Engineers at Texas A&M University conducted a series of tests on the new bridge support design, created using experimental technology. Its working title is “hybrid sliding-swinging bridge”, and the idea for it was taken from the structure of human limbs. Two bones in a joint are inseparably attached to each other, but at the same time they can be displaced quite significant distances and at different angles to compensate for the load.
The main idea is not at all to make a super-strong bridge, which does not care about any seismic shocks – such a structure is unlikely to pay off even after a hundred years of service. Instead, study author Dr.Petros Sideris proposed the concept of supports that partially deform during vibrations, but these displacements are easily reversible. By analogy with the ligaments in the human body – during normal operation they hold the load, when overloaded they stretch, but they can be healed and the limbs return to their previous properties without replacing it entirely.
All mechanisms used in the prototype are experimental – there is no point in describing them. Engineers deliberately destroyed the first structure on the earthquake simulator, repaired it with mortar and spacers, and then destroyed it again. The performance before and after was evaluated, how the re-destruction took place, how good the repair was, what costs are needed and what can be avoided. The general conclusion is that the maintainability of the sliding-swinging bridge is several times higher than that of fixed monolithic structures, and it holds the load much better.
The disadvantage of this design is much higher cost due to the use of relatively complex mechanisms in the construction of the support instead of simple pouring of concrete. In theory, the initial costs will more than pay off due to the cheap and, most importantly, quick repairs later, when the bridge damaged by the earthquake is put into operation as soon as possible. It remains to convincingly prove this to bridge engineers.