Project Truss Bridge(1).docx

PROJECT TRUSS BRIDGE: ANALYSIS AND MODEL

COURSE CODE

BFC21403

COURSE NAME

STRUCTURAL ANALYSIS

FACULTY

FACULTY OF CIVIL AND ENVIRONMENTAL ENGINEERING

MEMBERS

1. MUHAMMAD SYAZWAN BIN AHMAD SHUKRI(CF170047) 2. MUHAMMAD NURHISHAM BIN MOHD AZLAN(CF170049) 3. NIK MUHAMMAD AKASHA BIN NIK ZAIN (CF170043 ) 4. MUHAMMAD KHAIRUDDIN BIN KASSIM (DF170136)

SECTION

6

LECTURER’S NAME

DR MOHD HANIF BIN ISMAIL

DUE DATE

MARK

TABLE OF CONTENT

1.

INTRODUCTION ..................................................................................................................................... 1 a.

BASICS OF TRUSS BRIDGE ................................................................................................................. 2

2.

PROBLEM STATEMENT .......................................................................................................................... 3

3.

OBJECTIVE ............................................................................................................................................. 3

4.

METHODOLOGY .................................................................................................................................... 4

5.

LAYOUT AND DESIGN ............................................................................................................................ 5 a.

DESIGN .......................................................................................................................................... 5

b.

SIDE AND PLAN VIEW .................................................................................................................... 5

6.

MODEL OF THE TRUSSES BRIDGE.......................................................................................................... 6

7.

RESULT AND CALCULATION OF LOAD TESTING .................................................................................. 12

8.

CONCLUSION ....................................................................................................................................... 23

1. INTRODUCTION

This project basically study of the deflection of the trusses and the load can accommodate by bridge after undergoes a laboratory test toward the model. The model is required has been prepared a flexural member based on specific dimension and length given by the instructor. For this project it was required to produce the bridge made of satay sticks and adhesive (5 second super glue) only. The descriptions for trusses bridges are the overall span length should be exactly 1200 mm. The bridge must be simply supported and there is no deck slab of the bridge. Next the height must be exactly 300 mm and width must be exactly 100 mm and for the base area must be exactly 100 x 100 mm. the last one is total weight not exceed 300 g. Then, the bridge will be tested with load P placed at the point A and point B of the bridge like the figure 1. Load is acted slowly with increment until the bridge fail. The load and the deflection of the bridge were recorded.

Overall Span 1200 mm

Figure 1: The description of the bridge model

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a. BASICS OF TRUSS BRIDGE Wooden truss bridges were used as early as the 1500s, but the first metal one was completed in 1841. They are very strong and have been used for railroad bridges mainly because of the heavy loads that they can support. A truss, a rigid support structure that is made up of interlocking triangles, holds up the roadbed and is set between two piers. The triangle is used because it is the only shape that is inherently rigid.

Truss is a formation produced by triangular components, in accordance with the truss bridge drawings, and coupled at joints known as nodes. The triangular units forming the truss are slim and straight in form. The truss bridges consist of a grouping of triangles that are manufactured from straight and steel bars, according to the truss bridge designs. The solid arms of the triangle are extended from the pier sides. The diagonal steel tubes project from the bottom and top of each pier, and assist in holding the arms in the correct position. Trusses are organized as straight elements that are connected at the ends by hinges to develop a secure arrangement.

On application of loads on the truss joints, forces are communicated to the truss elements. The steel truss bridge members are in compression or tension. The trusses possess a high ratio of strength to weight, and therefore are useful for being employed in truss bridges. Trusses are also suitable for use in several other structures like roof supports and space stations. Amongst the modern bridges, truss bridges are considered to be included in the older kinds. The famous truss bridges are relatively inexpensive due to effective utilization of the bridge materials. The truss bridge designs are an important factor in architecture.

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2. PROBLEM STATEMENT

Truss bridge is a type of bridge whose main element is a truss which is a structure of connected elements that form triangular units. Truss is used because it is a very rigid structure and it transfers the load from a single point to a much wider area. Truss bridges appeared very early in the history of modern bridges and are economic to construct because they use materials efficiently.

The nature of a truss allows the analysis of the structure using a few assumptions and the application of Newton's laws of motion according to the branch of physics known as statics. For purposes of analysis, trusses are assumed to be pin jointed where the straight components meet. This assumption means that members of the truss (chords, verticals and diagonals) will act only in tension or compression. A more complex analysis is required where rigid joints impose significant bending loads upon the elements, as in a Vierendeel truss.

The design of truss bridges can become very complicated depending on the situation. The triangles have to be the perfect size and there has to be the perfect amount in order for the truss bridge to be safe. Strengths and weaknesses of truss bridges Strengths: The truss bridge can support and resist lateral loads. Unlike the arch and beam bridge, Truss bridges prevents twisting and swaying during earthquakes and high winds. It resists forces of compression and tension.

3. OBJECTIVE

1)

To design and build the bridge with the highest structural efficiency.

2)

To test the strength of the bridge that accommodates the load.

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4. METHODOLOGY First of all, each member of the group has to sketch the design of bridge, after that we choose the best design for our project. We had done the calculation together with cooperation of all group members to find out the most effective bridge. To find the most effective bridge, we have to calculate the reaction forces, internal forces, and the moment for the bridge. So that, we can easily analyse the truss and create the bridge model by using satay sticks. As we aimed to reach a higher efficiency in our design, the lightness and the stronger is the main factor that we consider and aesthetic value was not our priority. We also tried out a few factors that could affect the efficiency of the truss bridge which is the number of layering of one member, the height and also the width.

Secondly, workmanship is one of the most important factors in efficiency of the truss bridge. To be fair, we distributed the work equally so that the outcome was good and even. Thus, everyone has their own work to do. After that, we make a sketch drawing and gave it a dimension and measurement so that human error and mistakes can be minimized. A truss bridge is a bridge whose load-bearing superstructure is composed of a truss, a structure of connected elements forming triangular units. The connected elements (typically straight) may be stressed from tension, compression, or sometimes both in response to dynamic loads. The individual elements are connected at nodes, the connections are often assumed to be nominally pinned. While, the external forces applied to the system and the reaction at the supports are generally applied at the nodes.

Lastly, we claimed that the bridge was fulfilling our criteria which are by strength, creative and possible to build. Thus, the figure below is the most efficient design of bridge that we choose for our project:

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5. LAYOUT AND DESIGN

a. DESIGN Design of the truss bridge that has been approved by Lecturer shown in figure 2:

Figure 2: The Design of the Bridge

b. SIDE AND PLAN VIEW The figure 3 and figure 4 shows the front and the plan view that been constructed in a piece of paper with measurements.

Figure 3: The plan and side view of the bridge design 5

6. MODEL OF THE TRUSSES BRIDGE The truss bridge produced should be built at the overall span length is 1200mm and the

bridge must be simply supported and there is no deck slab of the bridge. Next the height must be exactly 300 mm and width must be exactly 100 mm. For the base area must be exactly 100 x 100 mm and the weight of the bridge produced is not exceed 300 g.

a. FLOW CHART OF STUDY

DISCUSSION ABOUT PROJECT

DESIGNING

TESTING AND ANALYSIS

PRODUCING -Trusses Bridge using Stick

Diagram 1: Flow chart of study

b. MATERIAL USED

1. A bundle of Satay Sticks

Figure 4: Satay Stick

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2. Adhesive Glue

Figure 5: 5 Second Glue 3. Cutters

Figure 6: Cutters

4. Masking tape

Figure 7: Masking tape

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5. Sand grit papers

Figure 8: Sand grit papers

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c. METHOD FOR MAKING TRUSS BRIDGE: 1. First, cut the end of the satay stick like figure 15

Figure 9: Cutting Satay Sticks 2. Mark the satay stick with the pencil with the dimension needed 100mm, 150mm,175mm,200mm,250mm,300mm and cut the satay sticks that has been marked. That shown in figure 16.

Figure 10: Measure and marking

3. The satay stick has been double and glued together shown in figure 17.

Figure 11: Glue each satay sticks into layers

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4. The satay stick that has been glue was arrange neatly according the trusses

bridge shape with the length is 1200mm, base 100 x 100 mm and the height is 300mm. The satay stick was been glued in each section until it sticks each other. The figure shown in figure 18

5. Weighing the mass of the model

Figure 12: Weighing Model

6. Pre-test the model with 10kg load for 120 second

Figure 11: Pre-testing on model

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d. MODEL DISPLAY The final model of the truss’s bridges shows in the figure 19 below. The length of this model is 1200mm, the maximum height is 300mm and the base is 100 mm x 100 mm.

Figure 12: The bridge model

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7. RESULT AND CALCULATION OF LOAD TESTING The bridge was tested at the structure laboratory. The weight of the bridge was taken before the testing start. The weight of the bridge is shown in figure 20. The mass recorded is 317.4g and it is exceeding 17.4 g, but still allowable.

Figure 13: The mass of the bridge

After the mass of the model was record. The 10 kg load has been applied to the bridge for 120 second. The time was recorded and the figure is shown in figure 21. The bridge was success when it can hold the 10kg of load for 120s.

Figure 14: The test of bridge model

For the result, our bridge was success in accommodate the 10 kg of the load for 120second. The bridge is in good structure and no shown the sign of crack and failure.

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Displacement for indeterminate truss

CALCULATION Ʃ𝐅𝐘 = 𝟎 RAY + RGY = 0.05 + 0.05 RAY + RGY = 0.1kN

Ʃ𝐌𝐀 = 𝟎 0.05 (0.4) + 0.05 (0.8) − RGY (1.2) = 0 RGY =

0.06 1.2

𝐑𝐆𝐘 = 𝟎. 𝟎𝟓 𝐤𝐍

RAY + RGY = 0.1 RAY + 0.05 = 0.1 𝐑𝐀𝐘 = 𝟎. 𝟎𝟓 𝐤𝐍

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Ʃ𝐅𝐘 = 𝟎 RAY + RGY = 1

Ʃ𝐌𝐀 = 𝟎 1(0.6) − RGY (1.2) = 0 RGY =

0.6 1.2

𝐑𝐆𝐘 = 𝟎. 𝟓 𝐤𝐍

RAY + RGY = 1 RAY + 0.5 = 1 RAY = 1 − 0.5 𝐑𝐀𝐘 = 𝟎. 𝟓 𝐤𝐍 14

Internal Force Diagram

µ value

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member Length F µ FµL AB 100 0.02 0.23 0.46 AQ 141.42 -0.03 -0.32 1.357632 AR 100 -0.03 -0.27 0.81 BQ 100 0.00 0.00 0 BC 175 0.02 0.23 0.805 CQ 201.56 0.05 0.46 4.63588 CP 100 0.00 0.00 0 CO 201.56 -0.05 -0.46 4.63588 CD 175 0.11 1.02 19.635 DO 100 0.05 0.00 0 DE 150 0.11 1.02 16.83 EO 212.13 -0.02 -0.39 1.654614 EN 100 0.02 0.68 1.36 EM 212.13 -0.02 -0.39 1.654614 EF 150 -0.02 1.02 -3.06 FM 100 0.05 0.00 0 FG 175 0.11 1.02 19.635 GM 212.13 -0.05 -0.46 4.87899 GL 100 0.00 0.00 0 GK 212.13 0.05 0.46 4.87899 GH 175 0.02 0.23 0.805 HK 100 0.00 0.00 0 HI 100 0.02 0.23 0.46 IJ 100 -0.03 -0.27 0.81 IK 141.42 -0.03 -0.32 1.357632 JK 100 0.08 0.82 6.56 JW 105.41 -0.08 -0.87 7.336536 KW 33.33 0.00 0.00 0 KL 175 0.01 0.20 0.35 LV 91.67 0.00 0.00 0 LM 175 0.01 0.20 0.35 MU 250 0.02 -0.08 -0.4 MN 150 -0.02 -0.29 0.87 NO 150 -0.02 -0.29 0.87 OP 175 0.01 0.20 0.35 PT 91.67 0.00 0.00 0 PQ 175 0.01 0.20 0.35 QR 100 0.08 0.82 6.56 QS 33.33 0.00 0.00 0 RS 105.41 -0.08 -0.87 7.336536 16

ST TU UV VW NU

184.47 342.58 342.58 184.47 200

-0.08 -0.08 -0.08 -0.08 0.02

-0.87 -0.87 -0.87 -0.87 0.68

12.839112 23.843568 23.843568 12.839112 2.72 190.22266

Total area=A1+A2 =18(6𝜋1.52 ) + 27(2𝜋1.52 ) =763.41 + 381.70 =1145.11 mm2 E=0.04kN/ mm2(young modulus for bamboo) 𝐹µL

Displacement= 𝐴𝐸

=

190.223 1145.11×0.04

=4.15 mm2

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INTERNAL FORCE FOR SATICALLY DETERMINATE TRUSS

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Hence the new internal force for each member in the truss is calculated

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member Length F AB 100 0.02 AQ 141.42 -0.03 AR 100 -0.03 BQ 100 0.00 BC 175 0.02 CQ 201.56 0.05 CP 100 0.00 CO 201.56 -0.05 CD 175 0.10 DO 100 0.05 DE 150 0.10 EO 212.13 0.00 EN 100 0.00 EM 212.13 0.00 EF 150 0.10 FM 100 0.05 FG 175 0.10 GM 212.13 -0.05 GL 100 0.00 GK 212.13 0.05 GH 175 0.02 HK 100 0.00 HI 100 0.02 IJ 100 -0.03 IK 141.42 -0.03 JK 100 0.08 JW 105.41 -0.09 KW 33.33 0.00 KL 175 0.02 LV 91.67 0.00 LM 175 0.02 MU 250 0.03 MN 150 -0.04 NO 150 -0.04 OP 175 0.02 PT 91.67 0.00 PQ 175 0.02 QR 100 0.08 QS 33.33 0.00 RS 105.41 -0.09 20

ST TU UV VW

184.47 342.58 342.58 184.47

-0.09 -0.09 -0.09 -0.09

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Deflection of trusses

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8. CONCLUSION A truss bridge is a bridge whose load-bearing superstructure is composed of a truss, a structure of connected elements forming triangular units. The connected elements (typically straight) may be stressed from tension, compression, or sometimes both in response to dynamic loads. The bridge worked well. Throughout this task we worked well as a team and collectively designed and created a sophisticated bridge with a good weight: load ratio.

The bridge may have had a higher max load had we moved the net when testing on the rig. The amount hung from our bridge however was the 10kg; our designed bridge met the brief. We could also have increased our weight: load ratio had we substituted some thread for stringed sections. This however can only be done on areas where pure tension’s occurring.

The arch may have held more weight also had it been stiffened slightly. The arch had poor lateral stability when compared as a separate component to the warren truss, had we included more diagonal members to join the two arch sections our structure may have increased in stability.

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