Concept

Size effect — where it appears

The fall in nominal strength as geometrically similar specimens are made larger, which contradicts the idea that a strength is a material property. It exists where failure is brittle and disappears where it is plastic, so reinforcement removes it along with the brittleness.

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

A check made on a perimeter, not on a section

Every shear check in this collection is made on a plane cut through a member. A slab sitting on a column has no such plane, because the shear leaves in every direction at once — so the check is made on a closed line, and a line grows with the column while the load grows with the square of the bay.

internal-forces · punching shear

The bigger one is the weaker one

Two geometrically similar beams of the same concrete should fail at the same nominal stress, because a strength is supposed to be a material property. They do not. The large one fails at less, and the reason is that a crack releases energy in proportion to a volume and consumes it in proportion to an area.

materials · size effect

Named alongside it

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

Aggregate interlock Brittle failure Characteristic length Clamping force Column head Concrete strength Control perimeter Crack Effective depth Failure surface Flat slab Flaw

All concepts