How Was a SoHo Building Undermined?

The SoHo building was a 115 year old Landmark masonry building in New York City, SoHo district. After demolition, and during excavation at the adjacent lot, the ill fate of this building was set in motion. The building became undermined, tilted substantially, and needed to be evacuated. The building had to be shored and braced in order to prevent a complete structural collapse until it was subsequently demolished. Could this ill fate outcome have been prevented? Several factors lead to the building undermining and failure, including design and construction errors. The design team failed to fully investigate the existing conditions of the site and footings and they produced unclear, ambiguous and inaccurate construction drawings. Further, the contractor over-excavated the site and failed to properly protect the adjacent building. Additionally, the vacant, adjacent and excavated site remained open to the elements for a long period of time. This led to further deterioration of the foundation system below the doomed building. This presentation will discuss the events that caused the structural distress, damage and ultimate failure of the structure, with emphasis on lessons learned from this unfortunate failure.