Bridge Proposal

psithurismaccountantUrban and Civil

Nov 29, 2013 (3 years and 8 months ago)

97 views

Project Name:
Dennis H. Mahan Memorial Bridge


Customer Name:
Betsy Natter

Document Number / Version Number:
0021


Virtual
ly

Unlimited
,
2013

Issue Date:
Wednesday, 14 March 2012


Author:
Matt Hughes




1





Design & Society Winter Term


14 March 2012

Bridge Proposal

Dennis H. Mahan Memorial Bridge

Matt

Hughes


Project Name:
Dennis H. Mahan Memorial Bridge


Customer Name:
Betsy Natter

Document Number / Version Number:
0021


Virtual
ly

Unlimited
,
2013

Issue Date:
Wednesday, 14 March 2012


Author:
Matt Hughes




2


Bridge
Project Brief

1.

Purpose

This brief details the process of using the West Point Bridge Designer software in order to
simulate real
-
world engineering challenges for bridge construction engineering, as well as
providing an activity
-
based learning format which uses manila file folder
s in place of steel
for use in assembly of a scaled down version of the bridge designed using
said

software.

The
responsibility in designing a bridge with safety, aesthetic appeal, and cost in mind is
emphasized.

2.

Activi ty 1

Building Manila File Folder Brid
ges from Template
:
-



An exercise
t
o familiarize with the process of measuring
and fabricating bridge

pieces



Reading of the
accompanying documentation
to provide technical information

for

trusses and structural behaviour



Use of construction techniques
specific to this type of building material, some
overview of the strength properties



Discussions with
other team members, organization within a team, delegation of
responsibility, set meeting times
, time management



Discussion
and learning about compression

and tension forces and how to use them
to reach equilibrium



Testing of bridges to see behaviour under load



Insert 1. Bridge after crush parameter testing

Project Name:
Dennis H. Mahan Memorial Bridge


Customer Name:
Betsy Natter

Document Number / Version Number:
0021


Virtual
ly

Unlimited
,
2013

Issue Date:
Wednesday, 14 March 2012


Author:
Matt Hughes




3

3.

Activi ty 4



Each team member was tasked with designing a bridge using the West Point Bridge
Desig
ner software



Efforts were made to keep cost down while optimizing strength of the bridge under
design



Bridge was required to span 24m, carry 210kN load, no piers, no cables



Using a Pugh matrix, designs were compared for their merits and a s
u
itable
c
andidat
e was chosen for construction (Pugh matrix listed below)


Design by Colin May (final design)

Total Cost
:
$17
6
,0
00.00


Total Weight : 7681kg




Design by Matt Hughes

Total Cost
:
$178,047.81

Total Weight :

7924kg





Project Name:
Dennis H. Mahan Memorial Bridge


Customer Name:
Betsy Natter

Document Number / Version Number:
0021


Virtual
ly

Unlimited
,
2013

Issue Date:
Wednesday, 14 March 2012


Author:
Matt Hughes




4

Evaluation Matrix


Evaluation Criteria___5=best, 1=worst___





Design Alternatives



Designer

Colin May

Matt Hughes

Ogee

Mo
n Charles
Bernadino

1

Cost

$180k

$180k

unavailable

unavailable

2

Weight (kg)

7681.23

7923.6

unavailable

unavailable

3

Safety:

5

4

4

4

4

Ease of
construction

5

4

3

3

5

Aesthetics

4

5

4

4





Total

14

13

11

11


4.

Activi ty 5



Member strengths and lengths were tabulated using spreadsheet software



Calculations were
made for scaling the bridge down from 24m span with 1/40 scaling
factor

making 60cm



The chosen paper bridge was required to carry a load of 5kg with a safety factor of 2
making gravity
-
oriented force vector 98.1N



The weight of the

steel

bridge

modelled
in
West Point Bridge Designer was the truss
mass multiplie
d by gravity vector



Total steel bridge load was its weight plus truck load (210kN), however, the team
was given a load of
3316
kN, for increased safety threshold



The final scalar multiple for the force
vector turned out as: Paper member force =
(Steel member force)*98.1/(2911+ (truss mass (kg)*9.81*1.25)/1000) =
0.00098
,
which is in line with a 1/40 scale paper model



Fabrication of bridge member pieces and adjustments for scaling factors
commensurate w
ith manila paper strength

was completed in a timely manner



Use of rubber cement for joining paper tubes as facsimiles of steel tubes and wood
glue was used to join bridge member pieces in the proper configuration



3mm wide strips of paper were chosen as a s
tandard for all steel bar members, as
the scaled measurements were deemed too narrow to be of practical value



3mm wide strips were used across the top for cross
-
bracing


Project Name:
Dennis H. Mahan Memorial Bridge


Customer Name:
Betsy Natter

Document Number / Version Number:
0021


Virtual
ly

Unlimited
,
2013

Issue Date:
Wednesday, 14 March 2012


Author:
Matt Hughes




5


Insert 4.
Final Bridge





5.


Conclusion

This bridge project was fun and it provided good opportunities for learning how to work
in a team, learning about the process of modeling real
-
world scenarios, discussions about
safety in design, and balancing cost.
Upon weight testing, the paper bridge pe
rformed
admirably, but reached its limit at 17.5 pounds or 7.94kg. The critical points were the ends,
which folded inward under the load.


Project Name:
Dennis H. Mahan Memorial Bridge


Customer Name:
Betsy Natter

Document Number / Version Number:
0021


Virtual
ly

Unlimited
,
2013

Issue Date:
Wednesday, 14 March 2012


Author:
Matt Hughes




6

6.

Reflection

The
Inquiry and Critical Thinking aspect of the UNST program seemed to be present in
many parts of this p
roject. As we were tasked with building the bridges from a template, we
adjusted to following directions and applying methods set out in the text, which were not
always clear or explicitly stated. Furthermore, as we moved on to designing bridges of our
ow
n, we met the challenge of using the West Point Bridge Designer software. While rather
simplified and intuitive,
this
may have presented somewhat of a learning curve

when it
came to optimization of members. The great achievement of the process was a combin
ation
of Inquiry and Critical Thinking of all the project members through implementing and
sharing ideas, which also touches on the UNST Communication goal.

In our study of the I
-
35W bridge collapse, our imaginations were sparked with
determining probable
causes of failure with large structures. We examined critical structure
dependencies and investigated the events which happened after the catastrophe. In doing
so, the groups who have a stake in such infrastructure were identified and their roles
discussed

in a group forum. These elements
exposed us to Ethics & Social Responsibility as
they apply to Design & Society.