🏗️ Define Section Calculator PRO
Preliminary calculator for slab, beam, column, stair, and core-wall sizing.
I. Define Slab Thickness
Meaning: Short span of slab panel.
Use: Used to check one-way/two-way slab and slab thickness.
Example: 4m × 5m slab → Lx = 4m.
Use: Used to check one-way/two-way slab and slab thickness.
Example: 4m × 5m slab → Lx = 4m.
Meaning: Long span of slab panel.
Use: Ly/Lx ≤ 2 = usually two-way slab. Ly/Lx > 2 = usually one-way slab.
Example: 5/4 = 1.25 → two-way slab.
Use: Ly/Lx ≤ 2 = usually two-way slab. Ly/Lx > 2 = usually one-way slab.
Example: 5/4 = 1.25 → two-way slab.
Meaning: Support condition controls minimum thickness.
Use: Choose simply supported, continuous, or cantilever.
Example: Both ends continuous normally allows thinner slab.
Use: Choose simply supported, continuous, or cantilever.
Example: Both ends continuous normally allows thinner slab.
II. Define Beam Section
Meaning: Quick rule for beam depth.
Use: Girder is usually deeper than normal beam.
Example: 5m span with L/14 → 5000/14 = 357mm.
Use: Girder is usually deeper than normal beam.
Example: 5m span with L/14 → 5000/14 = 357mm.
Meaning: Preliminary width from height.
Use: Tool uses width ≈ h/2, minimum 200mm.
Example: h = 400mm → b ≈ 200mm.
Use: Tool uses width ≈ h/2, minimum 200mm.
Example: h = 400mm → b ≈ 200mm.
III. Define Column Section
Meaning: Distance from column center to next column/beam at left side in X direction.
Use: Column receives half load from this side.
Example: Left bay = 4m → input 4.
Use: Column receives half load from this side.
Example: Left bay = 4m → input 4.
Meaning: Distance from column center to next column/beam at right side.
Use: X tributary = (X Left + X Right) / 2.
Example: 4m + 6m → X tributary = 5m.
Use: X tributary = (X Left + X Right) / 2.
Example: 4m + 6m → X tributary = 5m.
Meaning: Distance from column center to next column/beam at upper side.
Use: Column receives half load from upper bay.
Example: Up span = 5m → input 5.
Use: Column receives half load from upper bay.
Example: Up span = 5m → input 5.
Meaning: Distance from column center to next column/beam at lower side.
Use: Y tributary = (Y Up + Y Down) / 2.
Example: 5m + 5m → Y tributary = 5m.
Use: Y tributary = (Y Up + Y Down) / 2.
Example: 5m + 5m → Y tributary = 5m.
Meaning: Permanent load excluding slab self-weight.
Use: Floor finish, ceiling, MEP, partition allowance.
Example: Tile + ceiling ≈ 1.5 kN/m².
Use: Floor finish, ceiling, MEP, partition allowance.
Example: Tile + ceiling ≈ 1.5 kN/m².
Meaning: People, furniture, and usage load.
Use: Choose by building function/code.
Example: Residential preliminary ≈ 2.0 kN/m².
Use: Choose by building function/code.
Example: Residential preliminary ≈ 2.0 kN/m².
Meaning: Number of floors supported by this column.
Use: Input floors above the checked column.
Example: Ground column supports 3 floors → input 3.
Use: Input floors above the checked column.
Example: Ground column supports 3 floors → input 3.
Meaning: Concrete compressive strength.
Use: Use project concrete grade.
Example: 25MPa or 30MPa.
Use: Use project concrete grade.
Example: 25MPa or 30MPa.
Meaning: Rebar yield strength.
Use: Use steel grade from supplier/spec.
Example: 390MPa or 420MPa.
Use: Use steel grade from supplier/spec.
Example: 390MPa or 420MPa.
Meaning: Steel area ratio in column.
Use: Preliminary value often 1%–4%.
Example: 0.02 = 2% steel.
Use: Preliminary value often 1%–4%.
Example: 0.02 = 2% steel.
IV. Define Stair + Core-Wall Thickness
Meaning: Design span or inclined span of stair slab.
Use: Estimate stair slab thickness.
Example: 3.6m → input 3.6.
Use: Estimate stair slab thickness.
Example: 3.6m → input 3.6.
Meaning: Support condition for stair slab.
Use: Simply supported stair usually needs thicker slab.
Example: 3.6m / 20 = 180mm.
Use: Simply supported stair usually needs thicker slab.
Example: 3.6m / 20 = 180mm.
Meaning: Height of concrete core/shear wall segment.
Use: Used for preliminary thickness check.
Example: Floor height 3m → input 3.
Use: Used for preliminary thickness check.
Example: Floor height 3m → input 3.
Meaning: Minimum wall thickness.
Use: Common preliminary minimum 150mm or 200mm.
Example: Small core wall → start 150mm.
Use: Common preliminary minimum 150mm or 200mm.
Example: Small core wall → start 150mm.
Click Calculate to show result.