Shake Table Lab Blender 5.2

A 1:25 laboratory shake table carries three model buildings: a stiff low-rise, a tall flexible frame and a tall frame with base isolators or a tuned mass damper. Each is a multi-storey shear-building model solved with modal damping and Newmark integration. Drag to orbit, wheel or pinch to zoom, right-drag to pan. This is a physics lesson on scale models: numbers and colours only.

Presets

Ground motion (the table)

Input

Peak ground acceleration

Soil

Pulse period Tp

Shaking frequency

Sweep 0.2 Hz up to

Speed

Buildings

Storeys

Fundamental period T1 (fixed base)

Damping ratio of the frame

Same frame as the tall building

Protection

Isolation period T_iso

Isolator damping ratio

Mass ratio of the damper (to modal mass)

Tuning (1.00 = Den Hartog optimum)

Damper damping ratio

Display

Motion exaggeration (models are 1:25, shaking is scaled up for the eye)

Damage colours (peak drift so far) Labels

Graphs

Ground acceleration (g) and roof displacement (cm, prototype scale) of the three buildings

Response spectrum of this ground motion (5 % damped pseudo-acceleration) with each building's period marked. Tall dots = building periods

Peak inter-storey drift ratio by storey, selected building (colour bands = damage levels)

Mode shapes of the selected building (eigen decomposition)

Experiment: where does each building resonate?

Question: at which shaking frequency does the selected building amplify the ground motion most, by how much, and does the full multi-storey time simulation agree with the exact frequency-response (transmissibility) calculation? Every point below shakes the model with a constant-amplitude sine until the transient dies out, then fits the roof acceleration amplitude. The solid line solves the complex linear system (K - w²M + i w C) U = -M r independently; the dashed line is the textbook single-mass transmissibility sqrt((1+(2ζr)²)/((1-r²)²+(2ζr)²)) with r = f T1.

Numerical checks

The science