1. CKY IB Design Technology Name: _______________________ Class: ________ HL Topic 9 Structures

2. Your Job Design need Your company wants to build a transport bridge that can span from Hong Kong to Macau or a pedestrian bridge that can give people access from Hong Kong Island to TST. Owners requirements Choice between two outcomes: A bridge that will transport vehicles from Hong Kong to Macau A pedestrian bridge to transport people from Hong Kong to TST Preparation for Submission Research on existing products Report showing bridge analysis and construction requirements, forces acting on structures, factor of safety 3D CAD and development of design for prototyping Testing Prototype – using modeling materials instead of steel Some possible tasks: Research truss configurations Create the structural model Check static determinacy and stability Calculate reactions Calculate internal member forces Determine member sizes Check member sizes for constructability Draw plans. Build the bridge Research forces acting on – Forces lab Create a mood board of different types of bridges Look and study the different types of bridges Four types of bridges: Arch, beam, suspension, and cable-stayed IA: Bridging the gap Assessment Criteria – Research (R) and Development (D) Due: June 26 th 2012

3. Aspect 1Aspect 2 CreativityTechniquesSolution Complete / 2 Uses a range of innovative ideas to solve the problem, at least 6 varied design sketches showing details and descriptions Uses freehand sketching, isometric and perspective. Includes the use of computer modeling (CAD) and other creative methods of presentation Arrives at a good solution that is practical, functional, solves the design problem or need and is aesthetically pleasing Partial / 1 Only approaches a limited amount of innovative ideas to solve the problem. Ideas do not vary and lack creativity Presents ideas using a range of techniques but not to the extend as above. Satisfactory solution to the problem is reached, some aspects are still unresolved and need modification or improvement Not at all / 0 Idea generation is mundane or irrelevant. There is not a specific use or no development from what is already available Does not use various techniques to communicate design idea or the techniques used are inappropriate Does not arrive at a solution or the solution is not appropriate for the design need Not at all / 6 Comments: Development (D) Development Creativity o You have 5-6 original and creative ideas o You have used freehand sketching to show your ideas o Sketching and written information is completed to a high standard o You have annotated manufacturing methods and joining techniques suitable to your solution o You have explained how your design meets your design specification o You have explained strengths and weaknesses of your design o Your research has informed your design ideas Techniques o You have used freehand drawing techniques. o You have used isometric drawing techniques. o You have used exploded drawing techniques. o You have used perspective-drawing techniques. o You have used CAD drawing techniques. Solution o You have described your final design in detail. o You have used correct symbols in your working drawing. o You have included dimensions on your solution. o You have listed joints/construction techniques. o You have a parts list. o You have listed tolerances for your solution. o You have explained the finish of your solution. o You have listed the materials needed to make your solution. o You have a detailed plan of production. Po Leung Kuk Choi Kai Yau School - Internal Assessment Criteria – Development – SL_HL Student:Teacher: Miss GeeDate: Investigation/Project:Topics/option:Hours:

4. Aspect 1Aspect 2Aspect 3 StrategiesData collectionData processing and analysis Complete / 2 Identifies a range of suitable resources and strategies for research. Has very clear priorities for research that link well with the brief or research question. Collects a wide range of appropriate research material. The research balances both qualitative and quantitative and secondary and primary research methods. Represents information in many different forms. Processes research material astutely with detailed analysis. Final analysis allows for the development of ideas. Analysis supports the usefulness of the study and links this to the design brief or question. Good recognition of any errors. Transforms all data appropriately. Partial / 1 Identifies some suitable resources and strategies for research Research is planned and links to the design brief or research question. Collects some appropriate research material. Some different methods of research used and some information represented appropriately. Processes research material appropriately however analysis is limited. The analysis doesn’t always link closely to the design brief and these errors are not always monitored. Only some data transformed usefully. Not at all / 0 Does not identify suitable resources and strategies. Any strategies are teacher led. Does not collect any appropriate research material. Processes research material inappropriately. Not at all / 6 Comments: Research (R) Checklist – Research Strategies A written research plan with priorities of what you will research Primary and secondary sources of data Identified both qualitative and quantitative data Correct referencing where appropriate Data collection Research and data is focused and appropriate to project Balance between qualitative and quantitative Presented research in a variety of forms (graphs, tables, diagrams, drawings and photographs Research and data includes labelling and explanations of outcomes Data processing and analysis You have processed raw data and presented in an astute (clear) manner You have transformed data into a suitable form for analysis (graph, table etc) Your written analysis is detailed and explains how your design brief can be answered You have analysed the relevance and usefulness of your data You have identified any errors or uncertainties you encountered throughout your research/ data You have assessed and commented on the reliability of your data You have used correct referencing Po Leung Kuk Choi Kai Yau School - Internal Assessment Criteria – Research – SL_HL Student:Teacher: Miss GeeDate: Investigation/Project:Topics/option:Hours:

5. Procedure: The weight of the bridge will be recorded. The bridge will then be placed upon a testing stand which will consist of two surfaces, level with respect to each other and separated by 20cm. A bar will be placed across the roadbed (perpendicular to the bridge's length) at the weakest looking point of the bridge (a bridge being no better that its weakest point) and the weight adding mechanism suspended from this bar. Weight will be added at a slow, steady rate until the bridge collapses or sags to 90% of its original height. At this point, the total weight suspended by the bridge will be recorded. Scoring: The score for the bridge build event is determined by the following formula (efficiency of a bridge): score = (mass supported)/(mass of bridge). The points will then be scaled to a maximum of 100 points.

6. Final Submission (use the development criteria as a guide) Must be an online folio You must include the following: Moodboard on bridges Research into loads and forces Research into materials for bridge Research into different structures and beams Labelling of loads on your bridge Development drawings of your bridge Technical drawing of your bridge Testing prototype of truss bridge Testing and Evaluation A successful project will explain the following extensions of learning: How the factor of safety is used in design How scientific principles, mathematic tools, engineering concepts, experimental data, and practical considerations contribute to the engineering design process Have a model bridge to meet a set of design requirements Build a model bridge, consistent with a set of plans and specifications Compile your research project, images of testing prototypes into an online portfolio, they will be reviewed by a civil engineer practicing in Hong Kong. Review points: Adequacy of research Suitability/ appropriateness of structure Creativity or solution Communication and explanation Assessment of testing of prototype Procedure: The weight of the bridge will be recorded. The bridge will then be placed upon a testing stand which will consist of two surfaces, level with respect to each other and separated by 20cm. A bar will be placed across the roadbed (perpendicular to the bridge's length) at the weakest looking point of the bridge (a bridge being no better that its weakest point) and the weight adding mechanism suspended from this bar. Weight will be added at a slow, steady rate until the bridge collapses or sags to 90% of its original height. At this point, the total weight suspended by the bridge will be recorded. Scoring: The score for the bridge build event is determined by the following formula (efficiency of a bridge): score = (mass supported)/(mass of bridge). The points will then be scaled to a maximum of 100 points.

7. External load acting on a structure Body load Forces research (use forces link in the appendices):

8. Show the different forces that can act on beams: compressive, tension, torsion, bending, shear. Explain your results of testing the connection points of the various shapes – square, pentogram, heptagon. Which shape was strongest and how did you add support to various shapes? Look at the following images of products and explain the importance of consideration of stress and strain on material choices and design of products.

9. Bridges research moodboard Four main types of bridges Task: Draw a quick diagram of your bridge in 2D front view and label the external load and body load acting on it

10. Young’s modulus Young’s modulus is concerned with simple stretching (or compression), in which an applied force increases or decreases the length of a sample of material without altering its density. The Young Modulus is defined as the ratio of the tensile stress and the tensile strain within the elastic region of the stress/ strain curve. So we can write: Young modulus = ____tensile stress____ tensile strain We know that: Tensile stress = __force___ = F area A Tensile strain = ___extension __ = e original length l Stress strain curve – Colour and label the elastic region one colour and the plastic region another Draw a diagram showing necking and failure So we can write: Units for the Young Modulus are Pascals (Pa) or newtons per square metre (Nm-2). The Young Modulus describes pulling forces.

11. Terms you need to research to help the project External load Body load Weight Mass Equilibrium Structures Strength Beam Sections of beams Tensile and compressive forces Stress and strain curve Deflection Stiffness Bending moment Factor of safety Newton’s First Law: An object in motion will stay in motion unless acted upon by an outside force. An object at rest will stay at rest unless acted upon by an outside force. Newton’s Second Law: Fnet = ma This law says that if a force is applied to the bridge it will accelerate in the direction of that force. If the forces all add up to zero the bridge is in equilibrium and does not move. Newton’s Third Law: For every action there is an equal and opposite reaction. If a car is on a bridge it is exerting a force on the bridge, therefore the bridge must be exerting the same amount of force on the car. If the bridge is not moving it is in equilibrium and all the forces will add up to zero. Mechanical properties of materials Ductility Resiliance Toughness Elongation Brittleness Elastic limit Yield stress Ultimate stress Breaking stress Young’s modulus

12. Weight vs Mass… what would you weigh… Weight- The gravitational weight of a body is the force with which the Earth attracts the body. This force is proportional to the body's mass and depends on the location. Because the distance from the surface to the centre of the Earth decreases at higher latitudes, and because the centrifugal force of the Earth’s rotation is greatest at the Equator, the observed weight of a body is smallest at the Equator and largest at the poles. The difference is sizable, about 1 part in 300. At a given location, the weight of a body is highest at the surface of the Earth; it diminishes with altitude and with the depth below the surface. For example, the weight of a body diminishes by about 0.1% if it is raised 3 km above the Earth's surface or taken 6 km below the surface. Weight also depends to a smaller but measurable degree on the density of the Earth's crust below the body. Mass- Isaac Newton said that the mass of a body is the measure of the quantity of matter the body contains. Quantity here does not mean volume. Mass can be thought of as the tendency of a body to resist the change in velocity caused by an external force. Mass is therefore said to be a measure of inertia. It has magnitude but not direction and is therefore a scalar quantity. The SI unit is the kilogram (kg). Task: http://www.exploratorium.edu/ronh/weight/ Weigh your self and fill in the weight and mass on the various planets. Choose three of your own. Show all calculations. Extension question: Explain why your weight varies on the different planets.

13. Beams Task: Research the various types of beams, use technology student and your bridge research to help you. http://www.technologystudent.com/forcmom/force2.htm Bending moment = Force x Distance Units – Newton Metres (Nm)

14. Beams Name: ________________ Class: ___________ Beams bend and flex due to the mending moments. Different types of beams are then required in order to cater to various design requirements. 1. Research the different materials used for beams and explain positives and negatives of each, solid wood, concrete reinforced, metal sections. 2. Draw the different type of metal sections you can get in beams. 3. Discuss the economical or structural reasons for using different types of beam cross sections. 4. Draw diagrams to show the three types of beams: Cantilever, overhanging and simply supported. 5. Below is an image of a shading using LVL (laminated veneer lumber). Research and explain the benefits of using LVL beams in construction, consider – design, stability, manufacture. Show examples of existing products. 6. Why would factor of safety be important with the design of beams? Explain your answer with examples from their use in real design situations. Formula: Young modulus = ____tensile stress____ tensile strain Tensile stress = __force___ = F area A Tensile strain = ___extension __ = e original length l Units for the Young Modulus are Pascals (Pa) or newtons per square metre (Nm-2). Stiffness – load deflection Factor of Safety = Design load (UTS) Normal maximum load (stress) F = Ma

15. End of Topic focused questions What is the correct definition for Young’s Modulus? Give examples of what it means by Yield Strength of a material? What is the difference between Plastic and Elastic strains? Draw how the force is effecting a beam that is contracting body load? Write down a definition for Mass? Draw a body is experiencing Tensile forces? Draw a diagram showing deflection taking place? Describe what is meant by a bending moment? What is the factor of safety? What is the definition of Stress? Strain is defined as the amount of deformation an object experiences compared to its original size and shape, how is this shown as a formula?

16. Appendices Useful websites: http://www.pbs.org/wgbh/buildingbig/bridge/basics.htmlhttp://www.pbs.org/wgbh/buildingbig/bridge/basics.html - types of bridges http://www.pbs.org/wgbh/buildingbig/bridge/truss_forces.htmlhttp://www.pbs.org/wgbh/buildingbig/bridge/truss_forces.html - forces http://www.ccmr.cornell.edu/educa)on/modules/documents/PhysicsofBridges.pdf http://www.pbs.org/wgbh/buildingbig/bridge/challenge/index.html http://www.fhwa.dot.gov/bridge/steel/pubs/if12052/volume01.pdfhttp://www.fhwa.dot.gov/bridge/steel/pubs/if12052/volume01.pdf - information on steels to be used in bridge construction and information on alloying, heat treatment, beams, Youngs Modulus http://www.fhwa.dot.gov/bridge/steel/pubs/if12052/volume05.pdf - Information on types of bridges http://www.fhwa.dot.gov/bridge/steel/pubs/if12052/volume05.pdf http://www.evolo.us/category/competition/

17. Due June 26th Compile your research project, images of testing prototypes, they will be reviewed by a civil engineer practising in Hong Kong. Review points: Adequacy of research Suitability/ appropriateness of structure Creativity or solution Communication and explanation Must be all compiled into an online folio document