Contents

• Timber fire design
  • Preliminary settings
  • Settings
  • Calculation parameters
  • Manual design
  • Auto design
  • Results
  • List
• Timber shell buckling
• Better visualization of Utilization results

Timber fire design

The design procedure is implemented according EN 1995-1-2: Prescriptive rules / Analysis of a member / Simple calculation model.

Charring depth calculation uses EN 1995-1-2 chapter 3.4.2(2) nominal charring rate and required time parameter, which can be modified on the User Interface. Nominal charring rate can be calculated automatically according to Table 3.1 (in FD softwood/beech/hardwood is not distinguished, hardwood parameters will be applied in solid timber bar cases).

Timber bars can be initially protected from fire exposure by structural elements or fire protective claddings (EN 1995-1-2 chapter 3.4.3). It means the charring can be delayed (using tch time) and/or decreased (k2 value), but after the protection failure charring rates could be increased for ta time due the standard specification.

The different time factors must fulfill tch<=tf<=ta condition, so where tch is calculated automatically, tf will be calculated as tf = max(tf_user_defined, tch).

Resistance calculation follows EN 1995-1-2 chapter 4.2.2 “Reduced cross section method”.

Preliminary settings

To reach this functionality at least one Load case using “+Fire” type and one Load combination (or Load group) of “Ua” (Accidental limit state) type which contains a “+Fire” type Load case  must be declared.

Settings

This functionality is selectable on “Timber design” tab Design options. 

Calculation parameters

Manual design

In manual design protective cladding type can be selected which are basically different type Gypsum board solutions, wood cladding and Rock fibre butt. For unique materials user defined type is available.

The different types/solutions have distinguished specification in the standard, so different input fields will be enabled due to the type selection.

Auto design

In Auto design range and increment of thickness can be set and specific protective cladding data.

Results

Timber bar fire design detailed result is similar to timber bar design detailed result, supplemented  with the burned-in section, fire design data, and the modification factors according to EN 1995-1-2 chapter 2.3.

Fire design data contains all major information in connection with charring depth calculation.

List

Bar, Combined utilization summary for Timber Bar design and Timber Bar Fire design.

Timber shell buckling

Buckling check is now implemented for timber panels.  In compliance with EC5-1-1-9.2.4.3 method described in section 6.3.2 is used, extended for the case when buckling direction is not parallel with grain direction of the panel.

First buckling length of the timber panel must be set and/or new buckling regions can be defined, in a similar way as for RC shells.

Buckling check results appear in

• Utilization dialog
• Orthotropic panel, Utilization, Load comb. table
• Max. of load combinations, Orthotropic panel, Utilization table

Details of calculation are displayed in Detailed result window.

Better visualization of Utilization results

New timber panel utilization result is implemented which displays the values by finite element nodes if the Timber panel/Utilization is choosed.