Structural Engineering & Statics
where the load goes
Concept

Anisotropy — where it appears

The property of a material whose stiffness or strength depends on direction. Timber is the standing case: along the grain it is some thirty times stiffer and ten times stronger than across it, so the same member rotated is a different member.

Named by 2 essays across 2 fields — each of them below, with the objects they name alongside it.

Also named here as grain, timber — the same set of essays touches all of them, so they are one junction rather than several.

02040608005101520angle to the grain (degrees)strength (N/mm²)Hankinsona straight linetension4.47 at 45°, not 11.821 per cent of the strength along the grain, at half a right angle

The material that has a direction

Every material in this collection so far has had one modulus and one strength. Timber has three of each, differing by more than an order of magnitude, and the consequence is not a correction to steel design — it is a different set of checks with a different one governing.

materials · anisotropy a12.12 kNb12.12 kNc5.02 kNd6.86 kNe6.86 kNf9.61 kNgoverning: mode c · 5.02 kN per shear plane

The smallest of six failures

Everything else in this collection that fails does so in one way at a time. A dowel through timber does not — the wood can crush while the steel stays straight, or one plastic hinge can form in it, or two — and the capacity is the smallest of the six, which is the kinematic theorem of plasticity applied to a joint rather than to a frame.

connections · dowel yield

Named alongside it

The objects these essays reach for when they reach for this one.

BearingGrainTimberBound theoremsCollapse loadConnection designDowel yieldDuctilityElastic modulusEmbedment strengthFractureFree body

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