InspectAPedia®   -   Search InspectApedia

Photograph of building damage near Los Angeles 1994  © Daniel FriedmanHow to Detect, Diagnose, & Evaluate Earthquake Damage
Earthquake-Damaged Foundations, Structures, Chimneys, Mechanical Systems

  • POST a QUESTION or COMMENT about how to recognize, diagnose, evaluate, and repair building foundation damage due to earthquake activity

Foundation damage due to earthquake activity:

This article describes how we recognize different types and causes of complex or combined building foundation movement & foundation damage. Earthquakes shake building structures in different patterns, sometimes unique to a particular quake.

The basic earthquake-generated forces that operate on buildings are side to side, up and down, or a combination of these. But depending on which forces are exerted, buildings shift and structural components fail in different patterns. Here we describe different damage patterns observed in building foundations or structures due to several different types of earthquakes.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Combinations of Building Foundation Movement due to Earthquake, Flood, or Storm Damage

Earthquake damaged bulding © Daniel Friedman at InspectApedia.comThe photographs of earthquake-damaged building foundations and structures shown here are rather dramatic (and terrible as there were certainly fatalities in these buildings). More subtle is the detection of small movements, not immediately obvious, that break gas mains or cause other dangerous building conditions following an earthquake.

Here we distinguish among vertical movement, horizontal movement, leaning, tipping, bending, differential and uniform settlement, earthquake and storm damage, and other foundation damage patterns.

This article series describes how to recognize and diagnose various types of foundation failure or damage, such as foundation cracks, masonry foundation crack patterns, and moving, leaning, bulging, or bowing building foundation walls.

To be used properly, this information must be combined with specific on-site observations at the particular building in order to form a reliable opinion about the condition of that building's foundation.

Watch out: Anyone having concern regarding the structural stability, safety, or damage of a building, foundation or other components, should consult a qualified expert.

Types of building movement: Northridge Earthquake 1994

As we describe here, the effects on buildings and how they moved or collapsed. Some building sections collapsed straight down while others were levered sideways by their supporting columns, moving sideways for a distance about equal to the height of the failing columns.

Types of building collapse or movement depended on both the combination of directions earthquake forces and construction details of individual buildings.

At the 1994 Northridge Earthquake in Los Angeles, a very strong lateral shift was visible on many buildings.

Force was sufficient to shift some entire buildings sideways in distances ranging from just an inch or so (broken gas mains, gas explosions, fire, burst water mains) to distances up to eight feet (where buildings were leveraged sideways as supporting columns failed). We observed:

  1. Vertical building collapses
  2. Horizontal building shifts, leans, tilts.
  3. Combined horizontal shift followed by vertical collapse of buildings. A lateral or horizontal movement that damaged building supports then led to both straight-down vertical collapses as well as combined horizontal movement followed by vertical collapse

1. Vertical Building Collapses due to Earthquake

The Northridge Earthquake in Los Angeles, California in January 1994 caused extensive damage as well as fatalities when buildings were shifted off of their foundations, leading to catastrophic collapse in some cases.

These photographs taken by the author at Northridge Meadows, a site of some of the worst fatalities, shows a section of building that collapsed straight down, compressing the first floor (and some occupants) to just a few inches.

Photograph of building damage near Los Angeles 1994  © Daniel Friedman

The left portion of the photo shows a third floor balcony aligned with the second floor balcony of a building segment that did not collapse. Earthquake resistant construction has as a primary objective to prevent just this sort of collapse, as an effort to reduce the number of injuries and fatalities from an earthquake.

Earthquake damaged bulding © Daniel Friedman at InspectApedia.com

Examination of construction details such as the sequence of original construction and the failure to continue staggered plywood sheathing and continuous floor joist framing appeared to explain why the right-hand portion of the building stood while an entire floor of the left-hand building section collapsed, killing occupants of the first floor.

2. Horizontal Building Movement due to Earthquake

But there were more subtle failures at work - hollow steel pipes that failed where concrete-filled steel Lally columns should have been installed.

The bent steel column (photo at above left) illustrates how a failing structural column, supporting foundation wall, or supporting knee wall can also lever a building sideways for a distance approximately equal to the column height.

Earthquake damage © Daniel Friedman at InspectApedia.com

Our photo above shows one of the bent, failed Lally columns. The building wall in the background of the photo was previously supported on top of this column.

This photograph was taken at the rear of the apartment building shown in the pair of photographs above.

Below our photograph shows that the bent Lally column top shows that the column was hollow.

Like other Lally columns that bent over completely leading to building collapse and sideways shift, this column had been wrapped in a fire-barrier coating.

An external inspection of the column after construction could not, without more sophisticated testing, disclose that the builder had use hollow steel rather than a properly-constructed concrete-filled column.

Earthquake damaged bulding © Daniel Friedman at InspectApedia.com

Structural engineers and experts with more experience than the author have examined this catastrophe. But we thought it worth noticing that some of the Lally columns that failed were hollow steel posts while others that remained standing at the same building project were ones that had been filled with concrete to resist bending.

We wondered if the schedule-pressure of original construction at Northridge Meadows contributed to use of columns that were not what was called for.

Photograph of building damage near Los Angeles 1994  © Daniel Friedman

This photograph (above left) shows an easy-to-determine case of significant lateral movement of a wood frame structure.

Often an improperly secured crawl space cripple wall simply leaned over, levering the building to one side for a distance equal to the height of the collapsing (cripple wall).

In this case the collapse was of a wood-framed supporting wall, not a masonry foundation.

The cripple-wall height of single family homes in the area was typically less than four feet.

As a result both sideways and vertical collapse distances were less severe than those endured by sections of Northridge Meadows apartments that had been supported on eight-foot Lally columns designed to give parking space below the building's first occupied floor.

Photograph of building damagenear Los Angeles 1994  © Daniel Friedman

Combination of movements due to earthquake damage is demonstrated by the photograph above of an un reinforced stone masonry foundation and wall home in California. Un reinforced concrete structures are no longer permitted by California building codes for construction in areas of earthquake risk.

Below: new foundation construction in Christchurch, New Zealand in 2014. Heavy re-bar use in slabs and foundation walls is designed to control damage in future earthquakes.

Christchurh NZ foundation construction re-bar reinforcement details in 2015 following the 2010 / 2011 earthquakes (C) Daniel Friedman at InspectApedia.com

Earthquake Damage Assessment & Repair References

 




ADVERTISEMENT





Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: our newly built townhouse vibrates and shudders and we hear banging

Just moved in to a new build town house which vibrates constantly and suffers with shuddering (top/3rd floor more noticeable with windows also shaking). On ground floor can sometimes hear banging, like someone has jumped or dropped heavy object from above. On a main road but this does not always happen when heavy vehicle drives past. Also suffering noise from pipes/ventilation outlets. - Lesley Anne 12/29/2011

Reply:

Lesley:

If the building movement and noises you describe were due to an earthquake or ongoing temblers or tremors, you could quickly confirm that condition with your local emergency services departments and building department, or perhaps even neighbors, as other buildings would be experiencing symptoms as well.

If that is not the case, then what you describe sounds specific to your individual building. Because some building movements, vibrations, and sounds can be symptoms of a pending catastrophic collapse, it makes sense to ask for expert advice promptly. An expert will listen to your concerns and will make his/her own thorough inspection of the structure both outdoors and inside, looking for

Indications of actual building movement and related damage, such as cracks, separation of framing, sticking windows or doors, floors or ceilings out of level, walls out of plumb.

Indications of foundation movement or damage such as cracks, leans, bulges, bows.

The purpose of the initial assessment of building condition will focus on the discovery of signs of an immediate life safety hazard. If that sort of hazard is comfortably ruled out, what remains may be construction methods and materials issues to review with the building owner, contractor, or an independent professional structural or civil engineer who is familiar with the type of construction used for your building.

Keep us posted, what you learn may assist other readers.


...

Continue reading at EARTHQUAKES, MAN-MADE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

Suggested citation for this web page

EARTHQUAKE DAMAGE - home at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING DAMAGE, DISASTER, REPAIRS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Or see

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING STRUCTURES

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification
when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Comment Form is loading comments...

Citations & References

In addition to any citations in the article above, a full list is available on request.



ADVERTISEMENT