Introduction

A procedure to calculate WikiHouse floor blocks is provided in this spreadsheet. More details can be found in the tutorial below:

Design parameters

250 series

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Where \(W_j\) is the section modulus at the side dovetail joint, \(W_{L/2}\) is the section modulus at the mid span, \(I\) is the effective (recommended) modulus of inertia and \(k_R\) is the rotational stiffness at the dovetail joint.

200 series

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Where \(W_j\) is the section modulus at the side dovetail joint, \(W_{L/2}\) is the section modulus at the mid span, \(I\) is the effective (recommended) modulus of inertia and \(k_R\) is the rotational stiffness at the dovetail joint.

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Useful formulae

Capacity

The moment capacity at the joint \(M_j\) and the moment capacity and the mid-span \(M_{L/2}\) can be calculated as:

\(M_j=W_j f_{c,0,d}\)

\(M_{L/2}=W_{L/2} f_{c,0,d}\)

Where \(W_j\) is the section modulus at the side dovetail joint, \(W_{L/2}\) is the section modulus at the mid span and \(f_{c,0,d}\) the compressive stress of the material (parallel to the grain if plywood).

Deflection

For a distributed load, the deflection in the mid-span can be calculated as:

\( v_{max}=\frac{5qL^4}{384EI}+\frac{qa^2}{2k_r}[L-a] \)

where \(E\) the elastic modulus of timber, \(I\) is the modulus of inertia, \(a\) is the distance between the castellated joint and the support, \(L\) is the span and \(k_r\) is the rotational stiffness of the joint.

How these values\formulae can be used?

These values can be used for design purposes. The formulas were also implemented in a design spreadsheet available here. Please check the worked examples section for more details.

Where do these values\formulae come from?

These values come from an experimental testing and analytical modelling. Please check the research library (specifically this article) for more details.