The building had no beams because it is a 2-way flat plate design. It was not a mistake as eluded to in the video. This design and construction method is very popular in the US because it simplifies the formwork, uses less concrete, and therefor is faster and cheaper. I’d be willing to bet the new condo next door is built with 2-way flat plate construction, although it’s probably post-tensioned with better connections.
With that said, the governing failure mechanism is punching shear, which is not a ductile failure mode…it happens suddenly. Beams, drop panels, and shear walls would have helped. There are many ways this building could have been better, stronger, more redundant. But developers want the cheapest building allowed by code. Contractors want the easiest building method. Architects love the ceiling height and views created by this method too. The end user, whom the building is supposed to protect, is not involved in the building process. So what incentive is there for an engineer to design something better if it costs more and is more difficult to build?
People assume that if it meets code then it’s safe.
But life safety is only one goal of the code committee’s who write the code and it is balanced with cost of construction. Concrete has to stay competitive with steel and vice versa. Post-tension has to be competitive with steel and RC concrete,etc. There appears to be a false presumption by the public that buildings are over-designed and redundant, but that’s not really the case. In reality they are rarely, if ever, tested to design loads and can generally sit there half empty with poor maintenance for a long time.
