Engineering a response to the Beirut blast

On August 4, 2020 the Lebanese capital of Beirut was rocked by an explosion that could be felt around 150 miles away on the island of Crete.

The blast, which took place in the city’s port area, was caused by the explosion of nearly 3000 tonnes of ammonium nitrate which had been stored in the vicinity for several years.

According to OCHA, the UN’s humanitarian affairs office, nearly 180 people were killed and over 6,000 injured in the blast, which destroyed most of Beirut’s port and surrounding neighbourhoods, leaving thousands homeless. The explosion damaged six hospitals, 20 health clinics and 120 schools.

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“The scale of the loss from the Beirut explosions is so vast, it is likely every single person in Lebanon has been touched by this terrible event”, said Najat Rochdi, the UN Deputy Special Coordinator, Resident and Humanitarian Coordinator, Lebanon.

The international response was as awesome as the supersonic shockwave that radiated from the blast, with numerous organisations including the International Red Cross and Red Crescent Movement mobilising efforts to restore a semblance of normality to the citizens of Beirut. Among them were members of SARAID (Search and Rescue Assistance In Disasters), a volunteer force that heeded the call of Lebanese local authorities and sent two teams to the stricken city.

After arriving in Beirut on August 6, SARAID set to work with local engineering teams and international Urban Search And Rescue (USAR) teams to assess the impact of the damage and help local engineers make the decision as to whether buildings are safe for occupation or not.

Among them was SARAID’s Suzie Cooper, a structural engineer at London-based engineering practise Elliot Wood who described the damage, which is visible throughout Beirut, as ranging from completely flattened buildings to glass damaged facades.

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“The scale of the destruction around the port is shocking,” she said via email. “The damage decreases quite rapidly from the port, but even 6km out there is still glass damage to some of the buildings.”

To hit the ground running, SARAID had seven engineers working in the UK to provide remote technical support. Cooper said that disaster zones are hectic places to be and that the Municipality of Engineers in Beirut were keen to start structural assessments as quickly as possible once SARAID had arrived.

“This meant we had limited time to understand their current processes and provide advice,” she said. “It was vital having a team back home who were able to research in country construction methods, collate information from previous structural assessment responses and review documents from the Lebanese authorities.”

Cooper added that towards the end of the deployment SARAID compiled a proposal document to aid the handover of damage assessment coordination to the Lebanese authorities. It included a summary of SARAID’s advice which has helped local engineers to continue the job they had started after the explosion.

“The team back home were instrumental in putting this together.” She said. “This left those of us who were in-country time to liaise with the local engineers as well as coordinate the international engineers. This ultimately led to a quicker implementation of a coordinated and effective structural assessment procedure.”

SARAID is staffed by volunteers and relies solely on public donations. It has been active for 20 years and has provided assistance following disasters that include earthquakes in Haiti, Sri Lanka, Albania, and Nepal. Cooper explained that whilst the forces of a blast act differently to those from an earthquake, the detailing in buildings designed for seismic loads will help those structures resist forces from a blast.

“Both events will impart large lateral forces onto a building,” she said. “In addition to this, as a blast engulfs a building it pushes the floor slabs upwards, the opposite direction than they would have been designed for. Damage from this is key to look out for.”

She added that structures built with different materials are affected differently by the two events.

“As concrete structures have a large inertia force, they will likely fair better in a blast,” she said. “A blast happens instantaneously; by the time the mass of concrete is mobilised, the force is over. This is different from seismic loads which occur over a period of a few seconds.”

In total, SARAID had 11 teams of international engineers assisting the local engineers with the structural assessments.

“Out of the data we received back from these teams, 88 per cent of buildings were habitable,” said Cooper.

She added that Beirut’s infrastructure is highly developed and that quality of construction and adherence to design codes will have increased the city’s resilience to the blast.

“How they now cope with the recovery is dependent not only on the local authorities but also how the international community come together to help this city,” she said.