RF-/STEEL AISC: Direct Analysis Method and Stiffness Reduction

AISC: Direct Analysis Method and Stiffness Reduction
AISC: Direct Analysis Method and Stiffness Reduction

Amy Heilig | Dlubal Software

Requirements for the design of structural stability are given in the AISC 360 – 14th Ed. Chapter C. In particular, the direct analysis method provisions, which was previously located in Appendix 7 of the AISC 360 – 13th Ed., are described in detail. This method is considered an alternative to the effective length method which in turn eliminates the need for effective length (K) factors other than 1.0.

Section C2.3(1) requires a stiffness reduction factor of 0.8 to be applied to all structural members’ axial and flexural stiffnesses that contribute to the stability of the structure. The code further suggest to apply this reduction factor to all members whether they contribute to stability or not to avoid artificial distortion. Additionally, the factor tau_beta should be applied to the flexural stiffness of structural steel members in the analysis. The factor tau_beta is a function of the required axial compressive strength (Pr) to the axial yield strength (Py) ratio.

RFEM can effectively and accurately take into account these considerations for member stiffness reduction. Under the “Edit Member” dialog box and the “Modify Stiffness” tab, the user has the option to select the Definition Type “According to AISC 360-10 C2.3(2).” Here, all previously mentioned variables relating to the axial and flexural stiffness reduction are listed.

The factor tau_beta can be set to “Iterative” for the program to automatically determine this value based on the equations C2-2a and C2-2b or can alternatively be “Set to 1.” The user must also define whether the alpha factor used in these equations should be based on an LRFD or ASD analysis.

Lastly, the flexural and axial stiffness multiplier factors are listed and set to 0.8 as defined by the Section C2.3(1).

More about steel structural analysis and design software…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp

Adjusting Graphic Margins

Adjusting Graphic Margins
Adjusting Graphic Margins

Moritz Bertram | Dlubal Software

Sometimes, a model in the graphic window is displayed without filling the entire window or with too large margins after clicking the [Show Whole Model] button. In order to set the size of the graphic margins, click “Options” -> “Display Margins and Stretch Factors”. The value specifies the percentage of the margin relative to the graphic window size.

More about the GUI of RFEM…

More about the GUI of RSTAB…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp

Synchronized Selection in Project Navigator

Synchronized Selection in Project Navigator
Synchronized Selection in Project Navigator

Lukas Sühnel | Dlubal Software

RFEM and RSTAB provides a wide range of selection options. Some of the previous posts have already described selection using “Special Selection” or tables.

Project Navigator can also be used as an immediately available tool for the selection of structural data and loads. In this case, the procedure is similar to selection in tables using the synchronized selection.

More about modeling in RFEM…

More about modeling in RSTAB…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp

Individual Display Properties

Individual Display Properties
Individual Display Properties

Sandy Matula | Dlubal Software

By clicking “Options” -> “Display Properties” -> “Edit”, you can change and save display settings for printout reports and your screen. For example, you can set individual colors for cross-sections.

For this, open the respective dialog box by double-clicking the color next to the section number and select a new color. In addition, it is possible to use the display properties for the screen also for the printout report by checking the option “Identical Settings for screen and printout report”.

More about the GUI of RFEM…

More about the GUI of RSTAB…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp

Measure Function

Measure Function
Measure Function

Sandy Matula | Dlubal Software

The “Measure” function available in the “Tools” menu allows you to measure distances and angles.

You can select from the following measurement functions:
– Distance between two nodes
– Angle between three nodes
– Angle between two members

For this, click the relevant object in the work window. The results are displayed in a dialog box.

More about modeling in RFEM…

More about modeling in RSTAB…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp

Designed with Dlubal Software: 18-Story Mass Timber Hybrid Student Residence, Canada

Designed with Dlubal Software: 18-Story Mass Timber Hybrid Student Residence, Canada
Designed with Dlubal Software: 18-Story Mass Timber Hybrid Student Residence, Canada

Robert Jackson | Fast + Epp

Brock Commons is an 18‑story mass timber hybrid student residence currently under construction at the University of British Columbia in Vancouver, Canada.

When completed in summer 2017, it will be the tallest mass timber hybrid building in the world at 53 meters high.

More about the project…

More impressive customer projects…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp

Snap Option for Background Layers

Snap Option for Background Layers
Snap Option for Background Layers

Markus Baumgärtel | Dlubal Software

In RFEM and RSTAB, you can import background layers from a DXF file. If the main nodes of the model have already been set, it can be useful to deactivate the snap mode of the background layer.

Especially in the case of very detailed background layers, you can thus avoid snapping incorrect intersection points by mistake when editing the model.

More about modeling in RFEM…

More about modeling in RSTAB…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp

Text Formatting as Superscript or Subscript

Text Formatting as Superscript or Subscript
Text Formatting as Superscript or Subscript

Sonja von Bloh | Dlubal Software

The printout report of RFEM/RSTAB includes a text block function. This feature allows you to create user-defined text blocks with formatting and heading and add it to the printout report.

In order to display text above (a superscript) or below (a subscript) the normal text, you can use the following keyboard shortcuts:
~ [CTRL] and [SHIFT] and [+] for the superscript formatting,
~ [CTRL] and [+] for the subscript formatting.

To revert the formatting change, select the relevant text and press the keyboard shortcut again.

More about result evaluation and printout report in RFEM…

More about result evaluation and printout report in RSTAB…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp

Cross-Section Information of Section Areas

Cross-Section Information of Section Areas
Cross-Section Information of Section Areas

Robert Vogl | Dlubal Software

The cross-section properties software SHAPE-THIN provides the option to combine the cross-section parts in a “section” and display the cross-section properties. Thus, it is possible to determine the values of the individual components in a composite cross-section.

The dialog graphic shows the selected objects, including the centroid S and the shear center M. The cross-section properties of the selected objects are listed in the table.

Conversely, the user-defined sections can be converted back into editable elements and point element by using the “Reduce Cross-Section” function.

More about cross-section properties software…

More information…

  • RSS
  • Facebook
  • Google+
  • LinkedIn
  • Twitter
  • XING
  • Mail
  • WhatsApp