Shake a five-storey frame until it fails.

1. Model the building as masses and springs — one horizontal degree of freedom per floor.
2. Shake it with a ground motion and integrate the equations of motion in real time.
3. Measure inter-storey drift: how far each floor moves relative to the one below it.
4. Decide where to stiffen. Each storey has six braceable bays; filling all six roughly triples that storey's stiffness. An unbraced frame here reaches about 2.7% drift and fails the 2% limit, while a fully braced one drops the natural period from 0.49 s to 0.29 s and peak drift to about 0.4%. Where the bracing goes matters as much as how much of it there is — leave one storey soft and the drift concentrates there.
5. Cost it. A brace low in the building resists the shear of every storey above it, so it is the expensive one: Rs 6 lakh on the ground storey down to Rs 2 lakh at roof level. Bracing every bay costs Rs 120 lakh against a Rs 55 lakh budget. Making a building stand is not the hard part. Making it stand cheaply is the job.
6. Check it against more than one earthquake. Three records shake the frame here, with dominant periods of 0.50 s, 0.43 s and 0.29 s. Bracing shortens the building's own period — from 0.49 s bare to 0.29 s fully braced — so stiffening moves it away from one record and straight onto another. Bracing every bay survives the first two and then fails the short, sharp third one at 2.27% drift, while the unbraced frame rides that same record out at 1.00%. The cheapest layout that beats one record costs Rs 11 lakh; the cheapest that beats all three costs Rs 35 lakh, and it tapers from the ground up — three braces on the ground storey, two above, then one, one, none. This is why a real design is checked against a spectrum of motions and not a favourite earthquake.

Running that check before anything is built is the everyday work of a structural engineer, and it is taught in the Civil Engineering programme at ICE.