Menu
As seen from the attached photos (pic-1 and pic-3) some of the crane runway beam bolts ruptured and runway beam bottom side moved.This problem occur only in one beam connection and same connection detail used along the facility.I need to find out the reasons behind this problem and since yesterday I found several alternative reasons as I mentioned below;- fatigue. (but i don't why only this one not the others.)- some bolt clearances of 'this' produced plate is different from the attached detail and so several bolts worked alone for runway beam dynamic loads.- lateral torsional buckling has occurred and lateral force at bottom flange ruptured the bolts.Any reasons else?Thanks,Dogan.RE: crane runway beam column seat connection bolts (Structural) 29 Jun 17 17:41. My first thought is to check the bolts for proper tightening.
![]()
Crane runway beam span - ver L ver = Label ft for max member forces and deflection calc Crane runway beam span - hor L hor = Label ft Crane runway beam span - ver L 1 = Label ft for max support reaction calc L 2. Analysis & Design Software for Cranes and Craneways. For suspension cranes, the bottom chord of the runway girder is subjected to local flange bending due to the wheel loads in addition to the main load bearing capacity. The structural engineering software for design of frame, beam and truss structures, performing linear and nonlinear.
If they are not preloaded to prevent slipping, you could easily have one bolt taking the load in shear. As that bolt fails, the connection slips until the next bolt is in bearing. It cannot take the entire load and it fails, this process repeats until all the bolts have failed.Looking at the bottom photograph, it doesn't appear the shim pack is fully compressed which would support the possibility the bolts were not installed and tightened properly.The second photo from the top seems to indicate the bolts were not the correct length, thus there is less engagement than the full nut.The top photograph appears to show the wrong type of fasteners were used.Best regards - Al RE: crane runway beam column seat connection bolts (Structural) 29 Jun 17 18:02. It is not a good design per the circled connection in the pdf file. The configuration restraints the crane beam end from rotating, and therefore the bolts or the crane beam will experience fatigue damage.
Of course, it also depends on the crane work class. The connection may be not critical for light work class crane. And there is no lateral supports on the top flange of crane beam ends. For your information: “Crane-supporting steel structures - design guides” gives some example how to setup the crane connection. RE: crane runway beam column seat connection bolts (Structural) 29 Jun 17 18:10. I notice from your PDF drawing that the crane girder is made up of 2-spans @ 8m each, continuous spans.With continuous crane girders it may be possible that your end-span connection bolt failures are due to tension forces when the crane is in the opposing/adjacent span, causing fatigue effects in the connection.To troubleshoot the probable-cause it may be worthwhile to up-close visually observe the end-connection when the far-span of the crane girder is traversing under load.RE: crane runway beam column seat connection bolts (Structural) 29 Jun 17 22:17.
Hard to tell in the picture but did they fail in tension or shear? I think It's ts possible that the failure occurred from over-tightening of the bolts. From the research I've done, it's typically recommended that these bolts be finger tightened for the reasons Shu Jiang mentioned.
I have also recommend nylon stop nuts in conjunction with the hand tightening to prevent the bolts from coming loose. However with the slotted connections you need to make sure your in plane lateral force is resolved, so slip critical connections might be required here. Modern cars, trucks, and other vehicles feature an ever-increasing number of sophisticated electrical and electronic features, placing a larger burden on the wiring harness that enables these new features. As complexity rises, current harness manufacturing methods are struggling to keep pace due to manual data exchanges and the inability to capture tribal knowledge. A model-based wire harness manufacturing engineering flow automates data exchange and captures tribal knowledge through design rules to help harness manufacturers improve harness quality and boost efficiency.
![]()
Hi All,I am interested in getting your opinions as to whether or not it is acceptable to consider the wheels of the crane as minor axis brace points for the runway beam. I have always considered the minor axis unbraced length to be the full length of the runway beam but it has just come to my attention that there is a school of thought which calculates the minor axis unbraced length using the crane wheels as brace points with the crane located in a position which generates the maximum moment.
It is my understanding that the reasoning behind this is that when the crane beam is fully loaded the opposite crane beam is minimally loaded and therefore has reserve strength to brace the fully loaded beam.What do you think? RE: Crane Runway Beam Minor Unbraced Length (Structural) 29 Jun 10 17:01.
I agree, I think weab had a really good point as well. All of your comments have mirrored my feelings. This came up as an optional setting in some design software which suprised me because I had never heared of it being done before. Apparently it is common enough to warrant such a setting and I was curious to learn a little more about how common it really is and how exactly the justification for a lateral brace is made.Thank you all for your input.
RE: Crane Runway Beam Minor Unbraced Length (Structural) 30 Jun 10 04:30. WaytshThere is a clause (which escapes me at present) somewhere in the British Standards, which states words to the effect that - you are not allowed `mutual dependency` of any restraint, there must be a positive connection to something solid. Your crane is effectively a mutual restraint to two runway beams with no fixed connection to anything solid and is therefore not acceptable. So I agree with the other comments and yourself, that you should take the full length of the runway beam. If this length is to great for minor axis bending, one solution is to place a channel section member (toes down) over the top flange of the beam, thereby increasing the section modulus in the lateral direction.Neil RE: Crane Runway Beam Minor Unbraced Length (Structural) 30 Jun 10 08:07. Modern cars, trucks, and other vehicles feature an ever-increasing number of sophisticated electrical and electronic features, placing a larger burden on the wiring harness that enables these new features.
As complexity rises, current harness manufacturing methods are struggling to keep pace due to manual data exchanges and the inability to capture tribal knowledge. A model-based wire harness manufacturing engineering flow automates data exchange and captures tribal knowledge through design rules to help harness manufacturers improve harness quality and boost efficiency.
![]() Comments are closed.
|
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
March 2023
Categories |