Concept

Tension stiffening — where it appears

The contribution of concrete between cracks, which still carries tension and makes a member stiffer than its cracked section alone would be. It puts the real stiffness between the gross and the cracked value, at a position that depends on how far past cracking the member is.

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

Stiffer than its cracked section says

At a crack the concrete below the neutral axis has gone and the steel carries the tension alone. Between the cracks it has not gone — bond drags it back into tension, the steel strain drops, and the curvature averaged over a length of beam is neither section's.

deflection · tension stiffening

The curvature nobody applied

Concrete shrinks as it dries, by about half a millimetre in every metre. In a symmetrically reinforced member that is a shortening and nothing else. In a member with more steel in one face than the other — which is every beam and every slab — the steel holds one side back and the section bends, with no load on it at all.

deflection · shrinkage curvature

Named alongside it

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

Cracked section Creep Curvature Deflection Reinforcement Serviceability Bond Camber Compatibility Cracking moment Differential shortening Interpolation

All concepts