Concept

Elastic foundation — where it appears

Support that pushes back in proportion to how far it is pressed, which spreads a concentrated load over a computable characteristic length.

Named by 3 essays across 3 fields — each of them below, with the objects they name alongside it.

1000 kN1/β = 2.56 mthe beam lifts off at 6.04 msettlement 3.90 mm · contact pressure 195 kN/m · moment 641 kNm, none of which contains the length of the beam

The beam that sits on the ground

Every other beam in this collection is held at points. A footing is held everywhere, by something that pushes back in proportion to how far it is pushed — and that single change hands the structure a length it did not choose. Two or three of those lengths from the column, nothing knows the load happened.

internal-forces · elastic foundation
the cable alonekink of 0.0083 radwith the stiffening girderthe cable takes 83% of the load; the girder spreads it over 183 mμ = L√(H/EI) = 4.93

The deck is not there to carry the load

A cable takes the shape of whatever is on it, which is exactly the problem — under a point load its shape is a kink, and a kink is not a road. The stiffening girder exists to spread the load until what reaches the cable is something the cable's own shape is right for.

structures · stiffening girder
4020080030002000000.20.40.60.81stiffness of each supportfraction of the deflection that is bendingrigid supportsare over here1%the beam drawn

The deflection that belongs to the support

A beam calculation answers a question about a beam sitting on things that do not move. Real ones sit on bearings, on other beams and on columns that shorten, and every one of those is a spring in series with the member — so a deflection is the sum of two things and only one of them is a property of the beam.

deflection · support flexibility

Named alongside it

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

StiffnessCharacteristic lengthDeflectionLoad sharingAxial shorteningBearingCatenaryCompatibilityDifferential shorteningForm findingFunicularGeometric nonlinearity

All concepts