Should new building codes address retrofitting in existing structures that are likely to collapse and kill during an earthquake?
After a decade of study and debate, San Francisco formally adopted a new law this past spring that requires owners to retrofit thousands of wood-frame soft-story buildings. This marks the most sweeping seismic regulation that California has seen in years. Now Los Angeles wants to pass a similar requirement, involving many more structures.
Structural engineers have long warned that wood-frame soft-story construction faces particular risk for collapse during a major earthquake because the garage must carry the weight of apartments stacked above them. Efforts at mandatory retrofitting, however, are blocked by the construction industry and tenants who fear rent increases. Property owners have balked at the estimated $60,000 – $130,000 cost per building, without considering the loss of income if their building collapses during the next big earthquake.
In January 1994, the Northridge earthquake caused the Northridge Meadows apartment building, a soft-story construction, to collapse. Sleeping residents were crushed in their beds and 16 died. If the building had been retrofitted, half these deaths may have been prevented and the building could have been repaired and reoccupied.
Building codes do not apply to existing structures, nor do existing laws require owners to retrofit. It is easy to become complacent. Memories of the last big earthquake inevitably fade, and a new generation is left at risk for an event that we know is coming.
The question remains: what is the balance between costs now versus the inevitable loss of life later?
Retrofiting of existing buildings ia a major issue concerning public safety. In my opinion mandatory retrofitting is extremely difficult to implement.Just consider the retrofit of a concrete construction.Assessment of the seismic capacity of the building,construction, which means relocation of tenats which means money. A mandatory retrofitting programm would be realistic only with significant financial incentives for the owners.
I was in Northridge California assisting the locals with disaster relief, crowd/traffic control after the quake. Something does need to be done. The older buildings falling on top of cars parked underneath apartment building parking spaces supported only by a four inch steel pole is not acceptable. Loss of life and property damage at the time was also unacceptable and still is. This needs to be addressed immediately before another earthquake strikes again and it will.