Resilience and Its Importance to Structural Engineering

New Information About Resilience for Structural Engineers

Many organizations initiated resiliency programs in 2016, making the new buzzword “resilience”. Resilience is characterized in many ways within the building and infrastructure industry. In 2014, resilience was described by the ASCE/SEI Sustainability Committee as the ability to experience less damage and recover from adverse events more quickly. In addition to external shocks in the form of natural or man-made disasters (hurricanes, floods, earthquakes, etc.), these adverse events are often economic, social, political, and cultural adverse events that could disrupt a community’s structure. This also covers the impact of climate change and the consequent rapid rise in the frequency of external shocks.

With two activities held at the White House, President Barack Obama has made resilience a priority in the past year. The White House Earthquake Early Warning Systems Summit was a full-day public broadcast event that addressed the advantages of earthquake early warning systems on risk reduction and resilience to disasters. The White House Conference on Resilient Building Codes was the second event. This event included the Obama administration announcing efforts by the public and private sectors to improve the resilience of the city through construction codes.

LEED Project Teams

For project teams that prepare and build for possible disasters in the project area, LEED provides three resilience pilot credits. This involves pre-planning and site investigation, designing a structure to be habitable after the disaster, and designing to resist future disasters. Such credits change disaster resilience from disaster recovery to mitigation of disaster danger.

To analyze their existing infrastructure and prioritize future planning, states and cities are designing resilience plans. New York City developed OneNYC in 2014, a resilience strategy that tackles flood mitigation along the 520 miles of coastline of New York City. Figure 1 depicts New York City’s Battery Park Underpass after Hurricane Sandy. Motivated by the extreme impacts of Hurricane Sandy in 2012, this initiative also discusses how the 400,000 New York City residents residing in a 100-year floodplain will alleviate flooding. The effects of sea-level rise have also been discussed by the city of Boston. The city has developed a Climate Change Adaptation Plan that includes flood threat maps that account for the increase in sea level, climate preparedness, and community involvement. The town of New Orleans also formed a resilience plan in 2014. This initiative explores flood prevention through the use of creative methodologies to preserve the city’s population and economies, such as parks and green streets. To incorporate many of their resilience plans, both New York City and New Orleans earned grant money from the HUD National Disaster Resilience Competition. These would have direct consequences for the work being carried out in the regions by civil and structural engineers. Resiliency programs have also been established in other parts of the world, including the city of San Francisco and the states of Washington and Oregon.

How will structural engineers, their work, and their projects impact these initiatives? The ASCE/SEI Sustainability Committee’s Disaster Resilience Working Group has studied several of the organizations discussing resilience inside the building construction sector. This article identifies these organizations together with their objectives of resilience and how structural engineers will be influenced by these goals.

Legal Matters

Cities have been aggressively working to improve their seismic strength within the state of California. A website was created by Wiss, Janney, Elstner Associates, Inc. (WJE) to track seismic ordinances throughout California. This website offers specifications for upgrades and related deadlines. The City of San Francisco implemented an order in April 2013 requiring the compulsory seismic retrofit of soft-story wood-frame structures (buildings with a weaker first floor that are prone to collapse in an earthquake). Around 4300 buildings were surveyed as a result of this ordinance and 2800 were found to have a soft story by engineers. In September 2013, all of the building owners impacted were informed and needed to send forms showing that their building had been inspected by a licensed skilled engineer by September 2014. This phase of the ordinance was 99 percent compliant. Those building owners who did not comply had a Notice of Violation placarded on their building. For those buildings impacted, the next step of the ordinance is to make an application for a permit with seismic retrofit plans. The building owner has one year to complete the retrofit once the permit application is submitted. By 2020, all retrofits must be completed.

The City of Los Angeles implemented an order in October 2015 requiring the mandatory seismic retrofit of soft-first-story wood-frame structures, similar to the San Francisco ordinance, and an order requiring the retrofit of non-ductile concrete buildings. About 15,000 buildings are covered by these ordinances.

To locate all of their unreinforced masonry structures, the cities of Portland and Seattle have developed interactive maps (URM). At present, both cities are working on creating legislation for URM ordinances mandating URM building retrofits.

A Climate Change Adaptation Task Force has been prepared by the City of New York that has produced climate forecasts for New York City through 2100. A study, Retrofitting Buildings for Flood Risk (NYC Planning, 2014), has also been developed by the City and revised to include increased flood risk in the New York City Building Code.

Conclusions

During a natural or man-made disaster, modern-day cities approach disaster prevention from a holistic perspective that involves the efficiency of the built environment. For long-term resilience, cities and regions are reviewing their infrastructure. In addition to the goals of an area, these evaluations and guidelines may have an impact on the severe loading demands that structural engineers use to test buildings. For example, coastal flooding danger maps have been revised by the cities of Boston, New York, and New Orleans to incorporate the impact of climate change and sea-level rise. To implement these updates, the City of New York has revised the New York City Building Code. The resources provided in this paper aim to help engineers design long-term resilience in a manner consistent with resilient plans for the region, state, and countries.

Within this article, the organizations and toolkits discussed each present various approaches to resilience and allow structural engineers to be part of the movement. This is by no means a complete list of organizations and instruments. It is necessary to bear in mind that resilience does not only apply to seismic hazards. In reality, its resilience pilot credits have been extended by the LEED sustainability metric to include floods, hurricanes, and wildfires. The northeastern United States begins to recover from Hurricane Sandy. The potential effects of climate change and natural disasters on their structures are being discussed by building owners. Most recently, due to storm surges, the Whitney Museum of Art building in southern Manhattan was built due to flooding.

As structural engineers, we are responsible for helping to protect cities from a range of disasters and strive to strengthen our societies continuously. Cities are witnessing the ability of their infrastructure and their capacity to recover first-hand as natural disasters become more frequent and greater in magnitude. In the United States, every dollar spent on mitigation of pre-disaster hazards results in four dollars in potential community benefits (ASCE/SEI Sustainability Committee, 2014). The harm caused by raising levels of rainfall and rising temperatures around the world has amounted to over US$1.4 trillion in the past ten years. The impacts of natural disasters and climate change are creating huge economic burdens for cities across the globe.

U.S. cities are implementing pre-disaster mitigation resilience plans to take advantage of the figure, minimizing the expense of post-disaster recovery and the impact of disasters in their neighborhoods. These methods of resilience would have a significant effect on the work of structural engineers and the course of the construction codes.

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