posted on August 26, 2013 |
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The Ranza Plaza building collapsed on April 24th, 2013, killing more than 1100 people and injuring 2500 more. One of the most tragic parts of this disaster is that there were clear signs the building was unsafe. Workers were told to continue anyway, but they weren’t told by engineers.
The building was located just outside the capital city of Dhaka, in Bangladesh. Countries with cheap labor, like Bangladesh, can produce goods at a low monetary cost, but as is clear, there are other costs to consider. The concern in these countries comes from inadequate inspection and oversight. This is compounded by failure to report modifications to structures. Without proper engineering consult, the results can be disastrous.
As reported in the New York Times, the building was being expanded without permits. Significantly expanded. Apparently, the top four floors were constructed without approval. Also, the building was built to house shops and apartments, not factories. There were five factories operating in the building at the time of the collapse. The heavy machinery and associated vibration, combined with an already overloaded foundation proved to be too much.
Good structures will give warning when something is wrong. Ductile materials, such as steel, will deform before breaking. They actually strengthen when deformed. This gives time to react. Concrete is a very brittle material and cracks can propagate quickly. That is why it is typically reinforced with steel rebar. Concrete is weak under tension, and the steel helps keep it from failing catastrophically if it does begin to fail.
Even if reinforced, concrete can crack if the rebar starts to stretch. This signals a critical situation. A large crack was reported by inspectors on the exterior of the building ahead of the collapse. This prompted some of the tenants to leave the structure, but the garment factory supervisors declared the building safe, and ordered the workers to continue.
In countries with minimal regulation, many builders will take shortcuts on the concrete itself. The mixture will use a disproportionate amount of cheap ingredients such as sand. This makes the concrete weaker. In many cases, steel reinforcement is not used to reduce cost further. Instead, the practice is to simply use more concrete. Inadequacies in the materials and the design lead to catastrophes like the Ranza Plaza collapse.
Whenever modifying a structure, or using it for purposes other than originally intended, it must be re-evaluated for suitability. This obviously has major implications for safety when regarding buildings, but many other cases are important too. Something to consider the next time you’re considering adding your personal touch to something around the house.