The incident in mentioned in passing in the Historia Augusta as one of several unfortunate events during the reign of Antoninus Pius (ruled 138-161 AD).

The details are laid out in a very slightly expanded snippet in the so-called Chronica Minora , ed Theodore Mommsen (vol 1, pg 146), late Latin collection of short odds and ends about various Roman emperors. In discussing Antoninus Pius it says hoc imper. circensibus Apollinaribus partectorum columna ruit et oppressit homines mcxii , basically, that in the time of this emperor at the [Games honoring] Apollo at the Circus [Maximus] a column supporting the scaffolding (partecta) broke and crushed 1112 people. (Partecta is a very uncommon word, not even in the Oxford Latin Dictionary. It has also been interpreted as outer wall.)

And basically, that's all she wrote.