The £20.3M crossing was closed to road traffic on Monday 14 January after one of the supporting ties broke free and fell to the deck.
It was during the investigations by designers Halcrow and contractor Edmund Nuttall into the cause of this that the crack on a similar connector on a second of the 14 hangers was observed. Following this Glasgow City Council notified the Clyde Harbour Master and river traffic has now also been suspended.
Glasgow City Council Land and Environmental Services executive director Robert Booth said: “It is anticipated that the bridge will now be closed for up to six months. Although the bridge is designed to allow for the removal of one support at a time for repair it is unclear at this stage what impact a second failure would have.
“There will be no pressure on the public purse,” he said.
“The contractor will meet repair costs.”
When it opened last year the Clyde Arc was the first new crossing of the Clyde in the city which carries vehicular as well as pedestrian traffic since 1969. It was built primarily to serve developments south of the river which includes the new BBC Headquarters.