soft story retrofit
Posted by EvolveDesign on May 30th, 2017
Soft story buildings are buildings which have weak or empty stories, such as tuck under parking or otherwise large gaps in the perimeter walls. During an earthquake, they are unable to cope with the lateral movement that an earthquake enacts.These stories are so weak, in fact, that they will collapse in on themselves during a quake. The entire building will cave in. A haven of safety can very quickly become a tomb.
Natural disasters are sudden, powerful, and terrifying. Only last year, a 6.6-magnitude earthquake in central Norcia, Italy, destroyed buildingsalmost 300 people died (BBC, 2016). If you are situated in an earthquake-prone area, earthquakes are aterrifying reality. They arehugely powerful natural force that is completely beyond your control. You can feel very helpless, and untrusting of the buildings around you. This is justified, as the California Institute of Technology has stated that out of 20,000 Los Angeles soft story buildings, an estimated 800 had been adequately protected against earthquakes in 2011 (Jessup and Tokumatsu, 2011). This is only 4%. Both unprotected buildings, and people lives are in jeopardy.The danger is very real, as seismologists predict that a 6.7-magnitude earthquake has a 99% probability of striking California within thirty years from now.
Los Angeles, an earthquake-prone area, currently has thousands of buildings with little or no lateral support. However, there is a potential solution. Developed by structural engineers, seismic retrofittingis an aid to these dangers. By reinforcing or filling soft stories, vertical support for buildings during earthquakes is possible, protecting lives and property. A program across Los Angeles, the Los Angeles Soft Story Retrofit program,identifies dangerous buildings through a set of criteria. It issuesinstructions to building owners to have their buildings seismically retrofitted within seven years of the issued Order. It is mandatory for buildings built before the enacted building codes standard of 1978, buildings with two or more stories of wooden frames, or an open floor space on the ground floor to be retrofitted. After having the Order issued, building owners should complete the work within seven years. They should begin the process by consulting engineering, architectural and contractual experts(LADBS).
The seismic retrofit cost can be staggering to some building owners. In fact, it can sometime reach to beyond 0,000 (Selna, 2008). The sheer cost of a retrofit can be an unrealistic target to many building owners. This is even more so in the current economic climate. However, the cost need not be unachievable. Schemes devised by the LADBS are in place to help. Landlords can divide the seismic retrofit cost between owned units, or pass on 50% of costs to tenants.Rent increases are capped at over 120 months. This can be extended until the approved costs are recovered.
As of 2011, only 4% of dangerous Los Angeles buildings have been protected. Seismic retrofitting can be affordable, and will help to save lives and property if this earthquake strikes.
