EMM 3108

STRENGTH OF MATERIAL 1

REPORT FOR

LAB PROJECT

Group Members:A5Mohd Haikal Bin Shahbudin 159062Muhammad Zafirul Bin Haris 158733Tan Weng Lam 159247B5Muhammad Ariff Bin Sulaiman 156770Woon Xian Yang 157792Syuhada Rajemah Binti Mohd Zaini 158949

Course: Bachelor of Mechanical Engineering

Lecturer’s Name:Dr. Nur Ismarrubie Binti Zahari

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Table of ContentsINTRODUCTION...................................................................................................................................3

The advantages of Truss Bridge..........................................................................................................3

Truss Bridge.........................................................................................................................................4

The list of materials for the bridge.......................................................................................................6

OBJECTIVE............................................................................................................................................8

METHODS..............................................................................................................................................9

ASSUMPTIONS....................................................................................................................................10

Truck Size and Weight......................................................................................................................10

Design-Build......................................................................................................................................10

Weather..............................................................................................................................................10

3D DRAWING OF THE DESIGNED BRIDGE..................................................................................11

CALCULATIONS.................................................................................................................................13

Weight of truss...................................................................................................................................13

Dimension of truss.............................................................................................................................13

Area of truss.......................................................................................................................................13

Volume of truss..................................................................................................................................14

Force for distributed load...................................................................................................................14

Weight of road...................................................................................................................................15

Free body diagram.............................................................................................................................16

APPENDICES.......................................................................................................................................17

REFERENCES:.....................................................................................................................................18

INTRODUCTION

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There are several types of bridge, i.e. beam bridge, arch bridge, suspension bridge, cable-stayed bridge and truss bridge. A beam bridge consists of beams on either side of a gap that hold up the bridge but the structural disadvantage this bridge is that the horizontal part can start to sag under the bridge's own weight or the weight of whatever is crossing. Secondly, an arch bridge allows the weight of the bridge to spread downward and outward along the arch's curve so that it does not sag in the middle. Next, suspension bridge includes tall support towers with arching suspension cables connecting them. Although this type of bridges is very expensive to build but it is the only realistic and safe option for bridges spanning long distances. A cable-stayed bridge does not require anchors and their cables attach directly from the support towers to the bridge's surface, which can be large and difficult to build.

For our bridge design, we choose truss bridge. A truss bridge is supported by trusses that composed of interconnecting triangles by connecting straight elements with the help of pin joints.

The advantages of Truss Bridge Support heavy weights

A truss is very efficient at supporting and distributing a load in many directions. It has a high strength to weight and volume ratio. Because the load is distributed over many points, the truss can break at several points before the entire support fails. Look at nature. Truss like frameworks are used everywhere.

Span across long distances truss members can only endure compression and tension forces. For instance in a typical through truss design all the top members experience compression forces and the bottom members experience tension forces. Then, depending on the truss arrangement of the member in between directly depends if they exert compressive or tension forces.

Most efficient geometric shapeTriangular-like arrangements are applied throughout truss bridges. In fact, triangles are both the most rigid structure and have the ability to transfer the load from a single point to multiple points. Therefore, the load over a single point decreases when the load transfer from a single point to multiple points due to the surface area increasing.

The erection are not to complex Truss bridges can be used to across straight obstacles. A truss is usually an open framework, so in a bridge, wind can pass through freely preventing horizontal force from stress the bridge unnecessarily. The parts of a truss bridge are usually straight and are connected in such a way that the bridge can stand weight and strain coming from the load of vehicles and people that pass over it.

InexpensiveThe way they are constructed allows for maximum use of materials, resulting in zero wastage. 

Truss Bridge Components of a typical Truss Bridge

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Figure 1.1

Elevation View

Figure 1.2 Types of Truss Bridges

Figure 1.3

Truss bridge designs

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Figure 1.4

There are thousands of different types of truss, but for our bridge project we choose to do a Camelback (Pratt) Truss due to their unique shape and design.

Camelback (Pratt) TrussFigure 1.5

The list of materials for the bridgeMaterials have always played a key role in the evolution of bridge structures. Enhancements of the traditional materials of concrete, steel, and timber will continue, but the most revolutionary changes

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will occur in the areas of fibre-reinforced plastics (FRPs)[1], high-strength and high-performance steel, high-performance concrete (HPC)[2], and the blending of FRP and timber.

Natural stoneNatural stone is a hard material which last very long. For example, the bridges of Etruscans, with its piers and arches have been lasting for thousands of years. With stone, engineer can build a beautiful bridges, durable and large span. However, stone bridges are very expensive, if considered from the point of view of construction cost. Natural stone bridges are long lasting which they almost need no maintenance over centuries unless attacked by extreme air pollution. Stone is nowadays usually confined to the surfaces, the stones being preset or fixed as facing for abutments, piers or arches. Of course, sound weather-resisting stone must be chosen, and fundamental rock like granite, gneiss, porphyry, diabas or crystallized limestone are especially suitable. Caution is necessary with sandstones, as only siliceous sandstone is durable.

Artificial Stone, Clinker and BrickThe types of artificial stone used in constructing a bridge is clinker[3] and hard burned brick as liners and for bearing vaults. The sizes of these stones are standardized, and one can only choose between different types of joints arrangements. Small differences are colour and a pleasing treatment of the joints can embellish the surfaces. If the concrete is made up with colourful aggregates, which break when being split, the masonry-work produced with these artificial blocks can also look good, similar to masonry of natural conglomerates, which are in fact nothing else but natural concrete.

Reinforced and Pressurised ConcreteConcrete is an all-round constructing material. Almost every building contains concrete. It is dull grey colour. The construction of good durable concrete requires special know-how-which the bridge engineer is assumed to have. Good concrete attains high compressive strength and resistance against most natural attacks such as de-icing[4] saltwater, or CO2 and SO2 in polluted air. Its tensile strength is low, and the use of concrete alone is limited to structures which are only subject to compressive stress. But tensile stresses are occurring in abutment and piers due to earth pressure, wind, breaking forces, and temperature gradients. To resist these tensile forces, steel bars must be embedded in the concrete. This has led to the development of reinforced concrete. This steel bars come into its role when the concrete start cracks under tensile stress. If the steel bars placed correctly in the concrete, the cracks remains and harmless.Another method to overcome this tensile stress is by pressurising. It can be used to produce bridges with a longer span. Pressurising tendons are used to provide a clamping load which produce a compressive stress that balance the tensile stress that the concrete would experience due to a bending load. If it is correctly design, it shall has a high fatigue strength under the heaviest traffic loads. Pressurised concrete are soon cheaper than steel bridges, and they need almost no maintenance. - Again assuming that they are well designed and constructed and not exposed to de-icing salt. So as from the fifties pressurised concrete came well to the fore in the design of bridges. The extra cost for one-way curved surfaces, for tapering piers, for varying depth of beams or arch ribs is as a rule comparatively small. There is a disadvantage to concrete as is emerges from the forms: the inexpressive, dull grey colour of the cement skin. The surface frequently show stains irregular streaks from placing the concrete is varying layers, and pores or even cavities from deficient compaction, which ire then patched more or less successful.

Steel and AluminiumAmongst bridge materials, steel has the highest and most favourable strength qualities, and it is suitable for the most daring bridges with the longest spans. Normal building steel has a compressive and tensile strengths of 370 N/mm2 which is about ten times of a medium concrete in compressive strength, and a hundred times its tensile strength. Steel bridges are

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susceptible to rust and corrosion, however, and tend to require a lot of maintenance. Many steel bridges are painted to improve their appearance. Aluminium is sometimes used in place of steel because it is anti-corrosive properties. A special merit of steel is its ductility due to which it deforms considerably before it breaks, because it begins to yield above a certain stress level. This yield strength is used as the first term in standard quality terms. For bridges high strength steel is often preferred. The higher the strength, the smaller the proportional difference between the yield strength and the tensile strength. This means that high strength steels are not as ductile as those with normal strength.

Nor does fatigue strength rise in proportion to the tensile strength. It is therefore necessary to have a profound knowledge of the behaviour of these special steels before using them. For building purposes, steel is fabricated in the form of plates (6 to 80mm thick) by means of rolling when red hot. For bearings and some other items, cast steel is used. For members under tension only, like ropes or cables, there are special steels, processed in different ways which allow us to build bold suspension or cable-stayed bridges.

The high strengths of steel allow small cross-sections of beams or girders and therefore a low dead load of the structure. It was thus possible to develop the light-weight

"orthotropic [5] plate" steel decks for roadways, which have now become common with an asphalt wearing course, 60 to 80 mm thick.

Timber Timber has favourable qualities of strength for resisting compression, tension and bending. Rough tree trunks or sawn timber have been used since primitive times for beam bridges, raking frames and arches soon allowable larger spans. Timber should be protected against rain and therefore covered bridges with a roof and sidewalls with windows evolved, and many of these are rightly preserved in the Alpine countries, testifying to the high standard of their craftsmanship. Many now only serve pedestrians. Recently timber bridges have been given a new impetus by glue technology which allows larger cross-sections and larger lengths of beams to be made than grow naturally. Moreover timber can now be better protected against weather and insect attack. So, new possibilities have arisen or the choice of structure, for its shaping and for the size. Large timber trusses and even folded space trusses have been built using steel gusset plates for jointing the members. Timber bridges, however, have limits of span and carrying capacity, confining them mainly to bridges for pedestrians or for secondary roads.

OBJECTIVE

Bridge plays much significant roles on human civilizations. Since thousands of years ago human tried to build a structure that enable them to across the river or valley. Today's new era that makes people

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to move from one place to another - trying to go to the place in lesser time. Bridges making the requirement to be fulfill. Human's intelligence from centuries making this structure to be more attractive and dependable.

There are many types of bridge that existed. Beam bridge, cantilever bridge, arch bridge, suspension bridge and etc are examples of bridge that be constructed by engineers today. This bridges are varies with their design and uniqueness but their role are only one - to connect two places. The type of design that being chosen is based on the geography and the necessity itself. Malaysia itself has a long bridge, namely Pinang Island Bridge - a bridge that connects the state with the main land. The long bridge has benefits for transportation and logistics for the country, since Pinang Island has the biggest ship port, which brings considerable good economy income for the country.

It is our responsibility to come with a new idea and design of a bridge that satisfies the structural firm and steady. Considerations from the materials selection, design, and even calculations of possible outcome and vehicles must be taken into account to make sure the bridge is a tough structure. Forces of shear, bending, torsion, tension, compression, or even external forces, i.e. the wind must be encountered with the firm of the structure itself. We are considered to be more creative in designing this bridge, so that the ideas are fresh and did not get influenced by the existing designs.

METHODS

1. The design was made based on discussion among group members. Creativeness, toughness and durability are the main aspect to design the bridge. There were many types of designs of bridge being

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taken into consideration. This was done to make sure the bridge is a perfect one based on collective inspections.

2. All group members had played their own role on this project. There are designer, person in charge of calculations, materials selector, and editor to make sure this project can achieve the quality that we expected. Roles had been played well by everybody in the group to ensure this project can be completed in time. Meetings were held from time to time to make sure this project is progressive and on schedule. Every member had done their own research about the designation of bridges to contribute great ideas for this project.

3. We had also taken geographical issues in consideration in order to make a safe bridge. We assumed this bridge to be built across a river of 100 meter, mainly for the use of vehicles. By this assumption, the bridge should be a tough one and capable to withstand with any weight at any particular part of the bridge. The design is being drawn to enable ships or any water transports to move beneath it. This will make sure the construction of the bridge serve for multi-purposes.

4. Possible environment effects had been taken into account. By this, any inconvenience or fatal error that might be occurred can be avoided. The effects of earthquake, strong wind blows, resonance, tsunami, and many scenarios have been researched thoroughly so that the design is capable of reducing these unpredictable impacts. By this, safety and security are guaranteed to satisfy users of the bridge without any hesitation.

5. Drawing using CAD/CAM application is the best way to present our model of bridge. Its capability to display 3D images makes understanding of the concepts of building bridge to be easier. By using this application, it also enables us to make sure the scale to be logical and fit with the concept itself. Basic knowledge of using the CAD/CAM application is applied since it is one of our subject that has been studied for the last semester.

ASSUMPTIONS

Truck Size and Weight

Whether to allow larger and heavier trucks onto the roadways is a political issue that the engineering community will take very seriously. To predict as accurately as possible the consequences of such an

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action, extensive studies will be done to determine the relationship between the rate of deterioration and increased loadings. The resulting damage evaluation surveys, coupled with data from bridge management systems, will become the basis of a National debate on the financial effects on the transportation infrastructure.

Design-Build

The design-build method for project delivery will increase. Design-build specifications will become a major factor in acceptance and overall performance of the design-build method. The specifications need to require the contractor to consider both the life-cycle costs and the initial construction costs in the selection of materials and structure type. When the engineering community and the legal community work together to accomplish this, the bridge owners will become more comfortable with the design-build method and will begin to use it even more frequently. Successful design-build projects with improved speed of construction and reduced construction problems will continue to make this project delivery option attractive to owners.

Weather

Concrete is made up of from cement which is made up of calcium carbonate, CaCO3. Acidic rainwater contains water H2O and carbonic acid, H2CO3. In easy words, concrete are alkaline and acidic rain is acid. They are well react to produce salt and water. When rainwater falls on the concrete, reaction occur. The reaction occurred causing the concrete to erode, thus make it becoming weaker. A visual inspection of concrete that has been attacked by acid should reveal corrosion of the paste that holds the aggregate in place. The aggregate may or may not be corroded, depending on whether it is siliceous or calcareous. Knowledge of the conditions of the surrounding environment will also help in diagnosing corrosion as being caused by acid. A petrography [6] study of a thin section can reveal evidence of acid attack on a concrete structure. The composition of the aggregate, cement type, w/c ratio, air void system, identification of admixtures, and surface flaws in the paste should all be determined.

3D DRAWING OF THE DESIGNED BRIDGE

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Figure 2.1 2D View

Figure 2.1 2D View(1)

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Figure 2.2 3D View (2)

Figure 2.3 3D View (3)

Figure 2.4 3D View (4)

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CALCULATIONS

Weight of truss

Figure 3.1

Dimension of truss

Figure 3.2

Area of truss

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Part A=(2.5x4x0.5x0.3)-(1.9x3.4x0.5x0.3)=0.531m2

Part B=(10x8x0.3)-(10x4x0.5x0.3)-(9.6x3.4x0.5x0.3)-

2(9.6x3.7x0.5x0.3)=2.448m2

Part C=(25x8x0.3)-2(24.4x7.4x0.5x0.3)=5.832m2

Part D=(25x8x0.3)-4(24.4x3.7x0.5x0.3)=5.832m2

Volume of trussPart A=0.531x0.3=0.1593m3

Part B=2.448x0.3=0.7344m3

Part C=5.832x0.3=1.7496m3

Part D=5.832x0.3=1.7496m3

Total volume of one side= 2xPart A+2xPart B+2xPart C+ Part D=7.0362m3

Total volume of two side=2x7.0362=14.0724m3

Material of truss is aluminium bronze and its density is 7700kg/m3

Mass of truss=7700x14.0724=108357.48kg

Weight of truss=108357.48x9.81=1.06x106N

Force for distributed loadAssumption

Mass=10000kg per lorry or car

=5m per lorry or car

=2000kg per m

For two lanes on road,

Mass=4000kg per m

Hence, force=4000x9.81=39240N

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Weight of roadMass of road=10000kg

Weight of road=10000x9.81=98100N

Figure 3.3

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Free body diagram

Figure 4.1

+ ∑Fy=0

Ay+3.0x106+Cy-(39240x100+1.06x106+98100)=0

Ay+Cy-2.08x106=0 (1)

+∑MB=0

-Ay(50)+Cy(50)=0

Ay=Cy

From (1)

Ay+Ay=2.08x106

2Ay=2.08x106

Ay=1.04x106

Cy=1.04x106

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APPENDICES

1. Fibre-reinforced plastics (FRP): (also fibre-reinforced polymer) is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually fibreglass, carbon, or aramid, while the polymer is usually an epoxy, vinyl ester or polyester thermosetting plastic. FRPs are commonly used in the aerospace, automotive, marine, and construction industries.

2. High-performance concrete (HPC): Concrete that possesses high workability, high strength and high durability that made with appropriate materials combined according to a selected mix design; properly mixed, transported, placed, consolidated and cured so that the resulting concrete will give excellent performance in the structure in which it is placed, in the environment to which it is exposed and with the loads to which it will be subject for its design life.

3. Clinker:  a hard brick used as a paving stone. A clinker is coagulated slag or metal impurities that "melt" from the coal as it becomes coke. Most clinkers consist of pyrites that are naturally included in coal seams.

4. De-icing: The process of removing ice and accumulated snow from a road surface. Principal methods of de-icing in use today are heating, chemical treatment, and mechanical rupture of the ice deposit

5. Orthotropic: An orthotropic material has two or three mutually orthogonal twofold axis of rotational symmetry so that its mechanical properties are, in general, different along the directions of each of the axis. Orthotropic materials are thus anisotropic; their properties depend on the direction in which they are measured.One common example of an orthotropic material with two axis of symmetry would be a polymer reinforced by parallel glass or graphite fibres.

6. Petrography: Petrography is a branch of petrology that focuses on detailed descriptions of rocks.

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REFERENCES:

1. BRIDGE ENGINEERING: A GLOBAL PERSPECTIVE by Leonardo Fernández Troyano

2. BRIDGES: THE SPANS OF NORTH AMERICA by David Plowden3. THE CREATION OF BRIDGES by David Bennett4. From link: http://en.wikipedia.org/wiki/Wiki

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