Practical digital tools for everyday life
Business software for growing organizations
Free, fast, and easy to use
Draw truss bridges with steel joints, apply moving vehicular traffic loads, and watch real-time compression/tension stress maps with safety factors.
Direct stiffness matrix solver, moving loads, and yield limit analysis
Calculates exact nodal displacement vectors ($\{u\} = [K]^{-1}\{F\}$) and axial forces across Warren, Pratt, Howe, and K-Truss spans.
Simulate dynamic semi-trucks, freight trains, and heavy axle vehicles traversing the bridge deck to identify peak stress points.
Real-time visual distinction between tensile elongation (cyan/blue) and compressive squeezing (orange/red) with elastic deflection magnification.
Solves the global equilibrium matrix equation [K] {u} = {F} to calculate exact node deflections.
Sum of forces at each pin joint must equal zero (ΣFx = 0, ΣFy = 0) to maintain static stability.
Structural integrity requires SF = Yield Strength / Actual Stress ≥ 1.5 under design traffic loads.
Everything you need to know about Bridge Stress Lab
The simulator uses the 2D Direct Stiffness Method (DSM), assembling element stiffness matrices based on member lengths, cross-sectional areas, and material Young's moduli into a global system of equations solved with Gaussian Elimination.
Tension (blue members) occurs when forces pull outward, stretching the member. Compression (orange/red members) occurs when forces push inward, squeezing the member and risking buckling failure.
Safety Factor is the ratio of material yield strength to actual induced stress (SF = Yield / Actual Stress). An SF below 1.0 indicates structural failure, while engineering standards typically require SF between 1.5 and 2.5.
Deepen your exploration of structural dynamics, thermodynamics, and fluid mechanics.
Instant structural safety factor calculation ($SF = \sigma_{\text{yield}} / |\sigma|$) with catastrophic failure break points when loads exceed limits.
As vehicles roll across the deck, internal forces shift dynamically. Diagonals that experience tension when a truck is on the left side may reverse into compression when the truck moves to the right side.
A Pin Support (triangle) restrains movement in both X and Y directions. A Roller Support (circles) restrains only vertical Y movement, allowing free horizontal expansion due to temperature changes or bridge deflection.
Warren trusses distribute alternating tension and compression efficiently for highway spans. Pratt trusses orient diagonals in tension under gravity loads (ideal for steel), while Howe trusses orient diagonals in compression (ideal for timber).
Yes! Compare Structural Steel A36 (E = 200 GPa), Aircraft Aluminum (E = 70 GPa), Engineered Timber (E = 12 GPa), and High-Modulus Carbon Fiber (E = 230 GPa).
A member snaps (drawn as a flashing red dashed line) when the applied vehicle load produces internal stress exceeding the material yield strength (SF < 1.0).
Yes! Click 'Export CSV' to download complete member lengths, axial forces (kN), stresses (MPa), and safety factors, or click 'Snapshot' for high-resolution stress diagrams.
Yes, nodal displacements are visually magnified 5x so users can observe elastic curvature and deformation clearly while keeping calculations exact.
Yes! Adjust the vehicle weight slider from 30 kN (passenger cars) up to 450 kN (heavy loaded semi-trucks and locomotives).
No software installation is required. The finite element truss solver runs client-side at 60 FPS in your browser using HTML5 Canvas and TypeScript.