Truss Element

A truss element is a structural component in mechanical systems that carries only axial forces (tension or compression) and provides a linear connection between two nodes, while effects such as bending moments or shear forces are neglected. It is commonly used as the fundamental unit in frameworks arranged in a network of rigid bars.

Structural Features

• Axial Force Only: Truss elements carry force only along their own axis. Shear forces and bending moments are not considered.
• Two Nodes: Each truss element connects only two nodes.
• Linear Connection: Truss elements form straight, linear connections; they do not carry curved or twisted connections.

Element Stiffness Matrix (in Local Coordinates)

• E: Modulus of elasticity
• A: Cross-sectional area
• L: Length of the element

Areas of Application

• Truss Girders: In structures such as bridges and crane arms
• Space Frame Systems: For stadium roofs and wide-span buildings
• Truss Towers: Used in power line towers and communication masts
• Architectural Structures: Aesthetic, lightweight structures with large spans

Assumptions Related to Truss Elements

• Elements are subjected to loads only at their nodes, except for their self-weight.
• Effects of bending, torsion, and shear are neglected.
• Loads and reactions are applied only at the nodes.

Truss Elements in Finite Element Analysis (FEA)

In the finite element method (FEM), truss elements possess only two degrees of freedom (displacement in the x and y directions at each node). Rotational degrees of freedom (moment-carrying capacity) are not defined. Truss analysis is generally used in the preliminary design stages of structural systems to obtain quick estimations.