When “Raising the Roof” Results in “Lowering the Floor”
College partygoers at Clemson University got more than they bargained for when celebrating the school’s homecoming last weekend.
Thirty students were injured when the common area floor collapsed at an off-campus Clemson apartment clubhouse building. It was a tragic reminder of gravity, forces and structural limitations of common construction materials. Thankfully the injuries reported to date are not life-threatening. Witnesses who were on the floor below the dancing have said they could see the ceiling arching, and bowing or flexing as the dancing was becoming rhythmic; they moved to safety. Witnesses from upstairs in the dancing room explained that they were bouncing with the floor, they just didn’t think it would fail.
The catastrophic failure did indeed occur, more than likely as a result of overloading the designed gravity load capacity for this structure. The gravity load is made up of the dead load combined with the live load. The dead load is the non-dynamic forces that place continuous and permanent force on a structure, meaning the structure itself. The live load is temporary or transient forces that act on a building such as people, furniture or other things that move into or through it.
In the coming days and weeks the local building officials, as well as State Engineers, will evaluate the failure forensically, to determine the failure causation. The reports from partygoers described a few hundred attendees; that is not to say that they were all in the same room at the same time. However, from photos and videos, it appears to be a quite consolidated crowd increasing the load per square foot. Todd Steadman, director of the city of Clemson’s planning and codes department, said the posted occupancy for the upstairs of the clubhouse was 135 people. Property representatives have said it is not normal to have gatherings such as this in the clubhouse.
It is possible that the original structural design is sound and the construction techniques and materials were appropriate and did not contribute to the cause of the failure. There is a high chance that it could have been caused by an overload of the designed capacity, for this occupancy type and its maximum anticipated load. Further contributing to this failure, based on firsthand account descriptions, could easily be the effects of resonant frequencies which occurs when a physical system is periodically disturbed at the same period of one of its natural frequencies. As the Homecoming partygoers bounced with the music, people witnessed the floor moving up and down and continued to bounce in unison, they may have inadvertently caused to the failure.
While the celebrators were trying to “Raise the Roof”, they may have, by their own doing, unintentionally and instead lowered the floor.
** Photo Credit: Fox Carolina