Which statement is FALSE about earthquake-resistant masonry?
- AVertical reinforcement is required
- BDiaphragm action helps
- CMortar gaps enhance energy dissipationCorrect
- DBands improve ductility
Solution
Concept
Ductility and joint requirements in seismic masonry
Formula
Fully filled mortar joints required as per IS 4326
Step-by-step solution
1. Seismic resistance in masonry relies on box action, horizontal reinforced bands, and vertical corner reinforcement. 2. Diaphragm action of floors and roofs is essential to transfer lateral inertia loads into shear walls. 3. Unfilled mortar gaps create severe stress concentrations, reducing friction and shear capacity without adding energy dissipation. 4. Therefore, the claim that mortar gaps enhance energy dissipation is entirely FALSE. Answer: C
Explanation
In earthquake-resistant masonry construction, all mortar joints must be solidly filled with mortar to ensure full shear and compressive stress transfer. Gaps or unfilled mortar joints severely degrade wall strength and provide zero energy dissipation, making the statement false.
Why the other options are wrong
A) Vertical reinforcement at corners is a true requirement for tensile resistance. B) Diaphragm action is a true mechanism for lateral load transfer. D) Reinforced concrete bands truly enhance integrity and ductility.
Shortcut
Mortar gaps weaken masonry; joints must always be completely filled.
Common mistake
Misreading the question which asks for the FALSE statement regarding earthquake masonry.
Correct answer: C) Mortar gaps enhance energy dissipation