Structural Engineering & Statics
where the load goes
Concept

Thermal gradient — where it appears

A temperature difference through the depth of a member, which curves it if it is free and puts moment in it if it is not.

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

024681012141600.511.52cyclescurvature gained ÷ curvature at first yieldM/Mp = 0.30, ΔT = 20°C — elasticM/Mp = 0.60, ΔT = 120°C — shakedownM/Mp = 0.85, ΔT = 200°C — ratcheting

The structure that settles down, and the one that walks

A load that is safe applied once may not be safe applied ten thousand times. Nothing about that is fatigue — the structure never breaks, it simply arrives somewhere slightly further round every cycle, until it has arrived somewhere unusable.

materials · shakedown free at one end10.8 mmno stressheld at both ends75.6 MPaheld by a spring of 100 kN/mm53.2 MPaE·α·ΔT = 210000 × 12×10⁻⁶ × 30 = 75.6 MPa, at every length

The movement nobody applied

A temperature change is the only load in this collection that a structure can decline. Let it move and it produces a movement with no stress; hold it and it produces a stress with no movement — and that stress contains no length, no area and no second moment, so a bracket and a bridge girder carry exactly the same one.

deflection · thermal movement

Named alongside it

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

ServiceabilityBucklingCollapseExpansion jointImposed deformationIndeterminacyKinematic hardeningRatchetingResidual stressRestraintSelf equilibratingSelf stress

All concepts