From The M.E.N.
The 184ft (56m) sculpture, designed to look like an exploding firework, is made up of 200 solid steel columns.
Engineers and designers are carrying out an investigation into how the seven-foot spike fell to the ground.
A spokesperson for New East Manchester, who commissioned the sculpture, said they were "extremely concerned".
"There is no indication at this time that any other parts of the B of the Bang structure are unsafe," the company said.
The area around the sculpture was closed to the public at the time of the incident, as work on the sculpture is ongoing.
it is due to be officially unveiled by former Olympic champion Linford Christie next week.
The junction from Ashton New Road into Alan Turing Way and adjoining footpath were temporarily closed on Thursday as a safety precaution.
The sculpture is taller than the Angel of the North, in Gateshead, and leans at a greater angle than the Leaning Tower of Pisa in Italy.
It was designed as a tribute to the 2002 Commonwealth Games and named after British sprinter Linford Christie's famous saying: "I'll be gone by the B of the Bang."