Member Forces • Tension & Compression • Reactions • Equilibrium — Simulate • Explore • Practice • Quiz
Truss analysis is a fundamental topic in structural mechanics. A truss is a structure composed of slender members connected at joints (nodes), designed to carry loads efficiently through axial forces only — each member is either in tension (being pulled apart) or compression (being pushed together). Understanding truss behaviour is essential for designing bridges, roof structures, transmission towers, and crane booms.
The three most common truss types are the Warren truss (diagonal members alternate in direction, forming a W-pattern), the Pratt truss (verticals and diagonals sloping toward the centre), and the Howe truss (verticals and diagonals sloping away from the centre). Each type distributes forces differently through its members.
The method of joints analyses equilibrium at each joint of the truss. Since all forces at a joint are concurrent (meeting at a single point), only two equilibrium equations apply: ΣFx = 0 and ΣFy = 0. Starting from a joint with at most two unknowns, the analyst systematically solves for member forces throughout the entire truss. A positive result indicates tension, while a negative result indicates compression.
The method of sections is useful when only a few member forces are needed. A virtual cut is made through the truss, dividing it into two parts, and equilibrium of one part is analysed using three equations: ΣFx = 0, ΣFy = 0, and ΣM = 0.
Zero-force members carry no load under certain conditions: (1) at a joint with only two non-collinear members and no external load, both members are zero-force; (2) at a joint with three members where two are collinear, the third is a zero-force member (if no external load is applied). A truss is statically determinate when m + r = 2j, where m = number of members, r = number of reactions, and j = number of joints.
In Simulate mode, select a truss type (Warren, Pratt, or Howe), adjust the number of panels, dimensions, and load position using the sliders. The canvas displays the truss with colour-coded members: green for tension, red for compression, and grey for zero-force. Use presets for common loading cases. Switch to Explore mode to study 12 concepts across Truss Basics, Analysis Methods, and Forces & Members with worked examples. Practice mode generates random truss problems, and Quiz tests your knowledge with 5 randomised questions.
This simulator is designed for civil and mechanical engineering students, structural analysis trainees, and instructors teaching truss analysis, method of joints, method of sections, and structural design. It provides visual, hands-on understanding of axial forces in trusses without requiring laboratory equipment or complex FEA software.