Sorry to bring the house down, but having just sat in on our ‘rookie’ structures prof (sorry, Chuck..!) delivering an introductory concrete lecture to our first year grad students, the collapse of a reinforced concrete frame structure in Dhaka early this week was especially sobering.
Chuck made the point that reinforced concrete has to be designed so that the steel reinforcing fails first, since it will fail slowly, in tension. If the reinforcing is too strong, the concrete itself will crush in compression, which is a more violent and sudden occurrence. Reinforcement failures give you time to notice that the structure is sagging and cracking, which in theory gives you time to evacuate the structure.
And, from news reports, that’s exactly what happened. The Rana Plaza apparently began failing a full 24 hours before its collapse, and there are reports that workers notified various factory managers of cracks in walls and girders. Unbelievably, several of the factories housed in the structure opened for business the next day despite these cracks, apparently forcing workers to go back into the building.
The Times this morning suggests that these managers were acting under tremendous financial pressure to continue business as usual, and there are obvious parallels here with the fire in a Dhaka factory last November in which workers died in part because they were locked in to dangerous workshop rooms. In both cases, clothing in the wreckage has revealed that firms ranging from Tommy Hilfiger, the Gap, and Children’s Place may have been among the brands whose price points these managers were trying to meet.
It’s unconscionable that, given everything we know about structural and life safety design, these disasters can happen in some parts of the world and not others. Being born in Dhaka shouldn’t mean that your surroundings are any less well-designed or engineered, or monitored, than anywhere else in the world. It’s hard to imagine engineers and architects tossing out their standard-issue Gap button-downs, and I’m as guilty as anyone of taking advantage of off-the-rack brands’ affordability, but given what our professions know about failures like these, we surely owe the world a better situation than these workers faced…