Lock-Up Device/Shock transmission unit

Shock transmission unit(STU), also known as Lock-up device(LUD), is basically a device connecting separate structural units. 

It is characterized by its ability to transmit short-term impact forces between connecting structures while permitting long-term movements between the structures. 

It may be used to strengthen bridges and viaducts, particularly in cases where the frequency, speed and weights of vehicles and trains have increased beyond the original design criteria of the structure. 

It may be used for the protection of structures against earthquakes and is cost effective for seismic retrofitting. 

When used in new designs large savings can be achieved over conventional construction methods.