The Pacific Northwest is prone to four different types of earthquakes, depending on where they occur. Three of these source zones cause shaking that could threaten life and property: Cascadia megathrust, deep intraplate and crustal faulting. In May 2018, Portland’s city council decided to push their vote regarding the seismic retrofitting of 1,650 unreinforced masonry buildings, which are susceptible to collapse during an earthquake, to June 2018. Without the seismic upgrades, the brick buildings in question could be among those requiring the most attention from demolition companies in Portland if they topple during a quake.
The Dangers of Unreinforced Masonry Buildings
When you explore the Pearl District, Old Town and other Portland neighborhoods, you’ll notice character-giving vintage brick buildings that serve as a reminder of the city’s culture and history. Nine percent of the buildings in the City of Roses are made of unreinforced brick, making them among the most dangerous to be in or around during an earthquake because they’d likely be the first to crumble.
Portland and other cities across the United States constructed unreinforced masonry buildings from the late 19th century to mid-20th century to prevent fires. They’re no match, however, for large earthquakes. Many of the buildings don’t have roofs, floors and walls that connect. As a result, walls and floors could separate from each other during a tremor and cause the building to collapse.
People outside unreinforced masonry buildings during an earthquake aren’t much better off. In fact, most of the people severely or fatally injured by the buildings are outside and hit by pieces of falling masonry. Even if only 10 percent of the unreinforced masonry buildings in Portland collapsed, hundreds of people in and around the 165 structures could die or receive serious injuries. Furthermore, tall masonry buildings have the potential to collapse onto nearby buildings, causing even more damage.
To make the masonry buildings in question safer during an earthquake, building owners would have to make “collapse risk reduction” changes such as:
- Tying floors and roofs to walls
- Reinforcing parapets
- Thickening walls and floors
- Fitting the structure with a supportive metal frame
Implications of the Unreinforced Masonry Seismic Retrofit Project
Many of the unreinforced masonry buildings in Portland are apartments, commercial buildings, schools and churches. While many business owners recognize that seismic upgrades could save lives, they also see them as tremendous financial burdens.
In addition to the cost of upgrading a building, which could add up to $1 million or more, owners would have to evacuate the structures to promote tenant safety while Portland demolition and construction crews worked. This not only means a significant loss of income for building owners, but also the displacement of residences and businesses, some of whom depend on the affordable rent to make a living or keep a roof over their heads. Depending on the type of building and those who use it, building owners would have 10 to 20 years to complete the safety upgrades.
The Impact of Seismic Retrofitting on Portland Demolition Contractors
Portland demolition contractors are among the first on a scene after a disaster. Demolition often must occur to remove hazardous materials and debris before crews can begin rescuing and rebuilding safely.
Without seismic retrofits, demolition companies may spend more time clearing rubble after an earthquake before they can provide other vital support services. Rebuilding efforts could also take more time to complete, which could cost a building owner more money and increase insurance premiums. With seismic retrofits, building damage may not be a severe, allowing demolition firms to work more in tandem with first responders while helping more building owners and displaced tenants in a shorter amount of time.