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Ten lessons, one island. Build a structure in each, from a plank over a river to the lightest bridge across a chasm.

The lessons follow the island of the Playground: ten areas, each with a structure to build and one idea of structural engineering to take away. Each lesson starts with a picture of what you will build and the Grasshopper file, start and finished, then a few steps, a check against a hand calculation, and something to try.

Note

Every lesson runs without a license but one: the wall of lesson 9 is about 300 shells, past the 50 elements Alpaca4d analyses for free (License). In the Playground, all ten run in your browser.

1River — A plank acrossA simply supported plank, with the alpaca on it. Pin and roller supports, and how far a plank bends.Material · Section · Beam · Support · Load · Assemble · Run Analysis · Model ViewNew2Cliff — A balcony over the dropA cantilever. The same span and load bend a cantilever 16 times as much as a plank held at both ends.Fixed support · Nodal DisplacementsNew3Snowy roof — A rafter under snowHow deep it must be. Twice as deep is eight times as stiff; the L/250 limit.Linear Load · Gravity Load · Load Pattern · a slider on the sectionNew4Barn — A portal frame in the windRigid joints or hinges, and how much the frame sways.Several elements · Assemble · Hinge ReleaseNew5Valley — A truss bridge over the gorgeWhy triangles; tension and compression.Truss elements · Support · Model ViewNew6Market — Predict, then checkThe reactions and moments by hand first, then from the model. Equilibrium and moment diagrams.Reaction Forces · Beam ForcesNew7Watchtower — Legs that must not buckleHow end fixity and bracing raise the buckling load.Linear BucklingNew8Footbridge — It bounces too muchFrequency rises with stiffness and falls with mass.Natural Vibration · Mass PointNew9Wall with a window — Forces around an openingHow forces flow around a hole cut in a wall.Mesh Brep · ASD Shell · Plate Fiber · Model View · Principal Stress LinesNew10Summit bridge — The lightest bridgeMaterial only where the forces flow.Topology OptimisationNew

After the lessons

• How-to guides: one task each, such as a skewed support or a steel check.
• Concepts: why a model is built the way it is, axes and units, which element and which analysis.
• Examples: Grasshopper files to open, run and take apart.