Service Overview
Saunders led the non-ductile concrete seismic retrofit of an 18-story senior housing tower in Costa Mesa.
The retrofit included full-height exterior shear walls, extensive carbon fiber (CFRP) strengthening, and new foundations at the existing ground-floor columns.Challenges
The retrofit required new shear walls to extend several stories up the exterior of a tall building while interior strengthening reached every floor. At the same time, the senior housing tower needed to remain occupied throughout construction.
Our Solution
Saunders:
- Prefabricated multi-story reinforcing steel cages at grade, set them by crane, tied them into the existing structure with drilled and epoxied dowels, and completed the new shear walls from exterior scaffolding.
- Installed approximately 53,000 square feet of CFRP strengthening at columns, corridor walls, and spandrels, using approximately 4,590 fiber anchors.
- Coordinated interior CFRP work floor by floor in roughly 10-working-day windows, temporarily relocating residents from the active floor and moving them back when work was complete.
- Built a new foundation mat around the existing ground-floor columns, supported by micropiles.
- Coordinated specialty shotcrete and FRP installers under a single schedule and point of contact.
Outcome
The 18-story tower was strengthened from foundation to roof while residents continued living in the building. Saunders coordinatedexterior and floor-by-floor interior work to minimize disruption to the occupied senior housing community.
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