Structural Engineering & Statics
where the load goes
Concept

Base plate — where it appears

The plate that spreads a column's load into its foundation, in bearing over part of its area and in tension through holding-down bolts over the rest. Where the resultant sits inside the kern the plate bears everywhere; past it the plate lifts, the contact shortens, and the bolts begin to work.

Named by 3 essays across 2 fields — each of them below, with the objects they name alongside it.

600 kN90 kN·mresultant at e = 150middle thirdbolt carries nothingPartial contactbearing over 300 mm at 10 N/mm² · 50% of 20

Where the structure meets the ground, and when the bolts start working

Push a base plate off its middle third and it lifts off the foundation. The holding-down bolts then carry exactly nothing, and go on carrying nothing until the plate has crushed the concrete underneath it.

connections · base plate pivotthe same force of 60, moved along the levermoment about the pivot0.160 × 0.1 = 60.260 × 0.2 = 120.360 × 0.3 = 18

The moment the beam left behind

A beam reaction is drawn arriving on a column's centreline. It arrives on a cleat a hundred millimetres out from the face, and the difference is a couple that goes into the column and has to be shared between the lengths above and below it. Nothing about it appears in a frame model whose members meet at nodes.

internal-forces · column eccentricity 600 kN180 kN·mresultant at e = 300, outside the platemiddle third154.42 kNBolts engagedbearing over 150.88 mm at 20 N/mm² · 100% of 20

The failure that is in the concrete

An anchor bolt is a steel component and its capacity is usually decided by something else entirely — a cone of concrete pulled out around it, failing in tension, in a material every other calculation on the project has assumed cannot take tension at all. The exponent in the capacity says so: it is not the square the geometry implies.

connections · anchor breakout

Named alongside it

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

ConnectionEccentricityLoad pathAnchorageAxial forceBearingBending momentBreakoutBrittlenessCapacity designCompatibilityCover

All concepts