LFEM
Finite element software for bridges and civil engineering: a fast, validated solver, state-of-the-art elements and an optional specialized LFEM Agent.
Overview
LFEM is built on state-of-the-art element formulations: 3D Timoshenko beams with full shear deformation, MITC3+ and MITC4+ shells free of shear and membrane locking, accurate on distorted meshes and curved shells alike, and 3D solid elements. Beams connect directly to shell nodes: ribs, stiffeners and cross-beams are modelled without workarounds.
Beyond linear statics, LFEM covers modal analysis, response-spectrum seismic analysis and buckling, as well as the most demanding calculations: geometric and material nonlinearities, step-by-step phased construction with arbitrary changes to the structure, creep and shrinkage under the main code and scientific laws, and automated road and rail moving-load sweeps over influence lines and surfaces.
LFEM is optimised at every level: assembly, native sparse solvers, extreme-effect search, display and export. A single numerical core powers its web, desktop (Windows, macOS) and mobile (iPhone, iPad) interfaces.
Preview
Cable-stayed bridge
Steel-framed deck suspended from a pylon by stay cables. Deformation under a unit cable shortening: one step of stay-tension tuning. Displacement isocolors.
Finite elements
3D Timoshenko beam
12 DOF, constant or variable cross-section, offset shear centre, shear-locking free, arbitrary orientation.
MITC4+ / MITC3+ shells
Latest-generation Reissner-Mindlin quadrilaterals and triangles: free of shear and membrane locking, robust on distorted, warped or highly skewed meshes, with exact nodal normals for curved shells.
Beam-shell connection
Beams connected directly to shell nodes, with the rotation about the normal carried by an internal drilling degree of freedom; rib-to-shell rigid links that respect thin-plate kinematics.
Cables & bars
Uniaxial element carrying axial force only (3D truss bar), with optional tension-only nonlinear behaviour for cables and stays.
Prestress
Pre-tensioning and post-tensioning, internal or external tendons in beams, shells and solids, arbitrary tendon profile, instantaneous and long-term losses.
Rigid link
Rigid-body kinematics: master-slave constraint between nodes.
Spring link
6 independent stiffnesses between two nodes, optional nonlinear laws (elasto-plastic, gap, bilinear, friction).
3D solid elements
TET4/TET10, PENTA6/PENTA15 and HEX8/HEX20 volume elements, with automatic tetrahedral meshing and prismatic or hexahedral extrusion.
Boundary conditions
Rigid supports
Degree-of-freedom restraints: fixed, pinned, sliding.
Elastic supports
Spring stiffness in translation and/or rotation on each degree of freedom.
Matrix supports
Full 6×6 stiffness matrix at the node, with coupling between degrees of freedom.
Beam and shell on elastic foundation
Winkler foundation: distributed soil springs, constant or depth-varying reaction modulus.
Nonlinear supports
Nonlinear force-displacement laws: gap, elasto-plastic, bilinear, friction.
Analysis types
Linear static
Load cases, combinations and result envelopes, within linear elasticity.
Moving loads
Automatic influence lines and surfaces, concomitant max/min envelopes. EN 1991-2 models (LM1, LM2, LM4, FLM4 fatigue), French Fascicule 61 (A(l), Bc, Bt, Br, Mc, Me, exceptional convoys) and UIC 71 rail loading.
Phased construction
Activation and removal of elements, supports and links; fresh concrete cast on falsework or carried by the structure; tendon tensioning; time-dependent effects computed step by step, with automatic sub-steps.
Creep and shrinkage
EC2 laws (EN 1992-1-1 and EN 1992-2 Annex B, with calibration on test data), BPEL 91, AASHTO LRFD, fib Model Code 2010, CEB-FIP MC90, Bažant B3 and B4. Relative humidity per member, actual concrete temperature, custom creep and shrinkage laws.
Modal analysis
Natural modes, frequencies and effective modal masses.
Spectral seismic
Modal response-spectrum analysis, CQC modal and directional combination, residual mode for missing mass.
Geometric nonlinearity
Second order, large displacements and large rotations (corotational formulation), load, displacement or arc-length control.
Material nonlinearity
Fibre beams, section moment-curvature laws coupled with BridgeKernel, layered shells in elasto-plastic steel and reinforced concrete (EC2 law), imperfections and residual stresses (GMNIA).
Buckling and stability
Critical loads and modes: member buckling, lateral-torsional buckling of beams and shell buckling.
3D solid mechanics
Volume, surface, pressure, edge and thermal loads, stress recovery and N–V–M resultants on solid cuts.
Validation
Analytical oracles and cross-comparisons
Validated against thousands of analytical oracles and through cross-comparisons with other established finite element software: beams, shells, solids, eigenmodes, buckling, staged construction.
Public benchmarks
AFNOR (SSLL, SSLS, SDLS) and NAFEMS test cases, versioned with their published reference values, recorded before the calculation.
Every function tested
Every function of the reference manual is covered by at least one test against an independent reference: closed-form solution, Code_Aster, published case or reference software.
Independent cross-checks
Creep, shrinkage, prestress losses and phasing checked by independent calculations that never read LFEM's output.
Non-regression
More than 250 numerical validation suites and a full release gate, memory analysis included (ASan, UBSan), before every version.
Quality of life
Auto-meshing
Automatic discretisation of beams, polygonal shell zones and 3D volumes, including tetrahedral meshes and prismatic or hexahedral extrusions.
Parametric models
Variables, loops and conditionals describe complex geometry in a compact text file, easy to version and reuse across projects.
Real-time 3D viewer
Interactive 3D model and results (rotate, pan, zoom, preset views), updated live as you edit.
Results visualisation
Multi-palette isocolors, deformed shape, internal-force diagrams, reactions, solid stress fields, N–V–M cuts and min/max envelopes.
Smart editor
Validation on run: errors and warnings pinpointed by line, plus syntax highlighting and keyword auto-completion.
AI assistance
A dedicated LFEM skill helps the user's AI agents accelerate model setup, prepare and run solves, interpret diagnostics and correct errors.
Python interface
Drive the model, the solve and the results from Python: parametric studies, automated post-processing and integration into your own tools.
Section library
Coupling with BridgeKernel: mechanical-property computation, 3D solid rendering of sections, and a thin-walled section solver.
Pricing
LFEM licensing options and pricing will be announced soon.
LFEM AGENT
An agent specialized in LFEM syntax and operation.
Describe the structure you want to model or the problem you are facing. LFEM Agent assists you in creating or modifying the model, explaining commands, running the solver, diagnosing errors and working with the results.
Assisted model creation
Describe the structure, materials, supports, loads and analyses you need. The agent assists you in building a complete and editable .lfem model.
Review and verification
Checks the model structure, links between its objects, materials, sections, supports, loads and analysis choices, then reports inconsistencies and missing data.
Help and explanations
Explains LFEM syntax, modelling options, diagnostics, units and how to read the results.
Diagnosis and targeted repair
Validates the model, runs the solver, locates blocking errors or instabilities and proposes the necessary corrections.
Results post-processing
Navigates dense output to extract useful results, identify governing cases, compare phases and produce targeted PNG graphics.
Frontier AI models
LFEM Agent uses frontier models that also understand civil engineering, supplemented by specialized knowledge of LFEM syntax and operation.
LFEM Agent is optional and requires an internet connection. Every user receives an initial credit that can be refilled once depleted. Artificial intelligence can make mistakes: verify its outputs and correct them when necessary.