Metal Structures

Sign-Structure Repair

Several states utilize welded aluminum structures to support freeway and throughway signage. These structures are continuously battered by wind and vibration loads, freeze-thaw cycles, and other environmental conditions. These extra loads have put undue stress on the welds which has caused them to be damaged. In some cases, the welds at the joints of these structures have either partially or fully cracked. The exact failure mechanism has not been isolated, but the need to reinforce them is urgent.

There are dozens of different shapes, angles, and sizes of joint members, so construction of reinforcement clamps wasn't practical. Welding was not preferred, as that was the problem in the first place, and field welding over traffic was difficult at best.

In cooperation with universities and state agencies, Air Logistics has developed and tested a field applied FRP repair system which is currently in use to repair the cracked joint welds. Several joints with cracked welds were cut from dismantled sign structures and repaired with the FRP repair system. these samples were tested a the University of Utah in a series of tension tests and proved to be as strong as sound aluminum welds.

A second series of endurance tests was also conducted. In this series, two test specimens were set up and subjected to long term cyclical loads. The first included a composite reinforcement over a failed weld. The second specimen was a sound weld with no defects.

The final results were compared and it was determined that the composite reinforced welds performed as well as, or better than, a sound weld with no defects under a cyclical load.

A thorough field procedure has been developed and implemented for this repair. Surface preparation is crucial, and the procedure includes specified cleaning chemicals, abrasives, and safety gear. By using a kit concept, all the materials needed to do the job are readily available. Technicians are trained and certified for installations and most jobs can be done in less than one day.

Aquawrap® is the simplest, most cost-effective repair you can find.