80 The Terrace (formerly known as the AXA Building) was constructed in 1986 near the centre of government in Wellington’s CBD. Its prime position, with 14 levels of office space and 4 levels of lower level parking, made it attractive to tenants, particularly government related agencies. Following the Christchurch earthquakes and with the main tenant vacating the building, the building owners made the decision to assess the seismic performance of the building with a view to strengthening as well as refurbishment.
The initial engineering assessment to identify the strengthening works was only the beginning of this tricky project. Finding ways to implement the alterations in a manner which was sympathetic to both the overall aesthetic of the building, and its continued function as a working commercial office tower was where the real challenges lay.
We worked closely with the engineering team to achieve the goal of minimising consequential building works during the strengthening process. Minor alterations to the slab bracket meant that core walls could be left intact, alterations to the column tie design meant that sprinklers and HVAC could be reinstated into the same positions, and alterations to the stair brackets meant relocation of the sprinkler riser main could be avoided.
The major safety challenge was sequencing the stair improvement works in such a way that egress to the building was not compromised. More specifically the type of sliding joint implemented at each end of the precast stair runs were alternated every floor so as to consolidate disruption to one side of the scissor stair leaving the other clear during the out of hours works. With these strengthening measures in place the building was able to achieve an 80% New Building Standard (NBS) seismic capacity rating.
As part of the works we completed a full building refurbishment, a new lobby and five floors of office fitout.
The earthquakes of July and August 2013 left the building with no structural damage. Other offices around Wellington were not so fortunate and 80 The Terrace became a very appealing location for new tenants. The commercial benefits of a cost effective retrofit seismic strengthening solution and refurbishment have been fully realised with the building 100% leased in a prime Wellington location.