STAAD uses two types of coordinate systems to define the structure geometry and loading patterns.

**Global coordinate system****Local coordinate system**

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**Global coordinate system**

The

**Global coordinate system**is an arbitrary coordinate system in space which is utilized to specify the overall geometry & loading pattern of the structure.**Conventional Cartesian Coordinate System**

This coordinate system is a rectangular coordinate system (X, Y, Z) which follows the orthogonal right hand rule. This coordinate system may be used to define the joint locations and loading directions.

**Cylindrical Coordinate System**

In this coordinate system, the X and Y coordinates of the conventional Cartesian system are replaced by R (radius) and Ø (angle in degrees). The Z coordinate is identical to the Z coordinate of the Cartesian system and its positive direction is determined by the right hand rule

**Reverse Cylindrical Coordinate System**

This is a cylindrical type coordinate system where the R- Ø plane corresponds to the X-Z plane of the Cartesian system. The right hand rule is followed to determine the positive direction of the Y axis.

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**Local coordinate system**

A

**Local coordinate system**is associated with each member (or element) and is utilized in MEMBER END FORCE output or local load specification.
Each axis of the local orthogonal coordinate system is also based on the right hand rule. Note that the local coordinate system is always rectangular.

A wide range of cross-sectional shapes may be specified for analysis. These include rolled steel shapes, user specified prismatic shapes etc..