Complex sentence: The whole structure rests upon a thrust bearing, and is connected to its foundations by two concentric rings and shock absorbers, whilst the thrust bearing rests in a caisson; this is designed to allow it to rotate under computer control to face into the wind.
Split into simpler sentences: The whole structure rests upon a thrust bearing, and is connected to its foundations by two concentric rings and shock absorbers. This is to allow the building to rotate under computer control to face into the wind.