Precautionary seismic assessments of Tauranga City Council’s Spring Street and Elizabeth Street car park buildings have highlighted areas where strengthening and remediation work should be carried out to reduce the risk to users and extent of damage a significant earthquake event could cause.
Council Corporate Services General Manager Paul Davidson said that while there was no regulatory requirement to carry out the assessments, expert engineering advice suggested it would be prudent to do so. “A learning from the Canterbury and Kaikoura earthquakes was that buildings with long-span precast concrete flooring systems can have vulnerabilities and as both buildings utilise that system, we wanted to ensure that any works needed to surpass the required earthquake resistance standard were identified.”
Parts of both buildings do not meet the minimum 34% ‘new building standard’ (NBS) rating, which technically means they could be classified as earthquake-prone, requiring strengthening or demolition to be carried out within 25 years.
“Advice provided by Chartered Professional Engineers, Kestrel Group, stresses that the NBS ratings for the buildings do not mean they are dangerous, or that there is any need to change the current use,” Mr Davidson said. “We are now working with engineering consultancy Beca to finalise strengthening options and costs and develop a timeline for the structural work to bring both buildings up to at least a 55% NBS rating.“
He said work would be scheduled to minimise inconvenience for regular users, but it was likely that each building would need to be closed to the public for a period of time.
“We’ll be working hard to make sure the closure periods don’t overlap and keep them as short as possible. Council staff will also provide advice on alternative all-day parking options for car park users.”
Work to be undertaken on the Spring Street car park includes the installation of additional steel bracing components and provision of independent support for the bridge linking to the roof of the adjacent building at 29 Grey Street. An earlier component of work to apply seismic restraints to non-structural block walls on the north-eastern side of the building is expected to start this month.
Remediation work at the Elizabeth Street car park will focus on ramp transitions in the first four levels of the building and connections between the eastern stair tower and the building.
The Council is working with the co-owners of the Elizabeth Street building to minimise any effects of the work programme on their commercial tenants.
A report on the buildings’ seismic status was received by commissioners in a public excluded session of the Council meeting held on 8 March. That report is now publicly available and has been uploaded to the Council website.