Critical facilities in active earthquake zones must be designed to withstand a range of seismic events. It is imperative that we know repair costs and the time it takes to get these buildings back up and running following an event.
This is why Performance-Based Seismic Design (PBSD) is being increasingly used on building projects, especially for critical infrastructure like hospitals and schools. It is an approach to the design and construction of buildings for a given occupancy that is based on a realistic and reliable understanding of the risk of loss of life and economic loss that may occur as a result of future earthquakes.1 Performance-based seismic assessments examine a building’s design to determine the probability of experiencing different types of losses, considering the range of potential earthquakes that may affect the structure.
Take British Columbia’s (BC) new $2B St. Paul’s Hospital project for example, situated in the earthquake-prone Vancouver area. It is the largest hospital redevelopment in BC’s history and once completed, is expected to serve the local community for the next 125 years both as a regular hospital and as a post-disaster facility. As it needs to withstand a range of different magnitudes of earthquakes, project stakeholders required hard data and insights to understand how the building will perform during seismic events, the areas of greatest risk, the probable repair cost and the repair time estimates.
Ausenco provided the solution – we worked with the building design team to assess the repair times and repair costs of the hospital design for a range of potential earthquake scenarios. We helped our client use data to improve the design, enhance resilience, and reduce repair costs and time. And we gave the project’s stakeholders – including the owner and city government – specific information to enhance their confidence that their asset could operate effectively, post-disaster.
Better data, better decisions
How did we do it? In very simple terms, we conducted a series of performance-based seismic assessments to evaluate the likelihood of damage across structural and non-structural components following earthquakes. Using this approach, we were able to predict and analyze the time and cost required to repair the facility for three levels of earthquake shaking intensity.
The owner of the new St. Paul’s Hospital didn’t just want to understand what it would take to bring their facility back online from a time and cost perspective. They wanted a level of data granularity that would provide insightful information on a floor-by-floor and component-by-component performance level. For example, how many electrical panels would need replacing on each floor for a given earthquake level – and what would be the cost and time to make that happen.
This type of analysis at such high level of granularity has not been done before in Canada. It required the assessment of thousands of structural and non-structural components on 11 floors against three different earthquake scenarios. A massive amount of data needed to be collected and condensed, and steps needed to be taken to ensure the insights created through the analysis were actionable and practical for the design team.
We used the tool SP3-RiskModel (SP3 stands for Seismic Performance Prediction Program) created by Haselton Baker Risk Group (HBR) that carries out a type of performance-based seismic assessment commonly referred to as the FEMA2-P58 methodology. This approach, selected by the owners and the design team, provides guidance on determining post-earthquake metrics such as repair costs and repair times for a specific building and all its components. Our team developed in-house project-specific scripts that would run the raw data provided by the software through many cycles of post-processing to produce the floor-by-floor and component-by-component metrics the owners requested. Ausenco worked closely with HBR to customize the software to produce the results required specifically for the hospital, especially to calibrate the consequence functions predicting the performance of the medical equipment in the facility.
Our work wasn’t about certifications or demonstrating compliance with codes. It was to provide the design team and various stakeholders with the insights they needed to make informed decisions. For example, we were able to identify critical floors and equipment that allowed the design team to enhance the building’s seismic performance through purposeful design and detailing. We advised on which type of cladding would provide the best seismic resilience early in the schematic phase. This information allowed the team to make better decisions throughout the design process of the facility.
Better performance
The new St. Paul’s Hospital is not the only building in BC that needs to withstand the force of an earthquake. We’ve helped schools, universities, commercial building owners and government departments to address their seismic risks.
We expect performance-based seismic assessments to become much more commonplace over the coming years, and specifically the assessments using the FEMA-P58 methodology, which provides the high level of data needed to plan for asset resilience and facilitate accurate cost and time estimates for restoring building functionality following earthquake events.
Our seismic engineering team is investing time and resources into continually improving our expertise in conducting this type of performance-based seismic assessment and design capabilities. As the first firm to conduct this type of analysis at a high level of granularity in Canada, we are rapidly gaining experience across multiple types of facilities and are allocating resources to specialize in this approach. We have even worked with HBR to ensure our experience and customizations related to the seismic performance of medical equipment were embedded into the SP3 platform to enable others to perform similar assessments for future medical facilities.
Our focus is on helping our clients find a better way, and we are confident that performance-based seismic design and FEMA-P58 analysis can help improve safety and reduce the lifecycle costs for clients with facilities subject to experiencing a high probability of earthquakes.
Contact Behrad Keshavarz with any questions.
Poster: Building performance assessment of the new St. Paul’s hospital
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1 https://femap58.atcouncil.org/documents/fema-p-58/24-fema-p-58-volume-1-methodology-second-edition/file
2 FEMA is the US’ Federal Emergency Management Agency