Ridge Capital Investments
Charles Pankow Builders
When you're renovating a 14-story office building built in 1927 there are special considerations for not only the seismic strengthening of the structure but what will have minimal visual impact on the historic aesthetics. The existing construction consisted of a concrete encased steel framing system with cast-in-place concrete slabs supported by steel floor beams and columns. Lateral forces are resisted by property line walls, which are brick masonry infill walls, except for the north and west walls which are cast-in-place concrete. To validate the extent of seismic strengthening, a linear elastic response spectrum analysis was conducted on a full scale 3D analytical model per the requirements of ASCE 41, and for a Life-Safety performance objective at the BSE-1E earthquake hazard level. Based on these demands, various structural solutions such as added lateral braces, enhanced steel moment frames, and new concrete shear walls were explored.
To preserve the historical building context and adhere to tenant visibility, the final solution concluded with new concrete punched shear walls scabbed to existing walls, new full bay concrete shear walls, new reinforced concrete moment frames, and foundation enhancement. These solutions mitigated ground level soft-story, discontinuous, extreme torsional, and wall stabilization concerning conditions.
Various architectural and cosmetic renovations including a remodeled lobby, activation of the ground floor retail space, new core restrooms, and HVAC upgrades were incorporated. In addition, new waterproofing and new shotcrete walls with integral waterproofing additives are planned at the perimeter basement concrete walls to arrest the water infiltration.