Column Weight Calculator: Steel, RCC & Concrete Columns

General Weight Formula

$$W = V \times \rho$$

Where: $W$ = Weight (kg), $V$ = Volume (m³), $\rho$ = Density (kg/m³)

Solid Rectangular / Square Column

$$V = b \times D \times H \quad \Rightarrow \quad W = b \times D \times H \times \rho$$

Where: $b$ = width, $D$ = depth, $H$ = height (all in metres)

Solid Circular Column

$$V = \frac{\pi d^2}{4} \times H \quad \Rightarrow \quad W = \frac{\pi d^2 H \rho}{4}$$

Hollow Rectangular Section (RHS/HSS)

$$V = \left(B \times D - b_{i} \times d_{i}\right) \times H$$

$$b_{i} = B - 2t_w, \quad d_{i} = D - 2t_f$$

Hollow Circular Section (CHS)

$$V = \frac{\pi}{4}\left(D_o^2 - D_i^2\right) \times H \quad \text{where} \quad D_i = D_o - 2t$$

Steel Bar Unit Weight (Metric)

$$w = \frac{D^2}{162} \; \text{kg/m} \qquad (D \text{ in mm})$$

Derivation: $w = \rho \times A = 7850 \times \frac{\pi D^2}{4 \times 10^6} \approx \frac{D^2}{162}$

Steel Bar Unit Weight (Imperial)

$$w = \frac{D^2}{533} \; \text{kg/ft} \qquad (D \text{ in mm})$$

Total Main Bar Weight

$$W_{main} = n \times L_{bar} \times \frac{D_{bar}^2}{162}$$

Where: $n$ = number of bars, $L_{bar}$ = total bar length including laps & hooks (m)

Stirrup Cutting Length (Rectangular)

$$L_{stirrup} = 2(b' + d') + 2 \times L_{hook} - \text{bend deductions}$$

$$b' = b - 2c, \quad d' = D - 2c \quad \text{(c = clear cover)}$$

Hook length: 90° = 2d, 135° = 10d (seismic), 180° = 4d

Number of Stirrups

$$n_{mid} = \left\lfloor \frac{L - 2 \times z}{s_{mid}} \right\rfloor + 1$$ $$n_{end} = \left\lfloor \frac{z}{s_{end}} \right\rfloor \times 2$$

$z$ = end zone length, $s$ = spacing

Steel Reinforcement Percentage

$$p_t = \frac{A_{st}}{A_g} \times 100 \quad (\%)$$

IS 456 limits: $0.8\% \leq p_t \leq 4.0\%$ (up to 6% at lap zones)

Euler Critical Buckling Load

$$P_{cr} = \frac{\pi^2 E I}{(KL)^2}$$

Where: $E$ = Young's modulus, $I$ = second moment of area, $K$ = effective length factor, $L$ = unsupported length

Slenderness Ratio

$$\lambda = \frac{KL}{r} \qquad \text{where} \quad r = \sqrt{\frac{I}{A}}$$

AISC Limiting Slenderness

$$\lambda_r = 4.71\sqrt{\frac{E}{F_y}}$$

If $\lambda \leq \lambda_r$: inelastic buckling; if $\lambda > \lambda_r$: elastic buckling governs

Section Properties

Rectangular: $I_{xx} = \frac{bD^3}{12}, \quad I_{yy} = \frac{Db^3}{12}$

Circular: $I = \frac{\pi d^4}{64}$

Hollow Rect: $I_{xx} = \frac{BD^3 - b_i d_i^3}{12}$

Hollow Circ: $I = \frac{\pi(D_o^4 - D_i^4)}{64}$