 20 ft = 398.33 sft

            Punching Area                                    = (18+5.75) X (18+5.75) inch = 3.92 sft

`           Effective Area                                     = 398.33 – 4.17 = 394.41 sft

            Developed Punching Load, V_u              = 394.41 x 220.22 = 86856.97 lb = 86.9 lb

 

STEP- 2: DETERMINATION OF ALLOWABLE PUNCHING LOAD

           

            Allowable Punching Load, ɸV_c             = ɸ4ƛb₀d

            Reduction Factor, ɸ                            = 0.85 (BNBC 2006 Table- 6.6.1)

            Modification Factor, ƛ                        = 1 (Normal Weight Concrete)

            Punching Perimeter, b₀                       = 4 x (18+5.75) =95 inch

            Effective Depth, d                              = 6.5 – 0.75= 5.75 inch

            Concrete Strength,                                   = 3480 psi (Taking the lowest Strength from report).

                Allowable Punching Load, ɸV_c             = (0.85 x 4 x 1 x 95 x 5.75 x  ) lb = 109.56 kip

 

SO, WE CAN CONCLUDE THAT FLAT SLAB OF THIS BUILDING IS ADEQUATE FOR PUNCHING SHEAR.