How to check whether a given structural support or frame can support a given machine
How to check whether a given structural support or frame can support a given machine
(OP)
Dear all,
I wanted to find out if structurally, there is a rule for finding out if a given support or frame can support a given machine?
We have a current frame that supports a single machine but we need to connect or build an additional machine on top of this first machine and to support it with the same frame used for the single machine. How do i check if this is possible?
Thanks!
James
I wanted to find out if structurally, there is a rule for finding out if a given support or frame can support a given machine?
We have a current frame that supports a single machine but we need to connect or build an additional machine on top of this first machine and to support it with the same frame used for the single machine. How do i check if this is possible?
Thanks!
James






RE: How to check whether a given structural support or frame can support a given machine
RE: How to check whether a given structural support or frame can support a given machine
Thaidavid
RE: How to check whether a given structural support or frame can support a given machine
Thanks for your response. Don't you know of any citation or literature that can be of some help to me?
Thanks!
RE: How to check whether a given structural support or frame can support a given machine
RE: How to check whether a given structural support or frame can support a given machine
Thanks for the response. By load, do you mean the static load (weight) of the machine(s)? What about the capacity? Can you please throw more light on this, eg how is it computed?
Thanks again for support.
Jimmy
RE: How to check whether a given structural support or frame can support a given machine
You really need to consult a local structural engineer.
RE: How to check whether a given structural support or frame can support a given machine
Then there is the case of other load cases, seismic, wind, etc. That could change the capacity.
RE: How to check whether a given structural support or frame can support a given machine
What kind of frame is it? For a static load, the capacity of the frame can be calculated using principles of statics, frame analysis and strength of materials. The calculations will depend on the type and material properties of the frame.
Your question is too general to get any kind of sensible response.
BA
RE: How to check whether a given structural support or frame can support a given machine
Thanks for your input.
@ Jrisebo: I intend doing the following. We have two parallel beams & two cross beams at the ends of the parallel beams. The parallel or longitudinal beams are U-shaped. I want to determine the total weight of the machine and divide by 2 to be the weight taken by each longitudinal beam. Then i will set up an FEM Simulation with the beam fixed at both ends and the weight applied in the middle and determine the maximum bending stress including safety factor and compare it to the compressive strength (and not the tensile strength since beam is in compression between the machine weight and the floor) of steel, since the material is steel. If the computed value is less than that of the material i will judge the support to be safe.
Do you think the reaction forces at the fixed joints of the beam play a critical role due to the screws used in doing the fixing? I am thinking that they should be added to the FEA model?
Thanks as usual for your support.
Jimmy
RE: How to check whether a given structural support or frame can support a given machine
How are they fastened to the two "end" beams?
What exactly is the load path? Can you provide a sketch?
and what would you say is the difference between compression and tensile (yield) strength of steel?
RE: How to check whether a given structural support or frame can support a given machine
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: How to check whether a given structural support or frame can support a given machine
It's why you hire engineers.
RE: How to check whether a given structural support or frame can support a given machine
This forum is worldwide. And much structural engineering is done through outsourcing these days. A qualified PE can be found, and retained, with just a little bit of effort. Living in a jurisdiction without structural PEs is no longer the absolute handicap it once was. This sounds like he needs a qualified person to look at his situation.
Thaidavid
RE: How to check whether a given structural support or frame can support a given machine
Thanks for your Input. Appreciated.
I will try to answer your questions. The longitudinal beams are resting on the floor over their whole length as you suggested. They are fastened using a bolt and a nut (single at each point) and so four in total. I'm not sure about the next since i am yet to determine the load path. The sketch is attached in the screen shot attached. The rectangle in black is showing how the machine is mounted on the Support.
For the compressive yield and tensile yield strengths of steel, i got the following values from a text: 160N/mm^2 and 360 N/mm^2, respectively. Are you suggesting they should be the same? The exact steel material is S235JR.
Thanks again for your Support.
Jimmy
RE: How to check whether a given structural support or frame can support a given machine
S235 means fy = ReH = RP0.2 = 235 MPA. This is both tensile and compression.
you want to design for a certain % of that.
Your suggestion of approach doesn't add up, as the end connection of both beams don't have anything to do with how those beams react their force(s).
I'd model a uniform distributed load at the bottom, representing the floor, and two point loads on the top flange, as that's were the machine will make contact with the beams.
You'll want something that braces both beams, as they'll want to fall towards each other.
I don't know the dangers of this situation, either overbuild it or have it checked out by a competent person/firm.
RE: How to check whether a given structural support or frame can support a given machine
RE: How to check whether a given structural support or frame can support a given machine
RE: How to check whether a given structural support or frame can support a given machine
Why have you turned a considered suggestion for soliciting qualified help into a personal attack regarding my sense of humor? Is this your usual mode of operation? You know nothing about me, or my sense of humor, or else you wouldn't have made such an ill-considered statement. However, that didn't seem to slow you down from commenting on me personally, instead of keeping this forum focused on the poster, and his questions. @GregLoCock's contribution may have been offered in humor, but it also contained an assumption - regarding the availability of qualified help - which failed to address the options which I mentioned by follow up. That's all I said: that there are options available to the poster which were not mentioned in his post. None of this was offered by me in any way condescending or biased. It was a simple exhortation to let someone qualified assist with the design. There was nothing personal from me in any of that. And no need for anything personal from you in return. I would request that you forego your personal attacks, and keep this forum focused on helping each other.
Thaidavid
RE: How to check whether a given structural support or frame can support a given machine
BA
RE: How to check whether a given structural support or frame can support a given machine
RE: How to check whether a given structural support or frame can support a given machine
Thank you for your apology, and I can see now that your original statement was an attempt to poke fun at me. Surprisingly (to some), I actually do have a good sense of humor - much of it self-deprecating. In a terse, written format like this website, our attempts at humor or sarcasm sometimes do not read quite right on the other end. That is one reason that I try not to use such in a setting like this, but rather try to focus on the original poster's question, and not on the respondents specifically. I am American also, but I lived and worked in Thailand for over ten years (eventually teaching engineering college in Thai), and I have worked on projects around the world (from that setting, and later, for the US military). I have seen enough in that time that I understood that there are resources available for professional design no matter where in the world you are located. My second reply was simply an exhortation to the original poster to seek qualified help on an important safety subject. Some reader "starred" it, so they likely have had a similar experience too.
And I apologize for failing to catch the intent of your post. I didn't mean to offend you either.
Thanks,
Dave
Thaidavid
RE: How to check whether a given structural support or frame can support a given machine
I forgot to add that in one case, the beams are not touching the floor. In that case, the beams are connected to 4 rubber mountings of height 35mm. In this case i guess you will not add any load at the bottom of the beams in the modeling?
I agree that with the four bars, the structure is not stable. I remember for stability, S=2k-3 must be satisfied, with S the number of bars and k the number of nodes. For k=4, we get S=5 and so an extra bar would be needed as you suggested.
Thanks for your support.
Jimmy
RE: How to check whether a given structural support or frame can support a given machine
BA
RE: How to check whether a given structural support or frame can support a given machine
http://ocw.mit.edu/courses/mechanical-engineering/
Good luck! Suggest hiring out the review and then learning from it for the next one.
ZCP
www.phoenix-engineer.com
RE: How to check whether a given structural support or frame can support a given machine
RE: How to check whether a given structural support or frame can support a given machine
BA
RE: How to check whether a given structural support or frame can support a given machine
Thanks!
Jimmy
RE: How to check whether a given structural support or frame can support a given machine
RE: How to check whether a given structural support or frame can support a given machine
Thanks!
Jimmy
RE: How to check whether a given structural support or frame can support a given machine
1. Tell the boss he can't add another machine on top of the existing without modifying the existing frame.
2. Modify the existing frame as required to accommodate additional machine on top of existing.
BA