Prisms and cameras track aging roof beams at Pori ice hall

Yle reports that the city of Pori is monitoring the 55-year-old glued laminated timber beams in the roof of Isomäki ice hall with 11 prisms and two cameras. The measurements are intended to show how long the beams can remain in use and help determine when a renovation must begin.

The roof structures have reached the end of their calculated service life. The start date for a renovation costing more than 20 million euros has not been decided. The investment would involve renewing the old section of the 55-year-old hall, according to an earlier comment to Yle by Toni Wahlman, managing director of Kiinteistö oy Porin Jäähalli.

The prisms and cameras measure movement in the beams twice a minute, with summaries produced twice a day. The equipment is expected to collect data for at least two years, with an option to continue for a third. It is rented from Mitta oy for between 1,000 and 2,000 euros a month, including maintenance and servicing.

Officials are also monitoring movement that could result from snow loads. Safety limits for beam movement have not yet been set. They will be agreed with a designer specialising in arch beams and approved by building control authorities.

If the beams move beyond the agreed limits, the hall could be closed. Markus Kallio, a construction engineer at Porin YH-Asunnot, said he did not personally expect that to happen and described the hall as safe.

Pori has drawn on measurement experience from Lahti and Lappeenranta. Moisture meters have already been installed at Isomäki, and separate temperature meters and a wind meter on the roof are also planned.