Oregon Schools are getting ready for the Big One!

One in ThreeThose are the odds of a major Cascadia Subduction Zone earthquake happening within the next 50 years. Seismologists are predicting an earthquake with a magnitude of between 8.7 and 9.2 – commonly referred to as “The Big One” along the Cascadia Subduction Zone, which runs from Cape Mendocino, CA to Vancouver Island, Canada. Although no one knows exactly when the next Big One will occur, significant data indicates we are within the time frame interval of when the Cascadia has historically released its pent-up energy. The Pacific Northwest could be devastated.

Cascadia Subduction Zone

The Last Big One

The geological record indicates that these subduction zone earthquakes have been occurring in the southern end of the CSZ nearly every 240 years with a magnitude of approximately 8.0, and along the full margin of the CST every 400-600 years with a magnitude of 8.7 to 9.2. The Oregon Legislature has taken notice and last year approved a sale of $175 million in bonds to fund seismic safety grants for schools. In April, Business Oregon, the state’s economic development agency, awarded 41 recipient schools grants ranging from $289,000 to $1.5 million for seismic safety upgrades. This first round of grants totaled $50.3 million. A second round of grants totaling $125 million is anticipated to be awarded to schools this June.

How Can Ausland Help

Since our founding, Ausland has focused on complex and technically intensive projects, with a particular affinity towards fast-track renovations, and on fostering close collaboration between our team and the clients we serve. Throughout the years, we have chosen projects where our dynamic, educated, experienced, and technically advanced team of professionals can excel. We seek out challenging projects that fit our distinctive skill set and unique resources like the seismic renovation of the schools funded by these grants.

Examples of similar projects Ausland has helped clients seismically improve the safety of their buildings includes:

Churchill Hall Rehabilitation – Southern Oregon University – Ashland, OR

This $5M project consisted of a complete interior renovation and seismic upgrade to the oldest building on campus (circa 1926). Home to the President’s Office and University Administration, the project was carefully coordinated around existing building functions and staff schedules. During the process, Ausland developed an alternate method for funneling 350,000 pounds of steel into the building without removing the roof, saving the University $500,000.

Historic Jacksonville Courthouse – Jacksonville, OR Listed on the National Historic Registry, the preservation of the Jacksonville Courthouse, including its existing features, was of the highest importance. This seismic renovation included installing brackets and hardware to the original wood joists and anchoring them to the existing masonry walls to reinforce and strengthen the building and prevent the floors and roof from possible collapse in case of a seismic event.

Applegate Elementary School Renovations, Applegate, OR The school children of the small community of Applegate had to be set-up in makeshift modular units because of the unsafe conditions of this 100-year-old historic school building. Ausland led the entire award-winning process of this Design-Build project, completing comprehensive seismic safety and structural improvements, as well as substantial systems and architectural renovations ahead of schedule. Today, the kids of Applegate, Oregon enjoy a safe classroom environment in this unique historic building.

Seismic Evaluation of School Buildings in Oregon

The building code currently in force in Oregon is the 2014 edition of the Oregon Structural Specialty Code (OSSC), which is based on the 2012 International Building Code. According to this code the seismic risk category for elementary and secondary schools is III. They are not generally classified as “essential facilities” (risk category IV) unless they are also designated to be emergency shelters or emergency response operation centers. The seismic importance factor Ie is adjusted accordingly. What this means is that for most schools the level of design is

“The Churchill Hall project by Ausland was one of the best values for any capital improvement I have been associated with.”

- Drew Gilliland, Facilities Director, Southern Oregon University, Owner

for life/safety. That is, if the school is not designated as an essential facility it may be damaged in a large earthquake but it must not collapse or fail in a manner that would threaten those inside. Spectral response acceleration parameters, both mapped and design, can be downloaded from the US Geologic Survey web site, and design procedures are described in the American Society of Civic Engineers (ASCE), Code Standards 7: Minimum Design Loads for Buildings and Other Structures as modified by the OSSC.

We know that seismic risk is much greater west of the Cascade mountain range than east as seen in the Big One map above. Seismic loads result from sudden ground movement. A building has inertia that is proportional to its weight. When the ground moves suddenly inertia causes the building to resist moving with it and shearing forces develop between the ground and the building and also between the building roof and upper floors and the foundation. A direct load path from roof to foundation is required. The heavier the building the larger the resulting forces. The taller the building the greater is the demand placed on the load path.

The school buildings in Oregon are for the most part one or two-story structures with flexible diaphragm (wooden) roofs. Wood-framed structures are relatively light and resulting seismic forces are relatively small. Seismic upgrades of single-story wood-framed structures usually entail little more than strengthening connections between roof and walls and between walls and foundation, though sometimes it is necessary to add or reinforce existing shear walls with plywood. Occasionally a steel frame may be required to carry load around an opening. In 2-story wood-framed structures it may also be necessary to strengthen connections between upper floor framing and walls.

Upgrading masonry buildings can be more complex. The starting point to break down complexity into efficient seismic renovation solutions is always a thorough inspection of the structure and an investigation of all existing documentation. Masonry is both heavy and brittle, and the resulting seismic forces can be large. Again connections between walls and diaphragms and between walls and foundation are critical, but the brittleness of masonry adds the risk of possible catastrophic failure. Reinforced masonry can be designed to withstand large seismic forces but most older masonry buildings are not reinforced, and walls may require external reinforcement, often in the form of braced steel frames.

Other remediation options such as dynamic dampers and base isolation are available but these are seldom cost-effective for relatively small buildings like schools. We believe that simple strengthening will typically prove to be the most reasonable approach for seismic upgrade of the Oregon school buildings under consideration. In addition to strengthening the seismic force-resisting systems it is also necessary to securely fasten all permanent components such as electrical and mechanical equipment, bookshelves and so forth so that they cannot cause injury by falling on someone in the event of an earthquake.

Gregory W. Ausland. P.E.Principal | Ausland Group