---
title: "Double angle tension member 300 kN"
subject: "Design of Steel and Timber Structure"
chapter: 5
key: "semester_6/design_of_steel_and_timber_structure:tension-double-angle-300kn"
source: https://www.bctengineer.com/q/semester_6/design_of_steel_and_timber_structure/tension-double-angle-300kn
site: BCT Engineering
---

# Double angle tension member 300 kN

Design of Steel and Timber Structure · Chapter 5: Tension Members

- Asked in: 2074 Bhadra, 8 marks
- Video: [Design of double angle tension member](https://www.youtube.com/watch?v=6lqaBPgwjo8) — Simpleciviltamil
- 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/tension-double-angle-300kn
- Whole chapter: https://www.bctengineer.com/md/semester_6/design_of_steel_and_timber_structure/chapter-5

## Question

Design a tension member of double angle section connected on the both sides of gusset plate. Member is subjected to an axial tension of 300 KN.

## Short answer

Use 2 ISA 75×75×6 placed on opposite sides of gusset plate. Connect with 4 M20 grade 4.6 bolts at 50 mm pitch (double shear). Block shear capacity 316 kN governs and exceeds 300 kN.

## Answer

**Assumptions (not given):** factored tension 300 kN, E250 steel, M20 bolts of grade 4.6 in double shear (angles on both faces of a 10 mm gusset), $d_0=22$ mm.

#### 1. Bolts
- $V_{dsb}=\dfrac{400}{\sqrt3\times1.25}(245+314)\times10^{-3}=103.3$ kN
- Bearing on gusset ($e=35,\ p=50$): $k_b=0.508$, $V_{dpb}=83.2$ kN → bolt value $83.2$ kN
- $n=300/83.2=3.6$ → **4 bolts** (pitch 50, end 35 mm); capacity $333.0$ kN.

#### 2. Section
$A_g\ge\dfrac{300\times1.10}{250}\times10^3=1320$ mm². Try **2 ISA 75×75×6** ($2\times866=1732$ mm²), bolt gauge 40 mm from the heel.
- $T_{dg}=393.6$ kN
- Rupture per angle (150 kN): $A_{nc}=(75-3-22)\times6=300$, $A_{go}=(75-3)\times6=432$ mm², $b_s=w+w_1-t=75+40-6=109$ mm, $L_c=150$ mm, $\beta=0.979$; $T_{dn}=184.7$ kN
- Block shear per angle $=158.2$ kN
- Strength of the pair $=2\times158.2=316.3$ kN $\ge300$ ✓ (block shear governs)

Tack bolts (at no more than 1000 mm) with packing between the angles; $L/r\le400$ is satisfied for members up to about 9 m.

**Answer: 2 ISA 75×75×6, one on each side of the gusset, with 4 M20 bolts (4.6) at 50 mm pitch.**

## Check yourself

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

1. Bolt value is the lesser of shear (103.3 kN) and bearing (83.2 kN). What is the bolt value?
   A. 103.3 kN
   B. 186.5 kN
   C. 45.3 kN
   D. 83.2 kN
   Answer: D. The bolt value is the smaller of shear and bearing capacities, so bearing governs. (Key point: Bolt value)

2. How many bolts for 300 kN with a bolt value of 83.2 kN?
   A. 3
   B. 4
   C. 5
   D. 6
   Answer: B. 300/83.2 is about 3.6, so round up to 4 bolts (capacity 333 kN). (Key point: Bolt count)

3. For the pair: Tdg=393.6, Tdn pair=342.8, block shear per angle 158.2 kN. What governs the member strength?
   A. Block shear, 2 x 158.2 = 316.3 kN
   B. Gross yielding, 393.6 kN
   C. Rupture, 342.8 kN
   D. Bolt capacity, 333 kN
   Answer: A. The smallest of the failure modes governs; block shear gives 316.3 kN, which is still above 300 kN. (Key point: Governing check)

## Related in Design of Steel and Timber Structure

- [Double angle tension member 400 kN, M20](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atension-double-angle-400kn-class-c) — Design of Steel and Timber Structure, chapter 5
- [Tension member with lug angle, 400 kN](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atension-lug-angle-400kn) — Design of Steel and Timber Structure, chapter 5, asked 2×
- [Double angle tension member, M18, same side](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atension-double-angle-300kn-m18) — Design of Steel and Timber Structure, chapter 5
- [Single channel tension member, 280 kN](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atension-single-channel-280kn) — Design of Steel and Timber Structure, chapter 5
- [Angle tension member 250 kN with M20](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atension-angle-250kn-m20) — Design of Steel and Timber Structure, chapter 5
- [Single angle tension member, 100 kN](https://www.bctengineer.com/question.md?key=semester_6%2Fdesign_of_steel_and_timber_structure%3Atension-single-angle-100kn-m20) — Design of Steel and Timber Structure, chapter 5

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