Contents

• Periodic excitation
• Plastic steel bar analysis
• Extended imperfection calculations
• Storey fundamental frequency
• Faster non-linear calculations
• Improved 'Load mismatch' warning
• Display analysis messages
• Open last calculation report

Periodic excitation

The dynamic calculations are further expanded in FEM-Design 21, where it is possible to calculate periodically harmonic vibrations of dynamic effects, such as:

• the centrifugal substitution load of an unbalanced mass rotating in a plane (e.g. ceiling fan),
• piston machine, which is the load calculated from the acceleration-deceleration mass on a given line.

Plastic steel bar analysis

The analysis of post-elastic behavior (e.g., the behavior of the structure after the formation of the plastic hinges) and the consideration of the plastic reserve of the structural parts is a great opportunity for steel designers to design more cost-effective structures. Now in FEM-Design 21 plastic analysis of steel bars (modeled with a beam or column tool) is available for any steel cross section.

Extended imperfection calculations

Imperfection calculations are now available for all material and structure types, and with some additional improvements.

There is an option to override the automatically calculated amplitude of the buckling shapes with a manually entered value. This manually entered value will be taken into account in the imperfection and second-order calculations for any structure type and material (e.g., timber panels, and not just steel bars).

A new check box option is added to the Imperfections dialog:

Initialize amplitude with steel bars is checked: imperfection and second-order analysis are performed as in previous versions of FEM-Design and only for steel bars.

Initialize amplitude with steel bars is not checked: imperfection and second-order analysis can be performed based on custom amplitude values and for all structure and material types. The default amplitude value is set to be 1.0m, and they can be manually modified at the Load combinations settings, in the Setup by load combinations table.

Note: A significant change in the representation of Imperfection results is that the displacements are displayed without units.

Storey fundamental frequency

According to EC 1995-1-1 7.3.3 some residential buildings containing timber slabs need to be checked for fundamental frequency. Thanks to the new dynamic analysis type, Storey fundamental frequency that has been added in FEM-Design 21, it is now possible to do that and calculate vertical storey fundamental frequencies for all materials types.

Faster non-linear calculations

The newest version of FEM-Design has been improved significantly in terms of nonlinear calculation time. All non-linear iteration analysis of 3D structures, such as uplift, crack-section, non-linear soil and plastic analysis, are 2-3 times faster, compared to the computational capability of previous versions. The actual difference in the computational speed depends on the project and the tasks to be performed.

Improved 'Load mismatch' warning

In order to help in evaluation if a misplaced load can be ignored, or not, we expanded the Load mismatch message with information of how much of the misplaced part will be ignored in relation to the total load.

Surface load has parts outside of the structure:

• information about the area of parts outside of structure, compared to the total area of the load, will be displayed. For example: "Load mismatch. This surface load has parts (0.2/32,3 m2) outside of structure therefore those parts will be ignored."
• one summation message about total area of parts outside of structure will be displayed. For example: "Load mismatch. 0.85/54,3 m2 area of surface loads is outside of structure therefore it will be ignored. Maximal area of a surface load outside of structure is 0.25 m2."
• the (warning) arrow points to the middle of surface load, instead to the corner (as it was in previous versions).

Line load has parts outside of the structure:

• the information about the length of part outside of structure, compared to the total length of the load, will be displayed. For example: "Load mismatch. This part (0.2/32,3 m) of line load is outside of structure therefore this part will be ignored."
• one summation message about the total length of parts outside of structure will be displayed For example: "Load mismatch. 0.25/24,3 m length of line loads is outside of structure therefore it will be ignored. Maximal length of a line load outside of structure is 0.15 m."

Point load has parts outside of the structure:

• information about the number of loads outside of structure, compared to all defined point loads, will be displayed. For example: "Load mismatch. 3/17 point loads are outside of structure therefore they will be ignored."

Display analysis messages

During calculations it is not unusual to receive some warnings about problematic structural elements or loads. So far those messages were only displayed in the Messages dialog, but from now on, upon pressing the Save button, they can be displayed in the model space and saved to a dedicated Messages layer. This makes it possible to return to the individual messages after closing the Messages dialog.
 

Note:

• The messages can be turned on / off by changing the status of the Messages layer.
• The messages can be deleted using the Erase command (Modify > Erase).

Open last calculation report

FEM-Design 21 offers a possibility to retrieve the calculation report of the last performed calculations in the model. The feature is located in: Tools > Open last calculation report.

The content of the report file is temporary and changes dynamically from calculation to calculation. So if you want to save the report of a particular calculation, it is a good idea to save it under a specific name. before running next calculation. The first line of the report records the date and time of completion of the particular calculation.