Industrial

Heavy equipment installations

Runway cranes and rail girders provide a source of vibration and material fatigue concerns.  In this case an inappropriate top flange restraint bracket midspan (needed for design stability of the rail runway girder) had worked its way loose from the adjacent precast tilt-panel wall.  The problem was noticed when a heavy plate product lift caused the over head crane to oscillate in a swaying motion (perpendicular to the rail) well after the load crane movement had been stopped at the controls.  In the video above you can see the 15-20mm of movement driven just by hand manual force.

The bracket connection originally set with mechanical "dyna-bolts" were replaced with chemical epoxy set bolt fixings.  The brackets used which are fairly short are butt welded to the edge of the girder top flange.  Given the cantilever flexure required for ongoing restraint, weld inspection will be needed to monitor potential fracture concerns.  We would prefer to see some form of slotted connection through the beams vertical web to provide the required lateral restraint and thereby allow the attendant vertical sag deflect under load.

We recommend asset owners conduct their own detailed inspection of the crane installation in-service to assess current working conditions and allow a benchmark for future monitoring inspections.  Crane servicing contracts are useful but did not prevent the disruption to production once the problem was first observed by the owner.