Global Team of Engineers: Some Buildings are ‘Time Bombs’
- A group of structural engineers from around the world have examined buildings in Kathmandu and have found many questionable building practices the government and builders need to remedy in order to construct more robust buildings that stand a better chanc
Jun 5, 2015-
“Some of these buildings are literally time bombs,” said Art Schultz, professor of engineering at the University of Minnesota in the US and part of the team of 17 engineers with expertise in post-earthquake assessment who examined structures from mud-brick homes to hospitals, colleges, high-rise apartments, single-family homes, shopping malls and heritage sites.
The structural engineers formally assessed around 1,000 buildings while analysing an additional 2,000 for a report being shared with the government.
Brought to Nepal by Global Fairness Initiative, in partnership with Brick Clean Group Nepal, MinErgy Initiative, and Humanity United, the team worked with Nepali engineers and ranged across Kathmandu, Bhaktapur, Lalitpur and Sindhupalchok.
“We weren’t seeing a lot of consistent practices,” said Ken O’Dell of Los Angeles, California. “Some houses were built very well, but some had issues such as corroded reinforcing or joints in the concrete not fully filled. Lack of consistent construction could be overcome with a little more engagement from the government in setting up standards and ensuring they’re followed properly.”
Disturbingly, many errors are hidden from sight after homes are finished.
Take the case of the twisted rods. One home the engineers examined was going up in stages, and the old and new pillars didn’t quite match up. So someone, presumably a workman, bent the rebar rods to force them into the space. That casual decision doomed the home when the quake came, since its support system was already compromised.
Attractive exteriors can disguise threats. “Once the plaster is on a building, it looks excellent,” said Jason Ingham, professor of engineering at the University of Auckland in New Zealand, adding wryly, “You have extremely good plasterers here. But when you see the reinforced concrete work that’s holding it together, it’s quite rough. If they’d put the same care into the concrete as the plaster, a lot of these buildings would have performed better.”
The team said that engineers need to be involved throughout the building process to catch errors, contractors need appropriate training, and homeowners need to be familiarised with construction techniques so they will know if homes are being properly built.
What about Kathmandu’s high rises? Alarming as the spider web of cracks on many buildings may look, they’re often cosmetic rather than structural. “You should be congratulated on the success of a lot of projects, like apartments and malls, that have done quite well,” Ingham said. “Cracks look bad, but sometimes they’re part of the way the buildings might work. In reinforced concrete high-rise buildings we’ve seen, it’s almost always only the (non-structural) bricks that are broken, so the fix is as simple as replacing the bricks.”
“A properly engineered, well-conceived high-rise building is very doable here,” O’Dell said. “On the other hand, one with a lot of brick partitions? Probably not. All you’re doing is raising the mass of the building, and you’re going to make that building work that much harder. But I’d be happy to design a 25-story building in Kathmandu.”
Following codes, though, can make the difference between life and death. Tacking extra stories onto buildings approved for two or three stories was cited as one of Nepal’s most common and dangerous practices. “A lot of failure we saw, and probably a lot of deaths, were due to not following standards,” said Scott Douglas of Seattle, Washington.
Another challenge is scant information on soils, slopes and foundations. “These drawings always show houses sitting on a nice flat piece of ground,” said Ingham, raising a copy of a Nepali building guide.
“Yet we know it’s not true. If we look at these guides, they’re very, very thin on anything about foundations. There’s a lot more attention to what’s above ground,” he added.
Many structures failed when they slipped down hillsides or sank into the ground, collapsed or tilted because of liquefaction, a process in which soil behaves like liquid during an earthquake.
“I hope the government will spend some time and money updating geological maps with the hope that the hot spots of liquefaction or soil movements could be identified and acceptable solutions developed,” Schultz said.
It should also be a top priority to develop standards for remote locations using locally available materials that can allow rural people to build safer homes affordably, they said.
In addition to structural assessments, they have also been engaged in plans to stabilise Hanuman Dhoka.
“I’ve found everybody here to be incredibly gracious and positive,” said Sonny Fite of Minneapolis, Minnesota. “Without those attitudes and characteristics, we wouldn’t have been able to have such a successful work experience. The positivity, energy and resilience of Nepali people in face of this challenge is encouraging, and that’s the fuel you need in moving forward.”
Published: 06-06-2015 10:36