Design of a two-way slab - Reinforced Concrete with FRP Bars: Mechanics and Design - page 326

The ratio of depth of neutral axis to reinforcement depth, calculated per
Equation (8-12) of ACI 440.1R-06, is

k f = 0.122

The concrete two-way capacity to resist punching shear is from Equation
(9-8a) of ACI 440.1R-06:

5
2 k4 fpsi

( ) ( )

V = ⋅ ′ ⋅ ⋅ bmin d,d=26.04 kip ⋅ ⋅

c1 c 01

f f1 f2

The concrete shear capacity per unit width, V c , has a minimum value is
1.6 per Chapter 4; therefore:

fbd ′

co

( ) ( )

V:=1.6 ⋅ fpsi ′ ⋅ ⋅ bmin d d ⋅ =34.2kip ⋅

c1min c 01

f1 f2

ϕV n1 := ϕ v ·V c1min = 25.647·kip

“O K” if VV ≤φ

u1 n1

Check_PunchingShear1:=

“Not good”otherwise

Check_PunchingShear1 = “Not good”

For example, including a drop panel at the corner columns could be a solu-
tion to prevent punching shear failure.

8.10.2 Check at column B1
The area of influence is

A I2 := (0.45·1 1 )·(0.5·1 2 ) - b col 2 = 126.822·ft 2

The factored shear force is

V u2 := A I2 ·TFL = 35.4·kip

The perimeter of critical section is

( )

b =2 b+ mind ,d
2

( )

( )

f1 f2

+b +min d,d 73 in ⋅ .

02

col col f1f 2