Source: http://enr.construction.com, October 31, 2011
By: Jim Parsons
Cracks in 13 cast-in-place pier caps supporting three bridges on the new Intercounty Connector toll highway in Maryland may be the result of a design flaw, according to the Maryland State Highway Administration.
More than 40 cracks—ranging in width from 0.005 to 0.035 in. and in length from 7 in. to 3 ft, 8 in.—were discovered during a routine MSHA close-out and acceptance inspection of the ICC’s $2.56-billion, 7.2-mile first phase.
The project’s first-phase contractor is Intercounty Constructors, a joint venture of Granite Construction Co., Watsonville, Calif.; Corman Construction Inc., Annapolis Junction, Md.; and G.A. & F.C. Wagman Inc., York, Pa.
Parsons Transportation Group and Jacobs Civil, both headquartered in Pasadena, Calif., provided design services.
MSHA spokesman Ray Feldmann says similarities in the cracks’ location and pattern spurred an investigation that eventually grew to include the joint venture’s contractors and designers as well as Jenkins Engineering Co., Towson, Md., an independent structural engineering consultant hired by MSHA.
Though the probe is ongoing, investigators discovered that a methodology used for calculating the amount of reinforcing steel on bridges with connected pier caps apparently was applied to the three steel-girder bridges, which are not connected to their pier caps.
“A different methodology should have been used,” Feldmann says, adding that the calculations raised no concerns during MSHA’s design review.
Parsons Transportation Group declined to comment.
Intercounty Constructors is reinforcing each pier cap with two 0.6-dia, grade- 270 post-tensioning strands, allowing the bridges to remain open while the investigation is completed and the joint venture develops a long-term corrective strategy.
“The question under investigation goes to the longevity of the bridges’ lifetime,” says Carla Julian, an Intercounty Constructors spokeswoman. She says the temporary modifications are being installed as a precaution, though inspections and reviews of the calculations show the pier caps to be safe.
No other flaws were found in the more than 60 bridges along the entire 18.8-mile project, which is scheduled for completion early next year.