The House That Shrugs Off an Earthquake - Fine Homebuilding FHB Logo Facebook LinkedIn Email Pinterest Twitter Instagram Plus Icon Close Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Main Menu
Subscribe

In every issue you'll find...

  • Expert insights on techniques and principles
  • Unbiased tool reviews
  • Step-by-step details to master the job
  • Field-tested advice and know-how
Subscribe Now!
Subscribe
  • How-To
  • Design
  • Tools & Materials
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
  • Join
  • Log In
Main Menu Subscribe
News

The House That Shrugs Off an Earthquake

By Scott Gibson
Article Image
University engineers in California developed a seismic isolator that allows a foundation to move during an earthquake without damaging the house. The bowl shape of the bottom plate helps the house return to its original position once the shaking has stopped.

Two relatively inexpensive modifications to conventional house design appear to offer effective protection from earthquakes as powerful as the 6.9-magnitude Loma Prieta quake in 1989 that did billions of dollars in damages in California.

A team led by Gregory Deierlein at Stanford University’s School of Engineering built and tested a house that withstood a simulated quake thanks to two innovations: seismic isolators that separate the house from the foundation, and  “unibody” construction that strengthens the building envelope.

“We want a house that is damage free after the big earthquake,” Eduardo Miranda, one of the researchers and an associate professor of civic and environmental engineering, said.

According to the university, engineers were looking for ways to minimize the shaking damage that typically cracks walls and ceilings, and causes other structural damage during big quakes.

Instead of attaching the house to the foundation with a series of bolts cast into the concrete, as is usually the case, the house was constructed on top of a dozen flat and bowl-shaped isolators made from steel. 

Floor framing is supported by plastic-tipped pins that rest on the isolators. During an earthquake, the foundation can move beneath the house without damaging it. The concave isolators prevents the frame from working its way off the foundation and when the shaking stops, their shape helps the house return to its original position.

“The idea of seismic isolation is to isolate the house from the vibration of the ground,” Miranda said. “When the ground is moving, the house will just slide.” That’s the same technique used on the San Francisco City Hall and buildings at the San Francisco International Airport.

“Unibody” construction means builders took extra steps to strengthen the house, either by using beefier-than-normal components or by using more robust connections between different materials. For example, the team substituted 5/8-in. drywall for more common 1/2-in. drywall, and glued the drywall to the frame rather than attach it with screws.  

Putting the ideas to the test

Researchers built a 36×22, three-bedroom house atop the Large High Performance Outdoor Shake Table at the University of California in San Diego, the largest test platform in the U.S. Its hydraulic pistons, controlled by computer, could simulate the shaking the house would be subjected to during an earthquake, Stanford said.

It took seven weeks to build the house and get it ready for testing. They shook the house at three times the intensity of the ground movement during the Loma Prieta quake, watching as the house moved from side to side before settling back in place, undamaged by the ride.

After removing the seismic isolators and bolting the house directly to the shake table, which would mimic a conventional connection between house frame and foundation, the house showed some superficial damage to stucco and drywall. Only when researchers turned the table up to its maximum setting did they see some serious damage.

This YouTube video describes how the house was designed and built, and includes footage of the shake test itself.

Deierlein says building a more rigid “unibody” house and adding seismic isolators would add between $10,000 and $15,000 to the price of a 1500-to-2000-sq.-ft. house, and lengthen the construction schedule by four days. But the extra costs seemed minimal when compared to the average annual premium of $676 for earthquake insurance. 

Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers.

Sign Up

Get home building tips, offers, and expert advice in your inbox

×
X
X

New Feature

Fine Homebuilding Forums

Ask questions, offer advice, and share your work

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

More News

View All
  • Come to Our Annual Party in Las Vegas and Support #KeepCraftAlive

  • NWFA is Making Sweeping Changes to Their Wood-Flooring Installation Guidelines

  • This Hat Provides Scholarships for Skilled Tradespeople

  • Hang Out with Fine Homebuilding and #KeepCraftAlive In Las Vegas

View All

Up Next

Featured Story

Cabin exterior

Cladding Details That Last

Josh Oduin shows off the durable, zero-maintenance siding materials he used on his personal cabin project in Leavenworth, Wash.

Featured Video

Install Cable Rail Around Wood-Post Corners

How to Install Cable Rail Around Wood-Post Corners

Use these tips to keep cables tight and straight for a professional-looking deck-railing job.

Related Stories

  • Podcast 319: Building in a Flood Zone, Who Pays for Warranty Work, and Converting Attics to Living Space

  • Fine Homebuilding Flashback: 1981, The Magazine's First Year

  • Podcast 318: PRO TALK With Adam Feldman, Pt. 1

  • Fine Homebuilding – February/March 2021, Issue #297

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Highlights

  • Fine Homebuilding All Access
  • Fine Homebuilding Podcast
  • Tool Tech

    Plus, get an extra 20% off with code GIFT20

  • "I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.

    Get home building tips, offers, and expert advice in your inbox

    Sign Up See all newsletters

Video

View All
  • FHB-Podcast, episode 319

    Podcast 319: Building in a Flood Zone, Who Pays for Warranty Work, and Converting Attics to Living Space

  • FHB Podcast PRO-TALK #318

    Podcast 318: PRO TALK With Adam Feldman, Pt. 1

  • flared cedar shingle siding detail

    How to Install Flared Sidewall Shingles

  • FHB Podcast 317

    Podcast 317: Natural Air Changes, Flashing Windows in Brick Walls, and Cleaning Construction Messes

View All

BOOKS, DVDs, & MERCH

Shop the Store
  • Fine Homebuilding Magazine Slipcase

    Buy Now
  • 2020 Fine Homebuilding Archive

    Buy Now
  • Musings of an Energy Nerd

    Buy Now
  • Code Check Building 4th Edition

    Buy Now
  • Shop the Store

Fine Homebuilding Magazine

  • Issue 297 - Feb/Mar 2021

    • Foundations for Success
    • Staircase Renovation
    • Ditch the Hose
  • Issue 296 - Dec 2020/Jan 2021

    • Insulating Glass Keeps Getting Better
    • Simple Way to Make Old Walls Straight and Plumb
    • Making Sense of Minisplits
  • Issue 295 - Kitchens & Baths

    • Condo Kitchen Reimagined
    • Row-House Remodel
    • Rise of the IAQ Monitor
  • Issue 294 - Oct/Nov 2020

    • Schoolhouse Reimagined
    • Tool Test: Folding Sawhorses
    • A Better Way to Build Tall Walls
  • Issue 293 - Aug/Sept 2020

    • A Practical Guide to Fall Protection
    • Installing Frameless Cabinets
    • Make Any Tablesaw Safer

Fine Homebuilding

Follow

Newsletter

Get home building tips, offers, and expert advice in your inbox

Sign Up See all newsletters

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Manage Preferences

Taunton Network

  • Green Building Advisor
  • Fine Woodworking
  • Fine Gardening
  • Threads
  • About
  • Contact
  • Advertise
  • Privacy Policy
  • Careers
  • Copyright
  • Terms of Use
  • Accessibility

© 2021 The Taunton Press, Inc. All rights reserved.

    Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Reader Projects
  • Magazine
  • Members
  • FHB House
  • Podcasts

  • FHB Podcast
  • ProTalk
  • Account

  • Log In
  • Join

    Podcasts

  • FHB Podcast
  • ProTalk
  • Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

    Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

    All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

    Shop the Store

  • Books
  • DVDs
  • Taunton Workshops

    More

  • FHB Ambassadors
  • Reader Projects
  • Podcast
  • Customer Support

    Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Sign Up See all newsletters

Follow

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 52%

Subscribe

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in