This talk was published in July 2010 after Heiti’s earthquake. Many people in the worlds saw the photos of the collapsed buildings in Haiti. National palace, supermarket in the Caribbean, nurses’ college and the general hospital, as well as the history of Economics and Finance building, all of them were collapsed in the earthquake. 

There were tremendous human loss in the earthquake in Haiti, but why?? Why building failed? After all , the collapsed buildings killed  220 000 people, injured 330 000 people, even cut off food and water and supplies for an entire nations. 

It was because of bad quality buildings. After the earthquake, they started bringing in earthquake engineers to figure out why the buildings collapsed to examine what was safe and what wasn’t. They inspected over 1500 buildings. The failure points were happened over and over again in the same way: walls and slabs not tied properly into columns, cantilevered structures, poor building materials, not enough concrete, not enough compression in the blocks, and so on. 

Engineers know how to build properly. There was evidence from Chile. A month later, a 8.8 magnitude earthquake hit Chile. This is 500 times the power of the 7,0 that hit Port-au-Prince. Adjusted for population density, that is less than 1% of the impact of the Haitian quake. Why? Seismic standards and confined masonry, where the building acts as a whole - walls and columns and roofs and slabs tied together to support each other. 

Thus, engineers brought more confined masonry training into Haiti, to those construction workers. They got the help to learn the proper techniques how to build safer buildings. 

This remind me the earthquake in Wenchuan in 2008. There were so many buildings collapsed as well. I believed that they learned something after that as well. 

slabs  平板，厚板