We illustrate the princimple here with boundary conditions, but also materials, eccentricities, … can be changed the same way.

• A model contains three bars with different boundary conditions.
  
  You want all bars to have the N = 100 kN/m boundary condition, without changing the other boundary conditions these bars already have.
• Select all bars and click on .
  The following dialog appears:
  
• Open the padlocks before N. Leave the other padlocks closed .
  Change the transfer of axial forces to 100kN/m.
  
• Hit “OK”.
  You now changed the boundary conditions for the transfer of axial force for all selected bars, whil not changing the boundary conditions for moment or shear.

In particular if your model contains soil layers and /or requires global imperfections and/or requires the calculation of the global buckling factor and/ or requires a modal, seismic or dynamic analysis. And there’s why:

1. Global imperfections

• A Diamonds project contains two columns. Both columns have the same geometry. All loads are the same except for the wind loads:
  
• We run a first order calculation with global imperfections.
  In the results, the bending moment My is not “mirror symmetric”. You expect to see the same absolute value in both columns. But that’s not the case.
  
• Reason: Diamonds applies the global imperfections using equivalent horizontal forces (example here). It will apply those equivalent horizontal forces in different directions. Of those directions, it shows the most severe in the results, not the envelope of all the directions! If two (or more) directions result the same |absolute maximum|, Diamonds shows one of them.In this particular example: if the equivalent horizontal forces are applied in the +X-direction, they will have a favourable effect on the bending moment of the left column and an unfavourable effect on the right column. If the equivalent horizontal forces are applied in the -X-direction, they will have a favourable effect on the bending moment of the right column and an unfavourable effect on the left column.
  The effect of the equivalent horizontal forces in the +X and -X on this structure is the same but the sign is opposite. Since the absolute value is the same, Diamonds only shows the results of one direction: +X in this case.
• Solution: create a separate Diamonds model for each structure.

2. Soil layers

• A Diamonds project contains two plates next to each other.
  Both plates have the same geometry and are supported by the same soil layer profile.
  
• In the deformations, you see that both plates affect each other. This is because of Boussinesq law More info in our webinar about Settlement calculations or in our e-learning course (only available in Dutch).
  
• Solution: place the plates far enough from each other. But what is “far enough”? In one model 50m might be enough, another model might require 100m. And does the model still remain pratical? Because comparing results won’t be so easy.
  For your own convenience, create a separate Diamonds model for each structure.

3. Global buckling factor

• Two frames have the same geometry, but they are loaded differently.
  
• We run a second order calculation.
  The lowest global buckling factor is 2,86. But from the table we cannot deduct to which frame that value applies. Oké, we could look at the first buckling mode and conclude the minimum factor is valid for the frame on the left.
  But what does it say about the global buckling behaviour of the frame on the right? Nothing!  
• Solution: create a separate Diamonds model for each frame.

4. Modal analysis

• A Diamonds project contains two independent beams.
  The right beam is significantly stiffer than the beam on the left.
  
• We run a modal analysis requesting 10 eigenmodes.
  In the results, 9 out of the 10 eigenmodes are found to the beam on the left.
  Only eigenmode 5, is related to the beam on the right.
  
• If these results are later used to describe the dynamic or seismic behaviour of these beams, how can you achieve sufficient accuracy in the right beam with only one eigenmode?
• Solution: asking 20 eigenmodes instead of 10? That’s not really a solution, because it doesn’t guaranteed that the next 10 eigenmodes will be in the beam on the right. Nor does it allow you to check if sufficient effective model mass is reached for each beam.
  The only reliable solution is to create a separate Diamonds model for each structure.

• If the transfer is between two (or more) bar elements, we use the name “hinge” or “joint”.
  Defined in Diamond using the button .
• If the transfer is between two (or more) surface element, we often use the name “hinge line”.
  Defined in Diamond using the button .

However, adding to many hinges will result in an arithmetic mechanism. Thus a structure that will not calculate or result in exaggerated deformations. We list the most common mistakes here together with their correct alternative.

BAD	GOOD	Why?
		A simple support cannot bear moments. By adding an internal hinge, you say that the column cannot transfer bending moment to the support. That’s saying the same thing twice. Remove the internal hinge.
		A built-in support can bear moments. By adding an internal hinge, you say that the column cannot transfer bending moment to the support. That’s saying the opposite thing. Remove the internal hinge and use a simple support.
		A simple support cannot bear moments. A tie rod is a hinged bar by definition (otherwise it cannot function as a tie rod). If you anchor a tie rod to the foundation, without any other bars meeting in that node, you should define the support as built-in. Because the simple support + hinged tie rod, is an arithmetic mechanism.
		N bars meet in a node (N=4 in this example). Neglect the tie rods, because internally in Diamonds, they will automatically be defined as hinged. You want the node to work as hinged (EN: truss, NL: vakwerk),  then you should apply a hinge to 3 bars, not all 4. If you apply a hinge to all 4 bars, you create an arithmetic mechanism. If bars 1 to 3 contain a hinge, the bending moment in bar 4 (which doesn’t contain a hinge) can’t go anywhere because every bar around it is hinged.

• C-Therm S100/S101 FD
• C-Therm S110/S111 FD
• Sherwin William paints: Firetex FC2002, FX2004, FX2007, FX5090, FX6002, FX6010
• Euroquimica paints
• Hempel paints
• Nullifire SC901/902

Other protective materials:

• Fibre-cement silicate boards
• Fibre-silicate boards
• Gypsum boards
• Mineral fibre
• Perlite
• Perlite and cement
• Perlite and gypsum
• Plaster
• Promalan_HT 150
• Rockwool Conflit P756

Note: in case of multiple layers of reinforcement, you enter the mean cover.

[Diamonds]

In Diamonds you define the gross coverage.

• Select the element for which you want to change the cover
• Click on and on the button “Reinforcement”.
  

[ConCrete]

In ConCrete you define the net coverage.  ConCrete will automatically add 10mm to the coverage.

So if you model a beam with a coverage of 35mm in Diamonds, and you want to model the same beam in ConCrete, you should set the coverage to 25mm. Because ConCrete will automatically add 10mm to the coverage.

1. Using the menu Select
2. Using Design types 
3. Using the right mouse button

This article focusses on the latter. The easiest way to explain this feature it with an example.

The selected support line in the model below has a spring constant of 300 000kN/m/m assigned to it.

To select all support lines with the same support conditions, do the following:

• Select the source element of the property. In this case thus the relevant support line. But you can apply the same principle to points or surfaces as well.
• Click with the right mouse button in the drawing area. Go to the menu Select identical (Bar) and choose the desired property. In this case Support.

• Result: Diamonds will select all lines that have the same support condition as the source element.

Notes:

• This feature is available in Diamonds 2022r01 (or newer).
• You can select based on the following properties
  • For points: support, footing, label
  • For bars: support, boundary conditions, connection, cross-section, material, eccentricity, orientation, fire coating material, label.
  • For surfaces: support, boundary conditions, cross-section, material, label

Introduction

Diamonds allows the modelling of masonry. Besides adding a new material to the library, you also need to define the behaviour correctly.

The purpose of this article is to give you more insight in the Diamonds options regarding the behaviour of masonry walls. We will also tackle some pitfalls related to that behaviour.

Notes:

• Our support-website explains how you can add a new masonry quality to the material library. You can find some mechanical properties for masonry in BuildSoft tutorials, but don’t copy-paste them blindly into Diamonds!
  Masonry is a combination of bricks and mortar. The bricks come in different qualities and sizes. So does the mortar. Thus, there is no such thing as ‘THE’ masonry quality, only ‘A’ masonry quality. Make sure the mechanical properties you enter in Diamonds, correspond to the bricks + mortar you’re planning to use. Directions on how to calculate the mechanical properties for masonry, can be found in Eurocode 6.
• Although Diamonds allows the modelling of masonry (behaviour), Diamonds DOES NOTsupport the DESIGN of masonry according to Eurocode 6. So yes, Diamonds can calculateinternal forces in masonry walls. But no, Diamonds cannot tell if those masonry walls can bear those internal forces.

Options for behaviour

Once a masonry quality has been assigned to a wall, you can specify the behaviour of that wall using the button . The lay-out of this dialog is as follows:

• In the lower part, you can define each degree of freedom separately as free/valued/fixed. By default, all degrees of freedom are fixed, meaning all internal forces can be transferred though the borders.
• The upper part contains predefined settings for masonry walls. Once you selected a certain option here, you’ll notice that the content of the lower part changes depending on the option(s) you selected.

In the next paragraphs, we investigate the predefined settings for masonry walls, thus focussing on the upper part of the dialog:

• At top border no tension
• No arch effect
• No in-plane moment

Influence ‘At top border no tension’

This option is used to prevent plates from pulling on the walls when loaded. Checking this option, results in an iterative calculation.

Deflection δy
Axial force Nzz

Notes:

• By checking the option ‘At top border: no tension’, the elastic analysis will become an iterative calculation. Consequences:
  • Increasing calculation time (if you don’t have other non-linear behaviour).
  • An iterative calculation doesn’t always convert to a solution. Meaning, it’s not guaranteed that Diamonds will always find a way to transfer the loads to the foundation while meeting all the boundary conditions you imposed. In case no convergence is found, Diamonds will show a warning.

Because this option makes the calculations more complex, it’s advised to use this option in a more final stage of the design.

• By checking the option ‘At top border: no tension’, you prevent tension from occurring at the top border of the walls. However, this option cannot eliminate tension in the ‘field’ of the wall.

Influence ‘No arch effect’

This option will describe how the loads are transferred downward.

Conclusion: when the option is checked, the wall transfers its loads directly to the beam as if the beam was directly loaded with q without the wall being present.

Notes:

• In reinforced concrete the arch effect can originate. For masonry, it is up for discussion. So for safety’s sake, it is commonly assumed that the arch effect cannot originate the masonry.
• The option will disable all components for membrane action in the stiffness matrix, except for the component that determines N_xx. If you would use a plate bearing in one direction ( > ), that would give the same result as .
  The option and a membrane ( > ) will not give the same results as a membrane will have all components for membrane enabled.

Influence ‘No in-plane transfer’

We want to test the influence of the option ‘no in-plane moment’. In the previous paragraph we learned that for the sake of safety, the option ‘no arch effect’ must be checked for masonry. So we did.

In a wall without openings

To test the effect of the option ‘No in-plane moment’, we use the model below.

If the wall bears the loads perfectly downward, the bending moment in point A of the beam B200/400 must be:

Let’s find out if we can approximate that 9kNm (mesh size: max = 0,8m; min = 0,4m).

Geometry
Bending moment in beam

The shape of the bending moment is more in line with the expectations when the option is checked. But the bending moment is not (yet) of the same magnitude as the isolated beam. This is caused by the position of the mesh nodes. The mesh nodes in the wall must be aligned with the ends of the beam, to obtain that perfect behaviour. The only way to force this, is by dividing the wall above the beam ends (we continue with the model in which the option is checked).

	Not divided	Divided
Geometry
Mesh (walls along the side and back were set invisible to increase readability)
Bending moment My

The division does improve the results significantly (reducing the deviation from 15% to 3%).

In a wall with openings

To test the effect of the option ‘No in-plane moment’, we use the model below.

If the walls bear the loads perfectly downward, the bending moment in the beam B200/400 above the window must be 4,69kNm and have a parabolic shape :

Let’s find out if we can approximate that 4.69kNm (mesh size: max = 0,8m; min = 0,4m). In this paragraph we learned that the option ‘no in-plane moment’ must be checked for masonry and that the mesh nodes above the beam ends must be aligned. So we did. Result:

This is a good approximation (less than 1% deviation).

Note: Without the division, the bending moment in the beam has the shape of a build-in beam (restrained at the ends). You might think that applying hinges to the beam, will resolve the issue, but it doesn’t affect the results.

No division, no hinges

No division, hinges applied

Conclusion: workflow for defining masonry in Diamonds

1. Calculate the mechanical properties of masonry using Eurocode 6. Create a new material in Diamonds using these mechanical properties. Assign this material to the masonry walls.
2. For perfect vertical-load-bearing behaviour:
   • Check the option ‘no arch effect’ and the option ‘no in-plane moment’.
     Pay attention to the horizontal stability of the building.
   • Divide the wall above the ends of a beam so the mesh triangles are aligned.
3. Turn the option only off for walls in which tension arises at the top.
4. With the options and checked, the relevant walls lose their stabilizing function. A structure containing only walls with these options checked, will be sensitive for horizontal displacements (due to for example wind loads).

Horizontal wind load

Horizontal displacement [mm]