Structural Engineering & Statics
where the load goes
Concept

Shape factor — where it appears

2 essays name this object, across 2 fields. What follows is each of them, and the objects they name alongside it.
the same, laid flatI = 0.06 × 10⁶1.0× the firstsquareI = 0.75 × 10⁶13.3× the firsttall rectangleI = 10.00 × 10⁶177.8× the firstI-sectionI = 24.29 × 10⁶431.8× the firstevery section here has an area of 3000 — only the shape differsthe bar is the second moment of area, to scale

The same steel in a different shape, and a factor of forty

Four sections of identical area, identical weight and identical cost. The stiffest is dozens of times the stiffest of the flattest, and the only thing that changed was the arrangement.

sections · section shape 024681000.511.5curvature ÷ curvature at first yieldmoment ÷ moment at first yieldrectangle: 1.50× the yield moment, at 4.1× the yield curvatureI-section: 1.09× the yield moment, at 1.1× the yield curvature

The section that yields from the outside in

A rectangle has half again as much moment in reserve past first yield as its elastic capacity suggests, and an I-section has a seventh. Read as a ranking that gets it backwards — the reserve is bought with curvature, and the rectangle pays four times as much of it.

materials · moment curvature

Named alongside it

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

DuctilityHollow sectionI-sectionLocal bucklingMoment curvatureNeutral axisPlane sectionsPlastic modulusPlastic momentRotation capacitySecond moment of areaSection modulus

All concepts