Structural Engineering & Statics
where the load goes
Concept

Crack — where it appears

A separation in a material that has run out of tensile strength, across which stress can no longer be carried directly. What crosses it afterwards — reinforcement, friction, aggregate interlock — is the whole of what the member has left.

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

36shearthe bars clamp, and do not carryasperity slope 54° · tan = 1.40clamping stress 2.50 N/mm² · resistance 3.50 N/mm²sliding without separating is not available to a rough crack

Shear across a crack that is already there

Every shear calculation in this collection starts from an uncracked solid — a principal stress, a shear flow, a diagonal tension. This one starts after the crack, on a plane with no tensile strength at all, and the coefficient it uses is not a coefficient of friction. It is the slope of the roughness.

internal-forces · shear friction 10321003161000316201234size (mm, logarithmic)nominal strength (N/mm²)the specimen: 3.10the structure: 1.14the plastic limitfracture mechanicsthe test overestimates by 2.71× · D₀ = 120 mm

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 interlockAnchorageBrittle failureCharacteristic lengthClamping forceConcrete strengthConstruction jointCorbelDilatancyFailure surfaceFlawFracture energy

All concepts