Steel construction problem, overhead crane rail 3

[johg]

We have some problems with the bolted connection in our steel construction. Due to the overhead cranes the construction is not static. Due to that fact there are some issues.
I would like to discuss these problems and even the correction on these issues.

It is a real challenge to find the right solution. We have some experts to look at it, but not very satisfying.

 

[hokie66]

johg,
I would include the bolts themselves as suspects in your investigation. Bolt quality can vary widely, particularly from some of the Chinese manufacturers. There may be problems with bolts from other locations as well, but the Chinese bolts are the ones I know about.

 

[ToadJones]

We call all recite the words of Fisher from Design Guide 7.
It is not the be all & end all document on design of crane buildings particularly when dealing with very large OTC's IMO; and particularly when dealing with thermal issues.

Bottom line in these buildings is something has to give. So you must design to allow for movement. Making flexible cap plates may be one way to achieve this but that comes with problems as well.

These buildings need to be designed with intimate knowledge of the cranes themselves. They are an extension of that machine. Reading design guides is not enough.

 

[pilesmakesmiles]

Are the bolts failing by yielding (suggests a strength issue) or in a brittle manner (suggests a material/fatigue problem).

Have you checked any other connections for problems? We've done a lot of inspections of buildings with cranes hung from the roof trusses, and it's rare that we DON'T find loose bolts all over the place.

In the most recent building we looked at, we arranged for all the bolts at key locations to be checked and tightened until some permanent remedial works are carried out. Since that has been done, crane breakdowns have reduced significantly. Might just be a coincidence