Structural Engineering & Statics
where the load goes
Concept

Preload — where it appears

A tension put into a bolt before any load arrives, clamping the plies so that the joint carries shear by friction rather than in bearing. It is what removes slip from a connection, and a joint that has slipped past it is a different mechanism with a different capacity and a different stiffness.

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

00.511.522.533.544.55050100150200displacement, mmload, kNfriction 137 kNbearing 188 kNslipthe rising branch is drawn, not solved: it is elastic shear of the plates

The joint that carries nothing until it slips

Tighten the bolts hard enough and the plates are clamped together with a force nothing applied. The joint then carries shear by friction, the bolts are in tension and not in shear at all, and the load path has nothing in common with the joint it looks identical to.

connections · slip critical 800 kN1.161.050.970.920.890.890.920.971.051.16an equal share675 mm = 33.8 dworst bolt 93 kN against a nominal 80 kN

The joint that has to be as good as the member

A splice exists because members come in lengths and structures do not. It has to deliver the same force, at the same stiffness, in the same distribution across the section, through a discontinuity — and each of those three requirements is met by a different feature of the detail, with the third one usually left to look after itself.

connections · splice

Named alongside it

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

ConnectionBolt groupBolt tensionContinuityContraflexureDuctilityFrictionJoint stiffnessLimit stateLoad pathLoad sharingMoment rotation

All concepts