Structural Design calculators
Structural design calculators: wind load, snow load, seismic base shear, bolt shear and bearing, slab punching shear, live load and seismic detailing.
What this group solves
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.
Two things only: where the loads come from, and whether the member carries them. The order is not negotiable — dead and live loads first, then combinations; wind, snow and seismic next, then the governing case. The three load tools here return characteristic values. Design still needs partial factors and combination (1.2 dead + 1.6 live, or 1.2 dead + 1.0 live + 1.0 wind), and the worst combination is what goes into the member check.
On the verification side the usual error is picking the wrong lever. In a bolted connection shear and bearing compete and thin plates always lose on bearing. In punching shear the concrete strength enters as a cube root, so C30 to C50 buys only 18% while depth buys 40%. Those are not footnotes — they decide which way to change the design, and getting them backwards means adjusting parameters for an hour with no movement in the answer.
Which one for your case
| Basic wind speed — pressure on a wall or roof | Wind Load Calculator |
| Ground snow load and roof pitch — roof snow load | Snow Load Calculator |
| Total horizontal earthquake force at the base of a building | Seismic Base Shear Calculator |
| Steel connection — what one bolt carries | Bolt Capacity Calculator |
| Will the column punch through the slab | Punching Shear Calculator |
| What live load to use, and where the code table is | Floor Live Load Lookup |
| Section sizing and whether hoops need tightening | Column Confinement Zone Calculator |
| Movement joints on a long structure and how wide | Movement Joint Width Calculator |
Where this group goes wrong
- Sizing roof fixings on windward pressure. Roofs see suction: at 10-30 degrees Cp reaches −0.9 to −1.2, larger than 0.8 and in the opposite direction. Designing for +0.8 halves the number of screws and is exactly how roofs peel off in a cyclone.
- Applying the roof factor to snow. Snow is measured over its plan footprint and the pitch reduction is already inside mu1, so multiplying by 1/cos(pitch) counts it twice — 15% extra at 30 degrees, eating half the margin.
- Scaling wind pressure linearly with speed. Going from 40 to 50 m/s is 25% more wind but 56% more pressure, because it is squared. Proportioning a cyclone-region scheme under-predicts badly.
- Expecting a higher concrete grade to fix punching. fck enters as a cube root, so C30 to C50 is 18%, while 20% more depth gives over 40% because d appears three times. Wrong lever, money spent, no gain.
- Checking bolt shear and forgetting bearing. An M20 grade 8.8 looks generous at 120 kN in shear, but against a 10 mm plate with 40 mm edge distance bearing is 104 kN and governs — and below 1.5d0 edge distance the plate simply tears out.