Retrofitting Historic Buildings Against Earthquakes

New construction is being built better than ever to withstand the threat of earthquakes.  Moreover since earthquake activity is not limited to the West Coast, local building codes throughout the country mandate that new construction be resistant to the strongest earthquake activity that is believed possible in an area.  This task has become easier with new high-tech materials that are available such as fiber-reinforced polymers, fiber reinforced concrete and high strength steel.  

One of the on-going phases in creating safer buildings is the seismic retrofitting of older structures to be more resistant to seismic activity and ground motion.  Among these projects include significant historical buildings that have the additional task of ensuring the structure is stronger while still preserving the distinctive characteristics that make the buildings special.  

Obviously first and foremost human safety is addressed and then the focus switches to work on retaining the distinct architectural features of the building. Common weaknesses in historic buildings when faced with earthquake activity include unreinforced masonry and structural connections between walls, floors, and foundations.  Older construction used unreinforced bearing walls that offer inadequate lateral resistance and ductility or flexibility when subjected to seismic activity.     

According to the NPS Department of Interior’s Preservation Briefs, it is imperative to put together a team of experienced engineers, architects, and building code officials as well as consulting with their agency’s administrative staff.  They state that, “Historic materials should be preserved and retained to the greatest extent possible.”  Also that, “New seismic retrofit systems, whether hidden or exposed, should respect the character and integrity of the historic building and be visually compatible with it in design; and that, seismic work should be ‘reversible’ to the greatest extent possible to allow removal for future use of improved systems and traditional repair of remaining historic materials.” 



 

Conco is a leading supplier of concrete services for the Western United States. We have built our reputation in the Los Angeles area with superior concrete formwork, reinforcing, place and finish, shotcrete and other ancillary services that benefit from our vast experience.  Our concrete services include commercial, educational, parking and other construction development as well as public works projects.