Reynolds Metals

Buildings: structural steel ties, are they all the same?

Many old buildings in the UK are made structurally safer by putting steel ties in to hold the walls upright. I thought these were done under heat and the tie would then contract on cooling to pull the walls in tight. Is this true? Also, there are different end plates. Some are Xs some are in the shape of an S. Is there a reason for the differing plates?

Public Comments

1. Ask 7 different engineers, get 7 different answers
2. smokes
3. Structural ties are fix using the coefficient of expansion principle, I don’t think so.. Common sense dictates that getting a metal rod hot to expand requires a great deal heat. The heat would need to be applied to the total length of the rod was expand sufficiently that when cooled it would contract enough to tighten it, otherwise the heat would be conducted away before sufficient expansion could take. Precise calculation at to the length of the rod would be need to ensure that contraction would be just enough to give the right pressure without causing a crushing effect. If this was not all, you have the problem of fixing a red hot rod without setting fire to the building or burning the operatives. Normally the rod was threaded at each end and gently pressure was applied by tightening a nut at each end. The idea was just enough pressure to prevent further movement. This sort of tie was not used to return the building to its original integrity. The plates at each end were there to spread the load. There design was a matter of preference X and double S patterns, some were round or oval plates of cast iron. Whenever this type of restraint is seen in a building it is normally and indication that there is insufficient lateral restraint. If are thinking purchasing a property with this type of restraint I would advise against.