Problem description

Structural user features (plates, embedded piles, anchors, etc.) in PLAXIS are automatically given a name in the Input program, such that that the PLAXIS programs can easily refer to these structural user features in the Model explorer, Selection explorer and the Command line.
This Model explorer from the Input program is also shown in the Output program at the left side of the model to easily inspect the model by hiding and/or showing items. However, the internal structure of the Output program uses a different numbering compared to the Input program’s numbering to display the model and the results: the Finite Element numbering from the generated mesh. This can be seen in Output’s model explorer when expanding for instance one plate element:

Figure 1. Model explorer with Plate_1_1 as shown in Input (left) and Output (right)

Here Plate_1 and Plate_1_1 can be recognized from Input’s Model Explorer. When expanding Plate_1_1 in Output, Output’s Model explorer will show the plate element numbers from the Finite Element mesh of which this Plate_1_1 consists. In the above example, you may notice a Plate 1 element number , which can be easily confused with the Plate_1 from the Input program (see left side of Figure 1).

This difference in naming of plate elements in Input and Output can be confusing sometimes:

• When hovering over an element with the mouse pointer, the status bar below the model plot will indicate the element number, not the name as used in the Input program:

Figure 2. Element number displayed in Output status bar when hovering the mouse over a plate element

• In the tables, the element number is shown together with the so-called chain number. A plate element could have a name similar to e.g., Plate 1-4. Here, the plate element number is four [4], and its chain number is 1. A chain is a group of elements in the data of the Finite Element mesh that belong together. Such a group consists of the same geometry as the geometry of an intersected geometric object in the Input program. In the example above, that Input geometric object would be Plate_1_1. This chain number and the Input geometric object are numbered indepently, hence there is no direct relationship between the two used numbers, and when looking at the table data there is no guarantee that the table’s Plate 1-1 is the same element as Plate_1_1.

Figure 3. Table of plate results. First column shows Plate 1-2 in which plate chain 1, plate element 2 is meant

This confusion may occur for any structural element, for example beams, plates, geogrids, embedded piles, embedded pile rows, interfaces, node to node anchors, fixed end anchors and wells.

Solution

This issue is now solved since PLAXIS 2D 2015.00 and PLAXIS 3D AE.00. Now when viewing the table, the element number is explicitly mentioned as Element. while also the structural element name (from the Input model tree) is shown.

For PLAXIS 2D AE (and earlier) and PLAXIS 3D 2013 (and earlier), be careful which element you are reviewing in the table, or which element you are hovering over with your mouse pointer. Please check the assigned materials and the coordinates to make sure you select the correct element or inspect the correct structural element in the tables.