Robot Structural Analysis

## Robot Structural Analysis

Valued Contributor
Posts: 59
Registered: ‎09-24-2012
Message 1 of 9 (390 Views)

# Overhead crane and gusset design

390 Views, 8 Replies
02-14-2013 12:30 PM

Dear All,

How am I supposed to model overhead crane which rests on columns gussets and which is also a part of the structure?

Suppose that I have gable like industrial structure an I have overhead crane(50 ton capacity) located at the middle of the columns. Which design path should I follow to correctly model the crane and also the gusset plates at the columns where is crane supposed to rest ?

Regards,

Valued Mentor
Posts: 416
Registered: ‎11-01-2011
Message 2 of 9 (363 Views)

# Re: Overhead crane and gusset design

Hi. I had a project with overhead cranes ranging from 20 tons to 180 tons. I tried several different methods for modeling but the best I could come up with is as follows:

1- model all the structural supporting elements but not the overhead cane.

2- perform a manual calculation to calculate the horizontal (both directions) and vertical loads and moments applicable to the columns supporting the runway beams.

3- create manual crane load combinations to take into account all the different load applications.

4- After analysis and design of steel structure, verify the runway beam using manual calculations to make sure the results are comparable to those from robot.

This is my input but I am sure others may have different approaches.

Hope this helps.

Ali Al-Hammoud
Structural Design Engineer
MZ & Partners Engineering Consultancy
Valued Contributor
Posts: 59
Registered: ‎09-24-2012
Message 3 of 9 (358 Views)

# Re: Overhead crane and gusset design

02-15-2013 01:24 AM in reply to: AJA14

AJA14 wrote:

Hi. I had a project with overhead cranes ranging from 20 tons to 180 tons. I tried several different methods for modeling but the best I could come up with is as follows:

1- model all the structural supporting elements but not the overhead cane.

2- perform a manual calculation to calculate the horizontal (both directions) and vertical loads and moments applicable to the columns supporting the runway beams.

3- create manual crane load combinations to take into account all the different load applications.

4- After analysis and design of steel structure, verify the runway beam using manual calculations to make sure the results are comparable to those from robot.

This is my input but I am sure others may have different approaches.

Hope this helps.

Thanks for helping,
Yes probably that will be the path I'll follow to design a structure which has a overhead crane.  I'm convinced that you just counted on your engineering judgment and intuiton on that.
To take into account overhead crane loads and comprise the load combination including wind, self, live, crane ,seismic, wind, snow etc.. loads should be enough to design structural stability and member size checking. Of course I'm not trying to take into account the crane girders as part of system, that should be taken  smply as statci or dynamic loading, that is for sure.
I would lie to draw your attention and little problem arises in my head on how to corectly design the gusset of the crane on the column side. My best approach would be to model the gusset as a frame element protruded horizontally from the column side(where I'll apply the crane loads) and based on the max. axial, shear, moment force acting on that protruded frame element, design the gusset plate  manually?
Regards,
Valued Mentor
Posts: 416
Registered: ‎11-01-2011
Message 4 of 9 (339 Views)

# Re: Overhead crane and gusset design

Hi. Yes that would be my best approach for designing the brackets. Remember that when you model these brackets in Robot to make sure that you use the correct length and offset it to the face of the column otherwise you would be basing your design on a larger unbraced length. (Unless you do the calculations manually).

Ali Al-Hammoud
Structural Design Engineer
MZ & Partners Engineering Consultancy
Active Member
Posts: 10
Registered: ‎01-10-2013
Message 5 of 9 (331 Views)

# Re: Overhead crane and gusset design

Valued Contributor
Posts: 59
Registered: ‎09-24-2012
Message 6 of 9 (319 Views)

# Re: Overhead crane and gusset design

02-16-2013 09:30 AM in reply to: luzer333

Dear All,

AJA14 :

Sure I'll do it the way you describe it, in order to take into account and not underestimate the bracing lengths, for FEM models its crucial to have all the model to be comprised on nodal basis, and all the frame/bar elements are supposed to connect and transfer loads only from those nodes, except if you don't have the cantilevers(where it may have unsupported and free node)

Luzer333's example has brought the new dimension:

Since its the official article from RSA I presume that its the legitimate way of doing it and recommended way by RSA developer team.

In the 5th example,  they modeled the brackets/gussets as small triangular-frame formation for 2,3,4 (left side) and 7,8,9(right side) frame members. This also seems very rational way of implementing it but at the same time poses the difficulties for. For example,

1. Which seciton am I supposed to check diagonal or horizontal one , because practically at site it will be produced as a bottom haunched profiles or haunched plates to the side of column.
2. If its been modeled as triangular frame formation, How its supposed to be produced at the workshop practically I mean as plate or as haunched profile section?

Active Member
Posts: 10
Registered: ‎01-10-2013
Message 7 of 9 (309 Views)

# Re: Overhead crane and gusset design

Why don't you just put the horizontal profile and apply all the crane loads including the railway on it? It will transfer all the loads acting on it to the column as it would in reality. I think replacing the "full" profile with haunched one won't change a lot because the railway generally sits on the middle of the profile where it is unchanged till the end (to the column). Additionally you can still add brackets under the "full" profile with Connection Design.

Valued Contributor
Posts: 59
Registered: ‎09-24-2012
Message 8 of 9 (297 Views)

# Re: Overhead crane and gusset design

02-16-2013 08:58 PM in reply to: luzer333

luzer333 wrote:

Why don't you just put the horizontal profile and apply all the crane loads including the railway on it? It will transfer all the loads acting on it to the column as it would in reality. I think replacing the "full" profile with haunched one won't change a lot because the railway generally sits on the middle of the profile where it is unchanged till the end (to the column). Additionally you can still add brackets under the "full" profile with Connection Design.

OK

Having the collegues all over the world which shares the same opinion and reasoning with me, helps me a lot to keep the sanity and put me in ease.

Luzer333 If you have more manuals/articles related to RSA do you mind to share them with us ?

Thank you all,

Active Member
Posts: 10
Registered: ‎01-10-2013
Message 9 of 9 (289 Views)

# Re: Overhead crane and gusset design

You can visit

Also a lot helpful videos on youtube. Unfortunately most of them are in various of languages.

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