Design a building by selecting its height, width, and foundation system. Adjust local ground acceleration and compare sway across foundation systems. The results use an assumed classroom model and do not predict the safety of real buildings.
If you change the foundation from rigid to base isolation, how will that affect the building's ability to survive a major earthquake?
Write your hypothesis in the Lab Report panel, then click Next.
Changing the scenario selects an assumed local acceleration. You can edit the acceleration directly. Magnitude alone cannot predict shaking at a building.
Each prediction uses the same 6 storeys, width 3 and 0.056 g local shaking.
| Foundation | Sway as % of height | Model result |
|---|---|---|
| Rigid | 0.04% | Below limit |
| Base Isolation | 0.02% | Below limit |
| Dampers | 0.03% | Below limit |
This qualitative classroom model treats each tower as a cantilever with stiffness proportional to width cubed and inversely proportional to height cubed. It assumes 500 kg per storey, fixed material rigidity and foundation force factors of 1.00, 0.45 and 0.65. A sway of 3% of height is an assumed comparison limit. It does not model resonance, soil response, structural damage or real collapse. The animation is illustrative. Results are not engineering safety predictions.
| # | Trial | Storeys | Width | Foundation | Magnitude(M) | Local PGA(g) | Max Sway(%H) | Result | Notes |
|---|
Magnitude describes the size of an earthquake. Shaking at a building depends on distance, depth, local ground conditions and the motion over time. This lab uses an assumed scenario mapping and lets you set peak ground acceleration directly.
The scenario mapping is 0.1 × 10(M − 5.5) / 2 g, capped at 2 g. It is a teaching assumption rather than a ground motion prediction. See the USGS explanation of magnitude and intensity.
Each storey represents 3 m of height and 500 kg of mass. Each width unit represents 5 m. The model treats the building as a cantilever with stiffness k = 3EI/H³ and an assumed EI of 16.67 million times width units cubed, in N m².
Static sway is force divided by stiffness. Taller towers sway more and wider towers sway less under these assumptions. The 3% height limit is an instructional comparison rule. It is not a structural design limit or a prediction of collapse.
The rigid case transmits all of the assumed lateral force. Base isolation uses a factor of 0.45 and dampers use 0.65. These fixed factors make comparisons repeatable. They are not measured reductions for particular devices.
Real designs depend on motion frequency, soil, material properties and structural details. USGS observations of earthquake protection describe measured building responses. This lab does not model resonance, soil response or damage accumulation.
