Why are triangles used so often in trusses?
AnswerA triangle cannot change shape without changing a side length
A triangle's angles are fixed by its three sides, so a triangular frame stays rigid under load.
Science · Facts & stats
Support facts & stats
7 fact-checked facts about structural supports, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
A rope holding up a hanging weight is under which kind of force?
AnswerTension
Tension pulls a material apart along its length, as in a rope or cable holding a load.
Going deeper
A stone arch carries its load mainly by which kind of force?
AnswerCompression
An arch turns downward loads into compression that flows through the stones to its supports.
What is a cantilever?
AnswerA beam supported at only one end
A cantilever is fixed at one end and projects freely, like a diving board or balcony.
Flying buttresses are best known for supporting the walls of which buildings?
AnswerGothic cathedrals
Flying buttresses carry sideways thrust from high vaults outward, letting Gothic cathedrals have tall walls with big windows.
Expert level
Why do I-beams put most of their material in the top and bottom flanges?
AnswerMaterial far from the centre best resists bending
Bending stress is greatest farthest from a beam's centre, so flanges there give high stiffness for little weight.
What is a caryatid in architecture?
AnswerA sculpted female figure used as a column
A caryatid is a carved female figure acting as a support, famously on the Erechtheion in Athens.
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