Building Structure Project 1

B U I LD ING S T R UCT U R E [ A RC 2 5 2 3 ]
F e t t u c c i n e T r u s s B r i d g e A n a l y s i s
G e r t r u d e L e e ( 0 3 0 6 2 6 5 )
K e e T i n g T i n g ( 0 3 1 0 0 1 9 )
M e e r a N a z r e e n ( 0 3 0 9 6 3 0 )
N u r u l J a n n a h J a i l a n i ( 0 3 1 0 2 1 0 )
S o n i a M a n y i e ( 0 8 0 1 A 6 5 7 0 4 )

T A B L E OF CON T E N T
I N T R O D U C T I O N
M E T H O D O L O G Y
P R E C E D E N T S T U D Y – H E N S Z E Y ’ S W R O U G H T I R O N B R I D G E
A N A L Y S I S
S t r e n g t h o f M a t e r i a l s
T r u s s A n a l y s i s – I n i t i a l t o F i n a l D e s i g n
T E S T I N G
T r u s s S t r u c t u r e A n a l y s i s
R e a s o n f o r B r i d g e F a i l u r e
S u g g e s t i o n t o S t r e n g t h e n B r i d g e
C O N C L U S I O N
A P P E N D I X
R E F E R E N C E S

I N T ROD UCT ION
For this project, we were assigned in a group of 5 to carry out precedent study of a truss bridge. Using the knowledge from the
research, we are required to design and construct a fettuccine bridge of 750mm clear span and maximum weight of 200g.
The bridge must be of high efficiency, which means using the least amount of materials to sustain a higher amount of load. This
bridge is tested to fail, therefore, its strengths has to be determined in terms of tension and compression strength as well as the
material strength.
Upon the agreement of the bowstring truss as our topic of interest, the Henszey’s Wrought Iron Bridge was chosen as our
precedent study. The report will be based on the compilation of our research on the bowstring truss and the application of our
understanding to the construction of our fettuccine bridge.
Bridge Requirement:
• 750mm clear span and maximum weight of 200g.
• Only fettuccine and glue are allowed.
• Loads have to be point load.
• Must be able to withstand each weight that is put on for 10 seconds.

ME T HODOLOGY
In order to complete the project, the following methods were carried out:
Precedent Study
Gives an understanding of a truss bridge. The connections, arrangement of members and truss type are focused on. Based on
the study, we would then adopt the desired truss design into our own fettuccine bridge design.
Material and Adhesive Strength Testing
Before constructing the bridge, the physical properties of the fettuccine is to be understood. Therefore, we have tested the
behavior of the materials when subjected to either tension or compression.
Model Making
In the beginning, simple sketches of the trusses were made. Once decision was made, a CAD drawing of 1:1 scale was
generated to ease the process in creating a more accurate model.
Structural Model
The truss is analyzed by determining which members are in tension or compression. The structural analysis is done using the
same method as that of the truss analysis exercises (appendix).

Precedent Study - Henszey’s Wrought Iron Bridge
Figure 1 is a picture of Henszey’s Wrought-Iron Bridge, a single span
wrought iron bowstring truss bridge. The bridge is named and based
after Joseph Henszey’s patent design in 1869, a prominent engineer
during his time. The durability and longevity of surviving metal bridges
built in the United States from the 1800s is truly impressive. The ability of
these bridges to defy time itself in a way that no modern bridge today
can is due to a variety of reasons. The wrought iron used during this
period was actually more rust-resistant and long-lasting than the steel
used today. Some bridges were overbuilt by engineers who may have
not been able to calculate the design of a bridge, while in contrast
A B O U T T H E B R I D G E
Figure 1
others may have been designed by engineers who were very skilled and creative and were able to come up with a bridge
design that was uniquely effective. After design, skilled craftsmen would carefully fabricate the parts for these bridges,
producing a well-built structure that would be ready to stand for over a century. All of these types of things might be
applicable to the long life that Henszey's Wrought Iron Bridge has enjoyed, however some might find cause to question the skills
of the craftsmen who fabricated this bridge. Today, Henszey's Bridge serves as a pedestrian walkway for students, faculty, staff
and visitors on the campus of Central Penn College, Cumberland, Pennsylvania. The bridge symbolizes the high-quality, hands-on
education that the college provides to connect students to their career dreams.

T E C H N I C A L F A C T S O F H E N S Z E Y ’ S W R O U G H T - I R O N B R I D G E
Figure 2 Span Layout
Figure 3 Foot Clear Roadway
Figure 2 shows the span layout of the bridge at 92 foot 4 inches (28.14m) from end shoe to end shoe with each truss subdivided
into eight panels. The approaches are formed by stone wing wall which rise to the level of the roadway and are fitted with pipe
railings. The span carries a 15 foot clear roadway of wood plank deck with a 4” by 4” wheel guard (Figure 3). U1 to U7
represents the top chords positions while L0 to L8 represents the lower/bottom chords positions. All members and chords are
wrought iron, but there are also cast iron components for the bridge's connections, floor beams, and bearings. The cast iron
components increase the rarity and significance of the bridge.
The top chords are fashioned from 7 15/16” x 5/16”cast Phoenix sections, between which
is a riveted a stem plate 11 ¼” x 5/16”. Stiffening bars, 2” wide and 5/16” thick are
inserted horizontally through the stem plate regular intervals and are riveted to the outer
flanges of the Phoenix sections (Figure 4).
Figure 4 Phoenix Section with Stem Plate
and Stiffening Bars

Figure 5 Top Chord Overview
Figure 6 Top Chord Connections
Figure 4 Phoenix Section with
Stem Plate and Stiffening Bars
The top chords are fashioned from 7 15/16” x 5/16”cast Phoenix sections, between which is a riveted a stem plate 11
¼” x 5/16”. Stiffening bars, 2” wide and 5/16” thick are inserted horizontally through the stem plate regular intervals and
are riveted to the outer flanges of the Phoenix sections (Figure 4).
Figure 7
The vertical posts of each truss consist of pairs of T-bars 3” x 1/2” x ½” which by means of flanges at
the bottom are riveted to the upper flange of each floor beam and the plates are riveted to the
top chord (Figure 7).The deck is suspended from the top chord, thereby placing all verticals in
tension.
The bottom chords consist of pairs of flat bars 4 ¾” x ½” with turnbuckles, on which rest the I-beam
floor beams which carries the I-beam stringers on which the flooring is laid (Figure 10).

Figure 9 Cast Iron Bottom Chord Connections
Figure 8 Bottom Chord Connections
The bottoms chords is also in tension as a result of the horizontal thrust exerted by the arched top chord. When a
load passes over the bridge, the load is conveyed to the vertical posts. As the posts are placed in greater tension,
the segment of top chord between the two posts is placed in compression. The flat verticals between posts of the
bridge thus appear to have been installed in order to counteract the tendency of a given arched segment of the
top chord to buckle upward under the force of the added compression.
Figure 10(a) Lower/Bottom Chord Connections to Flooring and Upper Chord Figure 10. Bottom Bracing at Lower Chord 2 and Lower Chord 6.

Figure 11 King Post under Floor Beam Figure 12 View of under the Bridge
In conclusion, the trusses for the Henszey’s Bridge are rather shallow. This is because the ratio between the maximum
truss depth (8 feet) and the overall length (92feet) is only about 1:11. Due to the arch configuration, deflection and
vibration increases especially when the outer end of the trusses are considerably shallower. Therefore, to decrease
deflection, inverted king posts are used below the floor beams (Figure 11). Moreover, placement of camber rods
below each beam in a king-post configuration also reduces lateral movement of the upper chords under live loads.

A N A L Y S I S
S T R E N G T H O F T H E M A T E R I A L
Materials used for this project are:
1. San Remo Tubular Spaghetti
Based on our research, the properties of the fettuccine are below:
1. Ultimate tensile strength = 2000 psi
2. Stiffness (Young’s modulus) E= 10,000,000 psi
(E=stress/strain)
Failure occurs when ultimate tensile strength is exceeded. As the length of the fettuccine
increases, the maximum load a fettuccini can carry before it breaks decreases.
2. UHU Super Glue
UHU super glue dries relatively quickly but is slightly flexible when dry. Moreover, the
required rigid glue joints can be achieved. PVA glue is not a suitable adhesive. Since it is
water based, the spaghetti is softened by the glue. Glue joints take forever to dry. Once
dry, joints are not very strong.

E X P E R I M E N T A T I O N O F T H E S T R E N G T H O F M A T E R I A L S
Types of Beams Numbers of Layers Result
L-beam 1 layer all sides Flattens and bends
L-beam 2 layers all sides Bends
I- beam 3 pieces Breaks at 5 seconds
I- beam 5 pieces Did not break
I- beam 6 pieces Did not break but
heavy
Lamination 2 layers
3 layers
4 layers
1 seconds
3 seconds
More than 40 seconds
Types of Glues Used Result
Bonding UHU Super Glue
3 second glue
PVA
Did not break
Bends/ flexible
Twists and breaks
Based on the results, it can be concluded that the I-beam made up of 5 pieces of fettuccines is the strongest.
Moreover, 4-layered lamination has also proved quite strong. The C-beam, L-beam and joists on the other hand, either
buckled or twisted when tested. Therefore, we have chosen to use I-beams and laminated fettuccine in our bridge.
Finally, as an adhesive, UHU super glue turned out to be the best option.

T R U S S A N A L Y S I S – F R O M I N I T I A L T O F I N A L D E S I G N
Bowstring Truss was selected as our fettuccine bridge design.
Figure above is a Typical Bowstring Truss
Figure below shows how the tension, compression and buckling may occur to the beams of a bridge while in this case, the
fettuccines.
We have found that for a regular fettuccine (diameter = 2mm), maximum load is approximately 4.5kg. Moreover, a structure
that relies on bending strength to support a load has very little strength. Triangles is the best design for trusses as there are no
bending moments in triangular element(truss strength depends on bending strength of members)

T R U S S A N A L Y S I S – F R O M I N I T I A L T O F I N A L D E S I G N
Bowstring Truss was selected as our fettuccine bridge design.
Front Elevation of Initial Fettuccine Bridge Design
The initial design of the fettuccine truss bridge weight was 286g. It was tested. Load was added until the bridge fails. The
bottom bracing deflected downwards when more weight was added and broke when it reached its limit. The other parts of
the bridge was still in tack. It is as shown below.
Side Elevation of Initial Fettuccine
Bridge Design
Besides being advice to test the bracing, as our bridge is weight, 286g, more than the requirement of
the brief, which is 200g, we were also advice to decrease the amount of fettuccines used at the truss
of the bridge. From the advice that was given, we designed a new bridge.

Front Elevation of Final Fettuccine Bridge Design
The final design of the fettuccine bridge weight was 198g as we have decided to adjust our final design to lesser bracings
which, reduces its weight. Instead of making all the truss X-bracing(diagonal), we decided to make the three most middle
trusses diagonal to each other while the rest triangular. In order to make the middle bracing stronger, we made the middle
bracing that was holding the load the strongest by sticking more fettuccines together. We also decreased the length of the
bridge
Final Fettuccine Bridge Design

P R E - T E S T I N G
TRUSS STRUCTURE ANALYSIS (Mock Up Model for Initial Design)
We have chosen the truss member based on the required force to withstand tension and compression after referring to past
material testing as well as the precedent study to make appropriate joint connections.
Failure Analysis:
The material needed to sustain the loads for this model was overwhelming. From our first testing, 2 fettuccine was placed in the
middle for bracing to hang the load. The bridge weighing at 284g was able to withstand 1.45kg of load. Using the same model
and with minor adjustments (placing 2 bracings, both shaped as I-beam), the model now weighing 286g was able to withstand
2.5kg of load. While the bridge did not break during the first testing, its weight is way over the requirement of 200g.
Based on the calculation, we have found that although the weight has increased, the extra support and strength from the I-beams
increases the efficiency of the bridge.
First testing on First Mock-Up Model
Load: 1.45kg
Weight of bridge: 284g
Efficiency = (load) ^2 / mass of bridge
Efficiency =0.007
Second testing on First Mock-Up Model
Load: 2.5kg
Weight of bridge: 286g
Efficiency = (load) ^2 / mass of bridge
Efficiency = 0.02

P R E - T E S T I N G
TRUSS STRUCTURE ANALYSIS (Mock Up Model for Final Design
After decreasing the number of trusses, the length of span of the bridge and the amount of fettuccines used, this is the result of
the bridge.
Load = 198g
Mass of bridge = 4.2kg
Efficiency = (Load) ^ 2/mass of bridge
Efficiency =
Failure Analysis:
For the final model, critical, tension and compression members were reduced. The diagonal bracings are only for the three
most middle trusses while the rest are triangular. From the truss analysis, triangular members are the obvious choice as these
members has no bending moments.

T E S T I N G
TRUSS STRUCTURE ANALYSIS
During the testing day, the 2 tables were 750mm apart from each other. The bridge was tested with a bucket and water as the
load. The water was poured into the bucket until the bridge fails.
During the testing, as water was poured into the bridge, one of the trusses popped out. As more water was poured in, the
bridge started to tilt. The bridge broke and was only able to withstand 2.648kg of load.
Load = 198g
Mass of bridge = 2.648kg
Efficiency = (Load) ^ 2/mass of bridge
Efficiency = 0.04

R E A S O N F O R F A I L U R E O F B R I D G E
All the vertical members
before was thought to be
compression members
Tension
Compression
LOAD
1. Decreasing the amount of compression and tension members and misinterpretation of compression and tension members.
We decreased the amount of members in order to fit to the 200g bridge requirement but then we forgot about how
decreasing the number of members affect the compression and tension between the remaining members on the bridge.
Besides that, we also misinterpreted which member will have compression and tension force acting on it.

2. The members are too far apart
Too far apart
As the members of the bridge was too far apart, it fails to support the compression force that was acting on the members.
The further the members are from each other, the amount of compression force that is acting on one member is more
resulting in the deflection of the base of the bridge.

3. The height of the bridge
The height of the bridge is too tall as the members are too tall. The taller the members, the weaker are the members in
withstanding the compression force of the bridge. As shown in the diagram above, the bridge started tilting due to the load
that was exerted on the bracing that was holding the load.

S U G G E S T I O N S T O S T R E N G T H E N B R I D G E
1. Decreasing the height of the bridge.
By decreasing the height of the bridge, the bridge will be more firm as the height of the bridge affects the stability of the
bridge. The shorter the members in the bridge, the stronger the members resulting on a more solid bridge.
2. Decrease the length between each members and add more members
HEIGHT
By decreasing the length between each members and adding more members, the force distribution will be more equal and
also it will be more solid compared to when it is further apart.

CONCL U S ION
Based on the research of the precedent studies and experiments that were done, we have developed an understanding of
the tension and compressive strength of construction materials and the force distribution in a truss. This understanding has
enabled us to evaluate, explore and improve the attributes of construction materials as well as to explore and apply the
understanding of load distribution in a truss. We are also able to evaluate and identify tension and compression members in a
truss structure, and explore different arrangement of members in a truss structure. Finally through this project, we are able to
design a perfect truss bridge which has a high aesthetic value and is made of minimal construction material.
Therefore, we would consider our truss bridge model a success. This is due to the fact that for the final model, the material and
weight lessened from 286g to 198g. Consequently, this produces better efficiency as the weight of load carried increases from
2.5kg to 4.2kg. We were able to discover the strategy in achieving better efficiency by doing testing according to the
maximum load the bridge can sustain. Moreover, we have discovered that time management and teamwork is crucial in
producing a bridge that is not only aesthetically appealing but also of high quality during a limited time.

A P P E N D I X
Exercise: Truss analysis
A total of 5 different truss systems which carry the same loads are analysed to
determine which truss arrangement is the most effective and why.
The following are the task distribution for the cases:
Case 1: Kee Ting Ting
Case 2: Gertrude Lee
Case 3: Meera Nazreen
Case 4: Nurul Jannah Jailani
Case 5: Sonia Manyie
The analysis and calculations of trusses are attached after this page.

Building Structure Project 1

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Building Structure Project 1