54 Cambridge Terrace, Wellington
Performance-Based Engineering

54 Cambridge Terrace

Location: Wellington, New Zealand
Project Duration: September 2022 – March 2023
Client Team: Prime Property Group

The five storey building at 54 Cambridge Terrace, Wellington was built in 1987 and is currently used for office and retail purposes. Miyamoto was engaged during the due diligence process prior to the purchase of the building. We provided a Detailed Seismic Assessment (DSA) to determine the current %NBS rating under the New Building Standard and are now designing a strengthening solution to improve the rating to 80% NBS.

The primary structural system is a concrete perimeter moment frame with a reinforced concrete masonry block wall core around the lift shaft. The floor system consists of 200 Dycore units with a 65mm topping.
Following the DSA, it was identified that the structural limitations governing the buildings global capacity were diaphragm capacity, insufficient seating of the hollowcore units and the potential of positive and negative moment failure of the hollowcore units.

Miyamoto has proposed a retrofit solution that utilises a combination of additional steel collector beams and fibre reinforced polymer (FRP) to strengthen the existing connection between the concrete frame and diaphragms. The proposed solution for the hollowcore floor units included supplementary seating angles including the strongback retrofit based on the latest Structural Engineering Society New Zealand (SESOC) guidance which is effective for preventing collapse of flooring units prone to positive and negative moment failure due to the rotation of adjacent frame elements.