Steel construction problem, overhead crane rail
Steel construction problem, overhead crane rail
(OP)
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.
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.






RE: Steel construction problem, overhead crane rail
RE: Steel construction problem, overhead crane rail
RE: Steel construction problem, overhead crane rail
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Steel construction problem, overhead crane rail
http://www.FerrellEngineering.com
RE: Steel construction problem, overhead crane rail
For your education, you might have a read of the CISC Publication, "Crane Supporting Steel Structures: Design Guide" by MacCrimmon. Also some of the publications by James Fisher.
RE: Steel construction problem, overhead crane rail
Thanks for the information so far.
RE: Steel construction problem, overhead crane rail
RE: Steel construction problem, overhead crane rail
Would like to see more info.
RE: Steel construction problem, overhead crane rail
If you can show us a photo of the general arrangement of the column/girder/crane rail intersection as well as close up photos of the girder ends, bolt failures, and the general bearing of the girder end on the support, it would be appreciated.
The cause of the broken bolts sounds interesting... to others as well.
Dik
RE: Steel construction problem, overhead crane rail
1. Broken bolt M30(fatique) connection of crane rail beam. We think the bolt takes forces due not calculated for. It is only calculated for shear. Due to crane movement it will have shear stress and tension stress.
2. Broken bolt M20(stress) connection support to crane rail beam. Due to bending an additional force other then shear will be applied.
For details see attachment
RE: Steel construction problem, overhead crane rail
At 200T, I would not have detailed it this way. Look into AIST and CISC manuals, but definitely get an engineer out there who specializes in crane runways..
RE: Steel construction problem, overhead crane rail
Whether the failure is in the bolts, the girder webs, or the connection welds, this is a problem that will be chased from one maintenance issue to the next. For example, the problem is currently identified in 2 failed bolts. Repairs for broken bolts include: reaming the holes and installing larger diameters, using higher performing bolts, extending the connection plate and installing more bolts. Strengthening the bolts means the overstress will shift from the bolts to either the girder or the connection welds.
By the way, make sure all of your bolts are installed slip critical.
RE: Steel construction problem, overhead crane rail
Prefarable The Netherlands, Germany or Belgium.
Your answers tell me that we where on the wright track. We just need to
find the wright man(specialist) for the job.
Many thanks
John
RE: Steel construction problem, overhead crane rail
RE: Steel construction problem, overhead crane rail
The structural engineer is working for same firm who fabricated the construction. We need to have an independent specialist, who is not biased in any way. We are talking about serious injuries if something goes wrong.
RE: Steel construction problem, overhead crane rail
RE: Steel construction problem, overhead crane rail
"by the way, make sure all of your bolts are installed slip critical"
Why is this the first option of some many designers?
Is it for pretension reasons? Pretension and SC are not the same.
I have dealt with many crane runway issues over the years and sometimes thought that slip critical joints were part of the problem; not the solution.
In particular, if one is using slip critical connections in a girder to column cap connection in a setting where thermal expansion is a MAJOR issue....do you design these connections for these astronomical thermal forces (+/- 100 degree F in a day)?
If you are using SC bolts in a long span runway girder how do you account for the expansion of a runway girder especially if the bracing scheme for the building does not lend itself to proper thermal expansion (seen this many times)? If the girder has to move thermally and the columns are restrained, something has to give.
I have seen 3" thick column cap plates broken almost completely from the columns on 300 Ton crane runways.
RE: Steel construction problem, overhead crane rail
RE: Steel construction problem, overhead crane rail
Thicker cap plates are more likely to crack than thin ones, far more material is yielding for a given rotation. Thinner, more flexible, is better so it goes along for the ride without yielding.
You want the bolts pretensioned so that the two faying surfaces are drawn together so that the passage of the crane doesn't force them together and cause stress cycles on the bolt.
RE: Steel construction problem, overhead crane rail
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.
RE: Steel construction problem, overhead crane rail
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.
RE: Steel construction problem, overhead crane rail
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