Developing Cost-Effective Relationships Between Federal Building Profiles and Seismic Retrofit Cost

Summary

Advancements in measurement science are needed to evaluate the benefits and costs of risk mitigation activities (retrofits) implemented to improve seismic performance of buildings, based on observable building characteristics (construction type, size, age, and location). Performance is defined here as the ability of buildings to reduce risks to occupants and to continue to provide essential functions following earthquakes. Mitigation of structural and non-structural risks are considered. Estimates of the ratio of building mitigation costs to replacement value are generated, based on the analysis of: (1) historical retrofit cost data, which provide detailed accounting of the types of seismic upgrades performed, along with context (extent) for the improvements, and (2) statistical analysis of federal building inventory data, which capture seismic retrofit costs over a distribution of buildings types, relative code improvement (target performance), and hazard zones. A prioritization strategy, consistent with economic best practices, is developed to aid decision-making related to the staging of mitigation activities within or across buildings.

Description

Objective - To develop quantitative methods to evaluate the benefits and costs of risk mitigation activities implemented to improve seismic performance of buildings, based on building profiles (construction type, size, age, location), which can be applied to buildings that are federally owned, leased, financed, or regulated (‘federal buildings’). Performance is defined here as the ability of buildings to reduce risks to occupants and to continue to provide essential functions following seismic events. Mitigation of structural and non-structural risks are considered. A prioritization strategy, consistent with economic best practices, is developed to aid decision-making related to the staging of mitigation activities within or across buildings.

What is the Technical Idea?  Advancements in measurement science are needed to evaluate the benefits and costs of earthquake risk mitigation activities for existing buildings in general, and federal buildings in particular, to better inform investment and code decisions. Executive Order 13717 Establishing a Federal Earthquake Risk Management Standard states, “When making investment decisions related to Federal buildings, each executive department and agency (agency) responsible for implementing this order shall seek to enhance resilience by reducing risk to the lives of building occupants and improving continued performance of essential functions following future earthquakes.” Estimates of the ratio of building mitigation (including retrofit) costs to replacement value are generated, based on the analysis of: (1) historical retrofit cost data, which provide detailed accounting of the types of seismic upgrades performed, along with context for the improvements, and (2) statistical analysis of federal building inventory data, which relates seismic-related building improvement costs over a distribution of buildings types, relative code improvement, and hazard zones. 

The analyses will provide insights into actual investment decisions and their costs, including any staging criteria used to phase mitigation activities over time, avoiding large upfront costs. It will allow a linkage to be made between costs spent and remedied seismic risk, conditioned on factors such building size and prior risk state (e.g., building code at time of original construction).

What is the Research Plan? The research plan is comprised of three major activities: (1) developing a methodology to estimate seismic retrofit costs, with an application of the methodology to federal building inventory data, (2) quantifying benefits and other impacts of seismic retrofits, and (3) development of a staging protocol based on economic best practices. Activity 1 has been completed in FY18, with a focus on estimating structural retrofit cost. Further direct (e.g., nonstructural) and indirect (e.g., rental space) costs are investigated in FY19. Activity 2 will be the focus of FY20.

Historical retrofit cost data provide detailed analysis of the major cost drivers related to seismic mitigation in federal buildings, along with the nature of the work performed.  They are based on a limited number of individual building retrofit projects.  The data include US and Canadian building data and document seismic upgrades, including costs and extent of upgrade, and provide detailed information on specific engineering solutions and associated costs.  This research activity was completed through the use of freely-available data originally collected by FEMA.  In addition, the output informs the statistical effort, by defining minimum data requirements and identifying key cost variables and likely sources of cost variability.

The statistical analysis provides a general analysis on a large number of building retrofit projects, including information on the distribution of the types of buildings and associated retrofit costs. The results use historical retrofit cost data to predict retrofit costs for federal buildings. Federal building data is intersected spatially with seismic hazard maps in GIS to produce building profiles by hazard zones.  The federal building data obtained from GSA describes building records for executive-agency buildings. In the future, the statistical analysis can be easily applied to other data, such as DoD building data. The analysis quantifies correlations between mitigation costs and building location (seismic risk), age and construction type (relative to extent of code improvement), size (square footage; number of floors), and ownership.  Additional correlations can be measured depending on the extent of data obtained. As of FY18, the analysis only includes structural retrofit costs. Additional costs, including project costs, non-structural mitigation costs, and indirect costs, will be studied in FY19.

The results are meant to be generalizable to any ‘building profile’ (categories of buildings) rather than specific to particular categories of buildings, such as federal buildings.  The analysis answers questions related to the size of the investment needed to remediate federal buildings.  It is not meant to identify risks of individual buildings, nor to estimate individual building retrofit costs. 

The natural next step is to quantify the benefits of retrofitting buildings, e.g., such as the statistical value of lives saved. The range of benefits can then be compared to predicted costs to determine the value of investing in seismic retrofits for particular types of buildings. Estimation of benefits, and a comparison of benefits and costs, will be applied to a subset of federal buildings (e.g., in high-risk areas).

The evaluation of benefits and costs of seismic retrofits will inform the development of a prioritization strategy to facilitate the decision of staging mitigation activities within or across buildings.  These will be consistent with ASTM E06.81 standards on building economics. Given ranges of benefits and costs, one potential strategy is to select buildings on the Pareto frontier for seismic risk mitigation. This intersects with existing research by the Center of Excellence for Risk-Based Community Resilience Planning (in particular, Charles Nicholson).