This usually happens after the length of trailers are increased.
I remember when trailers went from 40' to 45,then to 48,next came 53'
From 40 to 45 it was not that drastic,but some of the first 48's & 53's did break in the center,when the axels were on the tail.
They were being over loaded when the trailers go bouncing down the road,they are prone to break.