Difference between Primary Secondary and Tie beam

Primary Beam:
A horizontal beam connecting columns (simply supported or shear connected.)
Function: It will transfer the load from secondary beam(if present) to the columns.

Secondary Beam:
A horizontal beam connecting primary beams (simply supported or shear connected.)
Function: It will transfer the load to the primary beam and not directly connected to the columns.

Tie Beam:
A horizontal beam connecting two rafters in a roof or roof truss.
Function:
This beam will transfer the rafter’s load to the column of the structure. Usually used in roof truss.

• Tie beam that ties the foundation at different level may be abbreviated as:
• Plinth beam at Plinth level
• Ground beam at Existing ground level

Their function is to tie the columns and foundation at that particular level.