Structural Engineering & Statics
where the load goes
Concept

Effective modulus — where it appears

A reduced elastic modulus, E/(1 + phi), that reproduces the strain a creeping material reaches under a stress held constant. It turns a time-dependent problem into an elastic one at the cost of assuming the stress never changed, and it takes a member's buckling load down with it.

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

1 d10 d100 d2.7 yr27 yr0123time under loaddeflection ÷ the deflection on day one1 year: ×3.005 years: ×3.29the deflection the calculation gives

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.

materials · creep 3210031610003162100000102030405060age (days, logarithmic)eccentricity including P-delta (mm)settles at 60 mmand this one does notfirst order 20 mmlong-term critical load 29% of the day-one one

The column that fails years later

A concrete column under sustained load goes on straining at constant stress, so its deflection grows — and because the second-order moment is the load times that deflection, the demand grows with it. There is a load below which the two settle and one above which they never do.

stability · creep buckling

Named alongside it

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

CreepServiceabilitySustained loadAmplificationBucklingCracked sectionCreep bucklingDeflectionDivergenceDuration of loadEccentricityElastic modulus

All concepts