---
title: "Deodar column 4 m, 300 kN"
subject: "Design of Steel and Timber Structure"
chapter: 11
key: "semester_6/design_of_steel_and_timber_structure:timber-column-deodar-4m-300kn"
source: https://www.bctengineer.com/q/semester_6/design_of_steel_and_timber_structure/timber-column-deodar-4m-300kn
site: BCT Engineering
---

# Deodar column 4 m, 300 kN

Design of Steel and Timber Structure · Chapter 11: Design of Compression Members

- Asked in: 2070 Magh, 10 marks
- Video: [Design of Column | Timber Designing | IOE TU](https://www.youtube.com/watch?v=IA1CXpJH1FM) — Parash Joshi - Civil Construction and Tutor
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/design_of_steel_and_timber_structure/timber-column-deodar-4m-300kn
- Whole chapter: https://www.bctengineer.com/md/semester_6/design_of_steel_and_timber_structure/chapter-11

## Question

Design a deodar column 4 m long to carry an axial load of 300 kN.

## Short answer

Use working stress design to IS 883. Intermediate column; effective length 4 m. Provide 225 mm x 225 mm deodar column, capacity 318 kN > 300 kN.

## Answer

**Approach.** Working stress design to IS 883:1994 (cl. 7.6 for columns, cl. 7.7 for combined axial compression and bending). Ends are taken as pin-ended, so the effective length equals the unsupported length $S$ (cl. 7.6.1.5).

#### Data and permissible stresses

Length $S = 4.00$ m = 4000 mm. Axial load $N = 300$ kN.

**Species:** Deodar (Cedrus deodara), Group C. **Location:** inside. **Grade:** Grade I (standard) (Table 1 values are for Grade I).

Permissible stresses (IS 883:1994 Table 1, inside location):

| Property | Table 1 value (N/mm²) | Used (N/mm²) |
|---|---|---|
| Bending / tension along grain $f_b$ | 10.2 | 10.20 |
| Compression parallel to grain $f_{cp}$ | 7.8 | 7.80 |
| Compression perpendicular to grain $f_{cn}$ | 2.7 | 2.70 |
| Horizontal shear $H$ | 0.7 | 0.70 |
| Modulus of elasticity $E$ | 9480 | 9480 |

Location and grade not stated: **inside**, Grade I (standard) assumed; a square section is chosen.

#### Trial section

Try **225 mm × 225 mm** (square). Area $A = 50,625$ mm²; least dimension $d = 225$ mm.

#### Slenderness and permissible axial stress (cl. 7.6.1)

$$
\begin{aligned} S/d &= \frac{4000}{225} = 17.8 \\ K_8 &= 0.584\sqrt{\frac{E}{f_{cp}}} = 0.584\sqrt{\frac{9480}{7.80}} = 20.36 \end{aligned}
$$

$11 < S/d = 17.8 < K_8 = 20.4$, so it is an **intermediate column**:

$$
f_c = f_{cp}\left[1 - \frac{1}{3}\left(\frac{S/d}{K_8}\right)^4\right] = 7.80\left[1 - \frac{1}{3}\left(\frac{17.8}{20.4}\right)^4\right] = 6.29\ \text{N/mm}^2
$$

$S/d = 17.8 < 50$ (cl. 7.6.1.4). OK.

#### Check

$$
P = f_cA = 6.29\times50,625/10^3 = 318.4\ \text{kN} \ge N = 300\ \text{kN}
$$

Safe.

#### Answer

Provide a solid Deodar column of **225 mm × 225 mm** cross-section (Grade I (standard), inside location). Capacity $318$ kN $> 300$ kN.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Location is not stated. What is assumed?
   A. Inside, Grade I
   B. Outside, Grade I
   C. Inside, Select grade
   D. Outside, Select grade
   Answer: A. The answer assumes inside location and Grade I when not stated. (Key point: Location assumption)

2. S/d = 17.8, K8 = 20.36. What class?
   A. Short
   B. Intermediate
   C. Long
   D. Over limit
   Answer: B. 11 < 17.8 < 20.36 gives intermediate. (Key point: Classification)

3. Using fc = 6.29 N/mm^2 for 225 x 225 mm, what is the result?
   A. 318 kN > 300 kN, safe
   B. 318 kN < 300 kN
   C. 225 kN
   D. 400 kN unsafe
   Answer: A. P = 6.29 x 50,625 = 318.4 kN. (Key point: Capacity)

## Related in Design of Steel and Timber Structure

- [Box deodar column, 60 mm planks, 350 kN](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atimber-box-column-deodar-5m-350kn) — Design of Steel and Timber Structure, chapter 11
- [Square deodar column 4 m, 350 kN, outside](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atimber-column-deodar-square-4m-350kn) — Design of Steel and Timber Structure, chapter 11
- [Square deodar column 4 m, 250 kN, open shed](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atimber-column-deodar-4m-250kn) — Design of Steel and Timber Structure, chapter 11
- [Built-up laced column, 10 m, 1000 kN](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Abuiltup-1000kn-10m-lacing) — Design of Steel and Timber Structure, chapter 6, asked 4×
- [Built-up column, lacing, 8 m, 1100 kN](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Abuiltup-lacing-1100kn-8m-fe410) — Design of Steel and Timber Structure, chapter 6, asked 4×
- [Built-up column with battens, 10 m, 1080 kN](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Abuiltup-battens-1080kn-10m) — Design of Steel and Timber Structure, chapter 6, asked 4×

## Related in other subjects

- [Brick column design for 80 kN axial load](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Abrick-column-80kn-roof) — Concrete Technology and Masonry Structure, chapter 8
- [Timber column under axial load and bending](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Atimber-column-combined-bending-axial) — Design of Timber and Masonry Structures, chapter 3
- [Safe axial load on a timber column](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Aaxial-capacity-timber-column) — Design of Timber and Masonry Structures, chapter 3
- [Corner stresses of 500 x 900 column (300 kN)](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Acolumn-stress-500x900-300kn) — Concrete Technology and Masonry Structure, chapter 8, asked 7×