{
  "comments": "A simple statically indeterminate structure.",
  "dimensions": 2,
  "nodes": [
    {"coords": [ 0,  0, 0], "constraint": "fixed"},
    {"coords": [10,  0, 0], "constraint": "slider"},
    {"coords": [10, 10, 0], "constraint": "free"}
    {"coords": [0, 10, 0], "constraint": "free"}
  ],
  "elements": [
    {"nodes": [1, 2], "material": "mat1"},
    {"nodes": [2, 3], "material": "mat2"},
    {"nodes": [3, 1], "material": "mat3"},
    {"nodes": [1, 4], "material": "mat2"},
    {"nodes": [3, 4], "material": "mat1"},
    {"nodes": [2, 4], "material": "mat3"}
  ],
  "forces": [
    {"node": 3, "vector": [4, 2, 0]}
  ],
  "materials": {
    "mat1": {"modulus":  50, "area": 2},
    "mat2": {"modulus":  50, "area": 1},
    "mat3": {"modulus": 100, "area": 2.8284}
  },
  "constraints": {
    "free": [false, false, false],
    "slider": [false, true, false],
    "fixed": [true, true, true]
  }
}

Add sample 4 as a statically indeterminate truss.
Add sample 4 as a statically indeterminate truss.
