Need help designing small bridge
dsto...@pol.net
We own some land that is divided in half by a small creek. We want to build a
small bridge over the creek. I need assistance in designing the bridge and am
hopeful that a knowledgeable person from this group can provide some guidance.
The total span across the creek will be approximately 20 feet. The largest
load the bridge should have to carry is a small farm tractor. The tractor
weighs 1,650 lbs. The maximal load anticipated for a fully loaded tractor
and wagon should not exceed 2,500 lbs. The width of the bridge will be about
5 feet.
The first thought I have is to create a reinforced concrete foundation and
support column on each side of the creek. The bridge itself would be 2-3
steel I-beams with 2x6 lumber as the deck. The tires of the tractor would be
forced to stay directly on the I-beams so as not to overload the 2x6 deck.
A number of questions come to mind.
1. Is this a reasonable idea for a simple bridge?
2. Is there an easier/simpler/cheaper bridge design than the above?
3. Can a rough estimate be made of the size of the concrete foundation and
pillars? I understand soil type, frost depth, etc. can have a significant
effect on the calculations.
4. What size steel I-beam would I need to span the mentioned distance for the
required load with a safety factor of at least 1.5-2?
Thanks to any and all who can provide useful information about the design of
the bridge. I normally do not read this newsgroup. Please respond by
e-mail. Thank you.
Douglas Stockman
dsto...@pol.net
Rochester, NY
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Direct Sales
Otherwise do not attempt to design this bridge. Hire an engineer!
Walter D. Graves
would risk his license in answering or providing advice on his design. I
gave him a list of design guides and told him the information is all in the
guides.
One of my curiosities is how state registration boards would view advice
transmitted over the internet. Would providing any advice be considered
practicing engineering and thus be subject to the registration laws? If so,
which states laws would apply? I think it is appropriate and professional
to converse on engineering quetions and principles with other engineers, but
I am very leary of providing any engineering type advice or lessons learned
to those who are obviously not in our profession. Any other opinions on
this matter?
Direct Sales wrote in message <368D0E56...@home.com>...
Ashton6745
but H beams. With the use of stringers the load can be transfered to the
beams.....another important consideration is water level and the created head
caused by waterway obstruction... Further more you need abutments of some sort,
not columns....I will write later with some calculations
Rob Munach
Hmm, I thought they WERE commonly called I beams unless the flange width
was equal to the depth and then they can be called H or I beams.
--
________________
Rob Munach, PE
Excel Engineering
Carrboro, NC
Rob Munach
>
> You should have learned this in any basic steel design class.
> Otherwise do not attempt to design this bridge. Hire an engineer!
>
a steel design class.
r...@engr.uark.edu
house across a creek and deck it with 2x6's. I drove over one dozens of
times visiting neighbors. Seemed to work!
In article <76ip1s$r2l$1...@nnrp1.dejanews.com>,
> ‰
Neovision
advise on what courses the guy should have taken in the collage,... Your
response successfully failed to make you sound like a "Green Horn" and I
doubt you ran to your calculator to re-do your collage steel design calcs.
Simple, to the point economical and efficient. That's what they should
teach the wanna be engineers in the college. Congratulations are in order.
With regards,
r...@engr.uark.edu wrote in article <76ll9k$1r$1...@nnrp1.dejanews.com>...
Walter D. Graves
liability by providing a response?
Rob Munach wrote in message <368E25...@pobox.com>...
dsto...@pol.net
I am the original poster. Sorry to cause such a debate. I was not really
asking for someone to put their engineering license on the line. I know if I
really want this bridge designed to exacting specifications I should hire an
engineer. I really just want to know what size "H"-beam can support the
weight listed and a rough estimate of the footer and abutment size I might
need. I will not hold anyone responsible. Basically, I looked on the net
for this information in on-line reference books but was unable to find any.
To locate this information in the city’s library can take a few hours given
travel time, paying for parking, etc. I figured you engineering types
probably have reference books sitting near your computers and it might
require 1-2 minutes work. If it makes anyone feel any better, the bridge I
design has to be evaluated and approved by the Town engineer. I hope this
engineer would not approve the bridge if it were unsafe.
A number of responders are correct. I am not an engineer. If I were, I hope
I would not be asking such a basic question. I am a physician. A similar
debate is going on in my profession regarding offering medical advice over
the internet. A number of publications suggest that many physicians will
provide medical direction with the closing statement being that they should
consult their own physician. It will be interesting to see how the
engineering and medical communities will resolve this issue.
Thanks again for any and all help.
Rob Munach
It sounds like you have been sued one too many times. I find it highly
unlikely that you could be held liable for providing "un-sealed" advise
over the internet. You are just as likely to be sued for a slip and fall
acident on your front porch.
--
John Lansford
>Greetings:
>
>I am the original poster. Sorry to cause such a debate. I was not really
>asking for someone to put their engineering license on the line. I know if I
>really want this bridge designed to exacting specifications I should hire an
>engineer. I really just want to know what size "H"-beam can support the
>weight listed and a rough estimate of the footer and abutment size I might
>need.
That information will require the services of a qualified professional
engineer, as the particulars will have to meet the existing
conditions.
John Lansford, PE
The unofficial I-26 Construction Webpage:
http://users.vnet.net/lansford/a10/
Marco Negri
Greetings
Marco Negri
Rome - Italy
(If you have further questions do not esitate to contact me)
John Lansford ha scritto nel messaggio <369ac024...@news.vnet.net>...
bs
>I agree completely. In fact, my reply to him was that no true engineer
>would risk his license in answering or providing advice on his design. I
>gave him a list of design guides and told him the information is all in the
>guides.
Not that I want to add to your paranoia, but this in itself sounds like a
consultation.
>One of my curiosities is how state registration boards would view advice
>transmitted over the internet. Would providing any advice be considered
>practicing engineering and thus be subject to the registration laws? If
>so, which states laws would apply? I think it is appropriate and
>professional to converse on engineering quetions and principles with other
>engineers, but I am very leary of providing any engineering type advice or
>lessons learned to those who are obviously not in our profession. Any
>other opinions on this matter?
Personally, I have no problem telling people in broad terms whether their
construction ideas may or may not be sensible. Either in conversation or on
the Internet. And that if they want the best possible service, they should
consult with an engineer for design advice based on the actual site
conditions, context, codes, etc.
Check out http://www.dca.ca.gov/pels/guide.html , ("Does My Project Require
a Professional?"), for the State of California's advice.
And IMO anybody posting requests for advice to a newsgroup ought to read the
newsgroup for replies.
- Bob Stahl
RobQ
I will trade you some structural engineering advice for some medical advice.
I have these small lumps on my upper thigh that have appeared in the
past 6 months. Should i worry about them? Are they cancerous? Should I have
them
removed?
The questions you should be asking over the internet for your project should
be a little
more conceptual rather that asking for the exact size of the beams (either i
beams
or h-beams, but could be c-channels). A 20' span is a significant span and
questions to
ask could be: what type of loading conditions do i have to impose on the
bridge? Just because
your tractor only weights a couple of thousand pounds doesn't mean thats
what the design load
should be. The next guy 15 years later might drive a wagon accross for a hay
ride with 30 kids
on the back of it. Or some guy with a full manure spreader.
Just some thoughts.
Rob Quiring
Abbotsford, BC Canada
. dsto...@pol.net wrote in message <76nlle$ip5$1...@nnrp1.dejanews.com>...
>Greetings:
>
>I am the original poster. Sorry to cause such a debate. I was not really
>asking for someone to put their engineering license on the line. I know if
I
>really want this bridge designed to exacting specifications I should hire
an
>engineer. I really just want to know what size "H"-beam can support the
>weight listed and a rough estimate of the footer and abutment size I might
r...@valmont.com
"bs" <xxx_bo...@sirius.com> wrote:
> Walter D. Graves:
> >I agree completely. In fact, my reply to him was that no true engineer
> >would risk his license in answering or providing advice on his design. I
> >gave him a list of design guides and told him the information is all in the
> >guides.
>
> Not that I want to add to your paranoia, but this in itself sounds like a
> consultation.
>
>
> Personally, I have no problem telling people in broad terms whether their
> construction ideas may or may not be sensible. Either in conversation or on
> the Internet. And that if they want the best possible service, they should
> consult with an engineer for design advice based on the actual site
> conditions, context, codes, etc.
>
> Check out http://www.dca.ca.gov/pels/guide.html , ("Does My Project Require
> a Professional?"), for the State of California's advice.
>
> And IMO anybody posting requests for advice to a newsgroup ought to read the
> newsgroup for replies.
>
> - Bob Stahl
>
>
My handling of the Internet has been similar to Bob's, I think. I have
discussed a variety of topics (mostly from home, but still engineering) and
have merely maintained the same level of care that I would with any
communication where judgement is involved. I really fail to see the
difference between the Internet communication and the multitude of phone
calls, faxes and conversations from people looking for information,
suggestions, and guidance before they take the final step of determining the
scope of their project and seeking true designs.
I am well aware of the litigation aspect of our society (for those of you
outside the US you need to evaluate your own country's legal system) and how
easy it can seem to get into trouble. However, I don't think we can afford
to live with that kind of fear driving our lives and interaction. If the
situation seems risky, qualify your opinion or don't offer one.
My two cents,
--
Dick Aichinger, PE
Pierre Lapalme
>Greetings:
Big Snip
> I figured you engineering types
>probably have reference books sitting near your computers and it might
>require 1-2 minutes work.
Not quite. I've worked with a few Bridge Design Codes here in Canada
and there's no Bridge Design Handbook. You have to dig in the Code,
apply the basic structural calculations, and validate the results.
Computer is fast in calculations, but keying the right values and
design parameters in can be long.
> If it makes anyone feel any better, the bridge I
>design has to be evaluated and approved by the Town engineer. I hope this
>engineer would not approve the bridge if it were unsafe.
Did the Town Engineer asked you to have a Design note sealed by an
Engineer? What code will he use to base his evaluation and approval?
AASHTO or NYDOT? Does he damands an hydrology evaluation?
Pierre Lapalme
plap...@laurentides.net
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