---
title: "Configuration factors for seismic safety"
subject: "Building Technology"
chapter: 11
key: "semester_6/building_technology:config-factors-seismic"
source: https://www.bctengineer.com/q/semester_6/building_technology/config-factors-seismic
site: BCT Engineering
---

# Configuration factors for seismic safety

Building Technology · Chapter 11: Earthquake protection & Retrofitting in building

- Asked in: 2079 Asoj, 5 marks; 2079 Jestha, 5 marks (asked 2 times)
- Video: [Top 5 Ways Engineers “Earthquake Proof” Buildings - Explained by a Structural Engineer](https://www.youtube.com/watch?v=141Zmuw9Xcg) — Mat Picardal
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/config-factors-seismic
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-11

## Question

What are the basic configuration related factors that should be considered for improving building for seismic safety? (Explain any five basic configuration factors considered while designing earthquake resistant buildings.)

## Short answer

Key configuration factors: simple symmetric plan; plan aspect ratio ≤3; symmetry of mass and stiffness to prevent torsion; regular elevation without soft storey; and light weight with low height.

## Answer

Configuration means the overall size, shape and arrangement of the structural and non-structural elements of a building. A good configuration is the cheapest way to improve seismic safety.

#### 1. Simple, symmetrical plan
Square or rectangular plans resist earthquakes best. Irregular shapes (L, T, U, H) twist and concentrate stress at re-entrant corners; where such shapes are needed, separate them into rectangular blocks with seismic joints.

#### 2. Plan aspect ratio
Length : width should not exceed about 3. Long buildings receive different ground motion at the two ends and develop large diaphragm stresses.

#### 3. Symmetry of mass and stiffness
The centre of mass and the centre of rigidity should coincide to avoid torsion. Place stiff walls and cores symmetrically.

#### 4. Regular elevation and avoiding a soft storey
Avoid sudden changes in stiffness, mass or strength along the height (open ground storey, set-backs, heavy top floor). Walls and columns should be continuous from foundation to roof.

#### 5. Light weight and low height
Earthquake force is proportional to mass, so use a light roof and floors, keep the centre of gravity low, and limit the number of storeys.

#### 6. Openings in walls
Openings should be small and centrally placed, away from corners: total openings not more than about 50% of the wall length in a storey, and not closer than about 0.5 m (or one-fourth of the wall height) to a corner.

#### 7. Seismic gap
Adjacent buildings should be separated by a gap (about 15-30 mm per storey as per IS 4326, depending on the structural system, and more in high seismic zones) to avoid pounding.

#### 8. Strong foundation and continuous load path
Use the same foundation type and depth throughout, tie the structure with a plinth band or tie beams, and provide a rigid diaphragm to transfer loads to the walls.

## Check yourself

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

1. Which plan resists earthquakes best?
   A. Square or rectangular
   B. T
   C. L
   D. U
   Answer: A. Irregular shapes twist and concentrate stress at re-entrant corners. (Key point: Plan shape)

2. Length:width should not exceed about:
   A. 1
   B. 3
   C. 8
   D. 10
   Answer: B. Long buildings get different ground motion at the ends. (Key point: Aspect ratio)

3. Torsion is avoided when:
   A. Walls are on one side
   B. They are far apart
   C. Centre of mass and centre of rigidity coincide
   D. Openings at corners
   Answer: C. Place stiff elements symmetrically. (Key point: Torsion)

4. A soft storey is avoided by:
   A. Open ground floor
   B. Set-backs
   C. Heavy top floor
   D. Continuous walls/columns and no sudden stiffness change
   Answer: D. Sudden changes concentrate damage. (Key point: Soft storey)

## Related in Building Technology

- [Earthquake protection and resistant building principles](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aeq-protection-principles) — Building Technology, chapter 11, asked 3×
- [Repair versus retrofit; configuration factors](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aretrofit-vs-repair-config) — Building Technology, chapter 11
- [Making brick masonry earthquake resistant](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aeq-brick-masonry) — Building Technology, chapter 11
- [Earthquake protection of load bearing masonry](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aeq-load-bearing-masonry) — Building Technology, chapter 11
- [Factors affecting foundation design, improving bearing capacity](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Afactors-design-improve-bc) — Building Technology, chapter 2
- [Factors for selecting roof covering](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aroof-covering-factors) — Building Technology, chapter 4, asked 2×

## Related in other subjects

- [Earthquake terminology and seismic construction](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aearthquake-terminology-and-seismic-construction) — Engineering Geology I, chapter 2
- [Seismic strengthening techniques for masonry buildings](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Astrengthening-retrofitting-masonry-buildings) — Design of Timber and Masonry Structures, chapter 7
- [Seismic design principles for masonry buildings](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Aseismic-design-principles-masonry) — Design of Timber and Masonry Structures, chapter 7
- [Seismic waves and earthquake mechanism](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aseismic-waves-and-earthquake-mechanism) — Engineering Geology I, chapter 2