SCHOOL OF ARCHITECTURE . BUILDING & DESIGN · Project 1: Fettuccine Truss Bridge Tutor: Ms. Norita Johar Group Members: ... the student a brief idea about the construction & design

SCHOOL OF ARCHITECTURE . BUILDING & DESIGN

Research Unit for Modern Architecture Studies in Southeast Asia (MASSA)

Bachelor of Science (Hons) (Architecture)

BUILDING STRUCTURES (ARC 2523)

Project 1: Fettuccine Truss Bridge

Tutor: Ms. Norita Johar

Group Members:

KONG REN HENG (0316416)

LIM WAI MING (0317068)

MICHAEL KON KEEN YIH (0300478)

PUA KEE HUI (0316672)

TAN MING LONG (0311069)

STANLEY WONG KHUNG YOU (0317236)

Table of Contents

1. Introduction

2. Methodology

3. Precedent Studies

3.1 Introduction

3.2 Structure Design

3.3 Truss & Joint

4. Analysis & Design Development

4.1 Adhesive Analysis

4.2 Material Strength Analysis

4.2.1 Properties

4.2.2 Horizontal Alignment

4.2.3 Vertical Alignment

4.3.4 I-beam Alignment

4.3 Design Development

4.3.1 Initial Design

4.3.1.1 Design Idea

4.3.1.2 Truss Analysis

4.3.1.3 Model Making Process

4.3.1.4 Model Testing

4.3.1.5 Efficiency & Improvement

4.3.2 Second Design

4.3.2.1 Truss Analysis & Enhancement



4.3.3 Third Design




4.3.4 Fourth Design




5. Final Design

5.1 Design Finalization

5.2 Amendment of Layers and Components

5.3 Layering & Joining Method

5.4 Model Making Process

5.5 Load Test & Forces Calculation

5.6 Efficiency & Improvement

6. Conclusion

7. Case Study

8. Reference

1.0 Introduction

In a group of 5 – 6 people, we are required to design & construct a bridge solely

with Fettuccine. The bridge must be design to maximize its load bearing capacity

meanwhile comply with the requirement of having a clear span 750mm and

weigh not exceeding 200g. The efficiency of the bridge will be calculated based

on the load it withstand.

This objective of this particular project is to develop students’ understanding on

forces distribution in a truss and also helps student to understand tension &

compression forces in bridge construction. Meanwhile, it trains student to tackle

the challenges through constructing the bridge which comply with the

requirement while not losing its aesthetic values.

2.0 Methodology

Students in a group of 5-6 were given a task to construct a truss bridge using the

only specific material – fettuccine pasta. Before the construction started, a

research on Calhoun Street Bridge in New Jersey, U.S. was conducted to provide

the student a brief idea about the construction & design of the truss bridge. Base

on the precedent study, students required to do further analysis about the joints

and structure component of the bridge to understand how the forces was

transferred between the members.

Before the constructing the bridge, a series of test is conducted to examine the

strength of the fettuccine. Besides that, various type of adhesive were tested to

identify the performance that is suitable to be use with fettuccine.

Pennsylvania truss have been selected as the construction method after analysing

its pros and cons. Details of the joints and the amount of fettuccine used for each

member was figure out based on the research & analysis.

Next, the drawings and the calculation of the bridge is produced to minimize the

mistakes during model making session. The main structural component of the

bridge is first erected then followed by the sub component. The bracing will be

installed to connect between components to enhance its stability.

In addition, the load testing will be carried out upon completion of each

fettuccine bridge. A bucket is hold by a hook is connected to a string that tied in

the middle of the bridge to serve as a point load. Then, water was added

continuously into the bucket until the bridge break apart.

Last but not least, a thorough analysis will be executed to examine the reason of

failure of each fettuccine bridge. Various way of improvement will be suggested

and developed into the next model in order to achieve efficiency.

3.0 PRECEDENT STUDIES

3.1 Introduction

The Calhoun Street Toll-Supported Bridge is the oldest of the 28 bridges (motor

vehicle and pedestrian) that currently span the Delaware River between

Pennsylvania and New Jersey. It is a Phoenix Pratt Truss with a total length of 1,274

feet, it also holds the distinction as the Commission's longest through-truss bridge

and the Commission's only seven-span truss bridge.

Calhoun Street Toll Supported Bridge, Source Google Maps

2D - Diagram of Pin Connected Prat Truss Bridge.

3.2 Structure Design (Function)

The Calhoun Street Bridge is a seven-span wrought iron pin connected truss bridge

containing 730 tons of iron and steel. A timber-plank pedestrian sidewalk is

supported by the upriver truss on steel cantilever brackets. It was posted for a

three-ton weight limit, eight-foot vertical clearance. On May 24, 2010, the bridge

completely closed to vehicular and pedestrian traffic to undergo much-needed

renovations including truss repair and repainting, deck replacement, and repair

of approaches.

.

The Calhoun Street Toll-Supported

Bridge is the oldest of the 28

bridges (motor vehicle and

pedestrian) that currently span

the Delaware River between

Pennsylvania and New Jersey.

The bridge is the most heavily used vehicular two-lane truss structure in the

Commission's system. It carried an average of 18,400 vehicles per day in 2009.

The bridge is currently posted for a 3-ton weight limit, an 8-foot vertical clearance

and a 15-mph speed limit. In 2008, an average 18,400 trips were made across the

bridge per day.

3.3 Truss & Joint

There are many types of truss bridges. We studied few types of truss system and

selected Calhoun Street Toll Supported Bridge as our precedent studies to analyze

the tension and compressive the strength of the construction materials used and

the force distribution in the truss.

Pratt truss

The truss has diagonal web members which

form a V-shape. It is designed by Thomas and

Caleb Pratt in 1844 and became popular for

railway bridges because it made good use of

iron.

The bridge has many variations, most with their

own unique name. E.g. the Baltimore, Pennsylvania, and the Parker are all based

off the Pratt. Having its diagonal members (except the end diagonals) slanted

down towards the middle of the bridge span. Under such structural arrangement,

when subject to external loads tension is induced in diagonal members while the

vertical members tackle compressive forces. Thinner and lighter steel or iron can

be used as materials for diagonal members so that a more efficient structure can

be enhanced.

The chords and members of a truss bridge

experience strain in the form of tension and

compression.

Joints

The use of details such as pinned joints, rocker joints and pinned eye hooks allow

the bridge to transfer loads so that the steel does not reach its yield point. These

joints help the bridge to move and adjust as loads are applied and removed.

Allowing the bridge to move in this manner places the steel and tension which

places the steel at its highest strength.

Detail 1 Detail 2

Detail 3 Detail 4

4.0 Analysis & Design Development

4.1 Adhesive Analysis

Since the components of a bridge is not manufacture in one-whole piece, it

requires bolts & nuts in order to join the component on site. Same goes to

Fettuccine Bridge, members need to be connected together using adhesive in

order to form a structure ensuring the forces applied can be transferred equally to

each member.

Various adhesive with different properties were used to test with fettuccini to get

the best result on achieving maximum stability of connection.

Types Observations Conclusion

3(s) Glue

(V-Tech)

1. Took shortest time to solidify.

2. Members are rigidly join

together when applied

Highest Efficiency

Can be apply on main

structural member.

UHU Glue 1. Took quite amount of time to

solidify.

2. Members are movable, having

chances to glide in the early

stage.

3. Components are bendable

after dried up.

Medium Efficiency

Can be apply on members

which are pre-stressed /

prone to bending

Hot Glue

Gun

1. Took longest time to solidify.

2. Creating bulky finishing when

dried up.

Low Efficiency

Same Effect as UHU glue but

it increase the weight of the

bridge.

From left: UHU Glue, 3 Sec Glue, Hot Glue Gun

4.2 Material Strength Analysis

4.2.1 Properties

Fettuccine is the only designated

material for this particular bridge

construction. Series of analysis

were done to identify the

properties and the strength of the

material before the construction

of the truss bridge.

Fettuccine is a type of pasta which

is flat and measuring about 1mm

thick & 4mm wide (it differs

between brands). It possess high

tensile strength while relatively low

in compression strength which

makes itself easily to snap due to

low elasticity value.

According to the research, Fettuccine’s maximum tensile strength is about 2000

PSI which equivalent to 137.9 Bar and the stiffness which according to Young’s

modules is around 10,000,000 PSI.

From the research, we can conclude that the compression strength of Fettuccine

need to be enhance in order to withstand the applied forces and transfer it to the

other member to achieve equilibrium state.

To identify the optimum stacking method, we have tested the Fettucine in three

types of configuration:

(A) Horizontal Alignment

(B) Vertical Alignment

(C) I Beam Alignment

4.2.2 Horizontal Alignment

Three layers of horizontal fettuccine stack

Before the test, we have chosen the fettuccine without any defects and set the

clear span to 200mm as the fixed variable. By manipulating the layers, the

maximum bearing load of the fettucine were recorded.

Length of Fettuccine

(mm)

Clear Span

(mm) Layers

Max Bearing Load

(Approx.) (g)

Horizontal Align

250 200 1 200

250 200 2 300

250 200 3 410

250 200 4 550

250 200 5 700

Observation:

The horizontally aligned fettuccine able to withstand up to 700g of water when it

is stacked into 5 layers. From the picture, we can notice that the fettuccine was

bended to counter against the shear forces applied to it. This has shown that the

Fettuccine is good in resisting tensile forces.

Conclusion:

As this configuration of fettuccine tend to be bent easily when a point load is

applied at the centre, we decide to avoid applying this type of configuration in

the design.

4.2.3 Vertical Alignment

Three layers of vertical fettuccine stack

Same as previous, the fettuccine without defects were chosen for the test and the

clear span is set to 200mm. By manipulating the layers, the maximum bearing load

of the fettucine were recorded.

Length of Fettuccine

(mm)

Clear Span

(mm) Layers

Max Bearing Load

(Approx.) (g)

Vertical Align

250 200 1 -

250 200 2 300

250 200 3 410

250 200 4 600

250 200 5 750

Observation:

The vertically aligned fettuccine is able to withstand more loads than the

horizontally aligned with the same 5 layers before it broke apart. From the picture

can clearly see that the extent of bending of this particular arrangement is not as

much as the previous arrangement.

Conclusion:

The vertically aligned fettuccine could resist the shear forces better but eventually

it broke as the load increases. Hence, we decide to use this configuration as the

non-structural members or bracing in the design.

4.2.4 I-beam Alignment

I-Beam configuration

After the previous testing, we started to construct the fettuccine to mimic the

style of the I-beam. The web (vertical member) is created by stacking more than

one layers of fettuccine, and then was covered by a layer of flanges (horizontal

members) on the upper & lower side.

Length of

Fettuccine (mm)

Clear Span

(mm)

Layers of

Vertical

Member

Max Bearing Load

(Approx.) (g)

250 200 3 850

250 200 4 900

Observation:

The vertically arranged fettuccine managed to withstand a larger amount of load

until the point where the centre bends and the load shears through the strip. This

further confirmed the assumption that fettuccine is good in resisting tensile forces.

Conclusion:

The added layers on top & bottom enhance the shear force resistance thus

maintaining the stability and stiffness. Hence, it is been chosen to act as the main

structural members in the design.

4.3 Design Development

4.3.1 Initial Design 4.3.1.1 Design Idea

First Fettuccine Bridge is designed and modified based on Pratt Truss. This bridge is

made to test the maximum load carried with the absent of consideration for the

weight of bridge. Then, the weight of the bridge will decrease radically for the

subsequence bridge to meet maximum weight of 200g as per requirement.

Based on the precedent study, we found that the highlighted points of Pratt truss

are the weakness to achieve even force distribution of the whole bridge for point

load. Therefore, we decided to modify the top chord into a curve instead of

straight line to achieve better force distribution.

‘X’ diagonal bracing is added in the middle segment as support member to resist

point load in the middle segment. Other long diagional bracing is also added in

order to distribute the force from the ‘X’ to the side. Besides, short diagonal bracing

is added help to distribute the force evenly.

Load

Layers of Fettucine of the bridge truss

The base is formed with I – beam as one of the important member in order to

withstand the forces from the point load and the members of the bridge. The

other members of bridge are formed by 3 layers of fettucine. The size of the

bridge is 150mm height, 825mm length and 80mm width.

First Bridge Model

3 layers of fettucine

I – Beam

4.3.1.2 Truss Analysis

Assumption analysis of tension and compression forces exert on each member of

the truss for point load testing.

Load

Tension Force

Compression Force

4.3.1.3 Model Making Process

I - beam was made with length 825mm as the base of the bridge.

Vertical components were erected on the base. The height of vertical

components were 150mm, 145mm, 135mm, 120mm, 100mm, 75mm and 45mm.

Curved chord was added on top of the vertical components.

Diagonal bracing were added in between the segments.

Horizontal components with width 80mm were added to join two trusses. Lower

horizontal components were sat on the base, while upper horizontal components

were joined under the curved chord. ‘X’ bracing was added horizontally between

the base components in the middle segment. Then, two horizontal components

which formed with 5 layers of fettucine were added on the ‘X’ bracing as load

hanging component. ‘X’ bracing was used help to distribute the force from the

load hanging component.


Load testing for First Bridge

‘S’ hook was hanging over the load hanging component of the bridge used to

hang a pail as shown in figure above. 500ml of water was added constantly into

the pail during the testing.

Snapped off load hanging component

The bridge with 0.269kg of weight was able to withstand 3.9KG of load. The failure

occurred at the load hanging component. It snapped off when the load was

added up to 3.9KG. The other part of the bridge remains fine. The reason of the

failure is the ‘X’ bracing under the load hanging component is not effective as it

is not distributing the force well to the base.

4.3.1.5 Efficiency and Improvement

EFFICIENCY = (𝑀𝐴𝑋𝐼𝑀𝑈𝑀 𝐿𝑂𝐴𝐷)^2

𝑊𝐸𝐼𝐺𝐻𝑇

= (3.9 )2

0.269

EFFICIENCY = 56.5

Suggested improvement:

1) ‘X’ bracing under load hanging component should be place on the base,

so that the force will transfer effectively from the ‘X’ bracing to the base.

2) Vertical diagonal bracing is joined by the side of the segments.

3) Decrease the number of layer of fettucine for the vertical diagonal bracing

and curved chord from 3 layers to 2 layers in order to decrease the weight

of bridge.

3.9KG

4.3.2 Second Design


Second Test Bridge

For the second bridge, we decreased the layer of fettuccine in order to reduce

the weight to around 200g. The vertical length of the fettuccine bridge remained

the same and the middle load distribution part is highly reinforced. The span of the

bridge and its width are maintained at 840mm and 80mm respectively, the height

is also maintained at 150mm.

Reinforced Load Hanging Member

The main load hanging member (red square box) is situated on top of both of the

bases. After that, both ends of the main load hanging member are joined with the

vertical member. This is to ensure that the load hanging member is well connected

to the whole bridge structure so that the load can be distributed effectively. An X-

truss is used to support the main load hanging member.

Two additional load hanging members (blue square box) are added to both sides

of the main load hanging member so that they can divert the load exerted

separately.


Around 1kg loading, the bridge showed a significant bend at the top of the

bridge.

Around 1.5kg, the top part of the bridge showed sign of collapse as it could not

support the load distributed any longer.

When the load reached 1.7 kg, the top of the bridge collapsed. After that, the

middle part of the main base collapsed as well. This is due to the fact that when

the top part of the bridge collapsed, all the loads are distributed throughout the

base only.

4.3.2.3 Efficiency and Improvement

Based on the load test, the second bridge is far from reaching our goal which is

supporting a load of 5 kg because the curved top part of the bridge is too thin. It

could not support the load distributed to it. Besides that, the bridge is too tall and

it is not in proportion, therefore unnecessary weight is increased for the bridge and

its efficiency is decreased.

Besides that, the edge of the curved part of the bridge does not touch the end of

the base, causing the load to be distributed unevenly at the edge.

Moreover, the curved part of the bridge is joined to the members at both sides by

being attached beneath the top vertical beam. This reduces the strength of the

chord as the joint is not as strong as if the chord is attached to the top of the beam.

Beam

Chord

Column

EFFICIENCY = (𝑀𝐴𝑋𝐼𝑀𝑈𝑀 𝐿𝑂𝐴𝐷)2


= (3.5)2

0.2

EFFICIENCY = 61.25

Suggested Improvement:

1) Increase the layer of the curved chord of the bridge.

2) Ensure the edge of the curved chord touches the end of the base.

3) Decrease the length of the vertical components.

4.3.3 Third Design


From the second design, the study about the failure have learned that the curved

top chord must be sitting on top of the vertical component in order to spread the

forces to the lateral member. The middle part of the bridge where the load will be

hang is further strengthen by doubling the vertical component which connects

the base and the curved chord. The snapping of the previous test bridge inform

us about the weakness of the curved chord. Hence, the layers of fettuccine were

increased from 2 to 3 with the support of lateral bracings added on the middle.

The span of the bridge and its width are maintained at 840mm and 80mm

respectively, but the height is decreased to 105mm.

Improvised Diagram of Third Bridge

(Red: Top Chord w/ 3 layers, Blue: Doubled Vertical Component)

The lateral bracing provide

support for the curved arc as well

as distributing the forces among

the members.


(A) The curved chord started to bent. (B) The force exerted ripped off the arc from the vertical component (C) Snapped arc (D) The load hanging

component also broke due to arc failure.

Before the load test, we have found that the curved arc member already bended

due to craftsmanship. The water is continuously added during the process. Around

2kg, the bended curved member started to deform. Eventually the curved arc

snapped causing the bridge to collapse when the water is added until 3kg.




= (3.5 )2

0.191

EFFICIENCY = 64.14

(A) (B)

(C) (D)

The load that the bridge can withstand has increased from the 1.7kg of the

previous bridge to 3.5kg. The middle load distribution part is very effective as it

doesn’t buckle. However, the fettucine at the upper curve part breaks and the

whole bridge collapsed. This is due to the curve part. Moreover, the spot on the

curve which broke first is not reinforced by bracings.


1) Increase the number of layers.

2) Support the bridge with overhead

bracings that further reinforced the

bridge.

4.3.4 Fourth Design


Due to the previous failure, using the same design, we decide to use the remaining

available weight around (10g) to add two more lateral bracing in the middle (total

four)and “V” bracing on the side to increase the arc stability.

The additional 10g is added with the addition of lateral bracing.


(A) The curved arc starts to snap at the end of the support of the lateral “X” bracing. (B) The Bridge starts to fail due to the loss of the arc support

(C) & (D) The failure component after testing.

When the water added reached 3kg, the arc started to bend at the end of the

“X” bracing. After a few moments, the deformation become worse. The arc

ultimately snapped but the bridge did not break immediately. It sustained the

weight for almost 5 second before it broke apart. It recorded the weight of 3.5kg.

(A) (B)

(C) (D)


The “X” bracing indeed play an important role in distributing the loads. But reason

that causing the bridge to fail is the incomplete braces. The “X” in the middle

distribute the loads to the side so does the “V” bracing. But, when the load reach

the end of the “X”, only one side of the forces transferred to the “V” bracing, the

other side remains on the arc which cause an imbalance situation. This eventually

turns the bridge to break apart.



= (3.5 )2

0.198

EFFICIENCY = 61.86


1) Uses “X” bracing instead of “V” for the top of the structure.

2) Improve craftsmanship in terms of cutting.

5.0 Final Design

5.1 Design Finalization

Final bridge design

After having 4 test bridges, we finalized our bridge design, overcoming its flaws

and optimizing the bridge’s load distribution efficiency.

1) The middle of the bridge is highly reinforced due to the fact that we

decided to use a single point load in the middle. We doubled the vertical

components in the middle of the bridge to increase its compressive strength.

2) The horizontal components remain the same from the start. It acts as a

connecting member between the two bridge trusses.

3) For the load hanging part, we decided to use back the design of test

bridge 1, which is an I-beam supported by a 4 layers x truss. Since the

previous positioning of the load hanging components appeared to be a

failure, we decided to place all load hanging components on top of each

other on the base so that the load can be distributed to the base and to

the other part of the bridge. If we place the x- truss between the two base

I-beams, the x-truss is only supported by the adhesive, thus minimizing the

load distribution efficiency.

4) The top chord of the bridge remains curved to increase its tension strength.

The flexibility of the curved chord enable load to distribute smoothly without

any obstruction. The end of the curved chords are connected to the base

so that the loads can be distributed to it and supported by the reaction

force.

5) Diagonal bracings are used to divert the load from the base to the curved

chord or vice versa. For the diagonal bracing, we used only the full slanted

components because they turn out to be more than enough to distribute

the load effectively. Therefore, we removed the smaller components and

used the additional weight to further reinforce the bridge.

6) In order to maximize the strength of the curved chord, we added lateral

bracing throughout the whole curved chord. The lateral bracings were

able to support the curved chord while receiving loads from the vertical

components.

(A & B) Load hanging component at the middle of the bridge (C) Top view (D) Lateral bracing

(E) Elevation (F) End part of the bridge

(A) (B)

(C) (D)

(E) (F)

5.2 Amendment of Layers and Components

For the base, we stick to our initial idea which is to make it an I-beam as I-beam

had the strongest compressive strength among the other beam design. Since the

base is the most important structure of the whole design, we wanted to make it as

strong as possible, but not too heavy until it contributes to the compressive strength

of the load itself.

Layers of Fettucine of the bridge truss

The vertical components remain as 3 layers because it is the ideal number of layers

in terms of support and weight. If we use 2 layers, the vertical components will be

too weak to support the structure and will end up like test bridge 2, breaking due

to the lack of reinforcing. However, a layer of 4 fettuccine is used for some bridge

component only because the extra layer of fettuccine increases the overall

weight of the bridge drastically, thus decreases the efficiency of the bridge.

For the curved chord, we decided to make it 3 layers as it provided the ideal

strength and flexibility. 2 layers are not recommended because although it had a

better flexibility, the components appeared to be too weak to support the

structure. 4 layers are not used as well because the curved chord will lose its

flexibility, making it unable to bend according to the shape of the vertical

components.

The diagonal bracing also remain as 3 layers to provide support to the entire

bridge. It holds the base and the curved chord together, preventing them from

collapsing. If a thinner member is used, the bridge will collapse immediately, while

if a thicker member is used, the bridge will appear to be overweight.


I - Beam

Layers of Fettucine of the bridge components

The horizontal components consist of 2 layers so that it can support the two truss

bridges, preventing them from crushing each other. If a single layer of fettuccine

is used, the support is too weak but if more than 2 layers of fettuccine are used, it

will appear to be wasteful as the components do not contribute to any load

distribution.

Lastly, the lateral bracing used for the 6 segments in the middle of the curved

chord are composed of 3 layers, while the lateral bracing used for other segments

are composed of 2 layers. This is due to the fact that the middle part of the bridge

experiences the biggest load, therefore 3 layers of fettuccine is used. As the forces

decreases while approaching the edge, lateral bracing of 2 layers are used so

that the bridge would not overweight.




I - Beam

5.3 Layering & Joining Method

Layering Method

Running Bond Pattern: Brickwork running bond pattern construction method was

adopted in the making of the curved chord and base components. Running bond

allow us to lengthen the fettuccine to the span we preferred in a way of

intersection when laying each other.

Beam: 4 layers of fettuccine were neatly overlapped on each other to create the

requirement thickness. After that, 2 fettuccine with the same length were pasted

on the rough surface of the overlapped fettuccine to provide compression force.

Therefore, the I-beam created is strong and durable enough to withstand heavy

loads.

Overlapping: Bracing and trusses were made of 2 to 4 layers of Fettuccine staking

together.

Joining Method

The Components are joined to each other in a way that each component is

connected to each other, so that the load can be distributed with maximum

efficiency.

The diagonal bracings are fit perfectly into each segment so that no additional

force is created.

Before the curved chord is joined to the vertical components, the tip of each

component is smoothening until a certain degree with sandpaper. This is to ensure

that the curved chord can lay perfectly on the vertical components and the load

can distribute evenly to the curved chord. If the curved chord is joined onto a

rough surface, an uneven load distribution from the vertical components will

cause the curved chord to collapse.

Lateral bracing is jointed perfectly between the two curved chords so that the two

curved chords are well supported. The lateral bracings also act as load distribution

members.

Cross section of I - Beam

Running bond pattern

The reason we fit all the members perfectly to each other is because we wanted

to make the bridge a whole, so that all members are dependent to each other,

one member snaps and the others will snap as well.

The model testing session was carried out 3 hours after the bridge completion. In

order to ensure the bridge reached its strongest state, we used a hairdryer to blow

the bridge with cool air for a few hours, so that the superglue can reach their

maximum bonding strength.

Condition of the bridge after the test

During the test session, the bridge appears to be very strong even the load

reached 2.5kg. After the load surpasses 2.5 kg, the curved chord of the bridge

appeared to budge a little, but there were no visible deformation on the bridge.

The curved chord started to show visible deformation as the load increases. When

the load reached 3.9kg, one of the base member snaps, after that the load

hanging part of the bridge instantly breaks while the other parts of bridge

remained intact.

5.5 Load Test & Forces Calculation

During the load test, the final bridge managed to perform well which bending did

not occurs on any members especially on the arc chord. But, out of our

expectation, the base cracks when the weight is added until 4 kg and eventually

broke apart. The other members were remain on position when the base failed to

withstand the forces.

5.6 Efficiency & Improvement



= (4.009 )2

0.191

EFFICIENCY = 84.15

The efficiency is lower than what we expected, but we still seek for more

improvement. After some analysis, we realize that our bridge faces member failure

rather than structural failure. One of the base members is not glued properly,

therefore influencing the other members.


1) Workmanship needs to be improved.

4.009KG

6.0 Conclusion

Upon the completion of this project, we successfully produce a very strong bridge.

Throughout the process, first and for most, precedent studies were done to give us

a clear direction for our bridge design. It also helped us to develop a better

understanding on how truss bridge works. This shows the importance of doing a

detailed precedent study for a specific project.

Although the bridge does not meet our expectation, we are still very satisfied with

the outcome. After spending days and nights making test models and doing

research, it was worth it as our bridge improved significantly in terms of aesthetic

and functional purpose. The experience is priceless as we managed to explore

more than what we learn in class. We also managed to sharpen our skills such as

critical thinking, problem solving, idea generating, workmanship, communication,

negotiation and most important, teamwork.

After this project, we fully understand the principles of tensile and compression

strength, distribution of force in a truss, jointing method and other else. Of course,

we would never improve so much without the guidance of our tutor.

Since our bridge faces member failure rather than structural failure, we believed

that our bridge can reach an even higher efficiency if we provide a better

workmanship to it. Leaning is a lifetime process, it is up to us to learn from our

mistakes to continue developing towards better understandings and beyond

better in future performance.

7.0 Case Study

Case 1

Case 2

Case 3

Member(s) with zero

internal force DE

Highest tension in

members

414.61kN,

member AH

Highest compression

in members

360kN,

member AJ

Member(s) with zero

internal force DE

Highest tension in

members

414.61kN,

member AH

Highest compression

in members

360kN,

member AJ

Member(s) with zero

internal force AJ, DE

Highest tension in

members

345.71kN,

member AB

Highest compression

in members

414.61kN,

member BJ

Case 4

Case 5

Case 6

Member(s) with zero

internal force AJ, DE, DF

Highest tension in

members

345.71kN,

member AB

Highest compression

in members

414.65kN,

member BJ

Member(s) with zero

internal force AJ, DE, DF

Highest tension in

members

345.71kN,

member AB

Highest compression

in members

414.628kN,

member BJ

Member(s) with zero

internal force AJ

Highest tension in

members

544.8kN,

member HJ

Highest compression

in members

511.4kN,

member GH

From the analysis we can see that:

1) The highest tension and compression forces in each cases are about the

same, with the exception of case 6.

2) Case 1, case 2 and case 6 have the least number of members with zero

internal force.

3) Case 4 and case 5 have the most number of members with zero internal

force.

Therefore we can conclude that the truss from case 1 and case 2 are the most

effective, while the truss from case 4 and case 5 are the least effective.

8.0 Reference

- Delaware River Joint Toll Bridge Commission. (2014). Calhoun Street Toll

Supported Bridge. Retrieved May 4, 2015 from website

https://www.drjtbc.org/default.aspx?pageid=78

- Francis D. K. Ching (2008) Building Construction Illustrated (Fourth Edition)

New Jersey: John Wiley & Sons, Inc.

Documents

SCHOOL OF ARCHITECTURE . BUILDING & DESIGN · Project 1: Fettuccine Truss Bridge Tutor: Ms. Norita Johar Group Members: ... the student a brief idea about the construction & design