Creep — where it appears
The deflection that arrives three years late
A concrete beam that passes every check on the day it is built goes on deflecting for a decade, and ends up three times where it started. Nothing about the load changed, and nothing about the strength was ever in question.
The strain that was imposed, and the stress that leaked away
Multiply a restrained shrinkage strain by the modulus and the answer is three times the tensile strength — which predicts that every restrained concrete member ever cast has cracked. Most have not, and the reason is that the material creeps while it is being stressed.
The hour that is really a temperature
A fire rating is quoted in minutes and there is no time in the physics anywhere. What decides is a temperature, and the stiffness reaches its limit sixty degrees before the strength does — so the way a member fails can change while it is burning.
Named alongside it
The objects these essays reach for when they reach for this one.
Elastic modulusShrinkageAgeing coefficientBucklingCracked sectionCrackingCritical temperatureDeflectionEffective modulusFireImposed deformationLoad ratio