The Wolf Trap Foundation has filed a $3 million lawsuit in Fairfax County against the firms that designed and constructed its Filene Center, where a gaping eight-foot crack in a steel support beam last year threatened "a collapse of the entire roof structure," according to the suit.

The lawsuit is the first to assign blame for the crack and names Dewberry & Davis, the architectural and engineering firm that designed the structure, and G&C Construction Corp., the chief contractor. It claims that the Filene Center was not "properly or adequately designed" and that there were "numerous instances of improper and inadequate construction."

The crack in the structure of the open-air center was discovered on Jan. 24 last year and buttressed in time for the opening of the center's season on June 8. The new theater had opened six months earlier after being rebuilt because of a 1982 fire.

"The $3 million reflects money actually spent to remedy the problems and a projection of what it will cost to complete remedial work," said Michael E. Jaffe, an attorney for the foundation, in the suit, filed in Fairfax County Circuit Court.

James C. Gregg, an attorney for Dewberry & Davis, a prominent architectural and engineering firm in Fairfax, said he had no comment yesterday. Sidney O. Dewberry, the managing partner who is named in the suit along with Richard Davis, did not return a reporter's calls.

Douglas P. Rucker Jr., a Richmond attorney representing the G&C Construction Corp., which is located in Fairfax, said, "It's my belief that the evidence will show that there are some definite design problems. The evidence will also show that G&C was not at fault."

The Wolf Trap Foundation was incorporated after Catherine Filene Shouse's gift of about 100 acres of farm land in Vienna and the funds for the construction of the original open-air theater, which was the nation's first national park for the performing arts.

"The method of designated construction which was employed at Wolf Trap is not unusual in the private sector, where completion of the construction project is important within a short time frame," Ben Biderman, the Park Service architect who oversaw the reconstruction, said yesterday. That method involves starting construction before the design is completed, Biderman said.

Biderman said that the building would not be accepted by the Park Service, which owns it, until "run of the mill" corrections have been made. "We're not a party to any litigation . . ." Biderman said. ". . . our only concern is that we continue to have a sound, safe building when it's turned over to us."

The foundation's lawsuit claims that "errors and inadequacies" in the Dewberry & Davis structural design resulted from a failure to perform necessary and customary calculations of the loads and stresses that would be placed on the box girders, including the effects of cold temperatures.

The suit also claims Dewberry & Davis failed to specify adequate testing procedures and to detect errors and deficiencies in G&C shop drawings and construction. The suit charges that the general contractor and its subcontractors "employed and allowed defective work and materials" to be used.

Other errors and inadequacies, the suit claims, resulted from Dewberry & Davis' "exaggeration of its own expertise and its failure and inability to discharge its responsibilities with the care and thoroughness customarily required and expected of architects and engineers."

National Park Service documents obtained by The Washington Post after the discovery of the flaw last year said that the foundation ignored park service warnings that shoddy workmanship could plague a rapidly rebuilt center.

Foundation officials have not denied in the past that they pushed for rebuilding the center quickly after the original was destroyed by fire, but they said that it had nothing to do with the crack. The reconstruction was financed with $18 million in grants and loans from the federal government and with private funds raised by the foundation.