Setting Deformation Coefficient kdef in Timber Design

A standard scenario in timber member construction is the ability to connect smaller members by means of bearing on a larger girder member. Additionally, member end conditions may include a similar situation where the beam is bearing on a support type. In either scenario, the beam must be designed to consider the bearing capacity perpendicular to the grain according to NDS 2018 Sec. 3.10.2 and CSA O86:19 Clauses 6.5.6 and 7.5.9. In general structural design software, it is typically not possible to carry out this full design check, as the bearing area is unknown. However, in the new generation RFEM 6 and Timber Design add-on, the added 'design supports' feature now allows users to comply with the NDS and CSA bearing perpendicular to the grain design checks.

The new RFEM software generation provides the option to perform stability design of tapered timber members in line with the equivalent member method. According to this method, the design can be performed if the guidelines of DIN 1052, Section E8.4.2 for variable cross-sections are met. In various technical literature, this method is also adopted for Eurocode 5. This article demonstrates how to use the equivalent member method for a tapered roof girder.

In the RF-/TIMBER Pro, RF-/TIMBER AWC, and RF-/TIMBER CSA add-on modules, you can consider the resulting deformation of a member or set of members. In addition to the local directions y and z, you have the option "R." This allows you to compare the total deflection of a girder to the limit values given in the standards.

Among others, the following cross-laminated timber manufacturers are available in the layer structure library:

• Binderholz (USA)
• KLH (USA, CAN)
• Kalesnikoff (USA, CAN)
• Nordic Structures (USA, CAN)
• Mercer Mass Timber
• SmartLam
• Sterling Structural
• Superstructures listed in Lignatec Edition 32 "Cross-Laminated Timber of Swiss Production"

By importing a structure from the layer structure library, all relevant parameters are adopted automatically. The library is continually updated.

The Timber Design add-on for RFEM 6 / RSTAB 9 is multi-purpose and combines a large number of additional elements. [*S16332764*] Timber Design Add-on for RFEM 6

Did you know? In the Design Supports, you can now define fully threaded screws as transversal compression stiffening elements for the "Compression Perpendicular to Grain" design. In this case, the pressing-in and buckling of the bolts is analyzed.

Moreover, the design shear resistance is checked in the plane of the screw tip. The angle of dispersal can be considered as linear under 45° or nonlinear (according to Bejtka, I. (2005). Verstärkung von Bauteilen aus holz mit vollgewindeschrauben. KIT Scientific Publishing.).