http://www.latimes.com/local/la/la-me-earthquake-concrete-20131013-dto,0,1555748.htmlstory
Hello Again Everyone:
You all are just knocking me backwards with all your support. I am very humbled by it all and I hope you'll show the same kind of love for Road Recovery
(http://www.roadrecovery.org). On to today's topic, concrete risks.
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Los Angeles c. 1940s
videogamesblogger.com |
It's no big secret that the City of Los Angeles sits on a network of earthquake fault lines. It's something that native Angelenos accept with a certain amount
sang froid. We all are aware of the fact that "the big one" is on its way, it's just a matter of time. In the meantime, Los Angeles has a very big issue (one of many) to deal with, more than 1,000 old concrete buildings and hundreds across the county are at risk of collapsing according to a
Los Angeles Times analysis reported by Rong-Gong Lin II, Roxanna Xia, and Doug Smith on Sunday October 13, 2013. Conservatively, as many as fifty of these buildings in the city would be destroyed in a major seismic event, exposing thousands to death and injury. Scary thought when stop and consider it carefully. So, it would stand to reason that the city and county would want to take action and reinforce these older buildings, right? Think again.
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Office Towers on Ventura Boulevard
en.wikipedia.org |
A cross-section of Los Angeles residents live and work in these buildings: seamstresses in downtown clothing factories, professionals in buildings along Ventura Boulevard, to loft and condominium dwellers on Wilshire Boulevard's "Millionaire Mile." They may appear sturdy but they're vulnerable to lateral movement and lack sufficient steel reinforcement bars to hold the columns in place. This isn't something new, in fact Los Angeles Building and Safety officials have known about this for more than forty years but have failed to compel building owners to make them safer. The city has have even rejected calls to identify these buildings. Shocking isn't it? This prompted university scientists to assemble the first comprehensive inventory of potentially dangerous buildings in Los Angeles. However, the scientists have not made the list public and are willing to share the information with building and safety officials, by request.
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Christchurch, New Zealand earthquake
brisbane.com |
Recent earthquakes in Christchurch, New Zealand (2011) and Kobe, Japan (1995) have spotlighted the potential danger of buildings held up by concrete. In the New Zealand earthquake, two concrete office towers toppled over, killing 133 people. In the Kobe quake, 6,000 people in concrete towers were killed. In 1971, the Sylmar, California earthquake took down several concrete structures, killing 52. In 1994, the Northridge, California earthquake destroyed more buildings including a Bullock's Department Store and Kaiser medical office. Just to add further dread, seismologists are predicting a bigger long overdue earthquake.According to Thomas Heaton, director of Caltech's Earthquake Engineering Research Laboratory,"We known darn well that if a bunch of people die, there will be lots of stories, lots of reports, things will change. But the question is do have to have lots of people die in order to make this change?" Good question. Unfortunately it sometimes takes pointless deaths in order for change to happen. Sad but true.
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Capitol Records
fineartsamerica.com |
In the twenties, concrete buildings helped transform the Los Angeles skyline as office buildings and apartments rose along the skyline. By the seventies, canyons of concrete lined streets such as Ventura boulevard, Wilshire Boulevard, Main and Broadway. These concrete canyons include landmarks such as Capitol Records tower, the Hollywood Plaza apartments and W Hotel in Westwood. In order to properly understand the situation, the
Times sent out a team of reporters who combed through building permits and sent questionnaires to building owners, asking them to review the details. The results identified sixty-eight buildings that were made from concrete. Of those, only seven were retrofitted. In the interest of full disclosure, the reporters' studied only a fraction of the older concrete buildings. The survey revealed the difficulties in accurately identifying concrete buildings. Some of the public records didn't specify construction materials. Some of the buildings that appeared to be made of concrete, while others seemed to be made of brick or steel were really made of concrete.
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Hollywood
gogonotes.blogspot.com |
The community of Hollywood, bisected by a fault that is capable of producing a 7.0 earthquake, has one of the biggest concentration of concrete buildings. In the few blocks around the famous intersection of Hollywood and Vine, the
Times found fourteen concrete structures built before 1976, when the city started requiring more steel rebars. Only three have been retrofitted. Sorry, the article doesn't list which buildings have been retrofitted. It's much of the same story along Ventura Blvd in the community of Encino. The 1994 Northridge Earthquake wrecked several concrete buildings including a ten-story hotel. The owners spent $4 million to protect it in an earthquake. Of the ten concrete buildings on that part of the boulevard, only the hotel and one other building have been reinforced.
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Santee Alley
thesanteealley.com |
In two downtown Los Angeles neighborhoods, along Broadway and Santee Street, the
Times found seventeen unreinforced concrete buildings. One of those buildings is owned by Scott Kim and his family. When they bought the building, the Kim family didn't think to have it inspected by a structural engineer. Not a great idea. "it went through other earthquakes, and it's still here," said Mr. Kim, whose family paid $5 million for the property ten years ago. "I know back in the day they buildings much sturdier than buildings today," added Mr. Kim. Here we have one problem with concrete buildings, the perception that they're more sturdy than recently built structures. However, Charlie Tan, a structural engineer who helped retrofit downtown buildings, is quick to put that myth to rest. Just because a building has survived earthquakes, doesn't mean it's safe. "I've had that said to me quite often: 'Look, this building looks good, has no cracks, no damage,'" says Mr. Tan. Further, "A lot of these specific ones in downtown haven't been tested yet with a high-magnitude earthquake in the exact vicinity." Yet being the operative word.
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Sylmar Earthquake headline
latimesblog.latimes.com |
While building owners might not be aware of the inherent risks, city officials have repeatedly warned about the dangers of concrete buildings since 1971. The Sylmar Earthquake wrecked two concrete buildings at the forty-six year old Veteran's Administration Hospital in the San Fernando Valley. Both three-story buildings pancaked when the concrete broke apart, leaving the red tile roof smashed to pieces on the ground. Many patients were crushed beneath the rubble, forty-nine people were killed. Seismic experts were further alarmed by the state of the Olive view Medical Center in Sylmar, which opened months before and built under stricter codes. The five-story hospital moved sideways when some of the first-floor columns broke. Three concrete stairwells toppled over, a two-story psychiatric buildings collapsed, and three people were killed.
Following the 6.6 earthquake, Los Angeles Building and Safety officials strengthened seismic codes for new buildings, requiring more steel reinforcement bars inside the columns to prevent concrete chunks from breaking away. The additional steel acts as a cage, keeping the concrete in place, even if the column cracks. Be that as it may, structures built before the mid-seventies remained at risk because many lacked adequate re-bars and can't bend, something engineers call "non-ductile." When more concrete buildings tumbles in the 1994 Northridge Earthquake, then Los Angeles Council member Hal Bernson and Kal Deppe, a to city building official, decided the time was right to push for tougher retrofitting laws. Their proposal called for a list identifying all vulnerable buildings across the city including concrete buildings. Property owners would be required to have a plan to retrofit them. Both Messrs Bernson and Deppe had reason to be optimistic. Ten years prior, they successfully pushed an initiative to require the demolition or retrofit of about 8,000 unreinforced brick buildings. However, in 1994, Los Angeles was still recovering from a recession after the earthquake and then-Mayor Richard Riordan didn't want to burden business owners with additional regulations. Thus, Council member Bernson's proposal died and officials had to settle for a voluntary retrofit program.
In a recent interview, Mr. Bernson stated, "There's two sides: There's the human risk. There's the financial risk...To me, there was never a question about the two. The question of human life was always more important than financial." In the early 2000s, retired building officials tried again to make City Hall focus on the dangers of unreinforced concrete buildings-nothing happened. In 2003, Mr. Bernson's former chief of staff Greig Smith, tried twice to revive the issue when he was elected to the City Council. Mr. Smith proposed an alternative: identify the concrete buildings and label the hazardous ones. That also failed.
Ironically, property owners have been the biggest opponents of retrofitting rules. I say ironically because you would think that someone like Scott Kim would want to retrofit his building if only to avoid the inevitable lawsuit that would result from the family of his workers who were crushed to death by falling concrete. The problem is that many business owners believe that they shouldn't have to for expensive fixes themselves. Yes, retrofitting a building is expensive but a lawsuit and fines is even more expensive. According to Carol Schatz, president and chief executive of the Central City Association, "The cost of doing this would be greater than the value of the building and that didn't make sense to us." It almost seems as if Ms. Schatz is implying that the safety and welfare of the human occupants is of little value in context to a quick building sale. Researchers who study how concrete buildings behave in in earthquakes say that 5% of the structures would collapse. In Los Angeles, that amounts to about fifty buildings, possibly including one occupied by Ms, Schatz. Many more require retrofitting.
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Los Angeles City Hall, c.1931
en.wikipedia.org |
Nabih Youssef, an engineer who helped strengthen City Hall and the Los Angeles Coliseum, said that based on his experience, approximately 30% of the older concrete buildings require major work. Some of his colleagues believe that number his higher. In order to determine whether or not a building requires retrofitting, an owner would have to spend about $100,000 on a structural study that analyzes what is inside the columns. Owners would have to hire engineers who might install angled steel beams to provide more support. Another remedy could be the addition of strong interior ground-to-roof concrete walls, which could cost upwards of $1 million. Would it help save lives and be better safety-wise? Of course, if you have the money.
In 2006, a team of engineers from UC Berkeley led by Professor Jack Moehle, backed with a $3.6-million grant from the National Science Foundation, set out to produce a list of older concrete buildings that might collapse in a major earthquake. Over the next seven years, Prof. Moehle's team identified 1,500 potentially vulnerable buildings in Los Angeles through examining public records and walk throughs. The list was intended to be a first step. Each building identified on the list would have to be studied more closely to determine if it needs strengthening. Prof. Moehle declined to release his list to the
Los Angeles Times, citing legal liabilities because the data is far from definitive. However, Prof. Moehle would make list available to the city, upon request, letting them figure out what to do with it. Proponents of retrofit say the list would give the city a place to start in dealing with this issue. "You need to an elected official who is willing to stick his neck out and the leadership role," opines Hal Bernson.
A spokesperson for Los Angeles Mayor Eric Garcetti said that the mayor is interested in the report and would review the issue. Without action from the city, the retrofit program would be limited. As downtown and Hollywood gentrified, developers were required to retrofit the concrete buildings and warehouses during their conversion residences. Others developers reinforced their buildings under pressure from insurance companies and lenders. Seismologists and engineers say the clock is running out to fix the buildings. If the long overdue "Big One" hits the San Andreas fault, the main fault line running through California, the shock waves would cascade into downtown at a magnitude that hasn't been felt since the earthquake in 1857. Another horrifying scenario would be a huge quake striking directly underneath Hollywood or the Westside. There are more than 300 fault lines criss crossing the L.A. Basin.
Previous earthquakes have sparked billions of dollars in retrofitting across the state with proven results. Hundreds of bridges and freeway overpasses have been replaced or retrofitted-all but two have been completed. Public and private universities and colleges voluntarily retrofitted their concrete buildings. State earthquake regulations have resulted in safer, more modern medical buildings. Los Angeles' 1981 requiring retrofitting of 8,000 brick buildings have save lives-although sixty people died in the Northridge Earthquake, none were in brick buildings. Nevertheless, structural engineers reported to the state, after the Northridge quake, that the collapse of a single unreinforced concrete building could have catastrophic effects, resulting in the loss of life not seen since the 1906 San Francisco Earthquake. Earthquake safety has rarely been an issue that draws serious public debate. Most seismic regulations are are approved after the fact and Los Angeles hasn't had an event in almost twenty years. Without a government mandate, the job of retrofitting is left to the property owner's discretion. Scary if you think about it.
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