Use of Ball Bearings In Bridge Construction

Ball bearings have been used in construction for many years now, in order to overcome various problems.

One of the most high-risk problems is building in areas that are prone to earthquakes. It is no secret that earthquakes can cause a devastating level of damage to buildings, which in turn can result in the loss of human life.

Engineers must therefore do their utmost to make sure that buildings are prepared for such an onslaught, so that if an earthquake happens, the level of damage, and consequently the level of injury, is kept to a minimum.

One of the most common forms of technology in earth resistance technology is the idea of seismic isolation, where the building itself rests on giant, frictionless ball bearings. This means that when the ground moves, the bearings move too, but the building does not. No force is therefore transferred to the building, meaning that (in theory), the building does not experience the earthquake.

There are many examples of this system being used in buildings around the world, with the most famous being the San Francisco International Airport Terminal.

Many other structures in San Francisco are fitted with this technology. Not least the Benicia-Martinez Bridge, which contains the largest ball bearings in the world. The bridge carries around 100,000 vehicles a day, and was also built with special concrete that weighs around 20% less than normal concrete, retaining a 6500 psi design strength and a stronger modulus of elasticity.

There are also seismic isolation bearings where the bridge meets land. Each of these weigh between 40,000 and 50,000 pounds, and allow an incredible six feet of horizontal movement in the event of an earthquake.

Similar seismic technology has also been used in other pieces of construction where vibrations are deemed to be problematic. Railways have become more high-speed and therefore the potential for an increase in vibrations is higher. Tracks are therefore fitted with technology that allows for a much smoother ride.

As well as counteracting against vibrations, ball bearings can also be increased in size in order to facilitate making large mechanical structures. One of the best examples of this is the mechanism used to open and close the roof of the Miller Park athletic stadium in Milwaukee, Wisconsin, USA.

But it is not only the mechanisms themselves where ball bearings play a significant role. They have also played a part in the actual construction process.

Many experts now believe that ball bearings were used in the construction of the enigmatic Stonehenge. Balls placed in grooved wooden tracks would have facilitated the movement of incredibly heavy stone, which could explain how the stones, which weigh many tonnes, were moved from the quarries to Salisbury Plain, Wiltshire.

Evidence for the use of such a mechanism was found in the form of stone balls, near a similar stone monument in Aberdeenshire Scotland.

These ball bearings were roughly the same size as a cricket ball, and fashioned to with a millimetre of the same size, suggesting they were used together rather than individually.

When a group of students decided to reconstruct this type of machinery, they found that they could transport heavy loads with ease. However it does not seem to shed any light onto the reasons why such a structure was built.