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STRUCTURAL INSPECTIONS & DEFECTS
AGE of a BUILDING - how to determine
BRICK FOUNDATIONS & WALLS
CHIMNEY INSPECTION DIAGNOSIS REPAIR
COLD POUR JOINTS, CONCRETE
COLUMNS & POSTS, DEFECTS
BUILDING DAMAGE ASSESSMENT & REPAIR
EARTHQUAKE DAMAGED FOUNDATIONS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOD DAMAGE TO FOUNDATIONS
FOOTING & FOUNDATION DRAINS
FOOTINGS EXPOSED, Repair Methods
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION CONSTRUCTION TYPES
FOUNDATION CONTRACTORS, ENGINEERS
FOUNDATION CRACKS & DAMAGE GUIDE
FRAMING DAMAGE, INSPECTION, REPAIR
GRADING, DRAINAGE & SITE WORK
GUTTERS & DOWNSPOUTS
INSECT INFESTATION / DAMAGE
MOBILE HOMES, DOUBLEWIDES, TRAILERS
MODULAR HOME CONSTRUCTION
MOISTURE CONTROL in BUILDINGS
RETAINING WALL DESIGNS, TYPES, DAMAGE
RETAINING WALL GUARD RAILINGS
STRAW BALE CONSTRUCTION
STRUCTURAL DAMAGE PROBING
STRUCTURAL WOOD ASSESSMENT
THERMAL EXPANSION of MATERIALS
TIMBER FRAMING, ROT
WATER BARRIERS, EXTERIOR BUILDING
WATER ENTRY in BUILDINGS
WINTERIZE A BUILDING
Foundation damage due to earthquake activity: this article discusses in detail the recognition of different types and causes of complex or combined building foundation movement and foundation damage. Earthquakes shake building structures in different patterns, sometimes unique to a particular quake. The basic movements are side to side, up and down, or a combination of these. 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 strucures due to several different types of earthquakes.
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The 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.
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.
Also see FOUNDATION CRACK EVALUATION for a discussion of the diagnosis of specific crack patterns in masonry foundations, and see FOUNDATION BULGE or LEAN MEASUREMENTS which explains a simple method for determining how much bulge or lean is present in a foundation or wall, then see FOUNDATION MOVEMENT ACTIVE vs. STATIC which helps determine if the foundation movement is ongoing, and see FOUNDATION DAMAGE SEVERITY for a discussion of just how much foundation movement is likely to be a concern.
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. Anyone having concern regarding the structural stability, safety, or damage of a building, foundation or other components, should consult a qualified expert. Photographs of types of foundation cracks and other foundation damage: we have a large library of photographs which we're in process of adding to this document. Pending completion of that work, contact the author if assistance is required.
In this photograph, taken from the rear of the building above, the movement caused by the Northridge Meadows earthquake is more clearly demonstrated. Notice that the bent Lally column top shows that the column was hollow?
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.
Manmade Earthquake Damage Sources: mining, oil or gas extraction & hydraulic fracturing or "fracking" activities can lead to earthquakes
In diagnosing earthquake type damage to buildings and their structures or foundations, note that even in areas that are not considered earthquake zones earthquakes may occur and may be traced to human activities. In March 2013 The New York Times reported on new earthquakes occurring at Loppersum in the Netherlands. Tremors have been recorded at a magnitude of 3.4 on the Richter scale. The Times reporter explained that after more than fifty years of natural gas extraction in the area, recent earthquakes have become more common.Quoting from the Times article:
Frequently Asked Questions (FAQs) about earthquake damage to building foundations
Question: How to distinguish earthquake damage from other structural movement
Is there anyway to prove earthquake damage to a foundation? I have a single story ranch house built in the 1930’s that has recently been subjected to a mild earthquake in 2009 and 2011 (Midwest) both of which I felt the house shaking and was awaken from a sound sleep.
I have glass block windows that have started to splinter in one of the sections of my basement. Started first sometime after March 2011 when I notice the blocks were cracked.
A couple of weeks later I found glass fragments splintering from blocks. Been watching it periodically then forgot until yesterday I found several larger pieces of glass block…corner pieces on two of them. The mortar that holds the blocks in window area show cracking as well. This would indicate to me that there is still ongoing stress to my frame house which is causing continual splintering from the glass blocks.
I contacted a structural engineer who said it was not possible by looking at it to tell whether it was earthquake damage or not. He indicated soil testing would have to be done which would be very expensive.
I am concerned that my home or at least parts of it will collapse. I have contacted my insurance agent but they do not provide any services of which to tell if it is earthquake related or not.
If you have any referrals or helpful information, I would appreciate it. - Thank you,- B.O. in Missouri
Reply: Expert, experienced inspectors should be able to form a reasonably confident opinion about building damage, extent, and cause
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with the structure, its history, probable cause, and extent of impact on the building and its safety.
I'm in no position by mere email to argue with your engineer, but having inspected a very large number of earthquake damaged buildings (while serving the Red Cross) it is my OPINION that an inspector, contractor, home inspector, or engineer who has familiarity with earthquake damage in general as well as with specific earthquake activity in a particular area can recognize the presence of damage to the building structure and form an opinion about its general safety.
If inspected by an experienced diagnostician, typical causes of building structural movement can almost always be traced to a probable cause. In all cases of building foundation or other structural damage, understanding the cause of the damage is an essential part in planning for the necessary repairs.
For example, lateral or horizontal "shaking" by an earthquake is likely to damage all sides of a building while differential settlement due to soil problems tends to cause focused cracking, bending, leaning etc. If the cause of foundation damage is inadequate footings the repair requirements may be quite different from earthquake damage.
I am unclear why soil testing is a high priority step in evaluating the building;
The first order of priority, which should not be delayed, is an inspection of the property for safety and safe occupancy. Unless your property actually has no significant damage of any kind (regardless of origin), that inspection needs to be performed for your own safety regardless of arguments about the root cause.
Watch out - some safety defects that may be present following an earthquake as well as following other structural movements or damage can be subtle such as gas leaks and unsafe electrical wiring - even if the visible structural damage is minimal. At Northridge following the LA earthquake some buildings were very extensively damaged by the side to side movement of the earth during that event. But other buildings looked just about perfect, still sitting square on their foundations. Yet some of those "perfect-looking" structures were unsafe due to gas leaks that risked (and in some cases occurred) explosions and fires caused when subtle building movements damaged the utility lines.
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
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.
Questions & answers or comments about how to recognize, diagnose, evaluate, and repair building foundation damage due to earthquake activity.
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