Contents

• New hot rolled hollow section type
• Single symmetric sections for composite beams
• Steel haunch
• Change panel direction
• Unit mass of fictitious bar
• Fictitious truss member
• Reset (cover) supporting structures
• Improved modification of library objects

New hot rolled hollow section type

In addition to the hot rolled cross-sections that can be selected in the built-in Section library, in FEM-Design 21 we can create custom-sized square or rectangular hot rolled sections. A new custom-sized hot rolled steel section can be created directly from within the Beam > Section > New > Size dialog, or in the FEM-Design Section Editor application. 

Single symmetric sections for composite beams

So far, only double symmetric cross-sections could be modeled for steel beams with concrete slab above. From now on, also single symmetric I-section and Hollow sections are allowed for Composite main girder beam sections.

Steel haunch

A common solution when designing steel frame structures is to increase the rotational stiffness of frame corners (beam-column connections) with haunches. This is now possible to model using the newest version of FEM-Design, and the new structural object Haunch.

Haunch properties:

• it can be placed at the end of a steel bar having I-shape cross-section; 
• its extra stiffness is considered in analysis; 
• the cross-section of the host bar is extended with dimensions of the haunch in the line where the two elements meet, and therefore taken into account in the bar’s steel design; 
• it is considered to act as a tapered bar in the analysis and design of the host steel bar.
   

The new Haunch tool is available in the Bar component drop-down menu (Structure tab):
 

To enter a haunch, follow these simple steps: 

1. Specify its dimensions at Default settings and its position (top or bottom) in the Haunch tool palette. 
2. Select the host bar element (I-shape section that is not tapered) that should be extended with the haunch segment. 
3. Select the bar end from which haunch should start.
    

Hint: 

• We can remove a haunch from a bar with the Erase command (Modify menu) and using box selection that includes only the haunch part. 
• We can run shell analysis for our frame part extended with haunch after bar-to-shell model conversion and some region editing (with Modify > Modify region command).
   

Change panel direction

In some models, the slab-to-panel conversion may generate panels in wrong direction, or a new orientation may be required due to a change in model size and geometry. In FEM-Design 21 it is now possible to change the direction for one or multiple selected items in one step using the new tool Change direction that is available in the panel input tool palette.

 

Unit mass of fictitious bar

From now on, the Unit mass physical property is available for Fictitious bars.

Note: Unit mass for Fictitious shell elements has been available since previous FEM-Design versions.

Fictitious truss member

A new fictitious bar type: Truss is introduced in FEM-Design 21, in addition to the previously available Bended bar type.. 

The Truss fictitious bar type has the following parameters: 

Stiffness to normal direction force (A x E). If its value is very large (e.g., 10^7) the fictitious bar can work like "perfectly plastic" truss member. 

Unit mass for dynamic calculations.

Strength behavior or material model for both compression and tension that can also be used to model nonlinear behavior with “tension only” or “compression only” setup:

• Linear elastic 
• Linear elastic – perfectly plastic, where plastic limit is defined with Capacity 
• Brittle, linear elastic until resistance reaches the failure limit defined with Capacity. The truss cannot bear any load if the equilibrium cannot be reached with a resistance force below the limit.
  
   

Reset (cover) supporting structures

Cover is a useful tool for creating surfaces that should not be taken into account in the calculations, but should transfer the load to the supporting structural elements. FEM-Design can find the supporting analysis model members of cover automatically  or can be specified manually. Version 21, however, introduces a new tool: Reset supporting structures that makes it possible to remove (reset) all supporting elements of one or more covers at a time.

Improved modification of library objects

During the modeling we sometimes have to modify the properties of items stored in libraries. In previous versions of FEM-Design, these modifications were not applied to existing elements in the model. But from now on, there is an option to approve modifications to already existing model objects, or only to future objects. 

This applies to the following libraries:

• Rigidity types of supports and connections,
• Materials
• Timber panel types
• Strand types of post-tensioned cables
• RC rebar types
• Bolt types of joints
• Fire protective materials

Note: If we choose not to perform a library item update on objects that are already in use, the library item will be duplicated: the modified item keeps the original name and name of the old item is supplemented by a post fix.