--- title: "Lintel loading and arching action in walls" subject: "Design of Timber and Masonry Structures" chapter: 5 key: "semester_5/design_of_timber_and_masonry_structures:lintel-load-arching-action-masonry" source: https://www.bctengineer.com/q/semester_5/design_of_timber_and_masonry_structures/lintel-load-arching-action-masonry site: BCT Engineering --- # Lintel loading and arching action in walls Design of Timber and Masonry Structures · Chapter 5: Design of Masonry Walls for Gravity Loads - Asked in: year not given, 5 marks - Video: [Structural Engineering Made Simple - Lesson 3: Design of Lintels in Masonry Walls](https://www.youtube.com/watch?v=GoCqlYsaTj8) — Jamshid Mohammadi - 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/lintel-load-arching-action-masonry - Whole chapter: https://www.bctengineer.com/md/semester_5/design_of_timber_and_masonry_structures/chapter-5 ## Question Explain how loads from the wall above an opening and from floors are considered in the design of lintels and in walls with openings. What is arching action? ## Short answer Arching action lets masonry above an opening self-support, transferring load to piers. Only masonry weight within an equilateral triangle of height 0.866L above the lintel is considered, plus any floor loads inside that triangle. This reduced load is used for lintel design; piers carry the transferred loads and must have adequate width. ## Answer When an opening is formed in a wall, the load of the masonry above it is not carried fully by the lintel. The masonry above acts as an arch (arching action) when it is strong enough, and the load tends to flow around the opening to the adjacent piers. #### Arching action Masonry over an opening forms a natural arch if there is sufficient height of masonry and well-bonded abutments (piers) at both sides, so that the horizontal thrust can be resisted. Only a small triangular zone above the opening loads the lintel; the rest of the load arches to the sides. ```text load spreads at 45 degrees to piers \ | / \ | / pier \ masonry above / pier ######## \_______|_______/ ######## ######## |_____lintel_____| ######## ######## || opening || ######## ``` #### Load on the lintel (common rules) 1. **Masonry load**: only the weight of masonry within an equilateral triangle on the opening span $L$ (height $= 0.866L$) is taken on the lintel. Masonry above this triangle is ignored. 2. **Floor / roof loads**: if a floor slab or beam lies within this triangle (height $0.866L$ above the opening), its load is added. If the floor lies above this level, no floor load is taken, because the arching action carries it. 3. **Concentrated loads**: a concentrated load within the triangle is taken fully by the lintel. A concentrated load just above the triangle is included only if its 45-degree dispersal falls within the opening span. 4. The bearing of the lintel on the masonry should be at least 100 mm or $L/12$, whichever is greater. #### Effect on piers The load of the masonry above the opening is transferred to the piers on both sides. Each pier therefore carries its own wall load, the half-span loads from the adjacent openings, and any concentrated loads. It is checked as a short column using the area factor $k_a$, which is low for small sections. Narrow piers between openings are critical, so the code limits their minimum width. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is arching action in masonry over an opening? A. The lintel bends into an arch shape under load B. Masonry above the opening forms a natural arch, so most load flows to the adjacent piers C. The opening is built with an arched top D. Floor load is spread evenly over the lintel Answer: B. Sufficient masonry height with well-bonded abutments lets the wall arch over the opening. (Key point: Arching action) 2. Which masonry weight is taken on the lintel of span L? A. All masonry above the opening B. Masonry in a rectangle of height L C. Masonry within an equilateral triangle of height 0.866L on the span D. Only the lintel's own weight Answer: C. Only the equilateral triangle on the span is taken by the lintel; masonry above it is ignored. (Key point: Masonry load on lintel) 3. When is a floor load added to the lintel load? A. Always, whatever its position B. Never, arching carries every floor C. Only if the floor lies above 2L D. If the floor lies within the triangle (about L above the opening); a floor above it is not included Answer: D. A floor within the triangle is added; above that level arching carries it. (Key point: Floor loads) 4. What do piers beside an opening carry? A. Only their own wall load B. Their own load, half-span loads from adjacent openings and concentrated loads C. Nothing, since the lintel carries everything D. Only the lintel reaction Answer: B. Load above the opening is transferred to the piers, which are checked as short columns, so narrow piers are critical. 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