Is it possible to perform fire resistance design of cross-laminated timber panels in RF‑LAMINATE?

Answer

Fire resistance design is not implemented in the RF‑LAMINATE add-on module by default.

However, you can calculate the charring rates yourself and consider them accordingly in the module. In the following example, this is explained on a simple plate.

Structural system (Figure 01):

  • Span 5 m
  • Plate width 2 m
  • LC1 (permanent) 1 kN/m² plus dead load
  • LC2 (medium) 2.5 kN/m²
  • 3 layers
    • S1 35 mm C24
    • S2 20 mm C24
    • S3 35 mm C24
The information regarding the correction factors and stiffnesses can be found in the attached file.

Factors for fire resistance:

  • Charring rate ß0 = 0.65 mm/min
  • Pyrolysis zone k0d0 = 7 mm
  • Charring time t = 30 min
  • Effective thickness def=t ß0+k0d0=30 min × 0.65 mm/min+7 mm = 26.5 mm
Remaining thickness of Layer 3 = 35 − 26.5 = 8.5 mm > 3 mm → thickness may be applied. (Figure 02)

Because of the modified layer thicknesses, a new stiffness matrix results, which is applied in RFEM for accidental combinations with the characteristic stiffness values. For the ultimate limit state, the design values are calculated here (Figure 03).

Keywords

Cross-laminated timber Fire resistance Pyrolysis zone Charring rate

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RFEM Main Program
RFEM 5.xx

Main Program

Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements

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3,540.00 USD
RFEM Other
RF-LAMINATE 5.xx

Add-on Module

Deflection analysis and stress design of laminate and sandwich surfaces

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1,120.00 USD