--- title: "Seismic bands and vertical reinforcement in masonry" subject: "Design of Timber and Masonry Structures" chapter: 7 key: "semester_5/design_of_timber_and_masonry_structures:seismic-bands-and-vertical-reinforcement" source: https://www.bctengineer.com/q/semester_5/design_of_timber_and_masonry_structures/seismic-bands-and-vertical-reinforcement site: BCT Engineering --- # Seismic bands and vertical reinforcement in masonry Design of Timber and Masonry Structures · Chapter 7: Seismic Design and Strengthening of Masonry Buildings - Asked in: year not given, 5 marks - Video: [Perfomance of masonry wall5-5|Box action|Role of band|Design of Lintel bands|Earthquake Engg|18cv741](https://www.youtube.com/watch?v=C98C83Ngg6E) — Dr Aravinthan. K - 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-bands-and-vertical-reinforcement - Whole chapter: https://www.bctengineer.com/md/semester_5/design_of_timber_and_masonry_structures/chapter-7 ## Question Write short notes on seismic bands and vertical reinforcement in masonry buildings, giving their purposes, locations and typical details. ## Short answer Horizontal bands (plinth, lintel, roof, gable) tie walls together, reduce out-of-plane span, and confine masonry. Vertical bars at corners, junctions, and openings increase flexural strength and ductility, forming a confined masonry system. ## Answer #### Horizontal seismic bands A **band** is a continuous horizontal beam (RC or timber) running through all load-bearing walls at one level, forming a ring. **Purposes** - Tie the walls together so the building acts as a box. - Reduce the out-of-plane span of the wall (supports it horizontally). - Prevent cracks from growing by confining the masonry, and distribute the roof load. **Types and locations** 1. **Plinth band** at the plinth level, also reduces differential settlement. 2. **Lintel band** at the lintel level of doors and windows (can double as lintel). 3. **Roof / floor band** below the roof or floor slab (not needed when an RC slab is cast over all walls). 4. **Gable band** along the top of gable walls. **Typical details (as per IS 4326 / NBC 202; check the code)** - RC band depth at least 75 mm, full wall thickness, concrete grade not less than M15 (1:2:4). - At least 2 longitudinal bars of 8 mm diameter, for spans up to about 5 m, with 6 mm stirrups at about 150 mm; bars are lapped and anchored at the corners. - Timber bands may be used in low-strength construction as two longitudinals connected by cross-members. #### Vertical reinforcement - Provided at corners, wall junctions and the sides of door and window openings. - Bars (typically 10–12 mm diameter, one or two as per the number of storeys and zone) start in the foundation, pass through every band and extend into the roof band; they are embedded in concrete or mortar (in the hole made in the masonry). - Purpose: increase flexural strength and ductility, tie walls at the corners, and prevent collapse of wall portions. ```text roof band ================ <- tie everything | | | | | | window | | | | | | <- vertical bar at jamb lintel ======================= | pier | | pier | plinth band ================= foundation (bars anchored) ``` Together, bands and vertical bars form a confined or reinforced masonry system that increases the ductility and avoids brittle collapse. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is the main purpose of horizontal seismic bands? A. Increase the weight of walls B. Replace the foundations C. Provide thermal insulation D. Tie walls into a ring for box action, shorten out-of-plane span and confine masonry Answer: D. A continuous band ties all walls together and supports them horizontally. (Key point: Purpose of bands) 2. Which are the band types? A. Plinth, lintel, roof or floor, and gable bands B. Only plinth bands C. Only roof bands D. Corner and jamb bands Answer: A. Bands are placed at plinth, lintel, roof/floor and gable levels. (Key point: Band locations) 3. What is a typical RC band detail? A. Depth 25 mm, one 6 mm bar B. At least 75 mm deep, full wall thickness, M15 concrete, at least 2 bars of 8 mm with 6 mm stirrups C. 300 mm deep with no steel D. Timber only Answer: B. These are the typical IS 4326 details, to be checked against the code. (Key point: Typical RC band details) 4. Where is vertical reinforcement placed and why? A. Mid-wall only, to resist gravity B. Only in the roof C. At corners, junctions and jambs, anchored in the foundation and roof band, to add flexural strength and ductility D. Anywhere unanchored Answer: C. It starts in the foundation, passes through bands and ties the walls, preventing collapse. (Key point: Vertical reinforcement) ## 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 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 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 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 - [Comparison of masonry units](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Amasonry-units-comparison) — Design of Timber and Masonry Structures, chapter 4 ## Related in other subjects - [Types of bands in masonry structures](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Abands-masonry) — Building Technology, chapter 11 - [Improving seismic performance of masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aseismic-performance-improvement) — Concrete Technology and Masonry Structure, chapter 9 - [Typical damage in masonry under lateral loads](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Atypical-damage-lateral-loads) — Concrete Technology and Masonry Structure, chapter 9, asked 2× - [Configuration factors for seismic safety](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aconfig-factors-seismic) — Building Technology, chapter 11, asked 2×