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Design Arrangement

Global Coordinate System

The global coordinate system is shown in the figure above. The x-axis is horizontal pointing to the right. The z-axis is vertical pointing downward.

Local Beam Coordinate System

Each beam has a local coordinate system. The local x-axis is directed from the begin node to the end node. The local z-axis is perpendicular to the local x-axis and follows from the right-hand rule.

Node Coordinate System

By default, the node coordinate system is equal to the global coordinate system. However, a local node coordinate system can be defined for each node. This is useful for supports on an inclined plane.

Sign Convention

  • Positive normal force: tension
  • Positive shear force: according to local z-axis direction
  • Positive moment: causes tension at the bottom fiber
  • Positive deflection: according to local z-axis direction