Strongback (girder)

A strongback is a beam or girder which acts as a secondary support member to existing structure. A strongback in a staircase is usually ordinary two-by dimensional lumber attached to the staircase stringers to stiffen the assembly. In shipbuilding, a strongback is oriented lengthwise along a ship to brace across several frames in the case of hull damage.

Some rockets like Antares (rocket), Falcon 9 used a structure called strongback to restrain the rocket prior to launch and reclined to several degrees away from the rocket to clear the launch, moment at liftoff or in some case a few minutes.