The collapse of the 12-storey residential building in Miami is tragic – but instructive.
Buildings collapse because they cannot support their loads. Loads can be categorised as short-term and long-term. Loads that are applied for a relatively short time include: hurricanes, earthquakes, collisions, and explosions. Loads that are applied for a long time include furniture and appliances, and those from human activities, like sitting, walking and dancing.
An occupied building that collapses, without being impacted by short-term loads, likely weakened to the point where it could no longer support the long-term loads.
ALL BUILDINGS WEAKEN.
A building weakens when its building materials deteriorate naturally. For example, steel reinforcement can corrode; moisture can damage timber, masonry, and concrete building components; insects can damage timber frames; and the sun’s intense heat and UV rays can damage plastics, binders, sealants, and paints.
Designers should try to reduce the rate of weakening, by selecting durable materials, and protecting non-durable materials. This tends to be done if maintenance is an important design criterion. It rarely is. For it to be, Clients should insist on it.
BUILDINGS COMMUNICATE.
Buildings that progressively weaken, normally signal that they are under stress with structural cracks. Therefore, it is critical that building cracks be accurately interpreted before any remedial action is taken.
If cracks are found to be structural in nature, then the building may need to be strengthened. If they are non-structural, then they may be sealed and painted.
Given the critical importance of accurate crack interpretation, and the limited number of experienced structural engineers to accurately interpret them, I wrote a simple descriptive book called “What Do These Cracks Mean?”. The book helps the public interpret cracks in buildings, to identify both structural and non-structural cracks.
SEE NO EVIL.
Some building owners want to know which cracks are structural, because they are concerned about the safety of the occupants. Other building owners are more concerned about attracting and keeping paying tenants, and do not want anything visible that may cause them alarm – certainly not a visible crack.
A building owner may be tempted to instruct that all visible cracks be sealed and painted over, to hide them from the view of occupants. This gives all parties a false sense of security. If a structural engineer inspector was unaware of repaired structural cracks, then the engineer may inaccurately report that the building is not under stress – when it may be under severe structural stress.
This tragedy in Miami should teach us not to ignore a building’s crack-warnings. Maintenance persons should never seal and paint over cracks – until they have been interpreted as non-structural.
SPEAK NO EVIL.
During my first term as president of the Barbados Association of Professional Engineers, I was contacted by several Engineers, who were visiting Barbados. They were alarmed at the structural condition of the hotels in which they were staying, and asked what sort of outfit we were running.
I admitted that I had not inspected hotels in Barbados – only outside of Barbados. So, I promised them that I would visit the hotels in question. I was appalled at what I observed. I immediately contacted the Ministry of Tourism, and the Barbados Hotel and Tourism Association, and we agreed to a strategy on the way forward.
HEAR NO EVIL.
I was to privately inform the hotels’ management of what I had observed, and suggest that they get it independently inspected and addressed. To my surprise, the hotels asked me to put my concerns in writing. I was elated that they were treating this with the seriousness that it demanded, and I hand delivered each letter.
Their response was alarming. I received letters threatened me personally with legal action, if I disclosed what I had seen. This happened near the end of my term as President. After seeing how harshly I was treated, the new President chose not to attract similar threats, and the program was abandoned.
BREAK FOR YOURSELF.
There is no requirement for structural inspections of buildings in Barbados, neither during nor after construction. Buildings generally appear to be unnecessarily designed and constructed to be high-maintenance – in the environmentally harsh Caribbean environment. That maintenance of buildings is a low-priority item, is evidenced by the number of abandoned buildings around Barbados.
Given that some building owners seem to think that structural cracks will magically repair themselves with sealing and painting, all building occupants must attend to their own safety.
BREAK FOR YOUR NEIGHBOURS.
If they see cracked concrete, corroding steel reinforcement, or deformed structural steel, especially in a multistorey building, they should insist on having it inspected.
If they see someone repairing structural cracks by sealing and painting, they should inform them that if they continue, and the building collapses, they may be charged with manslaughter. If they persist, then they should be informed that their now intentional act may upgrade the charge to murder.
The blogmaster invites you to join the discussion.