Officials of the main engineering firm for the city's new Municipal Center at 14th and U streets NW defended the building's walkways as safe yesterday and said a consulting engineer who concluded they might collapse was misinformed.

Department of Public Works officials reacted last month to a report by the consulting engineer, Carl C. Hansen, by erecting temporary supports under the walkways and instructing VVKR Inc., the chief engineer for the project, to design new permanent supports.

R. Randall Vosbeck, president of VVKR Inc., acknowledged that the original design for the concrete beams that support four interior walkways was flawed, but he said yesterday that Hansen's report was unfairly critical of measures taken to strengthen the beams.

Vosbeck said that steel rods that were installed inside the beams were much stronger than Hansen estimated. Hansen, who was hired by the District to assess the soundness of the walkways, estimated the rods could handle 60,000 pounds per square inch. Vosbeck said they can carry up to 105,000 pounds per square inch.

Vosbeck also said that Hansen questioned whether the rods had been properly welded to steel plates that bracket one end of the beams when "the welds had been X-rayed and were shown to be sound."

Hansen said yesterday that "an X-ray would not necessarily detect any weakness" in the welds. He said that while the rods may be stronger than he estimated, "there are . . . other problems" that lead him to question whether the walkways will hold.

Hansen said he had asked the Public Works Department for more information about how the beams had been reinforced before he prepared his report "and I didn't get it."

He said he went on the information he had because "I felt a certain amount of urgency to get my report in. We can't afford to take chances with anybody getting hurt."