Wind — IS 875 (Part 3)
Cl. 6.3 Vz = Vb·k1·k2·k3·k4 · Cl. 7.2 pd
k2 (height & terrain)
0.91
Table 2
Design speed Vz
35.49m/s
pz = 0.6 Vz²
0.76kN/m²
pd (Kd·Ka·Kc)
0.68kN/m²
Cl. 7.2
Net pressure
0.65kN/m²
Cpe 0.7 / −0.25
Building height
7.00m
Base shear — wind on long face
27.14kN
Base shear — wind on short face
47.49kN
Seismic — IS 1893 (Part 1)
Cl. 7.2.1 Ah = (Z/2)(I/R)(Sa/g) · Cl. 7.6.2 T = 0.09h/√d
Period T
0.26s
Sa/g
2.50
Zone factor Z
0.16
Ah
0.07
design horizontal coefficient
Seismic weight W
1460.87kN
DL + 25% LL
Base shear Vb
97.39kN
Storey forces — Cl. 7.6.3 (Wi·hi² distribution)
| Level | hi (m) | Wi (kN) | Qi seismic (kN) | Wind (kN) |
|---|---|---|---|---|
| Floor 1 | 3.80 | 926.3 | 32.92 | 20.94 |
| Roof | 7.00 | 534.5 | 64.47 | 6.20 |
Seismic governs. Seismic base shear 97.4 kN vs wind 47.5 kN. That shear is shared between the columns and added to the gravity moments on the design step. For a house of this size the frame is still sized by gravity load — the lateral case mainly sets the minimum column reinforcement and tie detailing.