San Francisco and the surrounding towns offer so much to our lives; we have great weather, gorgeous scenery and a town that is vibrant with culture and diversity. As with most things in life, it seems to come with a price and the price in this area is that we live in a geologically active area. Everyone has heard of the San Andreas fault, but there are eight major faults in this area, any of which could skip at any time. This precarious position might add a bit of a “seize the day” attitude to the population, but it also means we need to be extra vigilant about preparedness. This high level of preparedness extends to many aspects of our lives, and the element we focus on is making sure the homes of the Bay Area can withstand the forces unleashed by an earthquake. Consulting Engineers Corp is proud to be taking part in this program. We are a firm of engineers who have over 40 years experience and who have designed over 100 million square footage of space in the Bay Area over the years. We perform inspection, create custom fitted retrofit designs and implement the designs.
A Matter of Public Safety
Making sure the homes of this area safe and can withstand a medium sized earth quake, is a priority of many people involved in public safety as well as engineers and contractors in the area. Initiated in 2013, there is now a mandatory soft-story retrofit program in place. The impetus for this program was a large number of homes that sustained significant damage or were completely destroyed by the 1989 Loma Prieta earthquake. During this significant event, homes and businesses built prior to 1978 completely or partially collapsed as a result of soft story failures. This type of failure was responsible for 7,700 of the 16,000 buildings that were destroyed during that earthquake. This amounted to over 34,000 housing units being declared unsafe for human habitation. It is predicted that in a future earthquake, should it be even stronger than the Loma Prieta quake, 66% of homes in the area would be destroyed. It was these dire numbers that prompted the City of San Francisco to issue the mandatory soft-story retrofit program. On April 9th, 2013, city ordinance number 66-13 established a mandatory seismic retrofit program.This program is run by the Department of Building Inspection which is responsible for its implementation.
Why Do Soft Stories Pose a Risk?
To better understand what the program is, it is important to understand the problem that soft stories present. A soft story is the bottom floor of a wood frame structure that has, as so many buildings in this area do, a ground floor that is either a garage or retail space. If the bottom floor is a garage, it will, of course, have large doors and large open spaces on the interior. Retail spaces are similarly constructed, with large windows and, again, large open spaces. The problem comes when an earthquake occurs, and the structure is swayed, especially laterally. When this happens the soft story, which lacks the stiffness to withstand these forces, collapses. The upper floors can sometimes remain completely intact as they fall onto the collapsed soft story, other times; they can pancake down. The result of this collapse and possible pancake action is substantial property damage and the high risk of injury or loss of life.
To find out more about how the engineers of Consulting Engineers Corp. is actively strengthening the buildings of the San Francisco area as part of earthquake preparedness, check back for our next blog. If you are in need of seismic retrofitting, call us today to begin the process.