This is an individual exercise which comprises calculations plus a bit of research into structures and materials; not all of what you need to complete this assignment has been taught in class. Learning Outcomes It is intended that students will gain particular learning outcomes: • Analysis – the concepts presented in this assignment draw together both statics, material properties and design – you will need to identify which analysis to use and to make correct assumptions. As in any design process, there is no one correct answer (there are many); there are many more incorrect ones too! • Self-Directed Learning and Research – this problem simulates a ‘real-life’ problem of the sort you will encounter in your professional lives: you’ve done nothing quite like this in class, but you have seem the principles necessary for this analysis and you must gain some confidence in applying your knowledge to new situations. You will have to work alone and develop an individual solution. To do this effectively you’ll need to look at published information to see what common engineering approaches have been taken in the past. • Communication skills – You are to prepare a technical poster. Posters are often used to convey the results of a technical or experimental study. With limited space they encourage only relevant information to be included in a concise and meaningful way. Being able to do this correctly is vital for engineers. Figure 1 from L Herbert, 20 August 2009, Bridge over the River Thames, Get Reading, S&B Media, http://www.getreading.co.uk/news/s/ 2055936_bridge_over_the_river_tham es. This bridge has a mass of 27000 kg 2 Details of the Assignment In a battlefield situation and at times of civilian emergency or for festivals and other large organised events, it is often necessary to quickly erect a temporary bridge to allow people to cross rivers, deep earth works, etc. These structures are usually light (to allow them to be placed by crane), have a limited load-carrying capacity, and are removed after only a short period of time (so they need to be cheap). It is easy to find examples in the press of such bridges being used – it is also easy to find stories of such bridges which have failed (e.g. 1997 Maccabiah Games). Your job is to design a bridge to span 6 metres and to carry pedestrians (plus whatever the pedestrians are carrying, riding on, etc.), but not vehicles. You will need to: • Decide what load the bridge needs to accommodate and what factor of safety is appropriate. • You will need to state what occasion the bridge is used for and what volume of traffic it will see. • Find ways to ensure the bridge does not become overloaded. • Design the bridge structure and choose appropriate materials from which to manufacture it (do not consider cost). • Present your design as a sketch of the bridge with annotations showing key features. Present also calculations. • You may only use pin-jointed structures (i.e. you must assume that all members of the bridge are simply assembled using pins which do not prevent members from rotating around the axis of the pins as opposed to riveted or welded joints); this will allow simple assembly on site. • You should examine one representative joint to ensure that the pin will not fail in shear loading. The overall aim is to present a practical solution of the lightest bridge possible for the task at hand. Rules • This is an individual exercise. You must not copy from each other (you’d be surprised at how easy it is to spot collusion through common mistakes, assumptions etc.). You may seek from your friends only the sort of help a tutor would give. • The assignment is to be submitted by the due date and time. Submissions must be made via Blackboard. • Your provisional mark will be available on Blackboard grade centre within 4 working weeks of submission. 3 Submission • Submission will be as a poster in pdf format • The poster will be A0 size with no lettering below a font size of 36 points • I would suggest designing it in publisher, powerpoint or word as an A0 size document (designing it smaller and then blowing it up will lose quality) • Examples of good posters will be on blackboard • The poster will include, but not be limited to, the following:  A summary (one short paragraph including aims, analysis methods and results)  An introduction (including your background research in to bridges, their uses, designs and failures, and suitable space diagrams and assumptions)  Your analysis (your calculations and free body diagrams, etc.)  Your results (including checking by an order of magnitude calculation or other similar rough check that your results are correct)  Conclusions (tie this all together – do the numbers look right, how confident are you that you could do such a calculation safely, etc.) Marking Scheme • Design (20%) – how practical is the bridge? What weight is it? How is maximum load identified and controlled? Is an appropriate factor of safety applied? • Analysis (50%) – are the answers correct? Have the right assumptions been made? Have the right materials been selected and at the right cross-sections? Have appropriate calculation steps been taken? • Research (15%) – find and discuss real-life scenarios of good examples of bridges and a couple of failures (why did they fail?). What sorts of bridge designs are used as temporary structures? • Poster presentation (15%) – layout, quality of written English, quality of figures, clarity of the calculations and their results. Penalties • This assignment is worth 15% of the module total. • A penalty of 10% per day or part day will be applied for late submission (including 1 minute late) – ensure you submit in good time as one immutable law of the universe says that the network will crash 30 minutes before the deadline! • You will not be allowed to supplement incomplete submissions beyond the submission deadline, but will be allowed to before the deadline. • Submissions will not be accepted more than 2 calendar weeks late