Structural Engineering & Statics
where the load goes
Concept

Built up section — where it appears

A member made from several pieces fastened together, whose stiffness depends entirely on how completely the fasteners prevent slip.

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

neutral axispeak 82.8stressflow, q = VQ ÷ Imean stress 38.46 — the value a shear divided by an area would givepeak 2.15× that, and in the place bending ignoresthe flow is continuous; the stress jumps wherever the width doesq = 820.0connectors of 20000 each, at 24 centres, are what make this one section

The section made of pieces

Two plates bolted together are twice as strong as one plate. Two plates made to act as one section are eight times as stiff. The difference is entirely in the joint, and the joint has a calculable spacing.

sections · second moment loose: two beams, and the faces slide16.2 mmbonded: one beam, and the faces cannot4.0 mmI × 4with connectors at k = 200: 5.4 mm, 89% composite

Two beams, or one beam four times as stiff

Stack two planks and they bend as two beams whose faces slide past one another. Bond the faces and the pair has one neutral axis, four times the second moment and half the stress. Nothing was added but a restraint on slip.

internal-forces · composite action

Named alongside it

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

DelaminationFirst moment of areaNeutral axisSecond moment of areaShear connectionShear flowComposite actionParallel axis theoremPlane sectionsSlip resistanceStiffnessSuperposition

All concepts