---
title: "Splicing of bars and conditions"
subject: "Design of RCC Structure"
chapter: 7
key: "semester_7/design_of_rcc_structure:splicing-of-bars-and-conditions"
source: https://www.bctengineer.com/q/semester_7/design_of_rcc_structure/splicing-of-bars-and-conditions
site: BCT Engineering
---

# Splicing of bars and conditions

Design of RCC Structure · Chapter 7: Reinforcement detailing: Codal Provisions

- Asked in: 2068 Baisakh (old course), 5 marks
- Video: [Lapping in Beams || Basic Rules and design](https://www.youtube.com/watch?v=4AlLSFhZ0ao) — Civil Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/design_of_rcc_structure/splicing-of-bars-and-conditions
- Whole chapter: https://www.bctengineer.com/md/semester_7/design_of_rcc_structure/chapter-7

## Question

What do you understand by splicing of bars? Write down the primary conditions for the application of splicing in reinforced concrete structures.

## Short answer

Splicing joins bars via lap, welded, or mechanical splices. Conditions per IS 456 cl. 26.2.5: locate away from max stress, stagger splices (max 50% at one section), lap length ≥ Ld or 30φ (tension), ≥ 2Ld or 30φ (direct tension), ≥ Ld or 24φ (compression); no laps for bars >36mm; provide transverse reinforcement; in seismic zones, laps only in central half of column height with hoops.

## Answer

**Splicing** of bars is the process of joining two bars end to end so that stress is transferred from one to the other. The usual methods are (i) the lap splice, where the bars overlap and the force passes through bond with the surrounding concrete, (ii) the welded splice, and (iii) the mechanical splice with couplers.

#### Primary conditions for splicing (IS 456 cl. 26.2.5)
1. **Location**: splices should be kept away from sections of maximum tensile stress. They are best placed where the bending moment is small, e.g. column bars just above floor level, or beam bottom bars near the supports.
2. **Staggering**: splices should be staggered, and not more than half of the bars should be spliced at one section. Bars in a lap are placed in contact, or with a clear gap of not more than $4\phi$, so that stress is transferred properly.
3. **Lap length** (including the anchorage value of hooks):
   - flexural tension: not less than $L_d$ or $30\phi$, whichever is greater;
   - direct tension: not less than $2L_d$ or $30\phi$, whichever is greater;
   - compression: not less than $L_d$ (in compression) or $24\phi$, whichever is greater.
4. **Bar size**: lap splices are not used for bars larger than 36 mm. Such bars are welded or joined with mechanical couplers, and the strength of the joint must be at least that of the bar.
5. **Transverse steel**: closely spaced stirrups or ties are provided around the lap zone to confine the concrete and prevent splitting.
6. In members subjected to repeated or reversed loading, mechanical splices are preferred to laps. In seismic zones (IS 13920), lap splices in columns are placed only in the central half of the column height and are enclosed by closely spaced hoops.

## Check yourself

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

1. Where should splices be placed?
   A. Anywhere without restriction
   B. Only at supports of cantilevers
   C. At the section of maximum moment
   D. Away from sections of maximum tensile stress
   Answer: D. Splices should be where bending moment is small. (Key point: Location)

2. Which statement on splice arrangement is correct?
   A. Bars in a lap must be 10φ apart
   B. Splices must be at the same level
   C. Splices are staggered and not more than about half the bars spliced at one section
   D. All bars are spliced at one section
   Answer: C. Staggering avoids weak sections. (Key point: Staggering)

3. Minimum lap in direct tension is
   A. Not less than 2Ld or 30φ
   B. Not less than 12φ
   C. Not less than Ld/2
   D. Not less than 24φ
   Answer: A. Direct tension lap is 2Ld or 30φ, whichever is greater. (Key point: Lap length)

4. What is done for bars larger than 36 mm?
   A. They are lapped by 12φ
   B. They are not used
   C. They are welded or joined with mechanical couplers, not lapped
   D. They are lapped with 2Ld
   Answer: C. Lap splices are not used for bars above 36 mm. (Key point: Bar size)

## Related in Design of RCC Structure

- [Characteristics of reinforcing steel bars](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Acharacteristics-of-reinforcing-steel-bars) — Design of RCC Structure, chapter 3
- [Bent-up bars, 600 mm effective depth](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Abent-up-bars-600-mm-effective) — Design of RCC Structure, chapter 5, asked 2×
- [Splicing: meaning and need](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Asplicing-meaning-and-need) — Design of RCC Structure, chapter 7
- [Footing 350x350, 8-16 mm bars, reversible moment](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Afooting-350x350-8-16-mm-bars) — Design of RCC Structure, chapter 11
- [Ultimate moment of L-beam, doubly reinforced](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Aultimate-moment-of-l-beam-doubly) — Design of RCC Structure, chapter 4
- [Moment of resistance of doubly reinforced beam](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Amoment-of-resistance-of-doubly-reinforced) — Design of RCC Structure, chapter 4

## Related in other subjects

- [Reinforced concrete column stresses in steel and concrete](https://www.bctengineer.com/question.md?key=semester_3%2Fstrength_of_materials%3Arc-column-8-bars) — Strength of Materials, chapter 3
- [Primary and secondary structures; strike and dip](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aprimary-and-secondary-structures-strike) — Engineering Geology I, chapter 5, asked 2×
- [Primary versus secondary geological structures](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aprimary-versus-secondary-geological-structures) — Engineering Geology I, chapter 5, asked 4×
- [Fiber reinforced polymers and applications](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Afiber-reinforced) — Engineering Chemistry, chapter 4, asked 2×