Following the May 12, 2008 M8 Sichuan Earthquake, Miyamoto International and Global Risk Miyamoto immediately dispatched a team to the affected region. Our reconnaissance team is composed of Chris Heaton, Principal of Global Risk Miyamoto, Rocky Ng, engineer from China Rail Way, Tenth Group, Third Engineering Company, and the author, Kit Miyamoto of Miyamoto International and Global Risk Miyamoto.
May 20, 2008
8:30 amWe all slept a few hours last night; which is more than most nights. It is amazing what adrenalin does for you. We meet the NBC crew in the lobby of the hotel and are ready to go. We are heading to Hanwang, the Death Town, again.
10:45 am Mianyang steel plant
We stop over at a steel fabrication plant southwest of Mianyang. This building was built in 2003 and is a 1-story steel frame structure with steel cross bracing made of lattice plates. We are welcomed by a factory manager and we walk together into the factory. He is very grateful for our presence and he tells me that no one came to his mid-sized plant to check it out. As we expected, there is very little damage other than broken glass windows. The workers are still very scared and refuse to go into the factory causing production stoppage since the earthquake. Light weight steel structures always outperform unreinforced brick and nonductile concrete structures. We inform the manager that his building performed well and is safe for entry. He is very grateful for the news so he can pass this along to his workers.
12:20 pm - Hanwang
Hanwang must have been a very beautiful city before the M8 quake killed it last Monday. It is now a ghost town with acres of broken concrete and brick piles. The ground acceleration here must have been very high and the duration of the strong motion long to cause such incredible destruction.
12:30 pm
We park our vans. We walk into a deserted complex of 8-story residential buildings. These are all made of unreinforced brick walls and concrete slabs. We see a lot of diagonal shear cracks on the walls between windows, but the walls didn't collapse. The diagonal shear cracks are caused by the lateral seismic force.
These brick walls resisted the seismic force and protected the buildings from collapse. In this area, each room is very small and because of it, there are a lot of walls. The more walls that exist, the higher the seismic capacity of the structure. We have noticed that many old residential buildings performed well enough to prevent collapse.
I explain these structural engineering basics to an NBC producer as we walk. I enjoy being a teacher very much. It is important for the public to understand why buildings perform well or why they collapse. We don't see a single soul here, only a lonesome dog or chicken that has lost its owner.
1:50 pm
We leave the residential complex and enter an area of incredible disaster. We walk through a street where both sides are 20 feet high walls of concrete and brick piles.
We arrive at a school that is 80% collapsed. This was a 4-story school built in 1994. These school buildings are very weak against seismic forces. We're finding that many of the "total collapse" buildings are schools. These buildings have very little strength and ductility, which is a measurement of a building's seismic energy absorption capacity. If there is enough steel with proper detailing, concrete or brick can possess high ductility.
Again, I see precast concrete planks hanging by a thread against the black chalk boards. These planks were the floor... or they used to be. When the columns or walls supporting these planks gave way, the planks dropped with the kids on them. And the planks above fell on them... It is really sad to see the black boards with fresh chalk writings and framed pictures of the student body still on the walls. I can't imagine the horror these little kids and teachers must have felt when the floor above and below them suddenly gave way.
As structural engineers, we have a responsibility to prevent these disasters. I must say, as a profession, we fail the public we are supposed to protect when buildings collapse. There are dangerous buildings everywhere on earth. You will find plenty in the US, Canada, Japan, China, South America, Eastern Europe, Southeast Asia... Unless we speak out, we will see these tragedies many more times in our lifetimes. We must take a leadership role to communicate and educate the public. It is a very important task. Our loved ones' lives depend on it.
We see a dormitory building next to the school. It is similar in construction to the residential building I described previously. It is all cracked but is still standing just fine. I believe most of the kids were able to escape from this building. By the way, this is the intent of most building codes worldwide - life safety. A structure may experience major damage during a strong earthquake, but it doesn't collapse. Based on this principle, this building performed well.
3:00 pm
We walk by a group of workers who are having a lunch break. The man in charge tells us that his 8-year old boy is still buried under the school we just saw. His group is charged with cleaning up the whole area including the school...
3:18 pm
We walk into a factory. All brick walls have failed and collapsed outward, but the concrete columns saved the building from total collapse by providing an independent roof support. The roof structure is composed of steel trusses. The earthquake caused the heavy equipment to slide 6 inches or so. I saw this failure mode in a Niigata, Japan car parts manufacturing facility last year that led to a Japanese car production loss of several hundred thousands cars. Simple anchor bolts would have prevented this failure...
3:30 pm
An NBC cameraman climbs up a 30 ft high pile of concrete to take a few shots. Let me tell you that all the journalists I met here are dedicated, brave and a crazy bunch. They are in the field all day and they work till early morning editing and communicating with headquarters. The working condition is horrible. We are constantly covered with dust, chemicals and sweat. Added to this is the constant danger of aftershocks and potential disease outbreak. Whether you are a journalist or a structural-earthquake engineer, our jobs are not for everyone. I am really glad to have them with us to record the facts.
4:30 pm
We walk by a dead, decomposed body the rescue team has just dug up. It is hardly recognizable after exposure to heat and rain for 8 days. I try not to look...
4:40 pm
We find a one-story industrial building fully intact in the middle of the devastation. Again, it is a light-weight steel structure, but it is totally abandoned. The structure performed well but the business cannot function without workers and surrounded by collapsed buildings. Again, anchored equipment have slid off the base.
4:55 pm
Nearby is a 3-story concrete office building without damage except for the wood roof. It has a plenty of walls and appears to be a well designed structure. Yes, good design pays off and saves lives.
5:10 pm
We see an undamaged concrete water tower. This structure has a natural frequency that is different from the buildings in this area. It is much more slender and has a lower frequency; which may have help it survive high accelerations. Also, the shape and weight of the tower requires good concrete reinforcement and a strong foundation, resulting in good performance.
5:15 pm
As we walk back to the vans, we see a different complex of residential structures. One of the buildings has a big gash down the middle of the structure and is leaning to one side. Upon closer inspection, we discover that the ground floor brick walls have totally failed and pancaked the ground floor. At least four of these buildings failed in the same way. For the people on the ground floor, there was no chance of survival. Looking at one of the only surviving buildings, I notice that there are few walls to resist seismic forces. It's mostly windows; which provide no seismic protection. There is Chinese writing in red paint on the outside wall. Rocky tells me that it means there is a dead body buried at the point where the arrow is.
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6:00 pm
We get in the vans and head back to Chengdu. We drop by a small village near Hanwang. As soon as we get off the vans, we are swarmed by villagers asking us to examine their houses. The buildings in this town are mostly compact concrete structures. There is no collapse and most of the buildings have no damage. But the families are sleeping in tents anyway. We investigate a few buildings, and mingle with the people. I enjoy interacting with the locals. People here are probably one of the most polite and friendly group of people I've ever met. By watching smiling kids, a hard day melts away quickly.
9:00 pm Chengdu
We meet with a group of business men and a government official who are concerned about earthquakes and how all of the negative implications will impact domestic and foreign investment in this area. They invite us to a traditional Sichuan dinner. We tell them that with proper risk management and good structural engineering, it is possible to mitigate the earthquake risk. Investors should be informed of structural and insurance options to protect their investment. Dinner is great but I'm not certain if my colleague Chris is crazy about the idea of eating sea cucumber. It's nice and soft... a delicacy. I like it.
» Continue to May 21, 2008 entry
