MINNEAPOLIS — An engineering company that consulted on the Interstate 35W bridge in Minneapolis said Thursday it should not have to pay punitive damages because it didn’t know about the design flaw that caused the bridge to collapse in 2007, killing 13 people and injuring 145.

Attorneys representing 34 victims and surviving family members have asked to be allowed to seek punitive damages from San Francisco-based URS Corp., which they allege deliberately disregarded the bridge victims’ safety.

URS denies that, saying it was hired to conduct a specific fatigue and fracture study of the bridge, not assess whether it was designed properly.

“URS could not deliberately disregard any problem of which it was unaware,” attorneys for URS wrote in court documents filed Thursday in Hennepin County. If URS would have known a collapse was probable, it would have told Minnesota transportation officials, the filing said.

The bridge fell into the Mississippi River during a crowded evening rush hour on Aug. 1, 2007. The National Transportation Safety Board found that because of a design flaw, gusset plates on the more than 40-year-old bridge were half as thick as they should have been. Heavy construction materials on the bridge that day also stressed the undersized plates, which buckled.