A flitch plate is used to help increase the strength of the overall structure. A flitch plate is a metal plate that’s in the middle of wood beams secured by bolts. These are especially useful when framing large buildings because the columns have to be placed farther apart than normal.
Naturally this would cause an unstable environment. By using a flitch plate it allows for the stability to be there.
The Secret of a Flitch Plate
The secret of the flitch plate is actually very simple. Iron’s elasticity is vastly greater than that of wood. In fact when comparing wrought iron to hard pine you will find out that the elasticity is 13 times greater.
In other words, if you took a piece of hard pine and a piece of wrought iron with the same amount of load on each one the wood would bend 13 times as much! So the wood has to be eleven times the thickness of the iron so that the wood and iron plates bend at the same point. If this is not done the whole strain of the load might end up on just the iron rather than the flitch plate as a whole.