Compressive strength

What is compressive strength?

Compressive strength characterizes the ability of wood to withstand axial compressive loads without failing. It is an indicator of the load-bearing capacity of wooden components subjected to compressive stresses, such as columns, piles, and foundations.

Compressive Strength | Foto © by Hugo Kämpf

Determination of Compressive Strength

The determination of compressive strength is standardized in compression tests according to DIN 52190. In this process, a flawless wooden cube with a defined grain direction is subjected to increasing compressive load until the breaking point is reached. Compressive strength is reported as the mean compressive strength in newtons per square millimeter (N/mm²), calculated from the average compressive strength values of multiple test specimens.

Influencing Factors

The compressive strength of wood is affected by various factors:

• Wood species: Dense woods like oak and beech generally have higher compressive strength than lighter woods like spruce and pine.
• Moisture content: Dry wood exhibits higher strength than wet wood.
• Defects in the wood: Knots, cracks, and other wood defects can significantly reduce compressive strength.
• Load direction: Wood is much stronger in the direction of the grain than perpendicular to the grain.

The Importance of Compressive Strength
Knowing the compressive strength is essential for the structural design of wooden components. It allows for the safe sizing of columns, piles, and other components under compressive loads.

Example Values:

Spruce: approx. 30-60 N/mm²
Beech: approx. 50-70 N/mm²
Oak: approx. 50-70 N/mm²

Standards and Further Information:

DIN 52190: Wood - Compressive Strength Parallel to Grain - Testing Methods

In Simple Terms

Imagine stacking heavy weights on a wooden block. Compressive strength shows how much weight the wood can withstand before breaking. The higher the compressive strength, the more weight the wood can bear.