Is a Steel I-Beam Bolted to Concrete Block Foundation?

Connection

• The connection of steel and concrete differs somewhat from the connection of steel to steel or steel to wood. In the case of a steel to steel connection, the I-beam is welded to the other piece of steel. Steel to wood connections are similar to steel to concrete in that a bolt is typically used to draw the two together. With a steel to concrete connection, the steel beam is usually set in the concrete but still bolted for the purpose of reinforcing the connection.

Repair

• Aside from installing steel beams in the concrete to reinforce a new floor, steel I-beams can also be used for the purpose of repairing a foundation and providing additional reinforcement. They can also be used to support bowing foundation walls. In cases where the wall is of primary concern, the beams are installed vertically against the weakening concrete wall. These are usually attached to the concrete basement floor using a brace that is bolted down and one on the upper end bolted to the wooden floor joists above.

Expansion and Contraction

• One consideration regarding the connection of steel I-beams is the expansion and contraction of the concrete due to hot and cold temperatures. Beams that are attached with a bolt have to accommodate this expansion as well. This is often done by drilling out the hole for the bolt and then filling it with an appropriate grout, rather than having the steel bolt in direct concrete with the concrete itself.

Stress Considerations

• Because of the differences in strength and the relative resistance to stress, builders have to be careful to take these into account when connecting steel to concrete. Tata Steel notes that the safe working stresses for steel are 10 to 15 times greater than that of concrete. Concrete can't be formed as accurately or as precisely as steel, making it more susceptible to stress fractures. Tensile strength of concrete is nearly nonexistent, so the builder must deflect the load back into the reinforcement correctly to avoid fracturing.