---
title: "In-plane, out-of-plane failure and remedial measures"
subject: "Concrete Technology and Masonry Structure"
chapter: 9
key: "semester_5/concrete_technology_and_masonry_structure:in-plane-out-of-plane-remedial"
source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/in-plane-out-of-plane-remedial
site: BCT Engineering
---

# In-plane, out-of-plane failure and remedial measures

Concrete Technology and Masonry Structure · Chapter 9: Masonry structures under lateral loads

- Asked in: 2081 Baisakh, 6 marks
- Video: [Difference between In Plane and Out of Plane Loading](https://www.youtube.com/watch?v=-O6Vx2IlOEo) — Civil Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/in-plane-out-of-plane-remedial
- Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-9

## Question

Describe the in-plane and out-of-plane failure behaviour of masonry structure and its remedial measures.

## Short answer

In-plane failures: sliding, diagonal shear, rocking. Out-of-plane: overturning, vertical/horizontal bending. Remedial measures include RCC bands, vertical corner reinforcement, cross walls, rigid diaphragms, limited openings away from corners, and good-quality mortar.

## Answer

#### In-plane behaviour (force parallel to the wall)

The wall acts as a shear wall and is stiff and strong. Failure modes:

- **Sliding shear:** horizontal crack along a bed joint when the vertical load is small.
- **Diagonal shear (X-crack):** diagonal tension cracking, through the joints (stair-step) or through the units.
- **Rocking / toe crushing:** a slender wall or pier rotates about its toe, with horizontal cracks at the heel and crushing at the toe.

#### Out-of-plane behaviour (force perpendicular to the wall)

The wall acts as a thin plate or cantilever in bending; it has little tensile capacity and fails suddenly:

- **Overturning / rocking** of parapets, gables and free-standing walls about the base.
- **Vertical bending:** horizontal crack at mid-height between floor and roof.
- **Horizontal bending:** vertical cracks and collapse at wall junctions or between cross walls.
- **Two-way bending:** diagonal cracks from the corners when the wall is supported on all edges.

```text
 In-plane              Out-of-plane
 +--------+            ---|||---> force
 |\  X  /|             |wall|  crack at mid-height
 | \  / |  F ->        |~~~~|
 +--------+            ====== base
```

#### Remedial and preventive measures

1. RCC or timber **bands** (plinth, lintel, roof) to tie the walls together and give box action.
2. **Vertical reinforcement** at corners, junctions and jambs, anchored in the foundation and the roof band.
3. Limit the **height-to-thickness and length-to-thickness** ratios; provide cross walls, buttresses or pilasters.
4. Small openings (total width limited to about one-third to one-half of the wall length, depending on the number of storeys, as in IS 4326), located away from corners, with a lintel band.
5. A **rigid diaphragm** (RCC slab) or a properly braced roof anchored to the walls.
6. Good-quality bricks and mortar, proper bond and curing.
7. Repair and retrofit of existing buildings: grouting of cracks, steel mesh with plaster, ferrocement jacketing, and installation of bands.

## Check yourself

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

1. When does sliding shear occur along a bed joint?
   A. When vertical load is small
   B. When vertical load is large
   C. When wall is reinforced
   D. When mortar is rich
   Answer: A. Low compression gives low friction. (Key point: Sliding shear)

2. What limit on openings is suggested?
   A. Half the wall near corners
   B. Not more than one-third of wall length, away from corners, with lintel band
   C. No limit
   D. Only at corners
   Answer: B. Small, well-placed openings protect walls. (Key point: Remedy for openings)

3. Which measure ties walls and gives box action?
   A. Heavier roof
   B. Thinner walls
   C. Lime plaster only
   D. RCC or timber bands plus vertical reinforcement at corners and jambs
   Answer: D. Bands and vertical bars are the main preventive measures. (Key point: Box action measure)

## Related in Concrete Technology and Masonry Structure

- [In-plane and out-of-plane behaviour of masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ain-plane-out-of-plane-behaviour) — Concrete Technology and Masonry Structure, chapter 9, asked 9×
- [In-plane, out-of-plane; ductile behaviour](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ain-out-plane-ductile-behaviour) — Concrete Technology and Masonry Structure, chapter 9
- [Causes and crack patterns of out-of-plane failure](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aout-of-plane-failure-causes) — Concrete Technology and Masonry Structure, chapter 9

## Related in other subjects

- [In-plane and out-of-plane behaviour of masonry walls](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Ain-plane-out-of-plane-behavior) — Design of Timber and Masonry Structures, chapter 6
- [Remedial measures for slope failure](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aslope-remedial-measures) — Soil Mechanics, chapter 11
- [Out-of-plane bending of a masonry wall](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Aout-of-plane-wall-flexure-check) — Design of Timber and Masonry Structures, chapter 6
- [Remedial measures for sediment deposition in RoR](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aror-sediment-deposition-remedial-measures) — Hydropower Engineering, chapter 5