Seismic Retrofitting of Seton City Medical Center: A Race Against Time

Brief 

The Seton City Medical Center is under a tight deadline to meet the baseline seismic performance milestone set by the state, or face potential fines, loss of license and closure. Learn about the challenges the design team faced during seismic retrofitting and how they overcame them to complete construction in time.

Insight

The Seton City Medical Center in Daly City, south of San Francisco, California, is under a tight 2023 deadline to meet the California state-mandated seismic life safety performance requirements. The hospital tower, built-in 1965, underwent a seismic evaluation in 2015 that revealed certain deficiencies that needed to be addressed, such as the lack of adequate collectors to transfer lateral loads from the massive reinforced concrete floor system into the transverse walls.

The retrofitting work, which included strengthening to address non-ductile concrete columns and brittle precast wall panel connections at the podium, began in mid-2016. However, the facility had to halt the project after suffering financial setbacks in 2018 and a subsequent change in ownership. The seismic strengthening project restarted in the spring of 2020 under an even tighter schedule after new owners purchased the facility. The retrofit must be completed by the state-mandated deadline of 2023 or risk fines, loss of their operating license, and possibly forced closure.

The design team identified externally bonded fiber-reinforced polymer (FRP) collectors as a viable alternative to overcome challenges and keep the project on schedule. Simpson Strong-Tie was selected to provide designs for the collectors and concrete column-wrapping using FRP. After the Seton collector redesign began, Simpson Strong-Tie published its first International Code Council (ICC) approval for FRP materials in diaphragms and collectors (ESR-3403, 2021).

To use FRP collectors on this previously permitted project, the team requested an Alternate Method of Compliance from the Seismic Compliance Unit at HCAI. After discussions with the Seismic Compliance Unit, Simpson Strong-Tie volunteered to perform physical testing at their lab to prove the use of their materials for this application. The use of FRP collectors would overcome the challenges posed by the installation of steel plates in the cramped overhead ceiling and the alignment of pan joists in the floor system relative to the transverse walls that varied up the height of the building.

The seismic strengthening project at the Seton City Medical Center is a significant undertaking with challenges that can have a far-reaching impact on the community it serves. With the use of innovative materials like FRP collectors, the facility can meet the state-mandated seismic performance requirements, provide safe and reliable medical care to the community, and avoid possible fines, loss of operating license, and forced closure.

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Keyword 360

FRP

Related Questions:

• How retrofitting is done by using FRP composites?

• What are the methods of seismic retrofitting?

• What material is seismic retrofit?

• What does FRP stand for in earthquake?

Related Standards:

• ACI

• ASTM

• BSI

• ISO

• NIST

Related Refrences:

1. Teng, J.G., et al. “Seismic retrofit of reinforced concrete frames with fiber-reinforced polymer (FRP) composites: a review.” Journal of Composites for Construction, vol. 23, no. 2, 2019,
2. Chaallal, O., et al. “Seismic retrofit of reinforced concrete bridge columns with FRP: A comprehensive review.” Engineering Structures, vol. 238, 2021.
3. Kim, J.W., et al. “Seismic retrofit of reinforced concrete columns with fiber-reinforced polymer: State-of-the-art review.” Construction and Building Materials, vol. 284, 2021.
4. Dong, Y., et al. “Seismic retrofit of existing reinforced concrete structures using FRP: Recent advances and future directions.” Construction and Building Materials, vol. 290, 2021.

Related Challenges:

1. Lack of experience and knowledge: FRP is a relatively new technology, and many engineers and contractors may not have experience or knowledge in designing and installing FRP systems for seismic retrofitting of buildings.
2. Compatibility issues: FRP may not be compatible with all building materials and structural systems, which can make it challenging to retrofit certain types of buildings.
3. Cost: FRP systems can be expensive compared to traditional retrofitting methods, which may deter building owners from adopting the technology.
4. Quality control: The quality of FRP materials and installation techniques can vary widely, which can lead to inconsistent performance and reliability.
5. Long-term durability: The long-term durability and effectiveness of FRP systems in seismic retrofitting applications are not yet fully understood, which can make it challenging to predict their performance over time.
6. Building codes and regulations: The use of FRP systems for seismic retrofitting may not be explicitly covered by building codes and regulations, which can create uncertainty and delay in the approval process.
7. Structural complexities: Seismic retrofitting of buildings with FRP systems can be complex, requiring careful consideration of the building’s geometry, load-bearing capacity, and other structural factors.
8. Aesthetics: FRP systems may not be visually appealing, which can be a concern for building owners who value the aesthetic appearance of their properties.