A reinforced concrete slab (2400 mm x 2400 mm) x225mm thick is lifted by 4 cables attached to corners as shown in fig. The cables are attached to hook at a point 1500mm above the top of the slab. Each cable has an effective cross-sectional area A= 9 mm2. Determine the tensile stress in the cables due to the weight of the concrete slab. Weight density of the concrete slab is 24 KN/M^3

Weight of concrete slab=$24 KN/m^3$

Volume of concrete slab= $2400*2400*225$

$=1.296*10^9 mm^3$

$=1.296 m^3$

Now, weight of concrete slab which act as tensile force on wire or cables is W=weight density*volume

$=24*1.296$

$W=31.104 KN$

Now, these tensile force equally distributed to the each cable.

Force in each cable$=\frac{31.104}{4}=7.776KN$

Now, tensile strength is each cable=$\frac{force in each cable}{area of cable}$

Tensile stress in each cable=$\frac{7.776*10^3}{9} N/mm^2=864 N/mm^2$