B structures report

Building Structures [ARC 2522] Fettuccine Truss Bridge Analysis Report

CHEAH EUGENE 1001GH77034MARIA ROSA SEU 0317067

MEGAT KHAIRUR RASYAD BIN ZULKHAIRI 0320832NUR SYAZLEEN SIES 0321260

SUMITCHAI THAMDEE 0310892

Table of Contents

1. Introduction1.1 General Purpose of Study1.2 Report Preview1.3 Restrictions

2. Methodology

3. Equipment and Material Analysis3.1 Equipment3.2 Materials Strength Study

3.2.1Adhesive Types3.2.2 Adhesive Strength Test3.2.3 Fettuccine Types & Strength Study

4. Precedent Study4.1 History and Function4.2 Truss Analysis4.3 Joints

5. Analysis of Test Bridges5.1 Test Bridge 1 Analysis5.2 Test Bridge 2 Analysis

6. Analysis of Final Bridge6.1 Final Design of Truss6.2 Final Bridge Testing6.3 Failure Analysis

7. Conclusion

8. References

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1. Introduction

1.1 General Purpose of Study

The aim of this project was to successfully design an effective truss bridge through the analysis conducted with the precedent studies as well as the points discussed throughout the lectures. Students had to evaluate, explore and improve upon attributes of construction throughout the project with the given construction material, fettuccine pasta. This was achieved through numerous experimentations of different truss systems, adhesives and the types of joints used, while the construction material remained fixed. By applying our understanding of tensile and compressive strengths in a truss system, we then were able to develop our understanding of force distribution in the bridge constructed. Throughout the project, we were also able to calculate the load distribution in a truss system, demonstrated later in the report. We were then later able to identify which members and joints were to be strengthened in terms of tension and compression.

1.2 Report Preview

In a group of 5, we were tasked to choose an appropriate precedent study of a structural truss bridge. Later, based on the precedent, we had to construct a bridge consisting only of fettuccine and any adhesive materials we deemed fit (superglue). The requirement of the bridge was that it had a maximum weight of 150 g and a 600 mm clear span. As well as being functional and efficient, in that it can carry a high load, it had to be lightweight and aesthetically pleasing. It would then be tested to see if it could withstand different weights of acute, point loads (when a weight is focused on one specific part of the bridge) for ten seconds.

1.3 Project Restrictions

Fettuccine was the only construction material allowed for building the model truss bridge and we had to construct it with a 600 mm clear span and had to have a maximum weight of 150 g.

2. Methodology

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For completing this project, the following procedures were carried out:

Precedent StudyIn order for our group to have a better understanding of a real, functioning truss bridge, we chose a good precedent study to refer to and help us along the analysis of our model bridge. We focused on the connection of joints, arrangement of members and which truss type was the most efficient, as well as whether it was aesthetically pleasing. Based on our findings for the precedent, we then adopted that features worked best and implemented it into our design.

Material and Adhesive Strength TestingBefore constructing even the first test bridge, we had to experiment with the physical properties of the fettuccine, such as the ‘feel’ and behavior of it when subjected to abnormal amounts of weight. We experimented with different brands of fettuccine (Barilla vs. San Remo), the type of fettuccine (regular fettuccine vs. spinach fettuccine), and the types of adhesive used. It is important to test different brands of fettuccine to observe their strength when subjected to loads before skipping to the next phase of model making. Our analysis of how well different fettuccine behaves under different weights is recorded under the chapter “Material Strength Analysis”.

The adhesive was an important consideration, as what we used to bond the fettuccine together would affect the overall strength of the structure. There are various choices of glue with different characteristics available, so it is obviously crucial to choose the appropriate adhesive.

Model MakingWhen we began to design the bridge, we started out with drawing sketches of the truss. Once a general design was agreed upon, we drafted it on AutoCAD and these drawings were printed out in a 1:1 scale, so we could follow the design accurately and easily.

Fig. 1.1 & Fig. 1.2: Process photos of the crafting of the bridges.Structural Analysis

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The truss’s strength was analyzed by which understanding which members were used for tension purposes and which for compression. We based our structural analysis of the bridge on the same methods used in the truss analysis exercises given as case studies.

Model TestingThe initial draft bridge models were tested by applying loads attached to a string to the middle of the intermediate member of the model with the restriction of a 600 mm clear span. Every time a draft model could not hold the required weight, we analyzed the reason behind it and improved upon it with the next one until we made the final bridge for testing in class.

Working Schedule:

23rd March 2015 Forming of group2nd April 2015 Testing of the strength of the materials

(brands and types of fettuccine) and different adhesives,

7th April 2015 Initial designing of truss8th April 2015 Confirmation of design and crafting of

bridge #19TH April 2015 Testing of bridge #113th April 2015 Construction of bridge #215th April 2015 Testing of bridge #217th April 2015 Construction of bridge # 320th April 2015 Testing of bridge #324th April 2015 Construction of bridge #425th April 2015 Testing of bridge #426th April 2015 Construction of final bridge27th April 2015 Submission and testing of final

fettuccine bridge

Table 1: Working Schedule

3. Equipment and Material Analysis

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Fig.2: Typical materials and equipment’s used throughout the project.

3.1 Equipment

These were the tools we needed for the model making:

1) Pen Knife & Scissors:

The penknife and scissors were used in the model making process to cut the fettuccine strips.

2) Rulers & Scale Rulers

To help us accurately measure each fettuccine member.

3) Calculator

In order for us to solve the calculations accurately and quickly, we made sure to always have a calculator on hand in the duration of the project.

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4) Kitchen Balance

Measuring equipment for weighing our pasta to make sure it did not exceed the restricted weight, 150 g.

5) S-Hook

The S- Hook was used to connect the fettuccine bridge to the load (weights), at the center of the bridge.

6) Camera

A camera was used to document the working process as well as take videos for testing of the bridges.

7) Bucket

Buckets were used during the load testing to hold the loads- water.

Table 2: Equipment needed for project

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3.2 Material Strength Study

3.2.1 Adhesive Types

We experimented with different types of glues to obtain the best result for our connections:

Types of Adhesive Analysis3- Second glue (V-tech) Fastest bonding time- about

3 seconds. High connection bond

strength High efficiency Clean connection of joints Easy to apply However, it makes the

fettuccine brittle faster than the other glues and has a high tendency of cracking after a few days.

Super Glue (Elephant) Fast bonding time- about 10 seconds, but not as fast as the 3- second glue.

High bonding strength High efficiency Clean connection of joints Easy to use. Strength of bond between

connections still remained strong after a few days.

UHU Glue Slow bonding time- about 35 seconds.

Easy to apply. Average connection bond

strength. Average efficiency.

Glue gun Troublesome to use High connection bond

strength. Finish is bulky and messy-

increases weight of bridge. Joints flexible when dry.

Table 3: Comparison of different types of adhesives.3.2.2 Adhesive Strength Test

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Type of Glue:

Clear Span (mm)

:

Length (mm): Glue applied on fettuccine:

Layer of pasta:

Weight Sustained (g):

Super Glue

20 24 Whole 2 360.5

3- Second Glue

20 24 Whole 2 270

Table 4: Comparison between the strength of fettuccine after being applied with super glue and 3- second glue within a day.

According to the table above, super glue performed better than the 3- second glue as it has the highest strength in connecting joints and withstanding loads, although it takes a longer time to bond.

Next, we let the layers of pasta dry for more than one day:

Type of Glue:

Clear Span (mm)

:

Length (mm): Glue applied on fettuccine:

Layer of pasta:

Weight Sustained (g):

Super Glue

20 24 Whole 2 380

3- Second Glue

20 24 Whole 2 260

Table 5: Comparison between the strength of fettuccine after being applied with super glue and 3- second glue for more than one day.

After leaving the fettuccine layers to settle for more than a day, we conducted another test to see if the weight it could sustain was more or less than what it could in table 4. Super glue could sustain even more weight, while the 3-second glue sustained less. This may be because the 3-second glue made the joints brittle, causing the members to easily dislocate. This experiment proves that when using 3- second glue, we need to make sure that a test for a bridge would be carried out immediately after making it, while super glue could keep its hold longer.

Type of Glue:

Clear Span (mm)

:

Length (mm): Glue applied on fettuccine:

Layer of pasta:

Weight Sustained (g):

Super Glue

20 24 Whole 2 280

3- Second Glue

20 24 Whole 2 105

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Table 6: Comparison between the strength of fettuccine after being applied with super glue and 3- second glue for more a number of days.

The table above demonstrates how the strength of bond of both glues fell sharply after several days left to dry and settle. We concluded it was because of the fact the glue oxidizes and makes the pasta brittle and weak. However, between the two glues, super glue remained superior in terms of strength bond over 3- second glue so we decided upon using that for the making of the models.

However, the bridge would have to be done 2 days before testing to prevent oxidization from happening, so timing was a key factor.

3.2.3 Fettuccine Types & Strength Study

We carried out several strength tests on the 2 materials used for the bridge, fettuccine and adhesive, to see which brand or which type of each material was the strongest for carrying loads.

Fig. 3.1: San Remo was our choice of fettuccine for the final bridge.Fig. 3.2: Experimenting with different layers of fettuccine.

Since fettuccine was our main construction material, it was crucial that different brands and types of fettuccine were tested before making the physical model.

To build a strong and efficient bridge, different brands and its properties (rigidness, flexibility etc.) were tested to see which could withstand the highest load. Below are the three different brands of fettuccine we tested by hanging a load on one stick of fettuccine:

Image Brand Weight Sustained

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San Remo 180 kg

Barilla 160 kg

Kimball 120 kg

Table 7: Fettuccine brands and the weight they could sustain.

Based on the table above, it is clear that San Remo was the best choice of fettuccine as it could sustain the highest load. Also, compared to the other brands, San Remo had a flatter shape, this easier to stick into layers and create a quicker and more solid bond.

After we chose San Remo as main building material, we decided to test whether the “normal” fettuccine would be better than the spinach fettuccine:

Spinach type Regular Type

Could hold up to 179 kg. Color not as nice as the regular

fettuccine.

Could hold up to 182 kg and potentially more.

Color more aesthetically pleasing.

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Table 8: Comparison of spinach fettuccine vs. regular fettuccine.

When we decided that the regular type of fettuccine was superior, we also conducted a test in which we layered sticks of fettuccine to test how many layers was the strongest without jeopardizing the weight of the overall structure.

Layers of members

Length of fettuccine

(cm)

Clear span (cm)

Load sustained,

vertical facing (g)

Load sustained, horizontal facing (g)

1 24 10 400 2002 24 10 500 4003 24 10 800 8004 24 10 1200 1400

5 (I- beam) 24 10 - 1800

Table 9: The test results of different layers of fettuccine and the load each could sustain.

Another question we pondered upon was whether the orientation of the fettuccine while we stuck it into layers would affect the strength when used in our model design.

Type of glue Layer of sticks Glue applied Weight sustained (horizontal)(g)

Weight sustained (vertical) (g)

Super Glue 2 Whole 280 3603 Whole 385 4504 Whole 465 5305 Whole 585 525

Table 10: Comparison of horizontal and vertical orientation weight load as number of layers increase.

As table 10 illustrates, it is best to bond the layers vertically as it can sustain higher loads than the bonding it horizontally. However, this is only best up to four layers. For five layers, a better outcome will occur to bond it horizontally as it could sustain the highest amount of load.

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4. Precedent Study

B.B. Comer Bridge, Jackson County, Alabama, Unite States of America.

To aid us in designing the best possible bridge, we conducted a precedent study on the B.B. Comer Bridge.

Figure 4.1: Exterior view of bridge

Type of truss: Cantilevered Warren through TrussMain span length: 310.1 ft.Total length: 2,143.1 ft. (653 m)Deck width: 19.7 ft.Status: Open to trafficAverage daily traffic: 8639

4.1 History and Function

The B.B. Comer Bridge is a two lane, 2,143-foot (653 m) long, cantilevered warren through truss bridge spanning the Tennessee River along Alabama State Route 35 in Scottsboro, Alabama. The bridge is named after Braxton Bragg Comer, the governor of Alabama who served from 1907 to 1911. It was constructed by the Kansas City Bridge Company for the Alabama State Bridge Corporation, in which construction commenced in 1929 and was completed by 1931. As of 2013, this is the only remaining bridge of the 15 memorial toll bridges constructed by the Alabama State Bridge Corporation.

By 2007, the aging structure was classified by the Alabama Department of Transportation as being a structurally deficient bridge with an overall rating of 7.7 out of 100. Construction of a replacement bridge commenced in October

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2007, and is expected to be completed in late 2015. The Comer Bridge is scheduled to be demolished in 2015 although preservation efforts are underway and the Comer Bridge Foundation has been organized. On October 31, 2013, the B. B. Comer Bridge was added to the Alabama Register of Landmarks and Heritage.

Figure 4.2: Interior view of bridge

Fig 4.5: Historical photograph showing the construction of the bridge

Fig 4.3: Close up of structural members of the bridge.

Fig 4.4: Cantilever Warren through truss spanning over the Tennessee River.

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4.2 Truss System

Fig 4.6: Warren Truss

The bridge is a fixed metal 8- paneled warren through truss. The bridge has main spans whose truss spans have "towers" at the piers and thus have the appearance of a cantilever truss. However, the bridge appears to function as a rigid continuous truss since no hinges are visible on the central main span. The bridge also has a four simple through truss approach spans, as well as 14 steel stringer approach spans.

The warren truss that the B.B. Comer Bridge utilizes consists of equilateral or isosceles triangles, which minimizes the forces to only compression and tension. Warren trusses typically range from 150 ft. to 300 ft. When a load moves through across a bridge, the forces on the members switch from compression to tension. Most warren trusses consist of verticals to limit the length of the floor system panels and the unsupported length of the top chord. The verticals alternate in being tension members and compression members. They carry insignificant load in a through truss but full live loads in a deck truss.

4.4 Joints

The B.B. Comer Bridge makes use of a number of connecting joints:

1) Gusset plate connections

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2) Connections of portal bracing members

3) Connection of multiple diagonal members

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5. Analysis of Test Bridges

5.1 Test Bridge 1 Analysis

After studying the difference of each beam and the orientation of it, we started building our very first Fettuccine Bridge. Our main study was to test how much the base plays a role in carrying a load. We used “I” beam for the long span because it was proven to be strongest among other five type of beam. And then we focused on strengthening the load bearing part so it can withhold more load. We didn’t pay much attention to the truss, so it was a simple design just to accommodate some weight. A 2 layer 7cm piece of fettuccine was used as a connective part of two long span I beams.

Test Result

Test Load 10-Second test1 0.4 2 0.8 3 1.2 4 1.6 X

Efficiency = load2/weight of the bridge = (1.6)(1.6)/0.1 = 25.6

Problem Identification

Bridge InformationHeight: 12cm Width: 7cmClear Span: 750mmTotal Length: 900mmWeight: 100g

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5.2 Test Bridge 2 Analysis

As more weight added onto the bridge we noticed how big of a role trusses play in weight distribution. The top beam started to break and the bridge broke at weak spot of the I beam and break instantaneously. The base didn’t pay as much damage so we know we did the right thing with the base and wanted to use I beam and strengthening them by adding more layers and adding proper trusses.

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After having the right design for the base we started to focus on the design of out trusses. We used triangular shape because its supporting tension and compression member are theoretically better as it is more strong and effective. We used the base from our first analysis and improve our workmanship. We focused on learning from our last mistake by protecting the “weak spot” of the bridge and strengthening it by putting stopper to avoid rotation and putting a small piece of fettucine at the connection to react as a connecting plate.

Test Result

Test Load (kg) 10-Second Test1 0.5 2 1.0 3 1.5 4 2.0 5 2.5 6 2.6 X

Effectiveness = Load2/Weight of bridge = (2.6)(2.6)/1.6 = 42.25

Problem Identification

Bridge InformationHeight: 14cmWidth: 7cmClear Span: 750mmTotal length: 890mmWeight: 160g

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6. Analysis of Final Bridge

The bridge was sturdy until we start putting on more than 2kg. We can see that the bridge slowly shake and starting to fall apart. After we put on 2.6 kg, the trusses started to break and as the trusses break, gravity did its job and pulled the bridge downward which later cause shearing on the long span I beam which ended up broken. It was obvious that weak spot was still at ¾ of the bridge and it was the most breakable point after the trusses broke down.

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6.1 Final Design of Truss

92 cm

12 cm9

cm6 cm

14 cm 12

cm

Cantilevered warren through truss design.

Elevation of the truss with measurements

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6.2

Final bridge testing day:

Tension members start to buckle after 600 grams are added to the center of the bridge.

Top chord (compressionmember) begins to deflect at around 10 seconds into testing.

The bridge breaks at about 60 seconds into testing.

Bridge breaks completely in half at 1067 g.

The bridge was placed between two tables and an S hook with loads were attached to the center.

7 cm

Side elevation with dimension of deck width.

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6.3 Failure Analysis:

In our final bridge model testing, we made a mistake by using old pasta instead of a freshly opened one. It affected the strength of our final fettuccine bridge. We discovered that old pasta is weaker and its so much easier to break and instead of using two points we put the weight on only one point of the bridge, making the load distribution much more focused on the middle part and drags the bridge down more easier. This bridge is also heavier than our second testing bridge because we used more pasta to strengthen the trusses and joints. At the end it only withheld 1.067kg of weight and the efficiency dropped due to all these various reason.

Test Result:

Effectiveness of = Load (2) /Weight of bridge = (1.07) (1.07)/0.182 = 6.25

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7. Conclusion

We had constructed a few bridges and experimented with many factors such as types of beams, orientation of beams, design of the trusses and limiting the weight of the bridge and by doing so we chose the best proven method to build our final bridge in hopes that it will be the strongest of them all.

Other than understanding how each member works, we also learnt how important tensile and compressive members were in making the bridge more effective, as well as that the orientation of each member plays a big role in keeping everything together. Besides that, small things such as how long the material is exposed to air can affect the whole effectiveness of the bridge and how load distribution is important.

In conclusion, it has been a great experience to use an everyday-household item such as fettuccine to construct a bridge that can withhold more weight than expected. We are lucky to study the strength of the pasta and study how amazing by simple movement such as turning the pasta sideway can affect so much in constructing a strong and effective bridge. As an architecture student it is important that we know how all these things work so that we can design more effectively and not just for aesthetic reason. It is a privilege to understand all these because now we can use the information to make our future design, better and more effective.

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8. References

Ambrose, James E. Design of Building Trusses. 1st ed. New York: J. Wiley, 1994. Print.

Baughn, James. "B.B. Comer Bridge." B.B. Comer Bridge. Bridgehunter, 2 Oct. 2006. Web.

Boon, G. (2011, January 4). Warren Truss. Retrieved October 3, 2014, from Garrett’s Bridges: http://www.garrettsbridges.com/design/warren-truss/

Ching, F.D. (2008). Building Construction Illustrated Fourth Edition. Canada: John Wiley & Sons Inc.

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