Analysis Solver
The LIRA-FEM analysis solver is the computational core of the software package and implements the finite element method for performing static, dynamic, thermal, linear, and nonlinear analyses of building structures. It provides analysis of computational models of varying complexity — from individual structural elements to models with millions of unknowns.
Finite Element Library
The combination of an extensive finite element library, specialized analysis modules, and modern computational algorithms makes it possible to model the actual behavior of structures and efficiently solve a wide range of engineering problems.
The finite element library of LIRA-FEM covers the main classes of finite elements for modeling building structures — from simple bar systems to complex spatial models.
Linear and nonlinear modifications are available for most basic element types, along with specialized elements for modeling soil foundations, contact interaction, and heat conduction problems.
A distinctive feature of the library is its support for high-precision finite elements with additional nodes on their sides, which ensures increased calculation accuracy. Automatic generation of high-precision counterparts is implemented for the basic plate and solid elements.
Bar Elements
Designed for modeling trusses, frames, beams, pile caps, spatial bar structures, cable systems, strings, thin-walled and prestressed structures, and more. Linear and nonlinear modifications are implemented for most types, allowing the specific behavior of materials and structures to be taken into account.
Plate Elements
Used for modeling slabs, shells, and deep beams. The library contains triangular and quadrilateral finite elements for thin and thick plates and shells, as well as their nonlinear counterparts.
For orthotropic plates, a specialized tool for automatic generation of the elasticity matrix has been implemented, allowing stiffness characteristics to be determined for a wide range of structural forms, including ribbed, box-section, profiled, and hollow-core slabs.
Solid Elements
Tetrahedral, prismatic, and hexahedral solid finite elements are implemented for modeling the three-dimensional stress-strain state of structures, including physically nonlinear models and specialized elements for modeling soil masses.
Special Elements
The library contains a wide range of specialized elements that make it possible to model:
- structural connections (joints, embedded parts);
- elastic, one-way, and nonlinear connections accounting for gaps, friction, and limit forces;
- nonlinear hinges to account for joint flexibility;
- vibration protection systems (viscous dampers, seismic isolators, shock absorbers);
- prestressing and pre-compression;
- interaction of a structure with its soil foundation, including modeling an infinite soil mass using non-reflecting half-space elements.
Using special finite elements makes it possible to bring the computational model as close as possible to the actual behavior of the structure and to account for its structural features.
Thermal Elements
Bar, planar, and solid finite elements, as well as convective heat transfer elements, are implemented for heat conduction problems. They are used for thermal analysis of building envelopes, designing fire protection systems for building structures, determining actual fire resistance limits, and solving other building thermal physics problems.
The LIRA-FEM linear processor is designed for solving static and dynamic problems in a linear formulation and is used for a wide range of engineering analyses of building structures.
Static analysis is performed for force loads (concentrated and distributed) and deformation loads (prescribed displacements, temperature effects). For dynamic problems, modal analysis, the response spectrum method, and modern tools for seismic analysis of structures are implemented.
Key Capabilities
- static analysis of force and deformation loads;
- modal and spectral analysis of dynamic effects;
- seismic analysis of structures using response spectra, accelerograms, and seismograms;
- determination of displacements, internal forces, support reactions, and stresses;
- analysis of the overall stability of structures;
- calculation of nodal forces for plate and solid finite elements;
- automatic generation of code-based load combinations;
- superelement technology for efficient analysis of large-scale models.
Specialized Modules
The linear processor includes specialized modules that automate code-based calculations and expand analysis capabilities.
| Module | Purpose |
| DCF | Automatic determination of load combinations of forces from various load types. |
| DCL | Calculation of displacements and internal forces from standard load combinations. |
| Load and Action Combinations | Automatic generation of the most unfavorable combinations in accordance with Eurocode and other design codes, with the ability to create custom combination rules. |
| Task Integration (METEOR) | A subsystem for combining the analysis results of several computational models with identical topology into a single generalized result. |
| Stability | Analysis of the overall stability of a structure, determining the safety factor and buckling mode shapes. |
| LITERA | Calculation of principal and equivalent stresses according to various strength theories. |
| Load on Fragment | Determination of loads transferred between individual parts of a structure, in particular from the above-ground part of a building to its foundations, or between individual fragments of a model. |
Based on the LINEAR PROCESSOR, LIRA-FEM can be used to build the following automated structural design workflow.
The LIRA-FEM nonlinear processors are designed to solve a wide class of problems involving physical, geometric, and structural nonlinearity. They make it possible to model the actual behavior of structures, taking into account the staged application of loads, the formation and propagation of cracks, plastic deformations, loss of stability, contact interaction, nonlinear behavior of the soil foundation, and other factors not accounted for in a linear formulation.
Key Capabilities
- physically nonlinear analysis of bar, plate, shell, and solid structures;
- geometrically nonlinear analysis, including cables, membranes, and other structures with variable geometry;
- combined physically and geometrically nonlinear analysis;
- modeling of contact interaction, one-way connections, gaps, and friction;
- nonlinear analysis of the soil foundation;
- staged load application and modeling of the assemblage sequence;
- accounting for prestressing and pre-compression;
- modeling of crack propagation, plastic deformation, and the failure process of structures.
Based on the NONLINEAR PROCESSOR, LIRA-FEM can be used to build the following automated structural design workflow.
Calculation Methods
Step Method
Designed for solving problems in which the load is applied in stages, taking into account its loading history. It is used to analyze physically, geometrically, and genetically nonlinear problems, as well as time-history dynamics and transient heat conduction problems.
The method makes it possible to model crack propagation, plastic deformation, and loss of load-bearing capacity of structures, while simultaneously accounting for physical and geometric nonlinearity.
Iterative Method
Designed for solving structural nonlinearity problems related to contact interaction, one-way connections, nonlinear supports, and soil foundations. It is also used for physically nonlinear problems, time-history dynamics, and Engineering Nonlinearity.
It implements elastoplastic analysis with different loading and unloading branches, ensures correct force redistribution, and is effectively used for nonlinear static and dynamic problems.
Combined Method
It combines the capabilities of the step and iterative processors, providing simultaneous accounting of physical, geometric, and structural nonlinearity. It is used for complex combined models, such as reinforced concrete structures on a nonlinear soil foundation, systems with contact interaction, or models in which several types of nonlinearity are present simultaneously.
Additional Capabilities
Specialized modules have been implemented on the basis of the nonlinear processors for solving specific classes of engineering problems, including:
- Assemblage — models the construction process of a structure, accounting for assemblage stages, changes to the computational model, and construction loads.
- Progressive Collapse — analyzes the behavior of a structure under local failure of load-bearing elements.
- Time-History Dynamics — nonlinear analysis of structures under time-varying loads (accelerograms, seismograms, impact, and other dynamic effects).
- Pushover Analysis — nonlinear static analysis for assessing the seismic resistance of structures using a progressive loading method.
- Engineering Nonlinearity 1 — an iterative method for accounting for physical nonlinearity without a full step-by-step analysis. It is well suited for quick engineering calculations of reinforced concrete structures. Reinforcement can be selected automatically during the iterative calculation.
- Engineering Nonlinearity 2 — a step method that accounts for the loading history. It supports staged structural behavior, assemblage, joint behavior, temporary loads, and other effects requiring step-by-step modeling. Reinforcement is specified by the user.
The LIRA-FEM calculation processor combines modern finite element analysis methods, a wide range of finite element types, and specialized calculation modules, providing a unified environment for solving structural mechanics problems of varying complexity.
Evaluate the software
If you have any doubt, download the Demo version and evaluate the program or contact our Support Team for more details.