How To Calculate Channel Iron Load Capacity?

Question

I'd like to know how to calculate the load capacity of a piece of channel iron that's 23 feet long, about .5 inches thick, with two 3 inch flanges and a 9 inch web.

The reason I want this information:

I live in a 225 square foot house that is 15 feet x 15 feet. The original owners built it to be movable by putting the house on cinder blocks. This is not an adequate foundation, and the blocks are sinking, causing some of the wooden structure on the north side of my house to rest on the ground.

I'm trying to figure out how to retrofit my house with a peer foundation, without having to move the house. The idea I have is to put in 8 concrete peers just outside the foot print of my building, 4 on the north side and 4 on the south side. The span between these peers going north to south will be around 17-19 feet.

Can 4 beams of channel iron with the properties I described above span this 17-19 foot gap given that I'm estimating the load of my house to be 20,000 pounds?

Answer 1

No this beam will not support your house.If you support the beam in the middle,it may.the more.Without a peer or pillor in the middle your house will sag in the middle.So what you're saying is whenever this house was built they didnt pour a concrete footer before they laid the block.Just me but wouldnt it be easier to use the beams you have to jack up and support your house and tear out the old block,pour concrete,and them put the block back.This will not only look better but it will probably improve the resale value of your home.