--- title: "Diagonal shear and push shear tests" subject: "Concrete Technology and Masonry Structure" chapter: 10 key: "semester_5/concrete_technology_and_masonry_structure:diagonal-shear-push-shear" source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/diagonal-shear-push-shear site: BCT Engineering --- # Diagonal shear and push shear tests Concrete Technology and Masonry Structure · Chapter 10: Testing of masonry elements - Asked in: 2080 Bhadra, 5 marks - Video: [push Shear test](https://www.youtube.com/watch?v=8N8PUrqHOxQ) — DIPAK MANDAL - 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/diagonal-shear-push-shear - Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-10 ## Question Explain in detail the diagonal shear test and push shear test of masonry wall. ## Short answer The diagonal shear test applies diagonal compression to a 1.2 m square panel to failure along the loaded diagonal; τ = 0.707 P/An, ft = 0.5 P/An (An = (w+h)t/2). The push shear test pushes a brick horizontally from its bed joint to sliding, giving shear strength τ = F/(2Ab) and cohesion c = τ - μσv with μ ≈ 0.4-0.65. Diagonal test is for panel shear, push test for joint shear. ## Answer #### Diagonal shear test (of a masonry panel) **Aim:** shear (diagonal tensile) strength and shear modulus of masonry. - A square wall panel (about 1.2 m $\times$ 1.2 m) is rotated so a diagonal is vertical; steel shoes at the two opposite corners. - A jack applies compression along the diagonal at a steady rate to failure; the diagonal crack and the load $P$ are noted. LVDTs on the diagonals measure the deformation. $$ \tau = \frac{0.707P}{A_n},\qquad f_t=\frac{0.5P}{A_n},\qquad A_n=\frac{w+h}{2}\,t $$ ```text P | +--v----+ |\ | | \ | crack along the | \ | loaded diagonal +-----^-+ ``` #### Push shear test (in situ) **Aim:** shear strength of bed joints of existing wall. - A brick is isolated by removing a head joint at one end and the brick at the other end is removed to place a small jack and load cell. - The jack pushes the brick horizontally along the bed joints; the load $F$ at first slip is recorded. $$ \tau = \frac{F}{2A_b},\qquad c=\tau-\mu\,\sigma_v $$ where $A_b$ is the bed area of the brick (two joints), $\sigma_v$ the vertical stress at the joint and $\mu$ the friction coefficient (about 0.4 to 0.65). ```text +----+----+----+ | |[jack]->[brick] F pushes brick along bed joint +----+----+----+ ``` The diagonal shear test is a laboratory test on a panel (destructive); the push-shear test is done on the actual wall with little damage. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which statement is correct? A. Diagonal shear is a lab panel test (destructive); push shear is in situ with little damage B. Both are non-destructive C. Diagonal shear is in situ D. Push shear is on a prism in a lab Answer: A. The panel is destroyed; push shear only replaces one brick. (Key point: Test nature) 2. Diagonal tensile strength f_t is? A. 0.5P/A_n B. 0.707P/A_n C. F/(2A_b) D. P/A Answer: A. tau = 0.707P/A_n while f_t = 0.5P/A_n. (Key point: Diagonal formulas) 3. In tau = F/(2A_b), why 2? A. Two bed joints, above and below the brick B. Two bricks pushed C. Factor of safety D. Two jacks Answer: A. The brick slides on both its top and bottom bed joints. (Key point: Push shear formula) 4. Cohesion c in push shear is? A. tau - mu sigma_v B. tau + mu sigma_v C. tau / mu D. sigma_v - tau Answer: A. From tau = c + mu sigma_v, with mu about 0.4 to 0.65. (Key point: Cohesion) ## Close variants set in other exams - [Diagonal shear test of masonry wall](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Adiagonal-shear-test) — Concrete Technology and Masonry Structure, chapter 10, asked 6× ## Related in Concrete Technology and Masonry Structure - [Compressive and diagonal shear tests of masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Acompressive-diagonal-shear-tests) — Concrete Technology and Masonry Structure, chapter 10, asked 2× - [Push shear test of masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Apush-shear-test) — Concrete Technology and Masonry Structure, chapter 10, asked 2× - [Flat-jack and push-shear tests](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aflat-jack-and-push-shear) — Concrete Technology and Masonry Structure, chapter 10, asked 2× - [Elastic wave tomography and push shear tests](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aelastic-wave-tomography-push-shear) — Concrete Technology and Masonry Structure, chapter 10 - [Flat-jack test for brick masonry wall](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aflat-jack-test) — Concrete Technology and Masonry Structure, chapter 10, asked 2× - [Tensile tests; split test advantage; h/d ratio](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Atensile-tests-split-advantage-hd) — Concrete Technology and Masonry Structure, chapter 5 ## Related in other subjects - [Diagonal shear test and flat-jack test calculations](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Adiagonal-shear-flat-jack-numerical) — Design of Timber and Masonry Structures, chapter 8 - [Shear tests; direct shear calculation](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Ashear-tests-direct-shear-strength-calc) — Soil Mechanics, chapter 10 - [Shear strength tests (lab and field)](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Ashear-strength-tests-names) — Soil Mechanics, chapter 10, asked 3×