Consideration of groundwater filtration is an important task in many areas of construction (geotechnics, hydraulic engineering, ecology).

New type of created problem allows you to calculate pressure field and velocity of groundwater filtration in design models of arbitrary geometry in order to find stress-strain behavior from the action of the calculated pore pressure. The calculation is performing, both taking into account the physically nonlinear properties of the soil, and taking into account the change in the geometry of the structure (Assemblage + Filtration). In addition, the possibility of combining the calculation of filtration with the calculation of the stationary thermal conductivity is implemented into a single problem.

For modeling filtration problem in the SP LIRA 10.8 the following innovations were implemented:

• For material types of plane and solid soil filtration properties were added.
• New loading states types were created in the loading states library: «Stage of nonlinear loading with filtration calculation»; «Stage of the structure erection with filtration calculation».
• New type of nodal load has been added: «Fluid pressure for filtration». It can be assigned both on individual nodes and on a group of nodes with a linear distribution law or distribution law defined by the function.
• New type of restraint used in filtration calculations has been added.

These innovations allow you to model different situations of structure behavior both in two-dimensional and in spatial position.

Calculation Results

In the calculation results it is possible to evaluate the distribution of pressure and filtration velocity in soil mass, filtration direction, as well as displacements and stresses, which are caused by the action of the calculated pore pressure.

Steady-state heat transfer problem has been further developed in SP LIRA 10.8. Single-noded finite element of heat transfer (FE 151) has been added. You can set ambient temperature using this finite element.

Determination and visualization of heat flow is shown using an example of temperature distribution modeling in fragment of building envelope.

Calculation and visualization of heat flow

The finite elements collection for modeling of 3D problem of deformable solid bodies was replenished with geometrically nonlinear finite elements (FE 332-340).

Example of geometrically nonlinear problem’s solution is shown below. Column with one fixed end subjected to axial load and modeled using rods (FE 309), shells (FE 344) and solids (FE 336). Problems have been solved using stepwise method until buckling failure. Results are consistent between themselves and with Euler’s formula for determining critical load of elastic rod under compression.

Example of solution to geometrically nonlinear problem on compressive load

Finite element library has been replenished with pyramid finite elements with 5 and 13 nodes for modeling problem of deformable solid 3D bodies. Those are linear (FE 35, 40), geometrically nonlinear (FE 335, 340), physically nonlinear (FE 235, 240) and soil (FE 275, 280) finite elements.

Pyramid elements solve the problem of transition between triangular and rectangular faces of solid finite elements. Pyramid FEs significantly increase precision of problem solution in comparison to tetrahedron FEs.

Now the group of solid finite elements contains complete set of shapes.

These four shapes of finite elements can be used in different combinations during creation of 3D mesh of design model.

Pyramid finite elements can also be used in heat transfer problems (FE 35, 40, 335, 340, 235, 240, 275, 280) as well as in problems of steady-state filtration (FE 275, 280) (modeling filtration in water saturated soil).

Finite element library of SP LIRA 10.8 has been replenished with new physically nonlinear bending bar finite elements (FE 501, FE 504, FE 510), thin plate finite elements (FE 542-544) and thick plate finite elements (FE 546-550).

Thereby, a full nonlinear dynamic analysis can be carried out in DYNAMICS+ system in the time domain using instrumental or synthesized accelerograms in accordance to SP 14.13330.2014 “Construction in seismic regions”, p.5.2.2.

Nonlinear dynamic calculation

Displacements in linear and nonlinear problems

Static analysis also benefits from these changes as those finite elements are iterative, so a stage of nonlinear loading state can be solved in one step.

Consideration of creep has been implemented for new finite elements (FE 501, 504, 510, 542-544, 546-550).

Also, new physically nonlinear finite elements (FE 501, 504, 510, 542-544, 546-550) can be used in heat transfer and ASSEMBLAGE problems.

Pushover Analysis (nonlinear static analysis) is a tool for evaluation of structure’s bearing capacity.

Determination of structure’s bearing capacity is conducted by monotonous loading of vertically loaded design model with distribution of horizontal seismic loads. Loading is performed until user-defined displacement has been reached or until structural collapse. The goal is to evaluate final deformations and bearing capacity.

Nonlinear static analysis is carried out in two stages:

1. Distribution of inertial loads for calculation of natural oscillation forms is determined using response spectrum method for nonlinear multi-mass spatial design model of the structure.
2. Nonlinear static analysis is performed for multi-mass spatial design model:
   • for loading history of vertical loads;
   • for user-defined distribution of inertial loads or for distribution of inertial loads that correspond to natural oscillation form with highest modal mass.

SP LIRA 10.8 contains four variants of nonlinear static analysis. Those variants differ by method for obtaining a bearing capacity spectrum and subsequent processing of obtained results in accordance to following regulations:

• EN 1998-1:2004;
• DBN В.1.1-12:2014;
• STO NIU MGSU 2015.

Methods for obtaining a bearing capacity spectrum can differ by axes which are used for determination of initial bearing capacity spectrum of the structure:

• for EN 1998-1:2004 and СТО НИУ МГСУ 2015 bearing capacity spectrum of the structure is represented by relationship between shear force at the ground level and horizontal reaction (displacement) of selected node of the structure;
• for DBN В.1.1-12:2014 the initial bearing capacity spectrum of the structure is represented by «generalized spectral acceleration-generalized spectral displacement» relationship which is determined at loading steps.

Furthermore, DBN В.1.1-12:2014 recommends two calculation variants: nonlinear static analysis and nonlinear dynamic analysis of equivalent single-mass system for specified accelerogram of the earthquake.

Nonlinear static analysis for seismic action by EN EN 1998-1:2004 has been expanded for the following national annexes in SP LIRA 10.8:

• DBN В.1.1-12:2014;
• SNiP RK 2.03-30-2006;
• SP 14.13330.2014;
• STO NIU MGSU 2015;
• SP RK 2.03-30-2017;
• for mean spectral dynamics factor by the package of accelerograms.

The program automatically generates response spectrum for the specified regulations. Response spectrum has to be specified manually for arbitrary regulation.

Calculation results of seismic analysis in accordance to EN 1998-1:2004 are represented by:

• Bearing capacity spectrum of equivalent single-mass system;
• Bilinear curve which is built based on bearing capacity spectrum or based on iteration procedures if they were present;
• Graph of mass’ change for equivalent single-mass system;
• Graph of conversion factor’s change for equivalent single-mass system;
• Graph of period’s change for equivalent single-mass system;
• Graph of frequency’s change for equivalent single-mass system (allows to evaluate system’s degradation);
• Graph of secant stiffness’ change for equivalent single-mass system;
• Graph of target displacement’s determination.

Determination of seismogram via accelerogram and vice versa can be done during creation of nodal dynamic load «Seismogram/Accelerogram».

The following features are provided for analysis of earthquake’s accelerogram:

• determination of frequency composition using discrete Fourier transform;
• obtaining response spectrum of accelerations, velocities and displacements at specified relative damping.

Obtaining seismogram by accelerogram

Obtained results are presented in graphic and tabular forms (export to files of formats of accelerograms, seismograms, response spectrum of accelerations, velocities and displacements for SP LIRA 10.8 and Excel files).

There was implemented a possibility to use:

• obtained accelerograms and seismograms during calculation for seismic actions in time-dependent dynamics (DYNAMICS+) to describe effects caused by earthquake;
• response spectrum of accelerations, velocities and displacements during calculation by 41 dynamics module (seismic action according to response spectrum of single-mass oscillator);
• obtained accelerogram during calculation by 27 and 29 dynamics modules (seismic action according to single-component and ternary accelerograms).

In the SP LIRA 10.8 you can use both the classic interface (system menu and toolbars), and the ribbon interface or a combination of them.

Ribbon is a graphical control element in the form of a set of toolbars placed on several tabs. Each toolbar is filled with graphical buttons and other graphical control elements, grouped by functionality and designed to call specific commands.Due to the possibility to use the ribbon interface together with the classic interface, the program will be convenient for beginners and experienced users.

The possibility to configure properties of model representation in the application status bar has been implemented.

Simplified input of numerical information

In the previous versions of SP LIRA it was possible to use only the symbol "." to separate the integer part from the fractional part of a number. Engineers often had to switch the language of the keyboard layout, when working on the calculation scheme and entering numerical and text information. This could result in an erroneous entry of the "," character instead of the "." when specifying numerical information.In our new version SP LIRA 10.8 the ability to use both the symbol "." and the symbol "," to separate the integer part from the fractional part of a number has been implemented.

Extended features of the «Groups of Elements» mode

• The ability to automatically generate multiple groups of elements based on information about the orientation, location in space, the type of element, the assigned cross sections, materials, design parameters, has been implemented.
• The ability to work with architectural elements has been implemented.
• The concept of a floor has been added (this information is used in the calculation of floor centers of masses and stiffness).

Extended features of the «Load Analysis» mode

The ability to evaluate the moments of inertia of masses in the global and principal axes, based on information on the density of materials assigned to the elements, has been implemented.

For dynamic loadings in the «Load Analysis» mode the ability to evaluate the following parameters for each floor has been implemented:

• center of mass of the entire floor;
• center of mass, collected from horizontal elements of the floor;
• center of stiffness of vertical elements of the floor;
• distance (including its projection) between the center of mass and center of stiffness of the vertical elements of the floor.

Expanded library of loads

For all force loads, which can be applied to the plate and solid finite elements, the ability to choose not only a local or global coordinate system, but also a coordinate system for stress alignment has been added. A similar ability has been implemented for plate architectural elements.

Design combination of loads (DCL)

• The work with Tables of automatically generated DCL has been considerably accelerated.
• The ability to copy selected lines of automatic DCL to the user-defined DCL has been added.
• A summary table of user-defined DCL has been developed.

Determination of internal forces in steel-concrete composite span structures have to correspond to concreting process, in which part of the span structure is still steel and the other part is already steel-concrete composite.

Behavior of the structure is divided into two stages. Stress in steel beam, caused by own weight and reinforced concrete slab’s weight, is determined at the first stage. Stress in unified cross section, caused by other loads (bridge deck or pavement, sidewalk blocks, railing etc.) and by moving load, is determined at the second stage.

«Groups of internal forces and displacements summation» were implemented for determination of internal forces and displacements in steel-concrete composite beams. They allow to combine internal forces or displacements from different elements into other element of design model.

Groups of internal forces and displacements summation can be created manually or automatically.

The main criterion for the automatic creation of summation groups is the method of constructing a chain of design schemes. This means that identical elements in design schemes have to have the same coordinates in plan view.

Figure 1 illustrates the process of obtaining internal forces in steel and steel-concrete composite beams by example of slab’s concreting in 5 bays of three-span bridge according to scheme 42-63-42.

Figure 1. Bays of slab’s concreting B.1-B.5.

Two groups of internal forces are created during automatic creation of summation groups:

• the first one for summation of internal forces on elements of a steel part;
• the second one for summation of internal forces on elements of a steel-concrete composite part.

The automatic construction of force summation groups will work only if the element of the design scheme has a projection in plan view, otherwise the elements will be ignored.

To specify the groups of internal forces summation for bridge supports, you should define the summation groups manually.

There are no restrictions on elements positioning during manual creation of summation groups.

Figure 2 shows loading of design schemes during the process of steel-concrete composite bridge concreting and mode of summation.

Figure 2. Loading of design schemes and mode of internal forces and displacements summation.

The diagrams on the summation elements (both steel and steel-concrete composite parts) are constructed only from the values in the design sections and are connected by straight lines. This means that there are no adjustments for local loads.

Values of the bending moment after performing calculation for the concreting process in steel and steel-concrete composite beams are shown on Figure 3.

Figure 3. Bending moment in steel and steel-concrete composite beams.

Initially, this feature was created to obtain internal forces in steel and steel-concrete composite beams for the calculation of bridge structures, although it can be used for other purposes, for example, for accumulation of welding stress etc.

The requirements of SP 295.1325800.2017

Proportioning and checking of bar and plate elements in accordance to SP 295.1325800.2017 («Concrete structures reinforced with fiber-reinforced polymer rebars») has been implemented. Material database according to SP 295.1325800.2017 has been added.

Analysis of structures with fiber-reinforced polymer rebars is performed by ULS and SLS. Analysis by ultimate limit state consists of strength analysis. Analysis by serviceability limit state consists of calculation regarding formation and opening of cracks. Influence of load’s nature, environment, reinforcing method, joint behavior of rebars and concrete on fiber-reinforced polymer rebars is considered in calculation situations.

SP 295.1325800.2017 has been added to the database and following gauges have been added:

• TR 2296-014-13101102 Fiberglass;
• TR 5714-006-13101102 Basalt fiber;
• TR 5714-007-13101102-2009 Composite rebars.

Visualization of design parameters for longitudinal and transverse reinforcement in Structural design parameters editor has been changed for calculation by SP 295.1325800.2017. For basalt plastic rebars BPR (TR 5714-006-13101102) and basalt plastic composite rebars RCB (TR 5714-007-13101102-2009) the recalculation of design characteristics depending on the currently selected diameter is realized.

Factor of safety by reinforcement is implemented for fiber-reinforced rebars.

The possibility of combining various materials of reinforcement in the cross section according to the principle “material 1 for longitudinal rebars, material 2 for transverse rebars” is implemented. In this case, both steel and composite reinforcement can be used as a material.

Strength analysis is carried out using nonlinear stress-strain model.

Strength analysis of reinforced concrete cross sections for the action of transverse forces, torque, the joint action of twisting and bending moments, as well as torque and shear forces, is carried out according to SP 63.13330.2012 (Concrete and reinforced concrete structures).

The determination of the moment of cracks formation, that are inclined to the longitudinal axis of the element, is made on the basis of a nonlinear stress-strain model.

The results of reinforcement’s proportioning are visualized numerically in the form of tables, as well as graphically in the form of a mosaic. Results review is also available in Local results mode:

Steel-concrete composite structures

Proportioning of composite cross sections (round and rectangular tube) according SP 266.1325800.2016 («Steel-concrete composite structures») has been implemented.

Analysis of steel-concrete composite structures is performed by ultimate limit state. Analysis consists of strength analysis of composite cross sections with outer steel shell in the form of round or rectangular tube with reinforced concrete core. Design properties of cross section are calculated automatically:

Tube’s material and filler can be chosen for each type of cross section in accordance to selected regulations:

Regulations SP 266.1325800.2016 (GOST 27772-2015. Structural steel structure rolled products) has been added to the database:

Arrangement of the reinforcement in cross section is made according to the chosen arrangement method: Asymmetrical / Symmetrical / User-defined.

Design resistance of tube’s material under compression and tension, as well as design resistance of concrete under compression are being recalculated during reinforcement proportioning for each calculation situation in accordance to selected regulations.

The results of reinforcement’s proportioning are visualized numerically in the form of tables, as well as graphically in the form of a mosaic. Results review is also available in Local results mode:

RC local results

Visualization of Local results for reinforcement proportioning for single FE has been significantly improved.

Local results mode has been improved for better analysis of proportioned reinforcement.

The following menu items have been added:

• Display mode (View of results/Zero axis, diagrams);
• Additional information;
• Diagram settings.

The following is displayed in Display mode “Zero axis, diagrams” for selected cross section of the element:

• Stress diagrams in proportioned reinforcement;
• Stress diagrams in concrete;
• Deformation diagrams for reinforcement and concrete in selected points;
• Zero axis where stress and deformations are equal to zero.

The corresponding diagrams are given in a table form.

The settings of the diagrams are carried out in the corresponding menu, where the construction parameters are selected:

• Consideration of Rs, Rsc on diagram:
• Consideration of Rb, Rbt on diagram;
• One scale for stress diagrams.

Menu Additional information contains the following:

• Angle between zero axis and axis Y;
• Height of compressed area z.

Tool for view settings of Internal forces/DCF/DCL table has been added:

Option of creation of user-defined table has been added to Display mode “Zero axis, diagrams”:

A custom menu has been created for the user table, with which you can edit / delete / add rows.

For the selected tables, when changing to a new line, the diagrams are redrawn and additional information is recalculated.

Implemented requirements SP 16.13330.2017

The calculation of steel structures according to the requirements of SP 16.13330.2017 has been implemented. Basically, it concerns new requirements for grades and types of steel.In addition, changes concerning conditions of use factors of steel structures, coefficients of lateral deflection for I-beams during the general stability check have been made, as well as other changes.

Example of steel assignment according to the requirements of SP 16.13330.2017

New built-up two-branch sections

Ability of proportioning and control of built-up two-branch sections has been implemented.

In the SP LIRA 10.8 general two-branch section consisting of two branches and connecting elements between them has been developed.

Different types of general two-branch sections

As branches can be specified rolled I-beams, rolled or bent channel bars (with inside or out flanges), as well as square or rectangular roll-welded closed boxes. The connecting elements are realized in the form of a grid (angles, round beam, square) or lath (lane, channel bar). Herewith:

• Branches can have either the same or different kind of profile.
• Branches can have either the same or different size.
• For connecting elements in the form of grid, various arrangements of the braces and pillars can be made according to the Table 8 SP 294.1325800.2017 or Table 13 of the «Manual on design of steel structures» of 1989 year.
• For connecting elements in the form of grid one or two planes of connecting elements can be taken.

Example of setting two-branch sections

In the version SP LIRA 10.8 ability to estimate the work of the element of two-branch section (including the torsion) has been implemented. It is possible to do approximately, but with a sufficient degree of accuracy. It should be noted that in the instructions SNiP, SP, and DBN torsion of steel structures is not taken into account, with the exception for constrained torsion when checking the strength of normal stresses according to the requirements of SP. Torsion strain is not typical for two-branch sections, and it is usually avoided in the design. However, in real life such cases occur (for example, the supports of billboards). And the program should adequately respond to them, and not ignore, as it was in previous versions.It is with this the possibility of specifying a one- or two-plane grid of connecting elements. They work in a completely different way on torsion. Since torsion can cause bending of each of the branches from the plane of the connecting elements in two opposite directions (this is especially true for a single-plane grid), in the presence of torsion it is necessary to specify elements of a two-branch section by finite element of type FE7.

Example of torsion strain of a column with two-branch section with connecting elements from laths (Similar examples are obtained for other variants of connecting elements)

Added new types of sections and new gauges

• Implemented a section of welded T-beam.
• Added a gauges of rolled I-beams according to GOST R 57837-2017 (beam, broad-flanged, columned, piled, additional beam, additional columned).
• Added a gauges of rolled I-beams according to TU 24107-016-00186269-2017 (narrow-flanged, normal, middle-flanged, broad-flanged, columned).
• Added a gauges of rolled I-beams, special according to GOST 19425-74.
• Added a gauges of roll-welded closed boxes according to GOST R 54157-2010 (square and rectangular).
• Added a gauges of roll-welded closed boxes according to GOST 32931-2015 (square and rectangular).
• Added a gauges of hot-rolled and cold-formed boxes according to regulations of Israel SL 1458, part 2.2 (square and rectangular).
• Added special gauge of band-iron, that is recommended to use for setting the connecting lathes of two-branch sections.

Implemented ability to limit the dimensions of sections while proportioning

Ability to limit constructively overall dimensions and thicknesses for all rolling (hot-rolled and cold- formed) profiles, used in the mode of selection of sections, has been implemented:

Example of limiting of overall dimensions and thicknesses for rolling profiles

The calculation and visualization of pile's bearing capacity on compression and extraction according to the requirements of SP 24.13330.2011 has been implemented.

The calculation of stiffness characteristics, settlement and pile's bearing capacity on compression and extraction according to the requirements of DBN V.2.1-10-2009 (for single piles, pile clusters, and pile foundation as artificial) has been implemented.

Bearing capacity is determined as for driven friction piles, pressing piles of all types, and shell piles, driving without ground excavation (driven friction piles) with open and closed bottom end, club-shaped piles, solid and hollow piles with rectangular and circular cross section.

The Table of soil characteristics has been complemented by the values of necessary characteristics for calculating of the bearing capacity.

In the mode of visualization of calculation results the ability to analyze the utilization coefficients of bearing capacity of piles according to DCL, DCF and loading states has been implemented.

The calculation of stiffness characteristics and bearing capacity of piles of foundations for supporting structures of overhead electrical transmission lines has been implemented. Bearing capacity is determined for normal, intermediate, anchor and corner supports, supports of large crossings, and in other cases.

The features of calculation of pile's bearing capacity on compression and extraction in seismic regions were implemented. The automatic calculation of the design depth (hd), where soil side resistance of pile is not factored in during seismic impact, is performed.

The ability to analyze the horizontal soil shear has been implemented, which makes it possible to make a horizontal shear of the soil model at an arbitrary level.

Improved import from ifc format

• The number of ifc classes used during import has been increased.
• The algorithm of orientation of the cross sections of bar elements has been clarified.
• Automatic comparison of cross sections of bar elements of steel structures when importing from files created by AVEVA Bocad has been implemented.
• The ability of analysis and editing cross sections comparison log has been added.
• The materials comparison log with the possibility of its editing has been implemented.

Improved import and export of results in dxf format

1. The algorithm of import of cross sections and materials libraries has been optimized.
2. When exporting the results, the scale is placed in the plane of the view active at the time of export.
3. When exporting the results, list of layers has been extended:
   • General: body of the elements.
   • Attributes: Numeric values of the exported results.
   • Results: isofield or mosaic of the results.
   • Results (contour): contours of elements with a color corresponding to the result value.
   • Scale of results.

Results of reinforcement proportioning SP LIRA 10.8.

Results of reinforcement proportioning with values of SP LIRA 10.8

Layers in exported *.dxf.

Results in *.dxf

“Results (contour)” layer

Improved data import from Revit

• The ability to update the model already exported to the SP LIRA has been implemented. When updating the model, all parameters specified in the SP LIRA are saved as much as possible.
• The ability to set displacement vector of the whole model has been added.
• The ability to import only the elements visible in the current Revit view has been implemented.

• When importing of the load on design model, the ability to specify which objects (nodes, rods, plates) this load will be applied to when the task is started for calculation has been implemented. This information is specified once for each download using the comparison log.

• The features of comparison logs were improved. The ability to add, delete, edit comparisons without importing has been implemented.

Extended possibilities of the Tekla combination

• The features of comparison logs have been improved. The ability to add, delete, edit comparisons without importing has been implemented.
• The process of import has been significantly accelerated.
• The ability to export the calculation results of the steel construction system in Tekla has been implemented.