The BNZ building in Wellington, New Zealand was significantly damaged, and eventually demolished, due to the cumulative impact of three main earthquakes between 2013 and 2016. Although the building was equipped with a set of accelerometers, lack of an accurate SHM method allowed the damage level to remain hidden to engineers and property owners. An accurate SHM method would have quantified the seriousness of the damage in this building over each of three major events, enabling proper retrofit and better decision making.This study uses the hysteresis loop analysis (HLA) SHM method to investigate lateral stiffness changes for this structure, and the trajectory of damage accumulation for each story over all three events. HLA indicates the building suffered average stiffness reductions of 24%, 21% and 9% due to each event in the x direction, respectively, and 34%, 3% and 16% in the y direction. The first story lost ∼65% of its initial stiffness by the end of the third event. Between event differences or consistency, over all six stories, all events, and both directions, is ∼5% on average, providing an accurate, continuous SHM trajectory.HLA shows very good robustness and consistency in estimating elastic stiffness changes due to damage in this real-world, full-scale case analysis. Consistent, accurate estimation can help optimize decisions after major events. They also offer the future potential to build a virtual building model accurately predict forward what might happen to an already damaged structure in future events.