January 20, 2015 by Establishing "Why" Since 1966
Recently, Connecticut has been shaken by 12 earthquakes. Although they are considered low magnitude, these earthquakes can cause serious structural problems. Buildings are designed to withstand the downward pull of gravity, yet earthquakes shake a building in all directions up, down, and most damagingly sideways.
Often it is hard to tell if structural damage was caused by an earthquake or by other structural factors which predated an earthquake occurrence.
There are four main design issues that can make a building more susceptible to earthquake damage. The first weakness may be caused by the building having an inadequate foundation. Pier and post designed foundations, and inadequate bolting in foundation construction can increase a building’s susceptibility to damage. To complicate matters, building foundation slabs are usually poured in a two step process. Contractors pour the footing first, then pour the floor slab. When the two pours are not properly prepared, there may be loss of a binding connection between the two poured surface layers. This fact is only often discovered after an earthquake causes horizontal sliding between the concrete layers.
Unbraced cripple walls are another potential weak point in building structures. Soft story buildings such as apartments, parking garages, or retail buildings are extremely vulnerable to earthquake damage. Finally, nonreinforced masonry can increase a building’s susceptibility to earthquake related cracking damage. A typical nonreinforced masonry building has brick walls with no steel reinforcing bars embedded within them. Typical nonreinforced masonry buildings in the United States are: schools, factories, and apartment buildings.
Unfortunately, many home and business owners have no idea their building structure has weak points and can easily be damaged by even minor earthquakes. Once an earthquake occurs in a localized area, many property owners ask the question “Was my building damaged from the earthquake, or was the damage caused by something else?”
Highly qualified Geotechnical and Civil engineers can conduct a series of stress analyses and material failure examinations to definitively determine why the specific failure occurred. From the analysis these experts are able to assess the damage and determine if it was a direct result of seismic activity, or if there was another preexisting reason for the failure. They can also explain how to properly repair the structure to prevent future damage. To find out more or to submit an investigation, visit our website at www.forensic-analysis.com.