Design of a two-way slab - Reinforced Concrete with FRP Bars: Mechanics and Design - page 325

“O K” if ∆≤∆

LT limit

Check_:= ∆

LT

“Not good”otherwise

Check_Δ LT = “OK”

8.10 STEP 8—CHECK FOR PUNCHING
SHEAR (NO PERIMETER BEAMS)

Assuming that no slab-perimeter beams are present, the slab at columns
A1, B1, and B2 are checked for punching shear. It is assumed that columns
are square with sides equal to b col := 20 in.

8.10.1 Check at column A1
The area of influence is

A I1 := (0.45.1 1 )·(0.45·1 2 ) - b col 2 = 113.862·ft 2

The factored shear force is

V u1 := A I1 ·TFL = 31.8·kip

The perimeter of critical section is

( )

b =2 b+ mind ,d
2

f1 f2

.

=46.5in ⋅

01 col

b col +d/2

0.45ℓ

b col +d/2

0.45ℓ

The ratio of modulus of elasticity of bars to modulus of elasticity of con-
crete is

n f = 1.399