Recent natural disasters, such as Hurricanes Harvey, Irma, and Maria, and the damaging earthquakes in Mexico often cause the general public, building owners, facility managers, architects, and engineers to pause and reflect on why these types of events continue to result in significant damage to relatively new buildings.
The author would like to acknowledge and thank coauthor James Snow, P.E.S.E., ABS Consulting, St. Louis, for his contributions to this commentary.
Conventional wisdom would suggest that buildings designed in accordance with the most recent building codes, such as the International Building Code (published by the International Code Council), should not be significantly damaged during extreme natural hazard events such as tornados, hurricanes, or earthquakes.
What many people fail to realize is that current building codes are written as "life safety" documents with respect to extreme natural hazards. Typical buildings are designed to allow the occupants to exit safely without consideration of potential economic loss, repair costs, or the impact of the loss of use of the particular building.
Increasing Building Resilience
There are several organizations advocating for increased resilience in buildings, facilities, and communities to increase our ability to recover from damaging events. One of these organizations is the National Institute of Standards and Technology, which manages a multifaceted community resilience program. Advocating for increased community resilience can take many forms, including strengthening building codes, improving local and regional infrastructure, and enhancing emergency preparedness and response recovery plans.
For many, the sheer magnitude of the issue and the multitude of "moving parts" can be intimidating and may serve as an impediment to confronting the resilience issue. A typical conversation with a facility owner and/or risk manager about the resiliency of their building or facility may start with a discussion of the design standards for their buildings and equipment, emergency preparedness, response recovery plans that they have in place, and the robustness of the different external services (e.g., utilities) that are required to keep their facility operational. The conversation then often segues into a discussion regarding how (or if) the external utility service providers are protecting their assets. From there, the issue "expands" significantly and may leave an owner or risk manager feeling overwhelmed with a sense of frustration about how they can focus on such a large and complicated issue.
Incorporating Safety Standards
A good starting point for many facility owners and risk managers is to consider how they specify and design new buildings, structures, and infrastructure within their own facilities. Often owners will hire an architectural firm or other design consultant and leave the details of the design to that professional with the understanding that the final design will meet all of the local "code" requirements in addition to any functional requirements needed for operation of the facility. What is often missed in this standard practice is the owner's opportunity to cost-effectively enhance the resilience of the building, structure, or infrastructure against effects from potential natural hazards during the initial design, which in turn will increase the resilience of their overall operations.
An example is a planned building in a moderate or high seismic hazard region (this covers a large portion of the United States, as shown in Figure 1 below) that may also experience extreme wind loads and/or flooding hazards over the life of the building. Conventional loads, which include wind and seismic loads (for life safety) are specified in the International Building Code (the typical building code used throughout the United States). Other more extreme loads, such as tornadic wind and extreme hurricane wind forces, are not explicitly specified in the building code. While the standard seismic design of a building or structure may result in a more robust lateral load-resisting system, it may not fully protect the building or structure from the extreme wind (or flood) loads. Items such as uplift restraint of key structural members, more robust cladding and fenestration elements, and heavier roofing elements will all need to be considered.
Figure 1—2014 Seismic Hazard Map (Peak Ground Acceleration, 2 percent in 50 years) (source: United States Geological Survey)
Those familiar with the Federal Emergency Management Administration (FEMA) requirements for storm shelter design may recognize the shelter design wind speed map shown below in Figure 2. The figure provides a good illustration of those areas in the United States that are at risk from extreme wind loads. If those "at-risk" regions depicted in Figure 2 are compared to the regions of moderate to high seismic hazard shown in Figure 1, it is easy to see that there is considerable overlap between regions of moderate to high seismic hazard and those regions at risk from extreme winds.
The key is that, for a new building already being designed for moderate or high seismic loads, the increased cost to an owner to provide the additional enhancement for extreme wind (or flood) may be small—compared to the overall project cost—while greatly enhancing the resilience of the building, facility, and possibly the overall community.
When planning for new buildings, structures, or infrastructure projects, facility owners and risk managers should insist that the design teams consider all reasonable events that may impact their facility and investigate the nominal cost increase to provide the additional resilience in their designs. One day, this added resilience could allow their facility (and their community) to recover more quickly from a catastrophic natural hazard event.
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