By Jonny Lupsha, News Writer

A video taken two days before a fatal hotel collapse shows the building’s structural faults, CBS affiliate WWLTV reported. The Hard Rock Hotel in New Orleans was under construction when it caved in from the top, killing several workers. Load-bearing structures can be dangerous without proper engineering.

The video in question was filmed by a hired worker who narrated, in Spanish, the failings of the structure. The video clearly shows one of the temporary posts buckling under the weight of the concrete floor above it. Whether the cause of the collapse was the building’s design, the lack of support beams while the concrete cured, or other factors remains to be seen. Investigators are searching through the rubble to find more information on exactly what happened even while several lawsuits are being levied against the construction company in charge of building the Hard Rock Hotel. Several employees are said to have voiced their concerns about the structure but were told to keep working. Load-bearing structures face multiple risks that need to be addressed long before a building opens for use.

Getting a Building up to Code

According to Dr. Stephen Ressler, Professor Emeritus from the United States Military Academy at West Point, “The International Residential Code identifies five principal categories of load that are most relevant to our understanding of residential construction.” For these purposes, load means any force applied to a structure like a house or hotel.

Those categories of load, he said, are dead load, live load, snow load, wind load, and seismic load. Dead load involves the entire permanent weight of the building, from beams and columns to windows and permanent fixtures like bathtubs.

“Live load consists of the weight of people and all their movable stuff, like furniture, books, and housewares,” Dr. Ressler said. More on live load in a moment.

Snow load is attributed to the roof of a building, not its foundation, and obviously involves the weight of snow that any portion of a roof must be able to support without collapsing. Wind load and seismic load involve the forces exerted on a building by wind and earthquakes, respectively.

All five categories have minimum load requirements to meet in order for a building to pass inspection—and all are measured in pounds per square foot (psf).

Looking to Live Load for Answers

The best way to understand how load-bearing elements of a building work is by looking at live load.

“According to the International Residential Code, my living room floor should be designed to support a live load of 40 lbs. per square foot, applied to the entire floor surface,” Dr. Ressler said. However, anyone who’s been to a crowded house party knows that people standing shoulder-to-shoulder weigh far more than that. Dr. Ressler gave an example of six people standing as close as they can to each other, weighing a total of about 1,000 lbs., for an average of 85 psf on a floor.

“A true 85 psf live load applied to my living room floor would require enough people to fill my entire living room from wall to wall, all packed as tightly together as this group of six,” he said. “That would be about 200 people. But this simply couldn’t happen—in part because a substantial portion of my living room floor space is already occupied by furniture.”

As a side note, Dr. Ressler pointed out that people do stand this close together in the hallways and lobbies of other types of buildings, like theaters and auditoriums. “Not surprisingly, the code-specified loading for public corridors and lobbies is not 40 psf, but 100 psf—which actually gives us a nice margin of safety beyond the 85-psf loading we just derived.”

Dozens of people are often involved in constructing even a small home, let alone the hundreds who work on a larger building. Whichever person or people ultimately caused the Hard Rock Hotel to collapse remains to be seen. However, the physics involved very obviously spell out a failure to properly support the dead load of the building to the aforementioned International Residential Code psf specifications even before the building was finished, ending in a deadly example of why structures must be assembled up to code.

Dr. Stephen Ressler contributed to this article. Dr. Ressler is Professor Emeritus from the United States Military Academy at West Point. He earned a B.S. from West Point and an M.S. and a Ph.D. in Civil Engineering from Lehigh University, as well as a Master of Strategic Studies from the U.S. Army War College.