A structure is an assembly of individual components such as beams, columns, slabs, plates etc.. In STAAD.Pro, frame elements and plate elements may be used to model the structural components. Typically, modeling of the structure geometry consists of two steps:

1. Identification and description of joints or nodes.

2. Modeling of members or elements through specification of connectivity (incidences) between joints.

In general, the term MEMBER will be used to refer to frame elements and the term ELEMENT will be used to refer to plate/shell and solid elements. Connectivity for MEMBERs may be provided through the MEMBER INCIDENCE command while connectivity for ELEMENTs may be provided through the ELEMENT INCIDENCE command.

STAAD.Pro uses two types of coordinate systems to define the structure geometry and loading patterns. The GLOBAL coordinate system is an arbitrary coordinate system in space which is utilized to specify the overall geometry & loading pattern of the structure. A LOCAL coordinate system is associated with each member (or element) and is utilized in MEMBER END FORCE output or local load specification.