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Checklist for Seismic Retrofitting URM Buildings

Checklist for Seismic Retrofitting URM Buildings

It is a known fact today that buildings constructed using unreinforced masonry (URM) do not sustain the stress of seismic activity very well.  In fact, in the last one hundred years of recorded earthquakes, more URM buildings throughout all of California, not to mention the other states on the West Coast, collapsed than all the other construction methods used for commercial buildings.  URM constructed commercial buildings typically do not use steel reinforcements and without steel reinforcements, the brittle masonry cracks, twists, and collapses during and after the strong rocking and shaking of an earthquake.

Today, URM buildings are no longer built in earthquake prone areas. A  number of older URM buildings on the West Coast, however, having undergone through various levels of seismic retrofitting, currently remain standing.  Seismic retrofitting URM buildings in California increases the level of structural integrity  There are many ways to strengthen a commercial property.  Roof-to-wall anchors, for instance, can reinforce the likelihood that a building won’t come apart at the seams.  Ensuring proper wall anchoring not only protects a property, it also minimizes damage to surrounding structures.

If you are considering a seismic retrofit for your building, contact a professional with specific experience in commercial retrofits.  They can complete a multi-faceted inspection to determine the maintenance and structural needs of your building.

The generally recommended checklist for seismic retrofitting URM buildings is:

  • Use roof-to-wall and wall-to-floor anchors to prevent the building from pulling apart.

  • Have the height of the walls checked for the correct thickness and brace, if necessary.

  • Have the in-plane strength of URM walls inspected for inter-story displacement.

  • Add continuity ties throughout the building.

  • Replace plywood overlay on the roof, as needed.

  • Large windows may require a moment frame to handle the shear loads.

  • Walls may also need reinforcement using tube steel, gunite, or epoxy fiber wrapping.

  • Brace any item or piece of equipment that is hanging and loose.

Another element of earthquake preparation to include in the plan is the securing of all non-structural elements.  This should include loose hazards and hanging equipment that could swing and fall.  Be sure to check shut-off valves for gas and water lines to make sure they are secured as well.  After an earthquake, secondary damage often comes through fires and flooding from damaged lines that can’t be shut off.

URM buildings aren’t the only structures that require seismic retrofitting.  Commercial properties should be regularly inspected for structural integrity. While we can’t predict when a massive earthquake (“The Big One”) will strike, we do know that buildings experience aging and stress that can weaken the structure.  As a commercial property owner, your goal should be to have well-designed construction that allows a building to experience a contained amount of failure without adversely affecting the entire structure.  Seismic retrofitting helps older buildings that were designed and built before current engineering and construction technology were implemented.  If you are interested in avoiding potential structural failure with your URM building or if you would like more information on seismic retrofitting a URM building, call the professional experts at Saunders Commercial Seismic Retrofit today.

Southern California Office

(949) 646-0034


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