The New World supermarket located in Hasting New Zealand, was constructed in 1972. It features steel portal frames and reinforced masonry block walls. Over the years, there have been various architectural and structural modifications. However, to meet the minimum earthquake resistance requirements set by the City Council, structural seismic strengthening became imperative.
Two retrofitting options were evaluated. The first one involved reducing the building's weight by removing certain block walls and introducing new bracing elements. However, this was not accepted due to cost implications and the associated downtime. The second approach aimed to preserve the existing block walls, leveraging their capacity, and supplementing the structure with new members. This approach received approval, and the seismic strengthening design was subsequently implemented, as illustrated in the accompanying images.
The strengthening design involved nonlinear static analysis (i.e. Pushover analysis) to evaluate the post-yield stability of the existing steel portal frames. The vulnerability of the structural system was evaluated against the liquefaction-induced differential settlement of the foundation pads.
