Jan. 12, 2012 marks the second anniversary of the catastrophic earthquake that ravaged Haiti. This story originally appeared on the Cockrell School of Engineering website.
After the devastating earthquake in Haiti in 2010, the children of the Louverture Cleary School were too scared to return to their classrooms and dorms. Days had passed and they were still sleeping outside, fearful that an aftershock or tremor would collapse the buildings around them.
Patrick Moynihan, the school's director, sought help from Dr. Wassim Ghannoum, an assistant professor in civil engineering. Moynihan emailed photos of the buildings to Ghannoum so he could make a preliminary determination of their safety. Ghannoum, whose research focuses on earthquake engineering and the collapse of reinforced concrete structures, judged the school's buildings safe enough to use, pending further inspection.
But the children were still too frightened to return indoors.
Help was soon on the way, however, as a group of engineers, including Ghannoum, headed to Haiti. This relief effort, under mandate from the United Nations, was mounted by the Appropriate Infrastructure Development Group and the Multidisciplinary Center for Earthquake Engineering Research, organizations which had appealed for structural engineers fluent in French to go to Haiti and assess the safety of key surviving buildings.
Upon arriving in Port-au-Prince, they met school representatives and proceeded to the site.
"We inspected all the school's buildings that evening before we could stay in them, and then we stayed in their worst building," Ghannoum said. "We did this to reassure the students, many of whom had lost family members, that it was safe to go back in the buildings. That night they all slept inside and even though we had a minor aftershock the children did not panic."
That was the beginning of a week-long effort by a team of 10, which included both engineers with earthquake expertise as well as Haitian-born engineers familiar with local logistics. Using standards set by the Applied Technology Council, they spent 10-30 minutes performing initial evaluations of approximately 115 buildings, labeling them green (safe), yellow (safe with restrictions) or red (unsafe).
They focused on essential infrastructure -- hospitals, government buildings, telecommunications centers -- that were necessary to get recovery efforts organized and functioning and the Haitian government operational again. While more in depth assessments will be required, this initial evaluation was a critical first step toward getting people back to work.
"The main difficulty was that we did not know what was inside the concrete," said Ghannoum. "The amount of steel reinforcement is critical. We worked on the assumption that there was practically no steel ... That was the challenge, working blind, so I always assumed the worst case."
As he went from building to building, what Ghannoum could see was not encouraging.
"We saw the worst case scenario in substandard construction," Ghannoum said. "Usually we use deformed steel bars in concrete, which helps them bond to the concrete. Most of the bars we saw, maybe 80 percent, were smooth so they just slid through the concrete. There was practically no confining steel to keep the concrete intact during shaking. The concrete itself was very sandy, with very little cement. We could crumble the concrete with our hands."
The geography and geology of the Port-au-Prince area also worked against the city's residents. A major fault line, the Enriquillo-Plantain Garden Fault, lies not far from Port-au-Prince. Many of the hardest hit areas of the city were built on soft coastal deposits and artificial land fill, which are particularly vulnerable to ground shaking.
Ellen Rathje, another civil engineering professor with the Cockrell School of Engineering, led a team of engineers and scientists who examined the damaged areas to understand the relationship between the area's geology and the damage wrought by the quake.
"Each earthquake represents a living laboratory in which we can better understand how infrastructure withstands earthquake shaking," Rathje said. "As a geotechnical engineer, I am interested in ground failure due to soil liquefaction, the relationship between soil conditions and enhanced ground shaking and damage, the influence of fault rupture on overlying infrastructure, and the generation of landslides due to ground shaking."
Rathje and her associates used aerial photography, digital photos and GPS devices to document the location and extent of the damage. They also used a cone penetration device and surface wave testing to measure soil properties.
"Time is a factor because weather or clearing of debris can remove evidence of what actually happened during the earthquake," she said. "Developing the appropriate interpretations of what happened requires documentation of the effects as soon after the earthquake as possible."
The extent of the destruction in Port-au-Prince was due in large part to poor construction methods and quality control, which points to one of the many challenges in rebuilding.
"You can make concrete construction seismically resistant -- this is not inherently difficult -- but it costs more and requires seismic design expertise," Ghannoum said. "Haiti has no structural design codes and its engineers do not have the necessary expertise. We could not find any accreditation system for engineers like here in the United States. So any reconstruction effort in which local engineers would participate will require implementing design codes and educating Haitian civil engineers in using them."
The earthquake was a significant setback for Haiti, but there is hope that the sheer magnitude of this disaster will lead to changes that will benefit Haitians in the future. By offering their assistance and engineering expertise, Ghannoum and Rathje, as well as many other members of the engineering community, aim to help Haitians recover and build a stronger, more resilient Haiti.