I am currently constructing an MSE wall model in FLAC3D and trying to create ties (rigid tied connection) between the concrete wall facing (modeled as zones) and the geogrid (modeled as structural elements). I am using FLAC3D v9.
Here is the portion of my script used for linking the geogrid layers to the concrete panels:
structure link delete range group 'GG2Panel_L2'
structure link create target zone group 'GG2Panel_L2' ...
range structure group 'geogrid6' position-x 0.48 0.52 ...
target-range group 'Panel3' or 'Panel4'
structure link create target zone group 'GG2Panel_L2' ...
range structure group 'geogrid7' position-x 0.48 0.52 ...
target-range group 'Panel3' or 'Panel4'
structure link create target zone group 'GG2Panel_L2' ...
range structure group 'geogrid8' position-x 0.48 0.52 ...
target-range group 'Panel3' or 'Panel4'
structure link create target zone group 'GG2Panel_L2' ...
range structure group 'geogrid9' position-x 0.48 0.52 ...
target-range group 'Panel3' or 'Panel4'
structure link create target zone group 'GG2Panel_L2' ...
range structure group 'geogrid10' position-x 0.48 0.52 ...
target-range group 'Panel3' or 'Panel4'
structure link attach x rigid y rigid z rigid rotation-x free rotation-y free rotation-z free ...
range group 'GG2Panel_L2'
However, whenever I run the model, I receive the following error message:
*** Bad conversion of parameter number 9 (structure).
Expected tokens:
Keywords: active annulus aspect-ratio bmaterial by cmodel
collection component-id component-id-list concave
contact cylinder deformable deselected dfn dfn-3dec
displacement edge-length ellipse excavated extent
extra extra-list face-area fid fidlist fish
fracture-id geometry-distance geometry-space group
group-intersection id id-list index-list interface
jmaterial jmodel joint-set leader-id marker-type
mintersection name named-range not orientation plane
polygon position position-x position-y position-z
project-range radius rectangle region remove
rintersection seed selected set sphere sregion state
structure-type surface union use-hidden velocity
volume wall
I suspect the issue might be related to how I have defined the target-range or possibly with the syntax for the range keywords used in the structure link create command.
Could anyone please suggest how I can fix this issue or share the correct syntax for creating structural links (rigid connection) between geogrid elements and zoned concrete wall panels?
The structure keywork that comes after range needs to be structure-type followed by a type of structural element (i.e. beam, cable, geogrid etc…). See Range Phrases in the Itasca docs. Also the target-range keyword needs to come before the range keyword since it’s a keyword for the structure link create command. See here.
Thank you for your previous reply and suggestions. I have modified my script accordingly and used the following commands:
structure link delete range group 'GG2Panel_L1' position-x 0.48 0.52
; Create node-to-zone rigid links
structure link create target zone group 'GG2Panel_L1' ...
target-range group 'Panel1' or 'Panel2' ...
range structure group 'geogrid1' position-x 0.48 0.52
; Make translational DOFs rigid and rotational DOFs free
structure link attach x rigid y rigid z rigid rotation-x free rotation-y free rotation-z free ...
range group 'GG2Panel_L1'
However, after running the model, the following errors appear:
+++ 225 nodes were rejected because they already have links.
+++ No valid nodes were found, no links were created.
flac3d> range structure group 'geogrid1' position-x 0.48 0.52
*** Bad conversion of parameter number 1 (range).
Expected tokens:
Keywords: automatic-model-save ball ball-zone block brick
building-blocks call cfd clump contact contactfluid
continue customer-title-1 customer-title-2 data
directory echo echo-line element encrypt exit fblock
feblock fish floating-point-check flowknot flowplane
fracture fragment geometry group history inlet
ipython license list load log log-file mail massflow
measure model notice pagination pause playback plot
print program project python python-reset-state
pythonfile quit rblock remote return sketch stop
structure system table threads trace undo wall
wall-structure wall-zone warning zone zone-block
Could you please guide me on how to fix this issue?
It seems the problem may be related either to the range syntax or to existing links already defined for those nodes, but I’m not fully sure.
Any advice or clarification on the correct use of the structure link create and range commands for connecting geogrid elements to zoned wall facings would be greatly appreciated.
Check if ‘GG2Panel_L1’ is actually a group of links, it may be a group of elements is this line:
It looks like no links are being deleted, so when trying to create new links in the next lines you get the following warning:
Lastly, range is not a command. It cannot be used to start a command. It’s a specifier to select things for whatever the command does. Use it at the end of a command if the command allows.
I have some points I’d like to confirm first. Observing the command “structure link create target zone group ‘GG2Panel_L1’,” is this intended to be a connection between a solid and a structure? If so, the panel should also be modeled as a structure element, and the connection between the two structure elements should be made using liner elements.
Furthermore, and this is a crucial matter, do not use only a general liner element. You must use the Side 1 and Side 2 designation, as I introduced on that forum: the side in contact with the ground/soil should be Side 1, and both structural elements should be designated as Side 2.
To show you again, try applying it like this: structure node join side 2 group ‘expansion_joint’ range-target group ‘lining_B’ range group ‘lining_A’ position-y @tun_start @tun_end
Regarding the message “225 nodes were rejected because they already have links,”
I encountered this exact error myself in the past when I did not separate the liner into Side 1 and Side 2. Naturally, since the separation wasn’t made, the nodes with an already designated link were rejected for further connection. That is, try separating the liner into Side 1 and Side 2. If you do this, you will no longer encounter this type of error.
Thank you very much for your detailed explanation and suggestions.
In my MSE wall model, the panel represents the concrete facing connected to the geogrid layers. Could you please advise which type of structural element would be most appropriate to model this concrete panel facing—liner, shell, or another element type? A short example or reference would be very helpful for me to set it up correctly.
Regarding the connection between the geogrid and the concrete panel facing, you mentioned using liner elements with Side 1 and Side 2 designations. As I am still new to this part, could you please provide a small example or sample syntax showing how to define and connect the two sides properly? This would help me understand the correct setup and avoid node-link conflicts in my model.
Sir Please note that, I am using version 9.00.181 version. Also, I would like to provide rigid connection between panel and geogrid. I have attached two pictures of my model showing the concrete panel and ten geogrids embedded in the soil layer, which will be rigidly connected to the panel. I hope these pictures help you understand the scenario and provide the best suggestions.
Ah, I misunderstood. This isn’t a connection between structures, but a connection between concrete and geogrid, so a liner element isn’t necessary. I got confused because I was answering another question on the forum about expansion joints.
Anyway, as dblanksma mentioned earlier, it seems to be a Range phrases issue. I think this is because, as the error message suggests, using ‘structure-type geogrid’ instead of ‘structure’ should resolve it."
Thank you for your reply, sir.
So, just to confirm — I don’t need to create the panel using structural elements, solid or zone element will be the perfect for concrete panel facing and there’s no need to define liner sides 1 and 2, correct?
If I need to use any structural element such as shell, beam, pile, liner to model the concrete panel facing which element will be the best for concrete panel facing of a MSE wall?
Sir, if possible, could you please provide me with the correct syntax to resolve this issue? I’m still facing some difficulties, and it would be a great help if you could kindly review the script I shared in my post and point out the correct syntax.
I truly appreciate your time and guidance, sir. Thank you again for your support.
Sir, I’m still facing some issues and need your guidance.
I’m not entirely sure whether it’s correct to model the concrete panel facing of an MSE wall using solid (zone) elements, or if I should instead use a structural element such as shell, beam, pile, or liner.
Could you please clarify which structural element would be most appropriate to represent the concrete panel facing? Also, it would be a great help if you could kindly provide some brief guidelines or command steps on how to build the concrete panel using that specific structural element.
In addition, for the connection between the concrete panel (currently modeled as solid/zone elements) and the geogrid, how can I rigidly connect them? The geogrid should be connected continuously along the full width of the MSE wall. If possible, please provide the correct syntax or command steps to create this rigid connection.
I’m also a bit confused about one point — is there any difference or specific requirement for rigid connection between zone elements and structural elements compared to the connection between two structural elements (for example, shell to geogrid)? Or is the process of rigid connection similar in both cases?
I would be very grateful if you could kindly review this and provide the correct syntax or command details, sir. Thank you so much for your time and continuous support.
Ok Sir I will send my quarries to them.
Sir,
Kindly let me know whether it is correct to model the concrete facing panel using solid elements , or if I should use structural elements instead. If structural elements are more appropriate, please suggest which type would best represent the concrete panel.
Also, could you please guide me on how to rigidly connect the facing panel to the geogrid in the model?
I have found three possible commands in FLAC3D for connecting the concrete panel facing to the geogrid:
structure node join – rigidly connects two coincident structural nodes (structure-to-structure) by locking all six degrees of freedom (6 DOFs).
structure link create – defines a connection element between a structure and a target (which can be either a zone or another structure node).
structure link attach – specifies whether each degree of freedom (translation in x, y, z and rotation about x, y, z) is rigid, free, or spring-based.
From my understanding, to properly capture the real connection between the concrete panel and geogrid in an MSE wall, I should use both the structure link create and structure link attach commands.
The structure link create command establishes the link between the two components (panel and geogrid).
The structure link attach command defines the nature of that connection—rigid translation and free rotation.
Before using these commands, the structure link delete command should be applied to remove any existing links.
I have also used structure link list to check whether the connections are rigidly attached or not.
Here is the modified syntax I used:
; ==========================================================
; CONNECTIONS — LAYER 1 (geogrid1–5 → Panel1, Panel2)
; ==========================================================
; --- Delete existing links (optional on first run)
structure link delete range group 'GG2Panel_L1' position-x 0.48 0.52
; --- Create new links between geogrids and panel zones
structure link create range-target group 'GG2Panel_L1' range position-x 0.48 0.52
range structure-type geogrid group 'geogrid1' or 'geogrid2' or 'geogrid3' or 'geogrid4' or 'geogrid5' ...
position-x 0.48 0.52
target-range group 'Panel1' or 'Panel2'
; --- Set attachment stiffness: rigid translation, free rotation
structure link attach x rigid y rigid z rigid rotation-x free rotation-y free rotation-z free ...
range group 'GG2Panel_L1'
structure link list target range group 'geogrid1' or 'geogrid2' or 'geogrid3' or 'geogrid4' or 'geogrid5'
After running this script, I received the following errors:
*** Must specify a structure node by COMPONENT-ID or POSITION.
flac3d> zone group 'GG2Panel_L1' range position-x 0.48, 0.52
+++ No groups assigned to Zones.
Could you please help me understand how to fix this issue?
Also, do I need to define the group 'GG2Panel_L1' before using it in the command?
I have found three possible commands in FLAC3D for connecting the concrete panel facing to the geogrid:
structure node join – rigidly connects two coincident structural nodes (structure-to-structure) by locking all six degrees of freedom (6 DOFs).
structure link create – defines a connection element between a structure and a target (which can be either a zone or another structure node).
structure link attach – specifies whether each degree of freedom (translation in x, y, z and rotation about x, y, z) is rigid, free, or spring-based.
From my understanding, to properly capture the real connection between the concrete panel and geogrid in an MSE wall, I should use both the structure link create and structure link attach commands.
The structure link create command establishes the link between the two components (panel and geogrid).
The structure link attach command defines the nature of that connection—rigid translation and free rotation.
Before using these commands, the structure link delete command should be applied to remove any existing links.
I have also used structure link list to check whether the connections are rigidly attached or not.
Here is the modified syntax I used:
; ==========================================================
; CONNECTIONS — LAYER 1 (geogrid1–5 → Panel1, Panel2)
; ==========================================================
; --- Delete existing links (optional on first run)
structure link delete range group 'GG2Panel_L1' position-x 0.48 0.52
; --- Create new links between geogrids and panel zones
structure link create range-target group 'GG2Panel_L1' range position-x 0.48 0.52
range structure-type geogrid group 'geogrid1' or 'geogrid2' or 'geogrid3' or 'geogrid4' or 'geogrid5' ...
position-x 0.48 0.52
target-range group 'Panel1' or 'Panel2'
; --- Set attachment stiffness: rigid translation, free rotation
structure link attach x rigid y rigid z rigid rotation-x free rotation-y free rotation-z free ...
range group 'GG2Panel_L1'
structure link list target range group 'geogrid1' or 'geogrid2' or 'geogrid3' or 'geogrid4' or 'geogrid5'
After running this script, I received the following errors:
*** Must specify a structure node by COMPONENT-ID or POSITION.
flac3d> zone group 'GG2Panel_L1' range position-x 0.48, 0.52
+++ No groups assigned to Zones.
Could you please help me understand how to fix this issue?
Also, do I need to define the group 'GG2Panel_L1' before using it in the command?
Hello sir @dblanksma
To help you understand what kind of connection I need between the concrete panel and the geogrid, let me briefly explain my research methodology.
My research focuses on Mechanically Stabilized Earth (MSE) walls, where a concrete facing panel (made of several modular concrete blocks forming one full panel) is placed in front of the soil, and the soil is reinforced with geogrids.
The main objective of my research is to evaluate the internal and external stability of MSE walls under hydrodynamic loading (such as waves). When horizontal wave loads hit the concrete facing, the forces are transmitted to the soil and geogrids, and sometimes the waves may even overtop the wall. Therefore, proper load transmission from the facing to the geogrid is very important.
In the field, concrete panels and geogrids are connected using connector pins, bars, or rods embedded in the panels. The geogrid loops or steel connector strips are attached to these fittings. Common systems use U-shaped steel bars, stainless-steel hooks, or polymer sleeves, which link the geogrid to the panel through a bearing or sleeve system.
The connection is semi-flexible, not fully rigid — it allows free rotation at the connection point to accommodate wall movement and settlement, but is still strong enough to transfer tensile forces from the panel to the geogrid.
In my model, I added lines 64–65 to allow free rotation, and lines 66–70 to check whether the panel–geogrid link connection is set as rigid with free rotation. To verify this, I used the structure link, link list attach, and node list commands, then reviewed the results in the console. However, I’m still unsure whether the connection is correctly defined as rigid while allowing free rotation.
Could you please review my research methodology and current syntax, and kindly guide me on how to properly define a semi-rigid connection — that is, rigid in translation but free in rotation — between the panel and geogrid for this type of MSE wall?
Your guidance would be extremely valuable, as resolving this issue is very important for my ongoing work.
Thank you very much for your time and consideration.
