Structural Engineering & Statics
where the load goes
Concept

Stiffness distribution — where it appears

2 essays name this object, across one field. What follows is each of them, and the objects they name alongside it.
20H 10.0 M 22.2H 10.0 M 22.2the two base shears add to the applied 20 — the split came from stiffness, not staticsthe sway is exaggerated; a real frame at this load moves a fraction of a millimetre

The frame that leans, and what stops it

A rectangle of pinned bars folds flat. Make the corners rigid instead of adding a diagonal and it does not — which buys an unobstructed opening and costs bending in every member of it.

structures · portal frame centre of masscentre of rigidity1000 kNwest wall500 kN direct+ 39 torsional= 539 kNeast wall500 kN direct+ 39 torsional= 539 kNsouth wall0 kN direct− 19 torsional= 19 kNnorth wall0 kN direct+ 19 torsional= 19 kNcentre of rigidity at x = 15.00 m, y = 9.00 mtorsional radius r = 17.02 m against a plan radius of 10.10 mtorsionally stiff by the usual criterion

The corner that moves most

A lateral force is shared out in proportion to stiffness only if it passes through the centre of rigidity, which is not the centre of the plan and not the centre of mass. The distance between the two is a torque, and the wall that pays for it is the one furthest away and carrying least.

structures · plan torsion

Named alongside it

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

Accidental eccentricityCentre of rigidityDiaphragmEccentricityInstantaneous centreJoint rigidityLateral systemLoad sharingMoment connectionMoment diagramPlan torsionPortal frame

All concepts