Design, Builders Blamed for Roof Collapse at School

An independent engineering analysis of a roof collapse at the Cal State Long Beach music complex blames the project’s designers and builders, and also suggests that the university misread early warning signs of the roof’s instability.

The five-month investigation, released Tuesday by Cal State officials, concluded that the 120-ton roof of the Gerald R. Daniel Recital Hall was inadequately designed and improperly constructed. The report also stated that “substantial cracking” in the plaster ceiling, detected three months before the collapse, was treated only as a “cosmetic problem” by Cal State maintenance officials.

“The cracking may have been an early warning sign that some truss members were in structural distress,” the report said.

The roof of the 8-year-old recital hall collapsed July 2, the day after a group of high school students cut short a rehearsal when instructors noticed half-inch cracks in the walls and falling plaster. No one was injured in the collapse, but the incident led to the indefinite closure of five other buildings in the $6.3-million complex because of safety concerns.

“Enough things went wrong that after eight years the building got tired of holding up that kind of load and got tired of that kind of overstress,” said Lynn Bockemohle of Englekirk & Hart Consulting Engineers, the firm hired by Cal State to conduct the investigation.

Cal State Long Beach President Curtis McCray said the report places in serious doubt the safety of two other music complex buildings constructed with the same style roof. The buildings, among the first closed by the university after the recital hall collapse, may need new roofs before they can reopen, he said.

The Englekirk & Hart report concluded that the recital hall collapse was caused by “a loss of stability over time and conditions of overstress” caused by a combination of factors. Among those identified by investigators:

* Trusses in the roof were carrying loads as much as 158% heavier than the design intended.

* Nailing of the roof’s plywood sheathing to the trusses, the primary structural component of the roof, was inconsistent, including several areas with no nails, leading to possible stress 1,000% greater than specified in building codes.

* The plywood sheathing, which acts as a bracing system for the trusses, was also “not adequately connected” to the exterior walls.

* So-called X-braces--wood supports that connect the rows of trusses--were not installed, even though they were required by the truss manufacturer.

* The roof was not properly designed to accommodate the additional stress of several 1,600-pound smoke vents.

Investigators believe the roof collapse began in a truss near the smoke vents above the theater stage. As the weight of the falling roof shifted to adjacent trusses, the entire structure failed.

Englekirk & Hart did not lay blame for the collapse on any design or construction flaw, and concluded that “it is difficult to isolate the importance of any one” problem nearly a decade after the building was constructed. The report does state that the primary cause of the roof collapse can be traced to design, construction and maintenance problems.

“The report kind of dances around pointing fingers,” said Donald Gibbs, the Long Beach architect of the music complex. “I would take no exception with what it says.”

Donald Erb, the structural engineer hired by Gibbs for the project, and executives at Shirley Bros. Construction, the Pasadena builders, would not comment on the report. A spokesman for Trus Joist Corp., manufacturer of the trusses, would say only that the company is working with the university to repair the building.

McCray said the report, by spreading responsibility for the collapse, will help the university reach an agreement with the architect, contractor and roof system manufacturer for rebuilding the recital hall and repairing the other buildings. McCray said he hopes to have three of the buildings open by March, but officials said it could be well into 1992 before the recital hall reopens.