Question

What is PSF loading of the soil if, a 20-ton building transfers its load equally though a 1000 SF foundation to the earth?

What is the expected force required to break a 6’ x 12” concrete cylinder made from 3000 PSI concrete?

What is the stress in a no. 4 rod subjected to a force of 5000 lbs.?

how many times stronger is a no. 8 rod compared to a no. 4 rod made of the same material (Compare cross sectional area)?

Using the weight of rebar at .38 lbs./ LF, what is the weight of steel per cubic inch and per cubic foot?

Answer 1

a) Load = 20 ton = 40000 lbs

Area = 1000 sqf

Loading = 40000/1000 = 40 psf

b) We have

Force to break = F = 3000x113.1 = 339300 lbs = 339.3 kip

c) Dia of rod no 4 = 0.5 in

= 25.5 ksi

d) Dia of rod no 8 = 1 in

Dia of rod no 4 = 0.5 in

For same stress , force is given by

Therefore , bar no 8 is 4 times stronger than bar no 4

e) Let us take bar no 9

Weight is given by