Introduction to Truss Elements in FEA

Vocabulary practice flashcards covering core finite element analysis workflow concepts, coordinate systems, load categories, and formulation assumptions for 2D and 3D truss structures.

Truss

A structural system composed of straight members connected by pin connections that carry only axial loads (tension or compression) at the joints, with each member in equilibrium under equal and opposite end forces.

Pre-processing

The initial stage in the FEA workflow that encompasses constructing CAD, cleaning CAD, generating the mesh, applying element properties, and applying boundary conditions.

Post-processing

The final phase of the FEA workflow focused on evaluating the computed results (such as displacements, reaction forces, and element stresses) to determine if the solution is satisfactory.

Local Coordinate System

An element-oriented frame of reference whose axes align with the longitudinal and transverse orientation of an individual structural element.

Global Coordinate System

A coordinate system that represents the entire structure or body and is completely independent of the orientations of individual elements.

Natural Coordinate System

A localized coordinate system defined so that its coordinate variables are dimensionless.

Transformation Matrix ($[T]$)

A coordinate conversion matrix that transforms displacement and force vectors from the local coordinate system to the global coordinate system.

Dead Loads

Permanent static gravitational loads acting on a structural frame, comprising the self-weight of the truss, roofing, glazing, and fixed services.

Live Loads

Transient, temporary loads applied to a structure, including maintenance workers, tools, and temporary roofing materials.

Wind Loads

Environmental forces acting on structural surfaces that produce pressure, suction, uplift, and lateral forces.

Rainwater Loads

Water accumulation loads on a roof structure resulting from blocked drains or roof ponding.

Thermal Effects

Internal structural forces and deformations caused by temperature-driven expansion and contraction when member movement is restrained.

Seismic Loads

Dynamic inertia forces generated throughout a structure as a result of earthquake ground motion.

Construction Loads

Temporary forces imposed on structural members during lifting, handling, assembly, and installation.

Space Truss

A three-dimensional truss structure consisting of interconnected members that transmit loads across multiple three-dimensional spatial paths.

3D Space Truss Nodal Degrees of Freedom

The three independent translational displacement components ($u$, $v$, and $w$) along the Cartesian axes ($x$, $y$, and $z$) at each node, resulting in a global stiffness matrix dimension of $3n \times 3n$ for $n$ nodes.

Truss Bending Moment Assumption

The fundamental engineering assumption in rod, 2D truss, and 3D space truss element formulations stating that individual members experience zero bending moments and carry pure axial tension or compression only.