Most obviously the best advice I can give is READ THE QUESTION! But here are some other things to remember when tackling structures questions:
Unit 2 - Bending Moments, Shear Force and Bending Moment Diagrams
- Draw your diagrams clearly on squared paper and rememer to label everything. Check that your free body diagram at the top is right before going further.
- Remember that UDLs will create a slope on your shear force diagram, and point loads (including reactions) will create vertical lines.
- The Maximum Bending Moment occurs where the shear force diagram crosses the axis. Draw this point up to you free body diagram as well as down to the bending moment diagram so that you have an idea of the distance you expect to get through your calculations.
- Always draw the maximum bending moment onto your bending moment diagram.
- Remember that the bending moment diagram will be flat where there is only point loads, and only curved under a UDL. Make this clear on your diagram if you have a combination of them both.
- Calculate your reactions first. Remember to take moments about a hinge first (external forces only) and then use an up, down, right, left diagram to calculate the the hinge reaction. (Be careful with sloping forces.
- Choose the half which is easiest to keep. Lose the hinge reaction where applicable, or the side with the most forces in it.
- Forces which act through the node create no moments, so make sure to choose nodes in order to give you one unknown only. Try to work systematically
- Remember that you can take moments about a node which is not part of the section you have kept.
- DRAW ALL NODE DIAGRAMS SEPARATELY Clearly show all forces in the cut members as ties and this makes working out perpendicular distances easier as you can focus on one part at a time.
- Draw on your perpendicular distances so that you can be confident that you are working with the correct numbers.
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