Bridge Design
ProjectEDT Spring 2023
Sylvia Wang
Project Desc. Overarching goals of the project, materials provided & used
Procedure Project Parameters
Project Goal
● Create 3 bridge designs ● Create a 18" bridge with/without adbudments
in BridgeDesigner
● Can work in groups of up to 2 people
● Choose 1 and design it in
SolidWorks
● Build and test the bridge
Competition Goal
● Make adjustments if Competition Goal Formula for efficiency:
wanted
● Document progress using ● Create the most weight held (lbs)
your preferred method efficient bridge
bridge weight (g)
Week 1 Goals
Create 3 bridge designs in BridgeDesigner
● Bridges can be created with or without adbudments
● Bridges must be made with the settings: Quenched and Tempered
Steel, Hollow Tube, and either 150x150x7 or 200x200x10 for the size
● Tip: try to keep bridge tension/suspension under 0.85
● Tip: if bridge tension/suspension is over close to or over 1, the
bridge will fail
● Tip: try to keep to total cost of the bridge under $300,000
Choose 1 and design it in SolidWorks
Design 1 Notes:
● Bridge cost was a bit high
and tension was not spread
evenly throughout members
Bridge cost: $280,348
Highest tension force: 0.57
Highest compression force: 0.40
Design 2 Notes:
● Although the bridge is being
stretched to its limit, it is a
little too close to its breaking
point
Bridge cost: $206,591
Highest tension force: 0.96
Highest compression force: 0.87
⭐ This was the chosen design
Design 3
Notes:
● Combining the top half of
design 1 and the bottom half
(adbudments) of design 2, a
bridge with both low
compression force and low
cost was created.
Bridge cost: $220,952
Highest tension force: 0.38
Highest compression force: 0.67
SolidWorks Modeling
Sketched shape Used the swept Created half of the
of the bridge* boss/base feature road bed
I decided to stick with the design from BridgeBulider as much as I could in order to get results as similar to
what the simulator displayed. I knew if I skewed the design in SolidWorks, I could potentially cause the
design to fail.
*Referenced shape and added dimensions by utilizing the print to pdf option on BridgeDesigner
I mirrored my bridge across a face, and across the right plane. This ensured that the
bridge was symmetrical.
After creating the full bridge, I realized that when
creating the laterals, small spikes were created. I
removed them by creating a plane above them and
drawing small circles where the spikes were. I then
used the cut extrude option: up to surface to
cleanly remove the spikes.
Removing Spikes Overhanging bits
For the spikes on the
bottom, I created a sketch
on the right plane and
placed the sketch right For the overhanging bits, I
after the swept boss/base cleaned it up using by
feature for the diagonals drawing rectangles and
but before the extruded using the extruded cut
boss/base for the feature
floorbeam
I created the top laterals using the 3D
sketch option.
I created the bottom laterals using the top
plane and sketching normally.
I extruded each of the sketches with the
swept boss/base feature.
● Model and test the bridge
Goals for ○ Acquire a print of our bridge
○ Split the work of building the
Next Week
bridge with me and my
partner
○ Acquire materials
○ Cut materials to according
size
(building phase) ○ Assemble
○ Test
● Adjust our design if necessary
Building the Bridge Intersecting Joints
At first, when we were building the bridge, we cut the For the bridge, we connected
tubes at a slanted angle and pieced pieced them different tubes by crimping
together by shoving the slanted ends together. the ends of the tubes
or by cutting small flaps on
the sides to create “ears”
which we could then wrap
But after some light testing, around intersecting tubes.
we discovered that this type
of joint folded onto itself
very easily so we switched to
crimping the tubes.
Building the Bridge
We began building the bridge by taping a 1:1
scale drawing of our model. We did this by using
the SolidWorks model we had built the week
before, creating a drawing from it, and printing
the drawing.
Then we started to measure and cut tubes, using
the paper as a reference.
After we cut out the tubes, we doused the
crimped end in glue and inserted it into the next
tube. Under the joints, we placed clear Scotch
tape so the bridge wouldn’t get stuck to the
paper. We also used tape to secure the pieces
in the correct orientation in accordance with the
paper.
Building the Bridge
When we got to the center of the
bridge, we realized that we had
crimped the opposite ends of the tube,
so where the tubes met in the middle,
neither side was crimped. We decided
to just create a small tube with both
sides crimped to put into the middle.
For the arch part of the bridge, we used
the thick 0.4"Ø paper straw that was
provided, but for the rest of the bridge,
we used the thin 0.23"Ø paper straw.
Building the Bridge
We continued measuring and cutting the straws to fit our bridge. For the laterals, we cut
slants on opposite sides of the tube to create little ears. We then doused the laterals in
glue and firmly pressed the tubes in place and secured it with tape. This week, we finished
one side of the bridge and started on part of the other side. We also started to cut out
tubes for the floor beams and portal strut.
Final After we finished putting
together both halves of our
Submission bridge, we started to glue the
floor beams onto one half. We
glued them on vertically and
final building had to constantly monitor the
beams to ensure they dried
straight and not angled.
After gluing on all of the floor beams, we glued
on the testing bracket. Since the testing
bracket was heavier, we used tape to secure it
so that it would not fall over. For the duration of
the class period, we continued to monitor the
vertical tubes to make sure they did not tilt.
After putting the
bridge together, we We also realized the bottom
used our printed model of our bridge was not level,
of the bridge to stuff so we added a bit of paper
the ends of the bridges. padding to one of the legs.
After, we
made sure
that the
bridge fit well
into the
testing
bracket,
which it did.
Questions
How did your bridge react to the testing?
My bridge reacted well to the testing, although it had adbudments, we did not see too much
strain on the vertical axis.
Where did it break?
My bridge broke at the top segment of
the bridge. We did not take into account
that adding another segment, however
small it was, meant that there would be
more members that had to be accounted
for. I think this is was the main reason
our bridge failed.
What main force caused the failure?
The main force that caused the failure in my bridge was compression. The compression
caused the bridge to create an “S”, leading to its failure.
Conclusion
This project made me immensely grateful for the people who engineered the structures we
use everyday, and made me have a newfound appreciation for their amazing ability to
ensure everything is safe.
3D modeling this bridge helped me become more familiar with the “mirror” feature and “3D
Sketch” feature.
Building and testing the bridge taught me to manage my time and divide tasks evenly with
my group mate. I also learned that if I deviated from the original design, I should expect
different results, no matter how small the change was.
