High-Rise Building

Slab

Idealization of structure

Consider as a one-way continuous slab and design a typical 12 m interior span where

fck = 32 N/mm2

fyk = 460 N/mm2

Cover = 25 mm

Design load

Self-weight of floor plate = 8 kN/m2

Super imposed dead load = 3.5 kN/m2

Live load = 4.0 kN/m2

Design load = 1.2 × (8 + 3.5) + 1.5 × 4.0 = 19.8 kN/m2

Minimum thicknesses of slabs

Ds = 464 mm ≈ 470 mm

Design moments

Moment = 0.086 × 19.8 × 122 = 245.2 kNm/m

Reinforcement

Assume effective depth = 470 – 25 – 10 = 435 mm

K = Mbd2fck = 0.040

z = d21+1-3.53k = 426.6 ≥ 0.95d ………Not ok

z = 0.95d = 419.06 mm

As = M0.87fykz = 1462.1 mm2/m

Use T20 @ 200 mm crs. (1550 mm2/m)

*The dimension of basement slab and typical floor slab are same. So, the thickness is same.

Beam

Idealization of structure

Consider as a 12 m beam with the size of 500 × 1000 mm where

fck = 32 N/mm2

fyk = 460 N/mm2

Cover = 25 mm

Cover for beam

Self-weight of beam = 0.5 × 0.3 × 24 = 3.6 kN/m

Super imposed dead load from slab = 3.5 × 11.65 = 40.775 kN/m

Live load from slab = 4.0 × 11.65 = 46.6 kN/m

Design load = 1.2 × (3.6 + 40.775) + 1.5 × 46.6 = 123.15 kN/m

Design moments

Moment = wl28 = 2216.7 kNm

Reinforcement

Assume effective depth = 1000 – 25 – 16 = 959 mm

K = Mbd2fck = 0.151

z = d21+1-3.53k = 807.2 ≤ 0.95d ……… ok

As = M0.87fykz = 6862 mm2

Use 6T32 + 3T32 (7200 mm2)