Engineers Say Prevalent, Discredited Building Technique Raised Mexico’s Quake Deaths Garance Burke - Insurance Journal
go to original October 12, 2017

This Sept. 24, 2017 photo shows an apartment building that was partially destroyed during the 7.1 magnitude earthquake, on Emiliano Zapata Avenue in Mexico City. The eco-friendly apartment building with its wood-paneled balconies and a solar-paneled roof collapsed when a corner column failed, and the flat-slab structure pancaked, said Eduardo Miranda, a professor of civil and environmental engineering at Stanford and global expert on earthquake-resistant design. (AP/Miguel Tovar)

Mexico City officials were widely lauded for tightening their building codes after thousands died in the 1985 earthquake. But they left out one crucial reform: a prohibition on the building technique that caused 61 percent of the building collapses in last month’s magnitude 7.1 quake, which killed 369 people and blanketed tree-lined avenues in rubble.

The concrete slabs used to build floors and ceilings can be cast to include some rebar for reinforcement, and give builders greater flexibility in room layout and allow for higher ceilings.

But in an earthquake, without reinforced concrete walls or lateral bracing to resist forces pushing structures sideways, buildings with that design can move too much. The columns, and connections between the slabs and columns, can easily break, prompting collapse, as was the case at a school where 26 people died, most of them children.

“We have known for 30 years that this system killed lots of people, so why are we still using it?” asked Eduardo Miranda, a professor of civil and environmental engineering at Stanford and global expert on earthquake-resistant design who compiled the data. “The right decision after ’85 would have been to completely ban this kind of construction. We could have saved lives.”

Experts concur that the devastation caused by last month’s earthquake in the city of 8.9 million people could have been much worse had the building codes not been so strong, but it also has forced an uncomfortable conversation about their shortcomings. Now, as experts race to toughen standards to retrofit hundreds of damaged buildings, they are grappling with the reality that corruption has allowed hundreds of structures to be built outside the rules atop the soft soils of Mexico City’s ancient lakebed.

Read the rest at Insurance Journal

Related: An Earthquake of 5.1 on the Richter Scale was Registered in Mexico Today (novinite.com)

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