Typical damage in masonry under lateral loads

Under earthquake or wind, unreinforced masonry buildings show characteristic damage because the material is heavy, brittle and weak in tension.

1. Diagonal (X-shaped) shear cracks in walls and piers parallel to the force; stair-stepped through joints or through bricks.
2. Horizontal sliding cracks along bed joints near the base, plinth or above the lintel.
3. Vertical cracks at corners and wall junctions where walls separate because of poor connection and out-of-plane bending.
4. Out-of-plane collapse of walls, gables and parapets (overturning, bulging, mid-height horizontal cracking).
5. Cracks around openings: diagonal cracks from corners of doors and windows; piers between openings fail in shear.
6. Delamination of wall leaves in thick two-leaf or rubble walls.
7. Roof/floor damage and pounding: slab pulling out from supporting walls; roof falls when walls collapse.

 Diagonal cracks      Corner crack         Opening cracks
 +--------+           |   |                +----------+
 |\      /|         --+   +--              | /|  []  |\ |
 | \    / |           crack                |/ |      | \|
 +--------+                                +----------+

These damages can be reduced by bands, corner reinforcement, proper roof-wall anchorage and good mortar.