THE SEISMIC HAZARD WITH SUSPENDED CEILINGS IN OUR SCHOOLS AND SOME PRACTICAL SOLUTIONS
United Nations Centre for Regional Development-UNCRD, for decades has been playing an active role in making sure our schools are safe for learning and building resilience in communities through climate change adaptation. The project on “Reducing Vulnerability of School Children to Earthquake” under the School Earthquake Safety Initiative (SESI) is an example of how different stakeholders can be involved in retrofitting our schools with ecological products, resilient ceilings, smart devices, sustainable roofs, and climate change education. Suspended ceilings are a feature of modern commercial and residential buildings in Trinidad and Tobago and because its more economical to other ceiling installations majority of the ceilings in our schools are suspended (gypsum tiles). Some of the problems with suspended ceiling in our schools include; dislodged and broken ceiling tiles, separated grid members and broken connections, ceiling grid falling on people by failed perimeter wall angles. Suspended ceilings have been vulnerable to damage from earthquake, sustaining panel loss and grid failure in moderate earthquakes, even in absence of major structural damage. Such damage has resulted in business interruptions, block of egress during evacuation, and could present life-safety hazard.
CEILING DAMAGE IN RECENT EARTHQUAKES
According to damage reports following previous earthquakes and particularly the recent ones in New Zealand, suspended ceilings suffer considerable damage in earthquakes even when the structure remains almost undamaged. The elements showing considerable vulnerability to ground motion include cross tees and splices in main tees connections at perimeter fixings/wall angles. There is the possibility of buckling of tees under compression but the system mainly loses integrity when connections fail or the perimeter ledge provided for supporting the tees is insufficient. In some cases, the absence of sufficient perimeter hanger wires and spacer bars causes spreading of tees and downfall of tiles. Other common forms of damage observed include damage due to the differential movement of ceiling relative to the structure at perimeters or vicinity of rigid penetrating elements such as columns or sprinkler heads, interaction with services and mechanical systems above the ceiling or heavy fixtures lacking independent support.
Safer schools are necessary to prevent lives of children during disasters. The concept of school safety, however, is not limited to preventing the collapse of school buildings in disasters, and safety of teachers and students, but rather extends to meet the broader goal “disaster risk management”. This is because today’s children are tomorrow’s adult citizens. What they learn about safety today significantly contributes towards development of “disaster risk resilient communities” for long run. Here lies the importance of disaster education under school safety.
Kazunobu Onogawa Director
EARTHQUAKE RISK REDUCTION FOR SCHOOLS
Children who attend school in Trinidad and Tobago are advised by experts to “drop, cover, and hold on” if they are inside during an earthquake. This is because we are not as likely to see total structural failure as in other countries. Our buildings in Trinidad and Tobago generally do very well in earthquakes, and strict building codes reduce the risk of structural failure in our modern masonry buildings. Our greatest risk of injury during an earthquake comes from nonstructural hazards such as falling suspended ceilings, decorative pieces, fixtures, and heavy ceilings overhead. Nonstructural hazard mitigation is one of the least expensive retrofitting project for earthquake risk reduction in our schools.
EARTHQUAKE RISK REDUCTION AT WORK
Your workplace has the legal obligation to ensure that the work environment is free of hazards to employees. This includes items that may become dangerous during the seismic activities of earthquakes (such as suspended ceilings). Office buildings are known to shake and shift drastically during an earthquake turning heavy ceilings above our heads into deadly hazards.
SUMMARY AND CONCLUSIONS
Nonstructural components comprise a large portion of building inventory. In the past earthquakes, suspended ceilings have sustained damage in moderate events and in well-designed buildings, resulting in loss of life, lost of operation, and expensive repair costs. To mitigate such damage Mega Interior and Construction Limited have strict ceiling installation procedures. An alternate perimeter installation was engineered and tested to mitigate earthquake damage and lost of life. Making buildings and schools much more resilient with “Stretch Ceiling”.