Renovation of the Boeing 747 maintenance hangar
Coincident to the delivery of the first jumbo jets to Deutsche Lufthansa AG in 1970, maintenance hangar V of the Frankfurt airport, which had been specifically designed for this type of aircraft, was put into use.
Having a width of 320 m and a length of 100 m the hanger can accommodate a total of 6 Boeing 747s. These span widths as well as a hangar height of 23 m to 43 m imposed significant demands on the structural design of the hangar. The loads of the ceiling shell are transferred into the side-mounted trestles or the central frame by means of bracing wires and suspension straps made of pre-tensioned light weight concrete. Subsequently, these trestles transfer the loads into the soil via a concrete strut frame.
In order to examine the historical development of the corrosion protection of tendons used in the trestles after more than 30 years of service, and carry out possible renovation works in time, Lufthansa Technik AG Hamburg searched for a strong partner in the field of stressing technique for this significant undertaking. As a provider of stressing systems and tendon renovation services, DSI GmbH has been able to gather long-term experience in this field.
The investigation concept required locating and the endoscopic investigation of tendons. Should inadequately grouted tendons be discovered, the corrosion protection was to be restored for the next few years using vacuum grouting. More than 2,750 drill holes were made to carry out the endoscopic investigation, but only in about 200 areas vacuum measuring with subsequent vacuum grouting was required.