Progressive collapse — where it appears
Named by 3 essays across 2 fields — each of them below, with the objects they name alongside it.
The structure that survives losing a member
Every check in this collection asks what a structure carries. None of them asks what is left when part of it is gone — and two frames with the same members, the same weight and the same factor of safety can answer that question completely differently.
The force nobody put in the model
A slab strip whose ends cannot move apart is not the strip in the yield-line calculation. Deflecting shortens the chord between its ends, the ends do not come in, and the strip is forced into an arch — worth four times the load it was designed for, at a movement nobody would see.
A check made on a perimeter, not on a section
Every shear check in this collection is made on a plane cut through a member. A slab sitting on a column has no such plane, because the shear leaves in every direction at once — so the check is made on a closed line, and a line grows with the column while the load grows with the square of the bay.
Named alongside it
The objects these essays reach for when they reach for this one.
Alternative load pathRobustnessAggregate interlockCatenaryClamping forceCollapse mechanismColumn headCompatibilityControl perimeterDeterminacyDuctilityEffective depth