Moving loads in Advance Design


As the 2022 version of GRAITEC Advance Design introduced the Crane Moving Loads feature, in this short article we will take a look at the moving loads available in Advance Design – the Traffic load and the new Crane load. As the traffic load generator has been available for a long time, I will present only brief information about it and focus mainly on crane loads.

Moving load panel on the ribbon

Let us start with the traffic load. The traffic load generator enables us to create traffic loads on road bridges according to EN1991-2 (Section 4). In order to create the appropriate traffic loads on the road bridge (on planar elements), we define graphically the elements composing the carriageway: one or several traffic lanes, remaining areas and footways or cycle-tracks.

Carriageway definition

The next step is to add a Traffic loads family and select the appropriate load model, according to the provisions of the Eurocode. Five load groups are available, containing respectively:

  • gr1a – combination of the concentrated loads (Tandem Systems) and the Uniformly Distributed Load (UDL System) with the uniformly distributed load on footways.
  • gr1b – a couple of concentrated loads that represent a single axle of a truck, for creating concentrated forces along the lane.
  • gr2 – combination of the concentrated loads (Tandem Systems) and the Uniformly Distributed Load (UDL System) with  braking and acceleration forces and centrifugal forces.
  • gr3 – uniformly distributed load on footways.
  • gr4 –  uniformly distributed load on footways and traffic panels.
Traffic load model selection

After automatically assigning the load parameters to the roadway, we are ready for load generation in the model.

Carriageway load parameters

Depending on the load model selected, this results in load cases that include uniform loads as well as a series of consecutive steps in the position of the concentrated forces from the vehicle wheels.

Uniform loads and moving loads from vehicle (all steps are shown)
Loads in section for one of the selected steps

For loads from cranes, the process is somewhat similar. The first stage consists in defining graphically the route of the crane forces – it can be a single polyline to model the forces moving along a single rail (for monorail crane modelling) or two parallel lines to model the route for the forces from two trucks on both sides of the bridge crane.

Runway for the bridge crane placed on two beams

The next step is to add a Crane object. It is used to describe the geometry, such as the number and spacing of the wheels, and to describe the forces from the wheels.

Basic crane geometrical data

In the simplest case, the forces on each wheel can be defined manually, separately for each wheel. But it is also possible to use three different automatic methods, so that the wheel forces are automatically determined according to the rules of the standard.

Choice of force generation method

We have three methods available for the automatic determination of forces:

  • By crane loads (EN 1991-3) – for defining wheel loads automatically on the basis of entered crane loads, by using Eurocode EN 1991-3 rules. In this method several loads of different origin (e.g. loads from crane self-weight, from the weight of the load, from braking forces, etc.) are separately entered for each wheel. These load components are combined with the dynamic factors and the final wheel forces are determined. As the result this method gives several groups of load sets (ULS Group 1 to 6), according to the EN 1991-3.
  • By crane parameters (EN 1991-3) – for defining wheel load automatically on the basis of entered crane parameters, by using the Eurocode EN 1991-3 rules. The main difference compared to the previous method is that the values for each wheel are not entered, but the crane parameters (like self-weight of the bridge, self-weight of the trolley and the crane capacity) are given. The output is the same as for the previous method – six groups with sets of forces for each wheel.
  • By crane parameters (ASCE/NBCC) – similar to the previous one, so we do not enter the forces on individual wheels, but such loads are calculated automatically on the basis of entered crane parameters. But this time the method of automatic load generation is based on the general method, related to US/CAN standards (especially ASCE). But it is worth to mention, that the load generation rules are generic and are essentially independent of any standard.
Groups of loads per wheel calculated acc. By crane parameters (ASCE/NBCC) method

With the crane runway and the crane with the forces on the wheel, we can proceed to the next step, which is the definition of the load family. Here we determine the range of crane movement and the number/length of moving load steps.

Definition of move parameters for crane load family

The generation of crane moving cases is done automatically after using a ‘Generate’ command available when right click on the Crane Load case family. After it is run a set of moving load cases are generated, separately for each crane and each step position. They contain the forces from all wheels in a given position. Depending on the definition of the crane, these are both vertical forces and horizontal transverse or longitudinal (from braking) forces.

Load cases for each wheel position with forces

Together with the load case generation, sets of force envelopes from all force positions are also generated.

Automatically created envelopes

Importantly, we can define more than one crane and place them on the same or different runways. In this case, the program will generate for each crane a series of all force positions and then, when the envelope is generated, only the possible combinations of crane positions are considered.

One of the combinations of positions of 2 bridge cranes on the same runway

The final load combinations are defied by using typical load cases (dead, live, wind…) and Crane Envelopes. This is particularly important when there are a large number of crane steps and especially many cranes, as the final combinations consider only a dozen or so envelopes instead of thousands of crane position combinations.

The static calculation and the results for the combination cases do not differ from other load types and you can check the results for each crane position as well as for the envelope of the crane forces. Specific to crane is a new type of graphical output – the influence line diagram. It shows graphically the value of the result at a given point for all successive positions of the crane.  Although in this version of the program the influence line diagram can only be displayed for displacements in structure nodes, it is one of the additional tools useful when analyzing the results.

Influence line diagram

Graitec product release – Hidden Gems for 2022 release.


June 1st we released our products for their 2022 versions, this covers the entire Graitec portfolio, well within that there are few things that stand out to me coming from the Steel detailing and design background, that sound a clear intention of Graitec in this area.

Advance Design 2022

The first one is within our analysis engine ‘Advance Design’, the New feature of Cold Formed Design to EC3. This is a Game changer for those engineers using portal frame constructions and trying to design the most efficient systems for those structures. 

Powerpack for Advance Steel

The next one is more in the link between our Advance Design platform and Autodesk Advance Steel for the transfer of model data, for this version we have a Newly design GUI and Mechanism for the Synchronization of Data using the Graitec GTCX file format.    This new interface allows form many options to optimise what you wish to transfer and sync,

Figure 1-Example of new Dialog

Within the file and the options available we have the ability to have a dedicated object ID,  object type, Status display for New/Modified/Deleted,   Material,  Geometry, Element Type.

Figure 2-example of column types

Having all these options, we now have also filter options available, to help you dig down and only see the data you require.

Figure 3- filter example.

Also, the file has now the option to contain the level of the element within the model space.   It has two options to show the host location and the allocated level in the GTCX itself.

Also, all important one for model Tolerance, this allows for the user to control during the Sync process the variation between the model elements is acceptable, based upon those numeric values.

Figure 4- tolerance example

 Concrete elements are now also considered for the GTCX file and the transfer, presently standard column, and beam shapes for this version, but sure other more complex shape definitions will be added to this new feature.

There are a lot more elements and options to the GTCX and the New Sync process, these are explained in depth in the what’s new, that is available to customers via the Graitec Advantage site.

Powerpack Premium Steel – Stairs and Railings

Within the premium model, particularly for Stairs and Railings we have a great new feature for those working with panelised balustrades/railings, that is the inclusion of ‘Lugs’ to the panels.

We can now add vertical and horizonal/incline lugs.

This may only look like a small feature but for those of us that have to detail these, this will be a real time saver.

Figure 5-Lugs dialog – perpendicular/incline to rail
Figure 6- Lugs – vertical to post.

Anther part of the railings in the actual placement of panels within the rail, previously there where some limits on what we could achieve, but again the development team have worked on this to improve this function to accommodate more complex arrangements.

Figure 7- complex panel shaping

This also works with the frames type panels as well.

Figure 8- framed types

A new option is to allow for the user to turn off the top rail and still have the panels,  this can be useful in the situation of external fencing panels and picket type fencing arrangements.

Figure 9- fencing arrangement/ Stairs/ pickets etc.

For further information go to   https://www.graitec.com/

Look out for video and further blogs on the various Graitec sites in the coming weeks.

The new rebar drawings generator



With the new release of the Powerpack for Revit 2022 we are launching the new rebar drawings generator.

In this post I am intending to explain the concept behind the tool, assumptions that were made in order to obtain the best results and at the end I will add some tips&tricks.

As you know, we already had a view generator in the Powerpack. There were 2 issues that were making the mechanism basically unusable:

  1. ​​​​​​​​​​​​​​The mechanism used an external Revit file that contained the drawing configurations. Therefore, there was no initial link between the user’s Revit project and our drawing template. Of course, our template could have been customized but it would had presumed some time.
  2. In order to work properly, the rebar cage needed to be generated with the Powerpack so that rebars could have roles. After the generation, the mechanism knew the roles of the bars and knew what to do with them.

We decided to stray from this approach and we established the main pillars the mechanism will be based on:

  1. The mechanism will be totally based on the user’s Revit Template.
  2. It will use the active project’s view templates, detail view types and rebar schedules. It will read the Multi-Rebar Annotation, Tags and Title blocks families.
  3. The rebar cage inside the element can be manually modelled or generated by the Powerpack.
  4. The section of the elements will not be an issue. The mechanism will work the same for cast-in-place or pre-cast elements.
  5. We will implement the mechanism is such a way that it will take account of the user’s browser organization sorting rules by inserting Revit’s View parameters also.
  6. We will be able to generate wall drawings also.

In a few words, this is how the mechanism works:

  1. Using the drawing manager, the user will make his own drawing configurations for each category of elements (Beams, Columns, Walls, Foundations)
  2. The user will run the command and he will select the elements.
  3. After the selection is made, the grouping algorithms will decide if the elements can be treated as a group or not.
  4. The configuration dialog will appear, and the user is able to change the configurations.
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The drawing manager
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Selection of elements
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Create views dialog

Using the user’s Revit Template

This part of the implementation was easy-to-do. However, during the development we ran into the issue of multiple projects. We decided to not put the user to make the drawings configurations each time he starts a new project (Assuming that users have the same revit template).

We decided to create an .xml file that will contain all the configurations made by the user. This way, the settings will always be there when the user starts a new project. Of course, modifying the Revit template to a completely different one means that you should do the configuration again.

The .xml file is placed here: C:\Users\<User>\AppData\Local\Graitec\Advance Design modules\2022\Templates\Revit\DrawingConfigs

Furthermore, with this approach, the .xml file can be shared across the office. This way only one person needs to make the configurations.

Supported elements and Rebar cages​​​​​​​

​​​​​​​The mechanism will work the same for any Revit Family. We are not using any mapping mechanism. Any Loadable family will be supported. Model-In-Place elements are not supported.

We established that we needed to perform the drawings regardless of the method the rebar cage was obtained (by hand or generated by the Powerpack). In order to achieve this, we needed to use the Style of the rebar shape family.

Quick recap: The style of the shape can be Standard or Stirrup/Tie. There are no geometrical differences between these two, any rebar shape can be set as either of them. The difference comes from Revit’s rebar constraints mechanism. When placing a stirrup/tie bar, it will search for the nearest host rebar cover. Standard bars will additionally search for the stirrup bars handles. Basically, the Stirrup knows that it needs to tie Standard bars. This is especially helpful when modelling rebars by hand.

Thus, we are using the style of the rebar as an input parameter in order to know on which bars we are placing Multi-Rebar Annotation or for which bars we are generating bending details.

This is probably the most important point in order to achieve proper drawings.

Example:

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Rebar shape styles

​​​​​​​Drawing manager dialog

We needed to let the user configure his drawings according to his Revit template and requirements. The dialog will manage the Annotations, Bending details (General page) and drawing configurations (Element category pages).

In the following I will explain all the options inside the dialog.

General page

  • Generate views only by default configuration – Checking this option will bypass the Create views dialog. The drawings will be generated according to the check at the left of the configuration in the left panel. It was intended to speed up the process.
  • Name – The name of the annotation configuration. It will be further used in the drawing configuration
  • Rebars – The rebars that the user wants to place Multi-Rebar Annotations on.
  • Rebar Presentation – How the users wants to show the rebars in the generated view. Examples: Central bar, three in the middle…
  • Multi-Rebar Annotation – The family that the user wants to use for this drawing. The list will contain all the MRA inside the project
  • Group MRA – If the elements has multiple distribution of the same rebar number you can group the MRA in order to obtain a single distribution symbol. Example: For a beam with stirrups distributed on 3 zones you can obtain 3 MRA or only 1 MRA.
  • Multiple Tag Family – On rebars that are not distributed, we are placing rebar tags using our own tag multiple bar command. The user needs to set what tag family he wants to use.
  • Bending detail family – What family the user wants for the generated bending details

Drawing configurations:

  • View type – what kind of drawing the users wants his configuration to contain. He can choose from a list that is different for each element category.
  • Revit view type – We used detail views for the drawings. The user can choose what detail type he wants for his drawings. We considered that this option might be used also for the browser organization. The list will contain all the detail view types in the model.
  • View Template – What view template the user wants to apply to the view. The list will contain all the view templates in the model.
  • View scale – At which scale the user wants to generate the drawing. If the view template has the scale included, the value in the dialog will be ignored.
  • Length ratio: Percentage of the length/height of the element at which the section/plan view/node detail will be generated.
  • Annotation – the annotation configuration that the user wants to use in the drawing. The list will contain the configurations from the General page
  • Bending detail – the bending detail configuration the user wants to apply to the view. The list will contain the configurations from the General page.
  • Rebar schedule category – what type of rebar schedule do you want to generate for the select element (Structural Rebar, Fabrics etc.)
  • Rebar schedule type – a template that will be used for the newly generated rebar schedules. The list will contain all the schedules inside the model according to the selected category.
  • Titleblock ​​​​​​​- A list of all the titleblocks in the model

Revit View parameters and Browser organization

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Browser Organization

Advanced Revit projects are using a different browser organization rule. They are doing this with a combination of Revit View Parameters. We decided that the drawings should not be randomly generated and should take advantage of the user’s browser organization.

In order to do this, we needed to read the project’s view parameters and include them in our drawing configurations.

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Add Revit View Parameters

First you need to add them into the drawing manager by clicking on the “Manage” button. Some parameters might be included in the view templates definition, so you do not need to include all of them. After adding them in the drawing manager, for each configuration, at the end of the table, new columns will be added.

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Revit View parameters added to the configuration table

If you want all your drawings to have the same value for a parameter, you should insert the value into the drawing manager. However, if your values differ for each element, you should insert them into the Create Views dialog.

Grouping algorithms

Users have different ways of modelling in Revit so we needed to develop some connection algorithms that will allow us to group elements. Each element category needed to have its own grouping algorithms. Also, the grouping was made accordingly to the desired drawings.

We also took account of the design groups made in the Powerpack. Thus, if there are Multi-Span Beams or groups of Walls the user will need to select only one element inside the group.

Beams

For individual beams to be treated as a group they need to fulfill these two conditions:

  1. They need to share a node.​​​​​​​
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Connected node in order to treat beams as a group
  1. Their axis need to be coplanar.
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Different examples for beam groups.

​​​​​​​Grouping will allow the user to generate a full-beam elevation of elevation per each span. Sections will be placed for each span.

Columns

There are users that model columns individually for each level or who model them throughout the full height of the building. We needed to be able to obtain full column elevation. We also support slanted columns.

To be treated as a group, columns need to fulfill these conditions:

  1. They need to be concurrent.
  2. They need to share the same X and Y global coordinates
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Column Groups

Walls

            Structural walls are usually complicated drawings. They contain a lot rebars and usually they need multiple types of drawings (plan views, node details, sections, elevations and so on)

            Wall groups are also different from the other element categories because they need to be grouped on 2 different planes. First they need to be grouped on the horizontal plane in order to obtain the plan view and then they need to be grouped on the Z direction in order to obtain the full elevation.

            The discussion regarding the manner of modeling walls is the same from the column. They can be modelled individually or through the full height of the building, so we needed to address this issue.

In order to treat them as a group they need to fulfill these conditions:

  • For proper plan views:
    1. They need to share the same Base Constraint, Base Offset, Top Constraint and Top Offset
    2. They need to share an edge
  • For proper elevation:
    1. They need to be concurrent
    2. They need to share an edge​​​​​​​
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Wall groups

Final results:

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Full beam elevation with sections
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Wall drawings

Final Tips&Tricks

  1. Pay attention to rebar styles (Standard and Stirrup/Tie)
  2. I recommend making dedicated View Templates to each element category. This way you can automatically hide unwanted rebars or sections
  3. You can use multiple bending details tags
  4. You can use this tool also for the initial views the user needs to have in order to place the rebars. Generating drawings without multi-rebar annotations and bending details will be instantly done. You can use this in your advantage.

How to design a Steel deck in Advance Design?


Advance Design allows creating a new type of steel slab/deck: non-composite steel slab. The non-composite slabs may be used as floors in lightweight structures or as a form for reinforced concrete slabs.

Steel decks are created directly in the graphic area. The procedure for creating a non-composite steel slab is similar to the ones for other slab type elements. The position of the slab is specified by entering the coordinates on the command line or by snapping to other objects. The plate type can be selected from the General > Type drop-down list in the Properties window.

Steel deck in Advance Design

The element’s attributes can be configured in the Properties window.

Properties window

In the Properties window you can define the material type (according to the producer’s description), the type of profiled steel sheet, the steel deck connections, etc.

Working example

Let us assume we need to use a steel deck floor on the structure below (1-a). First, the position of the secondary beams (joists) is established as a function of the steel deck profile allowable span. For deck profile P3615-76, a span of 1950mm (1-b) is chosen.

1-a. Steel Structure and 1-b. Position of the secondary beams

The width of the profiled steel sheet is 914 mm and will be placed along the Y global direction. In order to properly consider the interaction with the joists, the 914 mm-wide deck sheets will be drawn one by one between them (2-a, 2-b). It is recommended to draw the deck parts in numerical order for a straightforward use of results. The steel deck definition is the same for all elements (3-a).

2-a. and 2-b. How to draw deck sheets

The lateral walls act like a diaphragm between the foundations and roof/floor. They take over wind pressures and distribute them at the horizontal level. The roof/floor diaphragm receives a linear load from the side wall.

We therefore run the analysis considering a linear load of 25kN/m (4-a). Advance Design automatically generates a set of four section cuts on each steel deck fragment.

3-a. Steel deck definition
4-a. Linear load and 4-b. Section cuts on each steel deck fragment

The Steel deck diaphragm verification report provides the maximum shear diaphragm for each element. The value results by dividing the Txy section cut tensor to the side length. The shear diaphragm is then compared to the steel deck Shear Strength (5-a, custom table 5-b).

An efficient use of materials is met by using different steel decks and connections. Therefore, one adjusts the deck settings for all the elements on a row according to the Shear Design Load Rate deficit (6-a, -b, -c). If the capacity exceeds the shear diaphragm, the number of fasteners or the steel sheet thickness may be reduced (6-d).

5-a. Comparison to the steel deck Shear Strength
5-b. Comparison to the steel deck Shear Strength (custom)
6-a. Adjusting deck settings
6-b. Adjusting deck settings
6-c. Adjusting deck settings
6-d. Reducing thickness or the number of fasteners

In the second step, you can notice the material optimization achieved by the properties changes (custom table 7-a).

7-a. Material optimization

Solar and light radiation study tools in ArchiWIZARD


  1. Real-time energy simulation
    ArchiWIZARD and his raytracing technology enables accurate and efficient simulation of solar and light radiation.
    Simulate and evaluate the impact of architectural and technical choices interactively and quickly to optimize the bioclimatic performance, including solar and light studies, of a project from the first sketches.

Results of light analysis in the bottom crossbar change in real time according to the modification of 3D model parameters by the user (for example building orientation, solar shading etc.).

  1. Solar and light tools
    ArchiWIZARD has ergonomic and efficient tools to analyze in detail the sunshine, irradiation and natural light of projects and optimize the exploitation of solar and light resources. These features make it an essential solution for the visual and educational evaluation and demonstration of the choices made, whether for the installation of the building or the sizing of the bays, sun protection, photovoltaic installations, etc.

• Solar Imagery
• Projected shadows
• Solar receiver
• Lighting map

These tools can be easily used through ArchiWIZARD intuitive interface:

2.1. SOLAR IMAGERY
This feature allows to visualize solar radiation cumulation received on project surfaces. There 3 types of calculation:

Irradiation
This represents the energy received by a point on a surface (walls, floors, roofs …) throughout the simulation period.
The flux received depends on the climate, the position of the wall (orientation, tilt) and masks present.

Sun exposure
This mode enables viewing of the time when a surface is exposed to direct sunlight compared to the time when the sun is up.
Sun exposure [%] = time when the wall receives direct sunlight [h]/ sunshine time [h]
The flux received depends on the climate, the position of the wall (orientation, tilt) and masks present.

Exposure to the ceiling grid
This representation shows the percentage of ceiling grid “seen” per wall. The reference is a horizontal wall without a mask: its exposure to the ceiling grid is 100%. Accordingly, this parameter depends on the tilt of the walls and the mask presence. This map display reveals the impact of near and far masks on the project.

2.2. PROJECTED SHADOWS
This feature allows to visualize the drop shadows of the stage (building and its environment). There is two mode:

Unique shadow
Allows to visualize the shadow of the project and his environment on a specific time (month/day/hour/minute).

Multiple shadow
Multiple shadows mode works as unique shadows mode. The difference is that the user can chose a step of time and visualize the evolution of the shadow for each step at the same times on the 3D model

2.3. SOLAR RECEIVER
Solar receiver is used to quantify solar and natural light received by a defined area. This area can be placed manually by the user.
The solar reception makes the difference between direct, indirect, and diffuse solar beam.

2.4. LIGHT MAP
The lighting map enables display of the daylight factor or lux illumination received on a horizontal plane in the scene.
It considers the geographical location, masks, the position of openings and their characteristics. Illumination with direct sunlight is also represented.
Artificial lighting is not considered.
This plan, represented by the map, can be positioned around the scene, interior as well as exterior of a project.

ArchiWIZARD has multiple tools to conduct studies on solar or light radiation from a project. These tools benefit from raytracing and allows accurate and adapted results.

Graitec PowerPack – Split Rebar In Revit


Revit allows you to place bars in a structural element in a very flexible way. This gives a great flexibility for placing rebar in a host, or to model bars of any shaping. On the other hand, it also possible to model an unfeasible shape because basically, Revit do not contain many for constructive dispositions. However, some concepts exist such as concrete cover, which can be respected (with some additional tools when placing the bars).

Figure 1 – Concrete Cover boundaries

When it comes to the shape of the bar itself, Revit allows you to create bars with no length limit. Thus, it is possible to create very long bars, without taking in account a maximum bar length for example.

Figure 2 – Example of straight bar with a high value of length in Revit.

The PowerPack Detailing allows you to address this topic with the Split Rebar command.

From a bar set distribution, this command will allow the distribution to be split according to different method.

Figure 3 – Split bar command interface

Several options to configure the splitting of the bars are possible with this dialog box but two are mainly impacting on the result:

  1. The method of splitting bars with three options proposed.
Figure 4 – Split bar method

2. The method of connection for splitting bars with four options proposed

Figure 5 – Connection bar method available

In addition, an option will allow the user to create an alternate distribution after splitting the rebar set.

Figure 6 – Staggered option and preview

Whichever splitting method is chosen, it will be possible to choose the direction of the cut and manage the distribution of each segment.

Figure 7 – Example of setting with splitting direction

The possible configurations by this tool are therefore very important. It is just needed to select the rebar set to get the result.

Figure 8- Example of staggered repartition with lapped bars

How to create a railing on any type of support?


The Railings, exactly like the stairs, are an important part of a building and used in many areas of it: balconies, decks, windows, roofs, stairs, and more.

In all these cases the support of the railing is different. It can be a concrete slab, concrete, steel or wood beam, a wall, basically any type of support.

Therefore, it can be very difficult to find the right way to build the railing without having the right support element.

Having this in mind, Graitec has developed the Railings macros available in the PowerPack for Advance Steel to be created independently of a support element.

SR Vault

Why is that possible and how? Because the Railing macros are designed to have 3 types of input! Each time a type of railing is created, the first thing that the user must define is the input type.

Types of input

The input of the Graitec Railings can be: Points, Beams, Lines.

The “Beams” input is the most limited one, because to create the railing, beams must be selected. Therefore, if no beams are available for selection, no railing is created.  Also, the shape described by the beams will be the railing shape. For example, curved railings cannot be created using beams as input.

This type of input is used especially for stairs with stringers made from straight beams, or on areas, like the platforms which the contour is made with beams.

Beams input

The second input type, much more flexible than beams, is “Lines”. The selected lines can be straight, arc or polyline. The lines are offering a lot of flexibility, allowing to create different shapes of railings with multiple configurations.

The railing shape will be the one defined by the line/polyline shape. Creating curved railings will be as easy as the straight ones.

Polyline input
Lines input

The third type of input “Points”, as the Lines, is offering a lot of flexibility and gives the user the possibility to build the railing directly where he needs it. No other preliminary preparation is needed, like creating beams or lines. Just to pay attention at the selected points.

The railing shape will be the one defined by the selected points. 

Points input
Points input

The most important benefits of the Lines and Points input types are:

  • The railing can be created wherever we need in the building, and can be manage outside of the big model, where the full structure is created.
  • Multiple railing shape, straight, curved, mix of both.
  • No specific type of input is needed.

In the end, having multiple types of input to create the railings is offering infinite possibilities.

How to quickly determine climatic loads according to Eurocode?


Climatic actions according to Eurocode

Climatic loads are a specific type of imposed loads to which almost every building object is exposed. Their nature and value is closely related to the type, geometry and location of the object. When preparing the design, the designer is obliged to include these loads in his calculations.

It has already happened in the past that incorrect consideration of this influence has led to disasters or failures. This aspect is often simplified or omitted due to a certain laboriousness of the determination of loads (especially wind loads) and their transfer to the calculation model, which will be the main subject of this article.

The current basis for the determination of climatic loads are Eurocode standards EN 1991-1-3 for snow loads and EN 1991-1-4 for wind loads.

In a similar way, these standards first determine the effect of the building location on the size of the characteristic load and divide the country into snow and wind load zones, respectively. The next step is to determine the nature of the load resulting from the geometry of the building itself – for wind it will be the external pressure zones and their distribution, while for snow it will be the roof shape factor. The whole is thus a basis and a relatively clear instruction for the determination of the ultimate snow and wind loads.

Automatic generation of loads in an FEA model

If the designer would like to determine these loads manually and apply them to the object in the calculation program, he has to reckon with a very labour-consuming task, mainly due to a multitude of coefficients leading to the final value and it is, so to say, complicated for even the simplest object. For example – we have to consider several wind directions, determine the range of external pressure zones, take into account the internal pressure, the value of pressure in individual zones, and to top it all off we have to take into account a number of dozens of variables and values (from dimensions, to location, to factors related to exposure, direction, terrain, etc.). The worst thing is that the whole thing is then drastically sensitive to change – a small change in the geometry of the building leads to a change in the external pressure zones.

Unfortunately, in most calculation programs we are forced to determine these actions manually and apply them in the form of loads to the FEM model of the structure, which often also requires us to prepare the model itself. Advance Design software has an automatic climatic load generator based on Eurocode, working on the principle of geometry discretisation to the appropriate standard schemes. The user does not have to impose any parameters connected with building geometry.

Above is a general diagram of how a climate load generator works (using wind as an example). Step 1 is practically just the preparation of the FE model for any subsequent analysis. However, it is important that the whole object is clad with cladding, i.e. panels, which do not have any mechanical properties but are only supposed to distribute the surface load on the structural elements. Their geometry is presented in step 2 – on this basis the program recognises the shape of the object and applies appropriate load schemes. Step 3 is the determination of the external pressure zones and the load values which are distributed from the cladding to the members and shells in step 4. In step 5 the final result, the wind load on the structure, is presented.

All these operations take place automatically and one could say that they are by default invisible for the user – the designer only prepares the geometry and as a result he gets the structure loaded by climatic actions. Importantly, any change to the design (geometry, assumptions etc.) allows the loads to be automatically updated to the current state of the model.

Guide to Advance Design generator

The 2020 version of the programme introduced a number of tools allowing to easily generate all cladding in an extremely short time e.g. by selecting linear/surface elements, by drawing or copying.

The cladding determines in which direction (x/y/xy/other defined by angle) it will distribute the load applied to its surface. It also determines certain parameters related to climatic loads.

The loads are determined from the parameters specified in the load cases.

The operation itself is trivial – the parameters we need to establish are those that are not possible to establish from the model but result from the project assumptions (altitude, thermal coefficient, terrain category, etc.).

After these two operations (cladding and load cases), the program is ready to generate loads. It will create exactly as many load cases as necessary from the point of view of uniform/nonuniform snow or different pressure values in the individual zones.

CNC2M – additional provisions for wind loads

Very importantly, the program implements the provisions of the CNC2M document. This document is a kind of annex to the French standars but it is universal in its nature regardless of the country. It defines rules for determining zones and pressure values for buildings much more complicated than those included in the general provisions of Eurocode, e.g. L-shaped or C-shaped buildings, awning canopies, additional provisions for wind shelters. In Poland we are not obliged to use such provisions, but it is a much more reliable approach than using a simple cuboid “cube” model for the whole building.

3 features every engineer should know in Advance Design


If you are new to Graitec Advance Design community then in this article we will draw your attention to useful tools that you may not have noticed in your first few weeks of work, but which can help you to complete your projects faster and more conveniently.

  1. Generate, not draw …

One of Advance Design’s favorite features for advanced users is the ” … on selected” from the context menu under the right mouse button (PPM). These capabilities are available by selecting one or more elements. In this way you can quickly apply loads, insert supports, generate points, connections …. It couldn’t be easier.

2. Stay up to date with the parameters of the FEA model…

Another solution that is ideal to use when working with a model is the “Hint Label”. Its advantage is that it can be turned on and off via the “status bar” (see screenshot below) but it is also configurable. This way you can e.g. check the length of an element, coordinates of end points or corners of an object. Why is this so important? With “tooltips” there is less clicking (e.g. the “measure length” function) or “reading” into the parameters in the properties window…

3 Hide/Display FEA model objects with one click…

Finally, I chose a function that I as a user myself discovered very late…. i.e. access to the shortcut in the context menu (PPM) “Display…”. This is essentially a shortcut to the object display settings. What I liked about it is that I can “peel” the model of loads, cladding etc without having to click on the “Project Browser” which takes my attention away from the model content. In conjunction with the “isolate” function I can get at objects that are not system related.

Easy selection and filtering in Advance Design


Among the many functions constantly used when working with FEM models are such basic ones as object selection and filtering, i.e. controlling whether objects are visible or hidden. And while every FEM analysis program has these functions, what makes Advance Design stand out is its ease of use. So, let’s take a look at a few possibilities and see how easy we can use them.

Leaving aside the graphical selection, let us first look at the simplest selection, that is, by basic criteria.

Criteria selection is the most basic type of selection – for example, when you want to select all elements of a particular cross-section or material or thickness in a modeled structure. In this case, simply select the relevant criterion, for example material, from the list. A window opens automatically in which you can enter a criterion – for example, select one or more materials from a list.

Among the many such critters available it is worth noting two: by System and by Name, as are extremely useful for a quick selection, especially if we have defined systems and subsystems and modified the default element names.

Other interesting quick selection criteria are Previous selection, which is the restoration of a previously existing selection, and Vicinity, which selects objects that are in contact with the currently selected items.

But what if we want to combine multiple criteria? Then we simply open the Select by Criteria window (for example by using ALT+S shortcut) and on each tab choose the criteria we want to use. For example, when you want to select IPE 300 and IPE360 profiles that simultaneously belong to a system called Front Structure. Just select these options from the list and press OK.

Interestingly, with a single click, you can change the default setting that selects items that meet all criteria (Intersection mode) to a setting that selects items that meet at least one of the selected criteria (Union mode). In addition, the operation can be performed on an existing selection. As you can see complex criteria are very easy to operate.
As mentioned earlier, splitting the model into systems makes the work much easier. For example, when we want to select elements from a given system, we just need to do it from the Project browser level.

Using the same method, you can instantly hide or isolate a section of the model. Furthermore, you can hide/show objects (including those contained in systems) even faster simply by double-clicking on the Project browser in the list.
On this picture just by few quick double clicks on the Project browser only columns and rafters are displayed.

All of these are simple operations, but they make working in Advance Design seamless because of their easy access and simple use.

FEA model for the whole object


Often the objects which we design require a more detailed analysis at the level of a specified fragment of the structure or element. For this purpose, often the whole object is modelled for the purpose of vertical element dimensioning, and horizontal elements such as floors are designed in a separate model, assuming their certain static scheme as faithfully as possible reflecting the global behaviour of these separated elements.

The problem begins to appear when the separated element must be loaded also with the remaining fragment of the structure, which we wanted to get rid of in order to reduce the large model. For the simplest example – I would like to analyse a complicated foundation slab – its separation from the model will not help me much, because loads which dimension it are transferred from the whole structure by means of columns or walls. The simple conclusion from this…I can isolate the slab as long as I load it according to the building scheme.

Advance Design allows you to exchange the support reactions of one model for loads generated in another model.

Fig. 1. Model of a simple residential and commercial building in Advance Design

At the moment I have a model of the entire building, which I can easily solve. However, I would like to divide the model e.g. into an underground and an aboveground part or into a foundation slab and the remaining part of the building. Maybe I need to analyse the foundation slab in detail and I need to reduce the size of the model to gain calculation time. Maybe I would like to divide the work into 2 workstations and leave the development of the ground slab to one of the co-workers and deal with the vertical elements of floor -1 or higher I am able to do this by creating, in a way, 2 independent models (e.g. of the said underground and aboveground part). The problem arises in the fact that the aboveground part will load the underground part, and I have just removed it from the model.

Fig. 2. Two independent FEA models

2 Foundation slab modelled on an elastic foundation, the part above the foundation slab supported by nominal rigid supports. At this point I can solve model one – i.e. the part above the foundation slab – without a problem.

Fig. 3. Reactions (vertical) from permanent loads

Saving reactions to a file and importing them in another task

Above are examples of support reactions from permanent loads. Of course, we can transfer all reactions (displacement/rotation) from all cases.

Please note that reactions are usually presented as an inverse vector, i.e. as a response of a support – here, however, our vertical reaction is directed downwards, as it is later to be a load on a foundation slab. The reverse of reactions can be reversed by changing the program settings in the results tab by switching off the option “Include reactions on supports”. On the BIM tab, the user can export the reactions to a text file and import them into the foundation slab model in the same way. The load cases and the position of forces in space are preserved.

Fig. 4. Reactions imported into the foundation slab model

Importantly, I can import reactions at any time, meaning potential changes to the output model are not threatening. I can also modify the geometry of the foundation slab freely – the loads are not associated with it, they are in a specific space in the model and load the element underneath them. The forces are in the same load cases as in the original model so the combinations do not change. I could, however, combine the loads differently because in a smaller, detailed foundation slab design I will be able to successfully prepare more combinations.

The only thing I would like to point out is that it is necessary to separate structural elements sensibly. Their work under loads may be influenced by the elements that we have removed. That is, in addition to transferring loads, they also stiffen the component under consideration and change its working character somewhat. It is relatively correct to separate the whole storey.

This method can also lead to a kind of phasing of the structure.

How to perform a pushover analysis on Advance Design?


Pushover analysis consists of 3 major phases, first the preprocessing phase in which the model is prepared for the analysis. Then, the processing phase during which the model is analyzed and finally the post processing phase where the results are interpreted.

1. Preprocessing phase:

the user first needs to define the plastic hinges at locations where they are expected to occur (ends of beams), or at locations where their arise needs to be monitored (ends of columns). The plastic hinges can be defined on individual linear elements from the properties panel.

Separately for each extremity, the user is able to select the degrees of freedom for which the hinge is applicable. The ID name of a plastic hinge is generated automatically, and it consists of prefix PLH-L (plastic hinge on linear element), ID of the element, the extremity (1 or 2) and the type of the element (B – for beams, C for columns). The definition of parameters of the plastic hinge can be done by using a dialog opened by a button on the Definition property. 

In a case the user decides that hinge parameters are calculated automatically, he can select the code (EC 8-3 or FEMA 356) and element type. The list of types (steel or concrete beams and columns) depending on the selected code. The content of the part with properties also depends on the selected code. Note, that some of parameters are computed during the next stage, during the pushover analysis. In case the user decides to manually define hinge parameters, then after selecting the code can unlock and edit available parameters.

The next step is the creation of pushover load cases and generation of pushover loads. For this, a Pushover load case family type can be defined from the Create load case family. On its property list we can set the basic data for load generation such as: the distribution type, the point of application and the directions of the loads.

There are several load patterns available to distribute the pushover forces on the height of the structure:

Where Vb is the maximum total lateral load and Fn is the maximum lateral load applied on level n.

Using the right click menu on the PushOver load case family we can then automatically generate the pushover load cases and loads. On the property list of each generated pushover load case we can set details related to the maximum total lateral load and conditions for stopping the analysis.

The maximum total lateral load is the cumulated sum of the lateral loads applied on last step of the pushover analysis. This load can be defined either as the imposed value or as a percentage of the load applied on the structure prior to the pushover. For the second case we can use either the total gravity loads or the seismic base shear force on X or Y direction.

2. Processing phase:

The pushover analysis is a list of sequential actions, activated by a dedicated Pushover checkbox control in Calculation Sequence dialog

The pushover analysis is a static nonlinear analysis during which the structure will be pushed laterally until reaching the maximum specified lateral force or developing a failure mechanism.

3. Postprocessing phase:

As with normal static calculations, FEM results such as displacements and internal forces are available. The results can be checked as for the non-linear calculations for each of the subsequent calculation steps.

A Pushover Results entry is available on the FEM results selection that allows for selecting the Hinge status result for linear elements. When activated, it shows status of defined plastic hinges for selected step of the selected pushover case. The status is displayed by using colors.

Using the Pushover results curves command, available on the Results ribbon, a pushover capacity curve can be generated.  It displays a relationship diagram of the displacement of control node with respect to the total applied lateral load.

The pushover capacity curve represents the structural capacity to resist lateral loading and is a reflection on how the structure will behave when loaded laterally (seismic loads). During earthquake, the structure will be pushed laterally until a certain maximum displacement of its control node (master node). The point on the pushover capacity curve having this maximum seismic displacement is called the performance point. Physically speaking, this performance point is the balance point between the structural capacity (pushover capacity curve) and the seismic demand (seismic response spectrum). Advance Design can calculate the performance point according to the Eurocode 8 N2 method and ATC 40 Capacity Spectrum Method.

Knowing the maximum lateral displacement provided by the performance point, the user can refer to the pushover step corresponding to this maximum displacement and check the locations and limit states of plastic hinges, inter story drifts …

Join Advance Design Award


Graitec, as a global software editor in the Design, Structural, Fabrication, and Data Management arena organizes an international contest dedicated to structural engineers and design offices.

The award is for the best practical use of Advance Design in Steel / Timber / Concrete design projects. This contest is open to customers and students who want to showcase their experience and technical knowledge through a project executed in Advance Design software. The projects will be judged by a professional jury. The final nominees and the winning projects will be made public to a wide audience through extensive marketing including social media.

Award Calendar:

•             10.3.2021 Contest launch – Project submission opens

•             30.7.2021 Entries close – Deadline for project submission

•             10.9.2021 Project Confirmation – Confirmation and announcement of projects accepted

•             11.10.2021 Jury Deliberation – Selection of winners

•             19.10.2021 Announcement of Results – Announcement of winners at the Advance Design User Summit 2021

Contest criteria:

The independent contest jury will gather in October 2021 to evaluate the projects. The judging will be done under the guidance of a dedicated Graitec Group representative. The representative is in charge of the contest. The jury will evaluate the projects taking the following criteria into consideration:

  • Technical level of the design, detailing and/or calculations.
  • Originality and prestige of the project.
  • Attractiveness, detail and presentation of the project.
  • Optimal use of software’s functionality.
  • The “story” behind the project – difficulties overcome, innovative approaches, benefits gained, etc.

Jury:

An independent and international jury composed of academics and professionals in the field will judge the submitted entries. Meet the members of our jury:

  • Francis Guillemard – Jury Chairman /  GRAITEC President of the Group and Chairman of the board / France
  • Rawad Assaf / ISSAE – CNAM Liban/ Lebanon
  • Olivier Chappat / Bouygues Bâtiment Ile-de-France / France
  • Piotr Nazarko / Rzeszow University of Technology / Poland
  • Rodrigue Coyere / EIFFAGE CONSTRUCTION Structural design office / France
  • Daniel Bitca / Technical University of Civil Engineering Bucharest / Romania
  • Mike Vance / Steelway Building Systems / Canada
  • Joseph Pais / GRAITEC INNOVATION / France

For more information, please visit Advance Design Award website – https://www.advancedesignaward.com/

Jiri Bendl, GRAITEC, Vice President SIMULATE comments: “Through the Advance Design Award organizations we want to reward our customers for being members of the ever-growing SIMULATE community and we want to encourage students to use the best possible tools for structural analysis. It is a great pleasure for me to be part of this project!”

About GRAITEC

Founded in 1986, GRAITEC is an international group (13 countries worldwide – 48 offices) helping construction and manufacturing professionals to successfully achieve their digital transformation by providing BIM and Industry 4.0 software and consultancy. GRAITEC is a developer of high-performance BIM applications as well as an Autodesk Platinum Partner in Europe and Gold Autodesk Partner in North America and Russia. With more than 550 employees including 200 BIM consultants, GRAITEC is an innovation-focused company whose products are used by more than 100,000 construction professionals worldwide.

For more information, please visit GRAITEC website – https://www.graitec.com/

For further information about Advance Design Award, please contact:

Lukasz Jedrzejewski, GRAITEC

Phone: +48 792 23 86 93

Email: lukasz.jedrzejewski@graitec.com

How to determine the shear stiffness of trapezoidal sheeting according to EN1993-1-3 ?


According to EN1993-1-3, formula (10.1b), the shear stiffness of trapezoidal sheeting connected to a purlin may be calculated as :

With:

  • t : thickness of sheeting (in mm)
  • broof: width of the roof (in mm) (roof dimension parallel to the direction of the panel ribs)
  • s: spacing between purlins
  • hw: profile depth of sheeting

Assume a purlin connected to the following trapezoidal sheeting, at each rib:

Roof width : 6,00m

Distance between purlins : 2,50m

This result sin a shear stiffness of 8361 kN.

Formula (10.1b) assumes the purlin is connected at each rib to the trapezoidal sheeting :

Purlin connected at each rib

In case the purlin is not connected at each rib but at every other rib, only a small portion (20%) of this S stiffness can be considered :

Purlin connected every other rib

If this value exceeds a certain value (Smin), the purlin may be regarded as laterrally restrained in the plane of the sheeting.

Assume an IPE140 purlin:

Iw = 1980 cm6 (warping constant of the purlin)

It = 2,45 cm4 (torsion constant of the purlin)

Iz = 44,92 cm4 (minor axis inertia of the purlin)

h = 140 mm (height of the purlin)

L = 6,00m (span of the purlin)

In our case, S > Smin.
The condition is met and the purlin may be regarded as laterally restrained.

In Advanced Design, such a purlin may have its ‘Continuous restraint along flange’ property enabled on the upper flange :

For more complex cases, when the member is prone to torsional effects (Channel or Z section for example), a more sophisticated calculation may be required (2nd order calculation with warping).

In this case, the shear stiffness (S) may be taken into account as the ‘Shear field’ parameter from the ‘Advanced stability’ dialog :

ArchiWIZARD integration in Revit


ArchiWIZARD allows a link with all the BIM solutions on the market thanks to a direct import in IFC format, SketchUp format and in REVIT format. ArchiWIZARD is responsible for the automatic creation of the energy model (rooms, walls, bays, thermal bridges, environmental elements) from the 3D digital architectural model. This common energy model is used for all ArchiWIZARD’s simulation engines.

Figure 1 – Environment ArchiWIZARD

A. REVIT model import
ArchiWIZARD has a standalone version and a direct ArchiWIZARD plug-in in REVIT.
The 3D model is exported by the geometric analysis in the ArchiWIZARD standalone version, and with the REVIT energy model in the ArchiWIZARD plugin of REVIT (process called BIM import).

Figure 2 – Two types of import

• Geometric analysis Import:
This is a simple geometry analysis of the 3D model. ArchiWIZARD will detect these closed volumes and it creates the project walls accordingly.
This geometric analysis will be used to generate an energy model adapted to the module used in ArchiWIZARD (Real-time module, STD module, Regulatory modules, etc.).

Figure 3 – Import by geometric analysis

• REVIT BIM import:
This feature can only be used in the ArchiWIZARD version integrated with the plug-in REVIT software and allows to generate an energy model based on parameters (location, wall compositions, materials and their thermal properties, name and room dimensions, among others ) from REVIT energy model and, of course, to get access to all ArchiWIZARD features.

Figure 4 – REVIT energy model preview in gbXML

B. Real time data synchronization
ArchiWIZARD and REVIT models are linked and some properties like thermal properties are synchronized in real time without having to synchronize.

Figure 5 – Parameter synchronization in real time
  • Display results in REVIT

Some ArchiWIZARD results may be displayed in the current Revit view such as light range, light comfort or thermal loads EN12831.

Figure 6 – ArchiWIZARD solar imagery generated in REVIT view

D. Access to all ArchiWIZARD features and interface

All ArchiWIZARD functionalities are accessible and operational in the Revit environment via the control ribbon.

Figure 7 – ArchiWIZARD control ribbon in REVIT view

Working with the ArchiWIZARD plugin gives access to both software simultaneously. The constant exchange of information in this BIM environment allows to optimally enrich REVIT’s 3D model as well as the ArchiWIZARD’s thermal model.

Extend Profile Controls content for Railing macros from PowerPack for Autodesk Advance Steel


One of the benefits of the Railing macros, available in PowerPack for Advance Steel, is that the library of profiles used to create the railing can be extended.

In other words, the user can add any section to the Railing macros from the Stairs and Railing Vault.

This feature is available starting with version 2021.1 of PowerPack for Autodesk Advance Steel.

Stairs and Railings Vault

All the Graitec railing macros can be configured to use records from the Autodesk Advance Steel AstorRules database – JointsGUIAllowedSections table. This behavior is like some Advance Steel standard joints.

This flexibility of the macros offers the users to go beyond existing restrictions and extend the list of available sections in the profile selection controls, for each type of main railing element such as:

  • post
  • top rail
  • middle rail
  • kick rail
Profile selection control inside the dialog 

To make this work, the following strings (names) for the JointName and JointControl columns in the table, for each railing macro and each main element type inside the macros, must be used:

How it works?

  1. Open the Table Editor from MANAGEMENT TOOLS – AstorRules database – JointsGUIAllowedSections table.
  2. Create a new table entry for the desired user section.

Add a new entry inside JointsGUIAllowedSections table:

Example: add half round solid sections to be used for the top handrail inside the Standard railing macro

New entry in JointsGUIAllowedSections table

Update the database and reload it in Advance Steel using the Reopen database option. Next time the Standard Railing macro is opened, the new type of profile section can be used inside the railing:

PowerPack for Advance Steel Stair Macros – Understanding the Philosophy


The Stair macros available with PowerPack for Advance Steel are powerful tools for anyone who wants to create stairs, but they are not magic.

To get the best from these macros it’s important to understand the philosophy of how it’s working. This philosophy is based on 4 aspects that you must have in mind before using the macro.

Let’s start with the first one.

A. The 2D setting out points defined

To ensure the macro works as expected, you need to have the 2D setting out points defined.

This is an important step to be done before starting the modeling.

The PowerPack Premium Stair tools use different setting out points. You need the bottom point of the first tread & top point of the last tread, exactly how is showed in the image below.

B. Don’t forget about the overlap

If your stair has a constant overlap, then move your last point horizontally to include the overlap.

In the example below the overlap is 50mm, therefore the blue point was moved with 50mm.

C. Know the length of the landing extension

For the staircases with 2 or 3 flights you need to know the length of the landing extension before using the macro.

In the example below, you can see 2 landing extensions for a stair with 2 flights: one of 230 mm in blue and the second of 460 mm in red.

D. Turning points for multiflight stairs

For the multiflight stairs created with the PowerPack macros, you need to define the turning points at the ground level, as you can see in examples below.

Going through these 4 steps before starting to use the Stair macro, will ensure that the macro is working as you expected and you will get the full benefits of its features.

How to activate “Advance stability” analysis on steel elements in Advance Design


In order to perform second order analysis on steel elements in Advance Design, Steelwork Design “To calculate” option must be activated from the element’s property list.

Figure 1 – Steelwork Design Activation

This feature is available either for each individual steel profile or for a multiple selection, by checking 2nd order with warping and imperfections checkbox, setting the Number of iterations and Stability 2nd order parameters.

Figure 2 – Advance Stability Activation

The “Advanced stability (2nd order)” parameters can be found in the Steelwork Design section of the property sheet for steel members. 

Figure 3 – Advance Stability Options

(1)    Checking the “2nd order with warping and imperfections” box will perform the analysis of the selected members during the steel calculation sequence. 
(2)    The 2nd order analysis being an iterative process , the user can set the maximum number of iterations. 


The 2nd order analysis uses the user-defined imperfections in order to determine the final 2nd efforts. The imperfections are applied step by step, incrementally, until the final imperfection defined by the user is achieved. At every iteration, the 2nd order efforts are recalculated starting with the previously calculated efforts. Calculations are made until convergeance – defined as the difference between 2 succesive iterations (automatically managed internally by the solver) – is achieved,  or until the maximum number of iterations is achieved. 


(3)    The “Stability – 2nd order parameters” will give access to a dialog where the user can define the various parameters to be considered during the analysis of the selected members. 
The definition dialog will show 4 tabs: 
•    Nodal springs
•    Bedding
•    Imperfections EC3
•    Loads offset

Figure 4 – Advance Stability Assumptions

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How to define nodal springs in “advance stability (second order analysis) solver


Although the “Advanced stability” from Advance Design feature considers the individual member, the intersections with the other elements are of course taken into account. In fact, the intersections are turned into nodal springs

Figure 1 – Auto Detect Spans Option

The selected member has intersections with other elements at x = 0.00m and x = 4.00m.

The “Auto-detect spans” button enables the users to see the intersections and alter the behavior of the corresponding springs.

The users can also add or delete nodal springs (only user-added nodal springs can be deleted) from the grid using the “Add” and “Delete” buttons. Moreover, they can reset the grid with the help of the “Reset” button.

Note: Even if the user does not open the Advance stability definition parameters, Advance Design will automatically take into consideration the intersections with the other elements during the analysis.

Note: If geometrical parameters are modified after the “Advance Stability” option is checked for steel members, “Reset” and “Auto-Detect Spans” options must be selected in order to reinitialize the position of the nodal springs. Any modifications made in the Advance stability window will be reset to default. Otherwise, the calculation will not be successful.

For each nodal spring, the user can set the status for each of the seven DOF.

    TxTy and Tz stand for the displacement along the x, y and z axes respectively 

    RxRy and Rz stand for the rotation about the x, y and z axes respectively

    Rw is the warping

Figure 2 – The seven Degrees of Freedom

Available statuses are:

  • Free: enables the release for the considered degree-of-freedom ;
  • Fixed: disables the release for the considered degree-of-freedom (this translates into a very high stiffness);
  • Auto: lets Advance Design automatically determine whether the degree-of-freedom is free or treated as an elastic release (the stiffness of which is automatically computed by Advance Design for each combination);
  • Elastic: defines an elastic release for the considered degree-of-freedom (stiffness imposed by user).

When set on “Auto“, Advance Design is able to compute the appropriate stiffness of the release as Force/Displacement, resulting in a stiffness value for each combination.

 Figure 3 – Stiffness definition

Warning: the “Auto” status means that the “Advanced stability” feature will attempt to re-create the boundary conditions based on the Forces and Displacements diagrams from the global model.

This can be challenging in some cases as the automatic determination has its own limitations.

For example, zero forces on a given node can either mean:

  • The degree-of-freedom (DOF) is free;
  • The DOF is fixed but no force was acting in the given direction.

Therefore, we would advise the users to manually set the free DOF”s on “Free” whenever possible as the “Advanced stability” feature is not able to import the boundary conditions defined on the member in the global model. The “Advanced stability” feature can only deduce the boundary conditions from the Forces and Displacements diagrams it imports from the global model.

We would also advise the users to make sure the member does not feature a free “Rx” DOF on both ends as this could lead to a numerical instability if no other intermediate nodal spring exists.

Setting the “Rx” DOF on “Fixed” can be a solution when the “Auto” detection method fail.

Figure 4 – Degrees of Freedom Status

The “Position” property enables the user to define an eccentric spring.

Eccentricity is meant in the z direction (Upper fiber, Neutral, Bottom fiber or User value).

Figure 5 – Nodal Springs Position Eccentricity

Stiffness auto correction 
There are cases when, by activating the “Auto-detect spans” option, the automatically calculated stiffness does not meet the minimum criteria in order to successfully perform the 2nd order analysis (for example, when displacements are automatically imposed at an element”s ends for which the automatically calculated stiffness is insufficient). By activating the “Stiffness auto correction” option, the program automatically imposes a minimum stiffness in order to successfully perform the analysis, but only when the values are very small.

Figure 6 – Stiffness Auto Correction Activation

Generally, the warping DOF (degree-of-freedom) is free and fixing it requires special rules for detailing, like the end plates, beam extensions, flat stiffeners.

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How to analyze irregular reinforced concrete cross-sections?


The reinforced concrete linear elements are usually characterized by square, rectangular or circular cross-sections. Advance Design computes the reinforcement for such elements with the Reinforced Concrete (RC) Design expert. For irregular, user defined cross sections, the RC design falls outside the standard procedure. Therefore, the real reinforcement may be determined following an iterative process, as described in the next steps:

1. Add a new user defined cross-section – follow the steps from Figure 1

Figure 1 – Steps to define a new user section

2. Define the cross-section geometry (shape and reinforcement position) and material in the Cross Sections module: draw the shape by point coordinates, define the reinforcement (automatic or manually) and concrete cover, define the material and calculation settings.

Note: It is recommended to define the initial reinforcement from the minimum reinforcement area.

Figure 2 – Define the cross-section shape and place the reinforcement

3. Set parameters and calculate the cross-section properties

Figure 3 – Calculation settings

4. Export the cross-section to the Advance Design library

Figure 4 – Close and export the cross-section to Advance Design library

5. The user defined section is attributed to the desired linear elements (columns). Run FEM and RC Design analysis.

6. On the selected element, check the RC design – element reinforcement results. The real reinforcement (imposed) can be compared to the theoretical reinforcement (computed). The verification can be observed on the interaction curves also. The section solicitation point should fall inside and close to the capacity curve (My/Mz, Fx/My, Fx/Mz), for a safe and economic design. If the imposed reinforcement does not satisfy these conditions, the initial reinforcement is increased: restart from Step 2.

Figure 5 – Check the proposed reinforcement