Quake risk: Why old brick buildings can collapse

California learned the dangers of brick construction when a major earthquake struck Long Beach in 1933.

Old brick buildings are one of the deadliest structures in an earthquake. Saif Hussain, a structural engineer who has helped write retrofit guidelines for Los Angeles and the American Society of Civil Engineers, explains why.

Individual bricks are strong, but mortar between is weak

(Raoul Rañoa/@latimesgraphics)

Where brick buildings fail

(Raoul Rañoa/@latimesgraphics)

Three ways to retrofit

Making old brick buildings safer can require more reinforcing material like steel. Think of a wooden table — it’s more likely to fall apart without long steel screws that keep it together when shaken, Hussain says.

(Raoul Rañoa/@latimesgraphics)

Other ways of retrofitting include adding to the walls steel-reinforced concrete or layers of glass or carbon fiber and adding plywood to the floors and roof.

The retrofit’s overall impact

The three retrofit methods combined give the brick building a steel skeleton that has a better chance of staying together when shaken.

(Raoul Rañoa/@latimesgraphics)

Sources: Structural engineer Saif Hussain, Federal Emergency Management Agency

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