# Structural Design

Quantity and verification are different jobs. The earlier groups answer how much material; this one answers whether it holds. On the load side there are three: the wind load calculator turns basic wind speed, exposure and height into velocity pressure and design pressure; the snow load calculator turns ground snow and pitch into roof load; and the seismic base shear calculator collapses the earthquake into one horizontal force by the equivalent lateral force method. On the verification side, the bolt capacity calculator shows whether shear or bearing fails first, and the punching shear calculator checks whether the column pushes through the slab.

Three counter-intuitive results are worth reading first. Wind pressure goes with velocity squared, so 25% more wind means 56% more pressure. Roofs feel uplift, not downward push — sizing roof fixings on the 0.8 windward value under-designs them by more than half, which is how light steel roofs come off in cyclones. Snow load multiplies the plan area, not the sloped area; treating it like tiles and applying the roof factor double counts. And punching resistance takes concrete strength as a cube root, so C30 to C50 buys only 18% — depth is the lever, not grade.

- Category page: https://jianzhujisuan.com/en/c/structural-design
- Data checked: 2026-10-25

## Tools in this group

- [Wind Load Calculator](https://jianzhujisuan.com/en/wind-load): Pressure goes with velocity squared; height enters through the exposure power law.
- [Snow Load Calculator](https://jianzhujisuan.com/en/snow-load): Steeper roofs hold less; above 60 degrees the shape coefficient is zero — but not at valleys and parapets.
- [Seismic Base Shear Calculator](https://jianzhujisuan.com/en/seismic-base-shear): Estimate the period, get the coefficient, multiply by seismic weight.
- [Bolt Capacity Calculator](https://jianzhujisuan.com/en/bolt-capacity): Shear or bearing, whichever is lower, governs — above 9 mm plate it is usually shear.
- [Punching Shear Calculator](https://jianzhujisuan.com/en/punching-shear): A column punching through a slab is a race between the perimeter ring and the load.

## Questions

### How do I calculate wind load?

Convert basic wind speed to velocity pressure, qb = 0.5 rho V² with rho 1.25, correct for height and exposure with Kz = 2.01 (z/zg)^(2/alpha), then apply the shape coefficient. At 45 m/s and 10 m in open terrain that is 1.06 kPa velocity pressure and 0.84 kPa on a windward face at Cp 0.8. For total push add windward 0.8 and leeward 0.5; for roofs use the negative value.

### How do I calculate seismic base shear?

V = Cs W with Cs = SDS/(R/I). SDS is the short period spectral acceleration, R the response modification factor for the system — higher for ductile frames, giving lower shear — and I the importance factor. At SDS 1.0, R 5 and I 1.0, Cs is 0.2, so a 10000 kN building takes 2000 kN of base shear.

### How much load can one bolt take?

Whichever of shear and bearing is lower. An M20 grade 8.8 in single shear gives about 120 kN in shear, but against a 10 mm plate with 40 mm edge distance bearing is only 104 kN, so 104 kN is the answer. Thick plates fail the bolt in shear, thin plates crush the hole — for thin plate connections add bolts rather than going up a diameter.