--- title: "Seismic design principles for masonry buildings" subject: "Design of Timber and Masonry Structures" chapter: 7 key: "semester_5/design_of_timber_and_masonry_structures:seismic-design-principles-masonry" source: https://www.bctengineer.com/q/semester_5/design_of_timber_and_masonry_structures/seismic-design-principles-masonry site: BCT Engineering --- # Seismic design principles for masonry buildings Design of Timber and Masonry Structures · Chapter 7: Seismic Design and Strengthening of Masonry Buildings - Asked in: year not given, 6 marks - Video: [Constructing Low rise Confined Masonry Buildings: a Guide for Builders and Architects](https://www.youtube.com/watch?v=mGcp98ae5z4) — Earthquake Engineering Research Institute (EERI) - Answer checked by Claude Sonnet 5.5 on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/design_of_timber_and_masonry_structures/seismic-design-principles-masonry - Whole chapter: https://www.bctengineer.com/md/semester_5/design_of_timber_and_masonry_structures/chapter-7 ## Question State and explain the principles to be followed in the planning and construction of masonry buildings in earthquake-prone areas. ## Short answer Plan should be simple, symmetric, and regular; limit height and storey height. Provide adequate wall density with small openings, horizontal bands and vertical bars at corners, rigid floor diaphragms, uniform foundation, and good workmanship. ## Answer Masonry buildings should behave as a strong, tied **box** so that all walls support each other during shaking. #### 1. Simple, symmetric and regular plan - Rectangular, symmetrical plans are best. Avoid L, T and U shapes (or separate them by seismic gaps), because they twist (torsion) and have stress concentrations at re-entrant corners. - Keep the length-to-breadth ratio not more than about 3, and place walls so that the centre of mass and the centre of rigidity are close. #### 2. Limited height and storey height Keep the number of storeys and the storey height low (commonly not more than 3.0–3.4 m per storey). Avoid heavy roofs (stone slabs, thick mud); use light roof materials. #### 3. Walls - Provide adequate wall density in both directions, with cross-walls spaced closely to limit the out-of-plane span. - Keep the thickness related to height (the $h/t$ ratio small) and avoid slender walls. - Use good-quality units and cement or cement–lime mortar, and fill all joints; use through stones in stone walls. #### 4. Openings Keep openings small, symmetrical and away from corners. As a guide (IS 4326): the total width of openings should not exceed about 50 percent of the wall length in a single-storey building (less for higher buildings); pier width should be not less than about 340 mm and openings should be about 600 mm from inside corners. Openings in adjacent storeys should be vertically aligned. #### 5. Bands and vertical steel Provide horizontal bands (plinth, lintel, roof, gable) and vertical bars at corners, junctions and door/window jambs to tie the structure. #### 6. Floors and roofs Use rigid diaphragms (RC slabs) or well-braced timber floors firmly anchored to the walls to distribute force by box action. #### 7. Foundation Use a uniform type of foundation on firm soil, with plinth beams; avoid foundations at different depths. #### 8. Quality of workmanship Fill the joints fully, make wall junctions toothed or bonded, cure the masonry well, and avoid cutting chases in walls because they weaken them. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why avoid L, T and U plans? A. They cost more bricks B. They need thicker walls C. They twist (torsion) and concentrate stress at re-entrant corners D. They are not permitted in any area Answer: C. Irregular plans cause torsion and stress concentrations; use simple rectangular symmetric plans or seismic gaps. (Key point: Regular plan) 2. What is the guide for openings in single-storey masonry (IS 4326)? A. Total opening width up to about 50 percent of wall length; small, symmetrical, away from corners B. Total opening width up to 90 percent C. Openings placed at corners for light D. Openings in adjacent storeys staggered Answer: A. Small symmetrical openings away from corners, pier width at least about 340 mm, and aligned openings between storeys. (Key point: Openings) 3. What makes the building act as a strong tied box? A. Heavy stone slab roofs B. Bands, vertical steel at corners and jambs, and rigid anchored diaphragms C. Wide spacing of cross-walls D. Foundations at different depths Answer: B. Bands, vertical bars and rigid floors and roofs anchored to walls make walls support each other. (Key point: Box action) 4. How do wall proportions affect out-of-plane safety? A. Larger h/t is better B. Cross-walls should be far apart C. Thickness is unrelated to height D. Keep h/t small and cross-walls closely spaced to limit out-of-plane span Answer: D. Slender, long walls bend out of plane; thickness related to height and close cross-walls reduce that. (Key point: Wall proportions) ## Related in Design of Timber and Masonry Structures - [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 - [Typical damage patterns in masonry buildings](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Adamage-patterns-masonry-lateral-loads) — Design of Timber and Masonry Structures, chapter 6 - [Seismic behaviour of unreinforced and reinforced masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Aseismic-behavior-urm-versus-reinforced) — Design of Timber and Masonry Structures, chapter 7 - [Seismic bands and vertical reinforcement in masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Aseismic-bands-and-vertical-reinforcement) — Design of Timber and Masonry Structures, chapter 7 - [Seismic base shear of a masonry building](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Abase-shear-two-storey-masonry-building) — Design of Timber and Masonry Structures, chapter 7 - [Masonry pier under axial load and in-plane moment](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Amasonry-pier-axial-moment-check) — Design of Timber and Masonry Structures, chapter 7 ## 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 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 - [Earthquake intensity, magnitude, seismic waves](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aearthquake-intensity-magnitude-seismic-waves) — Engineering Geology I, chapter 2 - [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