Find the value ofd the distance from the top of the beam to

Find the value of\'d\' (the distance from the top of the beam to the centroid of the rebar) in the shown x- section of the beam. 18\" Notes: fc = 6,000 psi Grade 60 reinf. beam = 150 pcf 8\" 30\" 8\" #8 bar (typ.) -7 total 8\" 3\" 2.5\"

Solution

The effective depth d is calculated by an equation depending upon the number of layers of the steel bars . For one row of steel bars, d = D - dia/2 - c

D = total depth = 30\"

Dia = diameter of steel bar = 8\"

C = effective cover = 2.5\"

Here there are two rows, hence the equation becomes

d = D - s/2 - c

S = spacing between the layers

So, d = 30 - 2.5- 3/2 = 26\"