Engineers have discovered why a suspended 20- by 25-foot section of ceiling at UCSB’s Bren Hall collapsed on October 10, a university spokesperson said yesterday. There were no injuries during the collapse, but an estimated 4,000 pounds of ceiling fell onto the floor of Bren Hall and had to be removed.

One of the support pins not embedded far enough in plaster, seen here right after the collapse
Rhys Alvarado (file)

The spokesperson said pins were placed in the ceiling to help support the structure, but were not embedded deeply enough within the plaster — they were embedded .75 inches into the plaster, as opposed to the recommended 1.125 inches. Because the pins weren’t installed correctly, they couldn’t hold the share of weight that was originally designated to them. The suspension wires attached to the pins were then holding an unequal amount of tension, leading to the collapse.

The collapse was investigated by Ehlen Spiess & Haight, Inc, a structural engineering firm. When Bren Hall was first investigated on October 31, a number of the support pins were found on the floor. Many of the pins were broken, and of those that weren’t broken, many were bent in half.

Cracks were found in other parts of Bren Hall, though that part of the ceiling was the only failure. The firm was concerned that other parts of Bren Hall could face a similar collapse, since the first one gave no warning, and that serious injury could occur.

Safety plans, approved by Chancellor Yang, included cutting holes in parts of the building to determine how it was holding up, and adding barricades under two- or three-story features similar to the one that had collapsed.

After some other parts of the buildings were shown to be constructed in the same way as the collapsed section of ceiling, they were removed. Failure in the pins was found in six of the seven removed structures. New plaster ceilings will be constructed over the summer to replace those sections that were removed.


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