Calculating Timber Panel Walls | 1. Determining the Ultimate Limit State and Stiffness
Technical Article
The stiffening of timber structures is usually carried out by means of timber panels. For this purpose, structural components consisting of slabs (chipboards, OSB) are connected with members. Several articles will describe the basics of this construction method and the calculation in the RFEM program. This first article describes the basic determination of the stiffnesses as well as the calculation.
Image 01 - Framing construction
Structure of the Timber Panel
The ultimate limit state of a timber panel is determined according to standards such as Eurocode 5 or NDS 2018. In many countries, the shear panel theory is generally used for the design.
As mentioned in the beginning, the design of the timber panels is not the main focus of this analysis. Therefore, it is described in the following only briefly according to the method regulated in Eurocode 5. Furthermore, these articles will not provide comprehensive information about the geometric rules or minimum distances of the fasteners.
A timber panel wall consists of the following elements:
- Head rib
- Inner rib, if applicable
- Cladding
- Fasteners
- Edge rib
- Foot rib
Ultimate limit state
The cladding consisting of OSB is usually connected with the ribs my means of staples.
Ultimate limit state of a fastener:
Equation 1:
Yield moment My,Rk = 150 ⋅ d3
Equation 2:
Hole bearing resistance fh,k = 65 ⋅ d-0.7 ⋅ t0.1
Equation 3:
Ultimate limit state ${\mathrm F}_{\mathrm f,\mathrm{Rk}}\;=\;1.1\;\cdot\;\sqrt{2\;\cdot\;{\mathrm M}_{\mathrm y,\mathrm{Rk}}\;\cdot\;{\mathrm f}_{\mathrm h,1,\mathrm k}\;\cdot\;\mathrm d}$
where
d = diameter of the fastener
t = thickness of the cladding
Equation 4:
Ratio wall width ${\mathrm c}_{\mathrm i}\;=\;\left\{\begin{array}{l}1\;\mathrm{for}\;{\mathrm b}_{\mathrm i}\;\geq\;{\mathrm b}_0\\\frac{{\mathrm b}_{\mathrm i}}{{\mathrm b}_0}\;\mathrm{for}\;{\mathrm b}_{\mathrm i}\;\geq\;{\mathrm b}_0\end{array}\right.$
Equation 5:
Ultimate limit state ${\mathrm F}_{\mathrm v,\mathrm{Rk}}\;=\;\frac{{\mathrm F}_{\mathrm f,\mathrm{Rk}}\;\cdot\;{\mathrm b}_1\;\cdot\;{\mathrm c}_1}{{\mathrm a}_{\mathrm v}}$
where
bi = total wall width
h = wall height
b0 = $\frac{\mathrm h}2$
av = distance of the fastener
Further important designs include, for example, the buckling analysis of the edge ribs, the design of the anchorage and the buckling design of the cladding.
Deformation
Equivalent to the ultimate limit state design, the four elements of a timber panel are important to calculate the deformation when determining the stiffness:
- Flexibility of the fastener
- Flexibility of the cladding
- Flexibility of the ribs
- Flexibility of the anchorage
Equation 6:
Flexibility of the fastener (staple) ${\mathrm u}_{\mathrm k,\mathrm{inst}}\;=\;\left(2\;\cdot\;\mathrm l\;+\;2\;\cdot\;\mathrm h\right)\;\cdot\;\frac{{\mathrm a}_{\mathrm v}}{{\mathrm k}_{\mathrm{ser}}\;\cdot\;\mathrm l^2}\;\cdot\;\mathrm F$
Equation 7:
Flexibility of the cladding ${\mathrm u}_{\mathrm G,\mathrm{inst}}\;=\;\frac{\mathrm F\;\cdot\;\mathrm h}{\displaystyle\frac56\;\cdot\;\mathrm G\;\cdot\;\mathrm A}$
Equation 8:
Flexibility of the ribs ${\mathrm u}_{\mathrm E,\mathrm{inst}}\;=\;\frac23\;\cdot\;\frac{\mathrm F\;\cdot\;\mathrm h^3}{\mathrm E\;\cdot\;\mathrm A\;\cdot\;\mathrm l^2}$
Summary
This article described the determination of the ultimate limit state and the stiffness of a timber panel. In the following articles about timber panels, these basics will be used to describe the consideration of these stiffnesses in a two- or three-dimensional calculation.
Keywords
Timber panel Timber panel wall Oriented strand board OSB
Reference
Links
Write Comment...
Write Comment...
Contact us
Do you have questions or need advice?
Contact our free e-mail, chat, or forum support or find various suggested solutions and useful tips on our FAQ page.
Screenshots
Associated Products
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
3,540.00 USD
Add-on Module
Design of timber members according to the American standard ANSI/AWC NDS
1,120.00 USD
Add-on Module
Design of timber members according to the Canadian standard CSA O86-14
1,120.00 USD
Add-on Module
Design of timber members according to the Brazilian standard NBR 7190:1997
1,120.00 USD
Add-on Module
Timber design according to Eurocode 5, SIA 265 and/or DIN 1052
1,120.00 USD
Add-on Module
Design of timber members according to the South African standards SANS 10163-1:2003 and SANS 10163-2:2001
1,120.00 USD
Main Program
The structural engineering software for design of frame, beam and truss structures, performing linear and nonlinear calculations of internal forces, deformations, and support reactions
2,550.00 USD
Add-on Module
Design of timber members according to the American standard ANSI/AWC NDS
1,120.00 USD
Add-on Module
Design of timber members according to the Canadian standard CSA O86-14
1,120.00 USD
Add-on Module
Design of timber members according to the Brazilian standard NBR 7190:1997
1,120.00 USD
Add-on Module
Timber design according to Eurocode 5, SIA 265 and/or DIN 1052
1,120.00 USD
Add-on Module
Design of timber members according to the South African standards SANS 10163-1:2003 and SANS 10163-2:2001
1,120.00 USD
