ACKNOWLEDGMENT Assalamualaikum, First of all, congratulations on the successful of our project, it’s a fantastic project. Second, we would like to say thank you for our beloved lecturer, Madam Nor Hayati binti Ghazali for her excellent skill in teaching us the subject structural analysis for this semester. She was a great lecturer that we have ever met. Besides that, we dedicated our full grateful feeling for our family especially our parents, for keep supporting us through up and down. Thank you for being there with us and give us a lot of spirit to keep going strong in each single day. Group members also play the main role in this project. Thank you and well done for each of us for making this project real and sent it in the time that had been given. Though we might busy with our own commitment, we still can finish up this project. We realized that we should take over the stress and take things positively. Never let things bring us down, instead we have to stay strong and have faith in Allah SWT. This is the best organization team in the universe. Lastly, huge thanks to those that has contributed in this project. We are very lucky to live a life among people who were never let us down. Keep supporting us!
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ORGANISATION CHART
CHAIRPERSON/GROUP LEADER Nor Ardilla Binti Aznam
ASSISTANT Nur Syazwani Afifah binti Mohd Saibi
SECRETARY
TECHNICAL
Julie Binti Mahadi
Suhailah Binti Jemari
TREASURER Hamidah Bt.Syd Othman
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EXECUTIVE SUMMARY
Introduction This project is conducted by a group of 5 students, and was given a task to design a truss bridge and must collapse at the load of 15kg. The bridge will be tested based on the lightness and least deflection and the creativity and build ability of the bridge model. The report aimed is to identify the problem and find the solution to solve it.
Overview The students groups identify the problem given and figure out the solution. The students choose 4 types of trusses and choose the best one that is Warren Truss. The students make the design according to the given dimension, draw the layout of the truss, calculate the deflection using Linpro software and by manually to compare the data, built a sample model to obtained the quantity of satay stick that have to use for each member, test the sample model, start to build the actual model and lastly test the actual model at the laboratory. The data collected is analysis and is compared with the data from calculation obtained. All the factors that influence the strength of the bridge also are analyzed.
Summary of Results
The deflection data using Linpro software is 0.00mm. The deflection data using manual calculation is 1.071mm. The deflection data when the bridge model is tested is 1.75mm. The bridge model is not collapsed when the load achieved to 15kg. The strength of the bridge is influenced by the type of the glue used, the type of design truss used and the compression and tension force of the truss member. The project is fail due to the model bridge fail to collapse at the load of 15kg.
1.0 INTRODUCTION
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Bridges are structure which helps people and vehicles to cross obstacles such as ocean or river as well as connecting villages and towns. In earlier times, people crossing over the river by stepping in stones or swimming but with heavy loads it may risk the people. The bridges structures improve as the technology evolves. Early bridges were made from local material such as woods, stones and fibers. Today's, there are many materials that suitable to make bridges. Nevertheless, structures and the materials are the most important criteria to successfully build the bridges. 1.1
Background Study The aim of this project is to encourage students to use their structural knowledge and creativity to solve practical problem in building small model bridge by using Satay Stick and encourage effective communication between group members. The students are encouraged to test their materials to find the tensile and compressive strength using Universal Testing Machine or other appropriate methods. The bridge considered pass if the bridge supported at least 10kilograms load to maximum 15kilograms loaded. Some calculations needed to obtain the suitable member size, internal forces of truss and deflection using hand calculation and check using suitable computer programs.
1.2
Objectives As a result of this project, student will able to do the following: 1. To design and build the lightest bridge with the highest structural efficiency that can span a given opening meeting the requirements as specified in these rules. 2. To made a creative and buildable of a model bridge. 3. To test the strength and weakness of bridges that accommodate the load 4. Learn about planning and Constructions Bridge and how about teamwork and working in groups. 5. To make a limited load applied model in between 10kg (min) to 15kg (max) load.
2.0 PART A: LAYOUT AND DESIGN
2.1
Types of Bridge Considered
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Truss bridges are a type of bridge design that uses multiple triangles to support very heavy loads. They are widely used and the most common with road traffic bridges due to their heavy load capabilities. Along with the triangular formations, joints and other forms of enforcement are used to further increase the bridge’s strengths. Therefore, three types of bridge design have been considered based on aspects below:a) Lightest structure, lowest deflection and carry the most weight. b) Concept and ease of construction. c) Creative and buildable of a model bridge. d) Economical to build. 2.1.1
Howe Truss Bridge
Figure 1: Elevation drawing of Howe Truss. History and Description: First patented by Massachusetts millwright William Howe (1803-1852) in July and August of 1840, the Howe truss featured heavy wood diagonal members in compression and lighter, vertical iron members in tension. The use of iron to stiffen parallel chord trusses had been used in Europe as early as 1823, but there is no evidence that Howe knew of this precedent. The use of threaded, adjustable iron tension members, secured at the ends by nuts, was the main difference between the Long truss and the Howe truss. This feature made Howe the first bridge designer to devise a method of adjusting a wood truss, the members of which have the tendency to pull apart under live loads and shrinkage (1, p. 57). Howe arrived at a simple, elegant solution to a problem that had confounded several generations of wooden bridge builders, the solution to joining in tension two wooden members. The classic weakness of a timber truss is not the individual members, but the connections. Tension connections proved particularly difficult to detail to insure minimum joint movement and maximum efficiency in transferring tensile loads to a joint. The genius of the Howe system is that the timber 6
verticals, which pose the most difficult problem in forming an effective connection, were neatly replaced with an iron rod. Eliminating the complex mortise and tendon connection simplified the work of millwrights, resulting in a truss that was not only easy to erect, but could be adjusted and parts replaced while remaining in service. Like the king post truss, the Howe truss was apparently first used as a roof truss, appearing in a church in Brookfield, Massachusetts. Its first use in bridge construction was in 1838 on the Western Massachusetts Railroad (later the Boston and Albany Railroad) over the Quaboag River in Warren, Massachusetts. In 1839, Howe hired his brother-in-law, Amasa Stone, Jr., as a foreman to oversee construction of several buildings in Warren, Massachusetts. When Howe later won a contract with the Western Railroad Company to bridge the Connecticut River at Springfield using his newly patented truss design, he hired Stone to assist in supervision of bridge construction (2). In 1841, Howe revised his patent of the previous year by reducing the diagonals to two in each panel (3, p. 61). Soon thereafter, Stone purchased the rights to build the Howe truss in New England and set up a bridge building company with Azariah Boody in 1842 to market the design. In August 1846, Howe won an additional patent for a timber arch design that he hoped would make his basic truss more widely adaptable for use by the railroads. In 1847, the first company set up by Howe and Stone was reorganized, with Stone retaining the southern New England rights and younger brother Andros claiming the remainder. Along with Boody, Andros established the Stone and Boomer bridge building partnership with Lucius Boomer of Chicago, Illinois. That company built a large number of Howe trusses for railroads in Illinois, Wisconsin and Missouri, but not always with success. A Stone and Boomer-built Howe truss bridge erected over the Gasconade River in Missouri collapsed in 1855, killing forty-three people and injuring another seventy, including some of the most prominent citizens of St. Louis. The following year, the partners also built the first railroad bridge across the Mississippi River, which was located between Davenport, Iowa, and Rock Island, Illinois. Howe trusses were a prominent feature of this bridge, which was widely reviled by steamboat interests as a hazard to navigation until it burned down shortly after completion. The Howe truss marked the beginning of the transition from wood to iron as a material for bridge construction, but attempts to express the design in iron structures often met with disaster. In 1876, a cast and wrought iron Howe 7
truss bridge designed by Amasa Stone and built in 1865 at Ashtabula, Ohio, collapsed, killing 85 people. An investigation by the ASCE condemned combination cast and wrought iron bridges in favor of all wrought-iron designs, but the real problem may have been the unsuitability of the Howe truss for all-metal construction. Bridge scholars generally agree that the wood Howe truss was the crowning achievement of the wood bridge era, and Howe’s patent was probably the most profitable wood truss patent ever granted due to the popularity of the type with railroads during a period of great expansion of the nation’s rail network. The Howe truss became the most widely used wood type for railroad use and dominated the bridge-building industry until all-iron bridges gained greater popularity in the 1850s. The Howe truss is commonly found in covered bridges in several states. For example, it is by far the most represented type among the covered highway bridges of Oregon. Significance Assessment: The Howe truss, a composite truss of wooden diagonal compression members, iron junction boxes, and threaded vertical wrought-iron rods to carry tension, was the dominant bridge type during the transition of bridge building materials from wood to iron. As stated above, the Howe truss is considered the crowning achievement of the wooden bridge era and the most profitable bridge patent ever granted. The Howe truss also represents the beginning of the transition from wood to iron. The Howe truss became the most popular bridge for railroads in American until the appearance of the all-metal bridges in the 1840s and 1850s. Thousands were built until the all-iron truss curtailed its popularity. Highly significant within the context of this study are examples of the Howe truss railroad bridges from the early development period, the 1840s and 1850s, as they are less common and are significant in the evolution of bridge building technology associated with the railroads and with the transition from timber to iron. Wooden Howe truss covered bridges of the second half of the nineteenth century and the first quarter of the twentieth century are relatively common, but are considered significant within the context of this study if they retain their character defining features. The Howe truss featured heavy wood diagonal members in compression and lighter, vertical iron members in tension. The intersecting wood diagonal members, the vertical metal rods, the parallel top and bottom chords and the struts are the primary character-defining features of the Howe truss. Like the previously 8
discussed timber trusses, the roofing and/or exterior covering of a Howe truss is of secondary importance, since in most, if not all cases, these features are modern replacements.
2.1.2 Pratt Truss
Figure 2: Elevation drawing of Pratt Truss. Pratt Truss History and Description: Thomas Pratt (1875), an engineer who studied at Rensselaer Polytechnic Institute in Troy, New York, and worked for the U. S. Army and several New England railroads, designed the first Pratt truss in 1842. In 1844 a joint patent (#3,523) was granted to Thomas and his father, Caleb, a Boston architect. As originally conceived, this design used vertical compression members of wood and wrought iron diagonals in tension, a reverse of the earlier Howe truss, which used diagonals in compression and verticals in tension. The great advantage of the Pratt truss over many earlier designs was the relative ease of calculating the distribution of stress throughout the structure. Because this design demanded a greater use of the more expensive metal than the Howe truss, it initially was not popular; however, as the nation’s railroads gradually began to favor all iron bridges, the Pratt truss became widely adopted (5, p. 11). Not only was the design simple, relatively economical, and easily erected in the field, it was also more trustworthy than the Howe. As an iron or steel bridge, the Pratt truss became the most popular span in America in lengths of less than 250 feet for highways and railroads. The Pratt truss was erected in large numbers during the last quarter of the nineteenth century and into the first decades of the twentieth century, when it began to be superseded in popularity by the Warren truss. The Pratt truss form may be found in through, pony, deck and bedstead spans. Pratt trusses generally have horizontal 9
and parallel chords connected by inclined end posts, but Pratt trusses with vertical end posts were also constructed. In the bedstead variation, the end posts extend below the plane of travel surface, thus serving as components of both the superstructure and substructure. There are a number of Pratt variations, which are discussed as separate truss types in this study (i.e., Whipple, Baltimore, Parker and Pennsylvania). One popular subtype of the Pratt is the half-hip pony truss, in which the hip vertical is eliminated and the inclined end post is made more perpendicular to the upper and lower chords, thus requiring less metal. It was limited to lengths of no more than about 60 feet, however. This type was used extensively by county road departments throughout the country for small stream crossings. Significance Assessment: When fabricated entirely of iron, and later steel, with riveted connections, the Pratt truss became the American standard for bridges of moderate spans well into the 20th century. In 1916, bridge engineer J.A.L. Waddell claimed that the Pratt truss was the most commonly used truss for spans less than 250 feet. Pratt trusses are among the most common nineteenth and early twentieth century bridge types discussed in this study. They are, however, significant in the evolution of bridge technology, particularly the early examples of the type. Early examples of the type that retain their character-defining features are highly significant within the context of this study, while later, more common examples are less significant. The later examples can still be significant if they retain character-defining features and are very good examples of the type. Character-defining features vary, as there are number of different subtypes of Pratt trusses. Because the vertical members and end posts of the Pratt truss handle compressive forces under load, they tend to be relatively heavy and visually prominent, and are usually composed of angles, channels or rolled sections. The diagonal members function mainly in tension and are relatively thin (the ones toward the center handle some compressive forces), and are often composed of square or round bars. The interior diagonals all slant down and in, at a pitch of 45 degrees, the optimal angle calculated by the Pratt, while the inclined end posts slant outward at the same angle. Although the patent drawings illustrate a design option featuring a curved top chord, the basic design was for a truss with a straight top chord, and this became a common characteristic of the Pratt truss. Character-defining features include the truss form, method of connection, top 10
and bottom chords, vertical and diagonal members, floor beams and stringers. For through trusses, the lateral top bracing and features of the portal (e.g., struts, bracing) are also character-defining features.
2.1.3 Metal Bowstring Arch Truss
Figure 3: Examples of Metal Bowstring Arch Truss History and Description: In 1840, Squire Whipple (1804-1888), a graduate of Union College in Schenectady, New York, and a surveyor for railroad and canal companies, built an approximately 82 foot-long, tied-arch “bowstring” truss bridge over the Erie Canal at Utica, New York. It was the second all-metal truss bridge constructed in the United States. The following year he obtained a patent for his design (#2,064), which had arches of cast iron functioning as the primary compression members, and vertical and diagonal rods of wrought iron. The “string” (or lower member) tying the ends of the arch acted in tension. Even before Whipple’s patent expired in 1869, bridge builders copied his design, some with slight variation to avoid infringement, and many without any respect of the patent. This type proved very popular over the next forty years for train sheds, other curved vault structures and short highway and canal spans of 50 to 100 feet, although some bowstring trusses were much longer. During the last quarter of the nineteenth century, it was one of the most generally adapted truss forms in bridge design. Whipple’s patent was adopted by Zenas King, David Hammond and other builders who secured patents for the configuration of the upper chord and other details. These men established bridge-fabricating companies to manufacture bridges by the thousands to meet the overwhelming demand for economic, short to moderate span, bridges for 11
burgeoning farm-to-market road systems. The King Iron Bridge Company of Cleveland (http://www.kingbridgeco.com/) and the Wrought Iron Bridge Company of Canton, Ohio, founded by King and Hammond, were two of literally hundreds of bridge fabricating companies established throughout the east and Midwest to meet demands. The companies employed agents who operated out of larger cities, covering territories and selling their bridges to county commissioners through catalogs, hence the name “catalog” bridges. Whipple himself operated one of the earliest bridge-fabricating companies, building hundreds of iron bridges. One such example is the Aldrich Change Bridge (1858), formerly at MacedonPalmyra Creek over the Erie Canal in Wayne County, New York. This span was recently restored to become part of the New York State Erie Canal National Heritage Corridor and the Canalway Trail system, and is now in Wayne County’s Aqueduct Park in Upstate New York. Metal bowstring arch spans from the nineteenth century, whether built of iron or steel (most were iron), may generally be distinguished from steel tied arch spans of the twentieth century by differentiation of historic context. The events, people (designers and builders) and technology for nineteenth-century bridges are far different than those for more modern structures. This reality is reflected by a statement in “Structural Study of Iron Bowstring Bridges,” the HAER narrative history prepared as part of the Iowa Historic Bridges Recording Project Phase II in 1996 (4, p. 13), which stated that, “the history of the bowstring truss is inextricably linked to the nineteenth century bridge companies.” Steel tied-arch spans of the twentieth century, therefore, which may occasionally be called “bowstrings,” are examined in the arch category of this study. Significance Assessment: The number of Whipple bowstring trusses is known, but the number of other surviving bowstring arch trusses is not. The bowstring arch truss is one of the more important nineteenth century bridge forms and dates primarily from the 1870s and 1880s. Bowstring bridges that retain their integrity (i.e., their character defining features) are highly significant within the context of this study. Character defining features include a relatively heavy arched top chord, a series of boxed “X” panels, and an outer, basically triangular panel at each end. Character-defining elements include the members that form the ‘X’s” within each panel and the end panels, the slender vertical rods, the bottom chord, floor beams, and method of connection. The small 12
numbers of intact Whipple bowstring trusses that remain possess the highest level of significance within this type
2.1.4 Warren Truss
Figure 4: Examples of Warren Truss
History and Description: The Warren truss was patented in 1848 by its designers James Warren and Willoughby Theobald Monzani, and consists of longitudinal members joined only by angled cross-members, forming alternately inverted equilateral triangle-shaped spaces along its length, ensuring that no individual strut, beam, or tie is subject to bending or torsional straining forces, but only to tension or compression. Loads on the diagonals alternate between compression and tension (approaching the center), with no vertical elements, while elements near the center must support both tension and compression in response to live loads. This configuration combines strength with economy of materials and can therefore be relatively light. The girders being of equal length, it is ideal for use in prefabricated modular bridges. It is an improvement over the Neville truss which uses a spacing configuration of isosceles triangles. Warren truss construction has also been used in airframe construction for aircraft since the 1920s, mostly for smaller aircraft fuselages, using chrome molybdenum alloy steel tubing, with popular aircraft such as the Piper J-3 Cub. One of the earliest uses for the Warren truss in aircraft design was for the interplane wing strut layout, as seen in a noseon view, on the Italian World War I Ansaldo SVA series of fast reconnaissance biplanes, 13
which were among the fastest aircraft of the First World War era. Warren truss construction is still used today for some homebuilt aircraft fuselage designs that essentially use the same 1920s-era design philosophies in the 21st century.
2.2
Comparison Types of Bridge selected Descriptions Howe Truss
Types of Bridges Pratt Truss Bowstring Arch (Half hip pony
Warren
Truss
Vertical Truss
truss)
Material Suitability Woods Metals/steel/iron
No Yes
No Yes
Yes Yes
Length Span(m)
Yes Vertical member <45
<45
<90
<45
Compression
Diagonal
Vertical
Tension
Vertical
Diagonal
Vertical and Diagonal Lower member
Vertical and Diagonal Vertical and Diagonal Light and simple Cheaper
Lightweights and Light and Heavy but easy Heavy arched Design simple erected top chord Design Demands Cheaper Expensive Expensive Table 1: Comparison types of bridge to be considered
2.3
Assumptions for Design
Based on “Statics and Mechanics of Materials”, by R.C. Hibbeler ( Third Edition in SI units), in order to design both the members and the connections of a truss, it is necessary first to determine the force developed in each member when the truss is subjected to a given loading. To do this we will make two important assumptions: •
All loadings are applied at the joints. In most situations, such as for bridge and roof
trusses, this assumption is true. Frequently the weight of the members is neglected because the force supported by each member is usually much larger than its weight. However, if the weight is to be included in the analysis, it is generally satisfactory to apply it as a vertical force, with half of its magnitude applied at each end of the member. 14
•
The members are joined together by smooth pins. The joint connections are usually
formed by bolting or welding the ends of the members to a common plate, called a gusset plate or by simply passing a large bolt or pin through each of the members. We can assume these connections act as pins provided the center lines of the joining members are concurrent. Because of these two assumptions, each truss member will act as a two force member, and therefore the force acting at each end of the member will we directed along the axis of the member. If the force tends to elongate the member, it is a tensile force whereas, if it tends to shorten the member, it is a compressive force. In the actual design of truss, it is important to state whether the nature of the force is tensile or compressive. Often, compression members must be made thicker than tension members because of the buckling or column effect that occurs when a member is in compression.
2.4
Type of Bridge Chooses or selected
Figure 5: Warren Truss with Vertical Support.
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For this project, we are choosing Warren Truss Type Bridge. The Warren Truss was designed by its James Warren and Willoughby Theobald Monzani at 1848. Based to the project requirement, Warren truss is fulfilled design meet to the project criteria which is lightest, economical to build, concept and ease of construction, carry the most weight and low deflection. Therefore, Warren truss bridge is selected as our project design.
2.5
Principle of Warren Truss The Warren truss is one of the simplest yet strong designs. This simple design already existed, but what made the Warren unique is that it uses equilateral triangles. Each side of the triangles is the same length. This marked an improvement over the older Neville truss which did not use equilateral triangles. It is one of the most popular bridge designs and examples of it can be found everywhere in the world. The Warren Truss uses equilateral triangles to spread out the loads on the bridge. This is opposed to the Neville Truss which used isosceles triangles. The equilateral triangles minimize the forces to only compression and tension. Interestingly, as a load (such as a car or train) moves across the bridge, sometimes the forces for a member switch from compression to tension. This happens especially to the members near the center of the bridge.
2.6
Model Specification and Element Dimension
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Figure 6: Element Dimension and Specifications. Following are specification required for bridge project: a. Clear span between supports should be 1000 mm. The overall length should not be less than 1200 mm b. The bridge must be simply supported c. The deck slab of the bridge should be horizontal and must be part of the bridge structure d. Maximum deck width is 110 mm and can be accommodate dual carriageway of at least 30 mm wide each. e. Two voids with dimensions of (10mm x 150mm) should be provided at locations as shown in the diagram (refer Figure 1) f. Maximum height is 300 mm. g. Base area at both ends must not be greater than 100 x 100 mm.
2.7
Layout of Selected Warren Truss Bridge 2.7.1
Three-Dimension Warren Truss Bridge Model
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2.7.2
Top View Elevation, Front View Elevation and Side View Elevations
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3.0 PART B: BRIDGE ANALYSIS CALCULATION
3.1
Data Calculation by LinPro Engineering Software 19
a) The Reaction Diagram
b) Deflection Diagram
3.2
Manual Data Calculation a)
Calculation Internal forces using Alternative method and the reaction on pin/roller support using Equilibrium equation 20
*Note: 1KG = 0.01KN ƩMA = 0,
(0.15KN) (0.5m) - VG (1.0m) = 0 0.075KN = VG (↑)
ƩFy = 0,
0.075KN + VA - 0.15KN = 0 VA = 0.075KN (↑)
ƩFx=0,
HA = 0
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b)
Deflection data by using Virtual Work Method
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Member
L (m)
F (KN)
µ
F.µ.L
AB BC CD DE EF FG AL LB LC LK KC KJ JC JD JE IJ IE IH HE HF HG
0.175 0.175 0.150 0.150 0.175 0.175 0.230 0.150 0.230 0.175 0.150 0.150 0.212 0.150 0.212 0.150 0.150 0.175 0.230 0.150 0.230
0.088 0.088 0.251 0.251 0.088 0.088 -0.116 0 0.116 -0.176 0 -0.176 -0.106 0.15 -0.106 -0.176 0 -0.176 0.116 0 -0.116
0.58 0.58 1.66 1.66 0.58 0.58 -0.77 0 0.77 -1.16 0 -1.16 -0.71 1.00 -0.71 -1.16 0 -1.16 0.77 0 -0.77
8.93 x10⁻3 8.93 x10⁻3 0.062 0.062 8.93 x10⁻3 8.93 x10⁻3 0.021 0 0.021 0.036 0 0.031 0.016 0.023 0.016 0.031 0 0.036 0.021 0 0.021 Ʃ= 0.433
Modulus of Elasticity = 16.17x106KN/m²
Where
Cross-sectional Area = 2.5x10-5m²
ΔD =
3.3
ƩFµL AE
=
0.433 6 KN ( 2.5 x 10−5 m2 ) ( 16.17 x210 ) m
= 1.071x10⁻3 m @1.07mm
Comparison between Software Data and Manual Data Description
Linpro Software Data
Manual Calculation
The Reaction on support Internal forces
VA=0.08KN,VG= 0.08KN Same
VA=0.075KN,VG= 0.075KN Same
Deflection Diagram (m)
0.0000
0.00107
Table 2: Comparison between Software Data and Manual Data
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3.4
Prediction of Failure
Since the bridge that we build must collapsed at the limit 15kg, we have decided to build a model of the bridge using only 1 stick and scale 1:2. This is to get the maximum satay stick for each member of truss that we have to use to make sure the bridge collapsed at the loading required. After the model bridge is tested it collapsed at the load of 5kg and after doing some simple calculation, we predict that the actual bridge prototype will collapsed at the load more than 10kg and by using 4 satay stick for each member of truss. From the calculation of bridge that we have design, the tension occurs at 9 members while compression occurs at 8 members. Since our design consist of more tension member than compression, we can predict that the truss have the tendency to buckle and did not crack. If the truss consist of more compression member, the tendency of the crack to occur is high and the failure mode is also high that can cause the bridge to collapse easily. Therefore we can say that in this project, it is better to had more compression force at the member than the tension force.
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4.0 PART C: MODEL 4.1
Apparatus and Material
Figure 7: Apparatus and Material.
4.2
Scissor Cutter Knives Pencil or Pen Ruler Clips Satay Stick 3 Second Glue
Methodology
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Fine Satay Skewer is chosen and reject stick is separated from being used.
The required dimension is marked on satay skewer using Pencil or Pen.
The satay skewer is cut based on its length and the member is combined using the glue.
All members are joined according to the design.
The bridge is completed.
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4.3
Procedure Making the Bridge 1. After the best sketch of three bridge design is choosing, the bridge is drawn using the Linpro Software to get the new data. The function is to compare the software calculation and manual calculation for the reaction on roller and pin, deflection and internal forces. 2. The materials used to build the bridge are listed out and are bought. 3. The work is divided into groups: i. The fine satay skewer is choosing. ii. The satay sticks are cut based on their length. iii. 4 satay skewers are combined on each member and the satay sticks is glued with iv.
coupling combination. Make sure the combination is not twisted when the satay sticks are combined
together. v. The picture is snap. 4. The bridge that was completely designed is build according to the original plan. 5. The bridge is left to dry the glue and is ready to be tested. 6. All the data collected from the test is recorded and observed.
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5.0 RESULT 5.1 Actual of Failure Bridge vs. Prediction of Failure Bridge
Based on the result of the tested bridge, our bridge design is not collapsed at the load of 15kg. This is far from our prediction that the bridge will collapsed at the load of above 10kg. This might happen because we did not consider about the compression force and tension force in the truss that we design and built, so the bridge is strong and not easy to fail. The deflection that we get from the tested result is 1.75mm while the deflection that we got from the calculation is 1.071mm while using the Linpro software we get 0.00mm deflection. The Linpro and manual calculation is not same because the software rounded off the data. That makes the deflection become zero and maybe we are not too professional in using the software and cannot get the actual result. There are differences between the result tested and calculated because the actual bridge that we build is not flat since the satay stick is not too straight. The bridge might bend due to the process of gluing the satay stick is not doing properly. Furthermore, the difference is so small and it is means that the bridge is built at good condition.
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6.0 DISCUSSION AND RECOMMENDATIONS
From the experiment, our bridge has not met the criteria that are required. Our bridge has not collapsed even the load of 15kg is applied. This might be because of the glue that we used that is 3 seconds glue and because of the way we connect the satay stick by using the joinery method that makes the bridge become stronger than it should be. Besides that the type of truss that we used also plays an important role to the strength of the bridge because different truss and joint gives different compression and tension to the internal member of the truss. The factors that will affect the strength of a truss is the type of truss uses, the connection of the joint, the length of each of the truss member and the cross sectional area of the truss. With the weight of 0.224 kg makes the bridge seems light but high in strength. Therefore this bridge design is suitable enough to be built in real situation to resist high load and is economic and easy to be built. Although our bridge did not succeed in this project requirement, it is a good bridge because it can stand very high load. So, we can conclude that this experiment is not succeeding since we fail to make the bridge collapsed at the required load.
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7.0 CONCLUSION As a conclusion, after completing this task, we learned about the types of possible loads, how to calculate ultimate load combinations, and investigate the different sizes for the beams (girders) and columns (piers) of simple bridge design. We also learn the steps that engineers use to design bridge, understanding the problem, determining the potential bridge loads, calculating the highest possible load, and calculating the amount of material needed to resist the loads. We know that bridges play an important part in our daily lives. We know they are essential components of cities and the roadways between populations of people. Some bridges are simple and straightforward, others are amazingly complex. Designing a building, bridge and many more is a huge responsibility of an engineer that he or she must be ready of any risk. We have to make sure that the design is suitable, safe, economic, and have own aesthetic value so that it will look more exclusive with high safety. We also realized that one of the most important steps in the design process is to understand the problem. Otherwise, the hard work of the design might turn out to be a waste. In designing a bridge, for instance, if the engineering design team does not understand the purpose of the bridge, then their design could be completely irrelevant to solving the problem. If they are told to design a bridge to cross a river, without knowing more, they could design the bridge for a train. But, if the bridge was supposed to be for only pedestrians and bicyclists, it would likely be grossly over-designed and unnecessarily expensive (or vice versa). So, for a design to be suitable, efficient and economical, the design team must first fully understand the problem before taking any action.
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8.0 REFERENCES Books Static and Mechanics of Materials, R.C. Hibbeler, published in 2011 by Prentice Hall Strutural Analysis, Menon Devdas, published by Oxford: Alpha Science in 2008. Websites http://www.deldot.gov/archaeology/historic_pres/bridges/pdf/context/context_ch3_1.pdf http://thenextgalaxy.com/advantages-and-disadvantages-of-truss-bridges/
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9.0 APPENDIXES APPENDIX 1 MINUTE OF MEETING 1/2016 BRIDGE ANALYSIS AND MODEL PROJECT FACULTY OF CIVIL AND ENVIRONMENTAL ENGINEERING
DATE TIME PLACE
: : :
03rd APRIL 2016 (SUNDAY) 5.00 p.m – 5.30 p.m BK-E8, Block G3, UTHM
Presents: 1. HAMIDAH BT SYD OTHMAN (DF140031) 2. JULIE BINTI MAHADI (CF150043)
(Secretary)
3. NOR ARDILLA BINTI AZNAM (DF150013)
(Chairperson)
4. NUR SYAZWANI AFIFAH BINTI MOHD SAIBI (DF150093) 5. SUHAILAH BINTI JEMARI (CF140088) Member Apologies : (NONE) NO SUBJECT 1.0
ACTION
CHAIRPERSON ADRESS a. Greetings to all members b. Project briefing on format and term c. Appointing organization Chart
2.0
3.0
FEEDBACK
PAPER PRESENTATION a. Types of bridge is briefly explore together with the members b. The materials for bridge are listed
a. Analyze content of project required. b. Dividing work
a. Brain-storming for type of bridge will be choosen. b. Buy all material listed
Go through design of bridge
Ideas accepted.
CLOSING All members were reminded about their part and the next peogress will be present by next meeting that will be held on 30th April 2016.
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Members agreed
Closing in satisfactionary.
Prepared by:
Approved by:
(Julie Bt Mahadi) Secretary
(Nor Ardilla Binti Aznam ) Chairperson
APPENDIX 2 MINUTE OF MEETING 2/2016 BRIDGE ANALYSIS AND MODEL PROJECT FACULTY OF CIVIL AND ENVIRONMENTAL ENGINEERING
DATE TIME PLACE
: : :
30TH APRIL 2016 (SATURDAY) 9.00 A.M – 05.30 PM ROOM D-111, TUN DR ISMAIL RESIDENTIAL COLLEGE, UTHM
Presents: 1. HAMIDAH BT SYD OTHMAN (DF140031) 2. JULIE BINTI MAHADI (CF150043) 3. NOR ARDILLA BINTI AZNAM (DF150013)
(Secretary) (Chairperson)
4. NUR SYAZWANI AFIFAH BINTI MOHD SAIBI (DF150093) 5. SUHAILAH BINTI JEMARI (CF140088) Member Apologies : (NONE) NO SUBJECT 1.0
2.0
ACTION
CHAIRPERSON ADRESS a. Greetings to all members b. Manual calculation vs Linpro Software
a. Dividing work b. Analyse truss using Linpro software
PAPER PRESENTATION a. Methodology and Appratus making the bridge.
a. Brain-storming for the procedure before making the bridge b. Prototype made first for determined
b. Model and Prototype
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FEEDBACK
Comparing Manual Calculation with Linpro Data Software
Ideas accepted.
amount of loaded to fail 3.0
CLOSING All members were reminded about their part and the next peogress will be on 14th May 2016.
Members agreed
Closing in satisfactionary.
Prepared by:
Approved by:
(Julie Bt Mahadi) Secretary
(Nor Ardilla Binti Aznam ) Chairperson
APPENDIX 3 MINUTE OF MEETING 3/2016 BRIDGE ANALYSIS AND MODEL PROJECT FACULTY OF CIVIL AND ENVIRONMENTAL ENGINEERING DATE TIME PLACE
: : :
14th MAY 2016 (SATURDAY) 2.00pm - 6.30pm ROOM D-111, TUN DR ISMAIL RESIDENTIAL COLLEGE, UTHM
Presents: 1. HAMIDAH BT SYD OTHMAN (DF140031) 2. JULIE BINTI MAHADI (CF150043) 3. NOR ARDILLA BINTI AZNAM (DF150013)
(Secretary) (Chairperson)
4. NUR SYAZWANI AFIFAH BINTI MOHD SAIBI (DF150093) 5. SUHAILAH BINTI JEMARI (CF140088) Member Apologies : (NONE) NO SUBJECT 1.0 CHAIRPERSON ADRESS a. Greetings to all members b. Prototype bridge test c. Making actual Model d. Report 2.0 PAPER PRESENTATION
ACTION a. Loaded test on prototype has been determined--4.5kg b. Making the actual bridge c. Dividing works for report
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FEEDBACK
Ideas accepted
a. Making Actual Model b. Prepare for report
3.0
CLOSING All members were reminded about their part and the presentation will be held on week 13.
a. Brain-storming for the procedure before making the bridge b. Making the actual bridge- 4 Ideas accepted. pieces satay stick for each members c. Take all pictures of bridge and all steps of procedure are listed Members agreed
Closing in satisfactionary.
Prepared by:
Approved by:
(Julie Bt Mahadi) Secretary
(Nor Ardilla Binti Aznam ) Chairperson
The sample model using 1 satay stick is tested:
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The actual model using 4 stick:
37
The completed bridge:
38
The actual bridge model at laboratory test:
The result of the data obtained: 39
Our group members:
40
