Comments on: 5 Steps to Building a Model Bridge

By: pratik

pratik — Sat, 04 Feb 2012 20:55:42 +0000

Hi Garrete,I am studing engineering and i am in 2nd years.Because of my interest in bridge design me and my group have taken part in a competition held in our college the problem assigned to us is:
i have built suspension bridge .plz tel me which material is required to make it

By: rerer

rerer — Sat, 26 Nov 2011 02:44:21 +0000

i agree

By: Shubham Shekhar Jha

Shubham Shekhar Jha — Mon, 12 Sep 2011 13:04:00 +0000

Hi Garrete,I am studing engineering and i am in 2nd years.Because of my interest in bridge design me and my group have taken part in a competition held in our college the problem assigned to us is:

Design a three dimensional self-supporting model bridge. The physical constraints of the bridge
are according to the following specifications:

Span 500 mm
Height 100 mm (minimum)
Width 120 mm (minimum)

DESIGN CONSTRAINTS/SPECIFICATIONS

The bridge should permit unobstructed movement over its deck ( there should be no
members inside the bridge ) No part of the deck should be more than 50 mm above the abutments (support level)

LOADING SPECIFICATIONS (FOR TESTING)

The rate of loading shall be specified during the time of the contest. Holding the load-carrier during loading is not allowed.
The bridge will be loaded by hanging weights from a 5 mm thick mica board of size 180
mm x 80 mm, through a V-bolt attached to it with spacing(l) between legs being 120 mm.

There are few more specifications and we have to design the bridge on paper and build a model with materials provided by college.

I request you to suggest me as i am a beginner.Thankyou.

By: Shivanandjrk

Shivanandjrk — Wed, 10 Aug 2011 12:38:00 +0000

Hi Garreti am studding engineering ….. i want to build a model bridge with wood … i need yr help…

By: uthm

uthm — Tue, 02 Aug 2011 14:33:00 +0000

what software you used to design?

By: RianGouws

RianGouws — Wed, 09 Mar 2011 10:28:30 +0000

Hi Garret
I’m an Engineering student at CUT and we have been assigned to build a popsicle stick bridge with cirtain restriction.
One which im not completely confident to do is this:
“• The bridge deck must have a minimum camber (upward curve) of 30 mm along the longitudinal axis of the bridge”
You think you can help me out?

Thanks
Rian

By: bonnier

bonnier — Thu, 21 Oct 2010 18:06:58 +0000

i love this website(:
thanks for the help i enpjoyed it so much

By: Brock

Brock — Wed, 18 Nov 2009 00:07:12 +0000

Great book and website. I do not agree with the previous comment that the larger members “attract” more load. This would be true if stiffness of members were a factor (moment resistance), but since this is a simple truss your assumptions are basically correct: larger loads should have larger members to reduce the stress (force per unit of cross sectional area) — especially the compression members, due to buckling.

By: Garrett Boon

Garrett Boon — Wed, 11 Nov 2009 07:06:34 +0000

Hello Menno,

Thank you for your comment. Unfortunately I have not had the opportunity to take any engineering classes, and base my ebook on my observations from my time spent building model bridges. The ebook wasn’t really meant to be a manual for learning the in-depth engineering concepts that would be useful for building bridges. However, I would love the chance to chat with an engineer about my ebook, and about bridges in general. I always strive to learn more about how bridges work, so thank you for informing me about this phenomena where making a member larger will increase the load acting on it. Do you have any resources where I could learn more about this? Is this something that always happens, or does it depend on the location of the member in the truss?

By: Menno

Menno — Sun, 08 Nov 2009 10:37:25 +0000

Hi Garret

Nice eBook. However, as a structural engineer I can tell you that you are making some fundamental errors in the ebook. Members taking the largest load does not always need to be the bigger member (for efficiency). This is mistake many young engineers make. Increasing the size of your member actually ‘attracts’ more load and so you achieve the opposite. I would suggest you have an engineer have a look at your ebook.

Besides that – good work.