Designing For Disasters

Roads, Rails and Race Cars

Designing for Disasters

Engineers have to consider natural disasters when designing projects.

Why do you think engineers have to design for disasters?

Can you name some types of natural disasters engineers must design for?

Flooding

Flooding is the most common, costly and deadly natural disaster in the United States per year.

To help minimize the effects of flooding civil engineers design and build levees.

What is a levee?

Levees

A levee is a man-made embankment built to keep a body of water from overflowing.

They also prevent ocean waves from washing into undesired areas.

Levees are constructed with compacted soil, rocks and concrete or steel.

Grass is sometimes planted on top to help minimize erosion.

Levee Failure

Earthquakes

Designing for earthquakes requires understanding the effects they have on buildings and soil.

Earthquakes cause both tension and compression forces.

Concrete structures are not very safe during earthquakes because concrete is strong in compression but weak in tension.

How do engineers solve this problem?

Earthquakes

To make buildings stronger in tension, engineers add steel. Steel is strong in tension and also somewhat flexible.

The elasticity of steels allows the structure to flex and return to its original state.

Engineers must also consider soil liquefaction. This phenomenon occurs when soil is shaken and begins behaving like a liquid.

Soil Liquefaction

Engineers try to avoid this by using soil compaction techniques such as dynamic compaction.

Dynamic compaction is used to increase the density of the soil by dropping a heavy weight repeated on the ground at regular spaced intervals.

Tornadoes

Tornadoes produce extremely high pressures and loads. Constructing tornado-resistant buildings are very expensive.

Instead the emphasis is placed on occupant protection and creating a hardened portion to be used as a safe room.

Joplin Hospital after Tornado

New Joplin Hospital

The new Joplin Hospital is designed to withstand a direct hit from an E5 tornado.

The Joplin Hospital design is focused on strengthening three areas. One is the roof.

Can you name the other two?

New Joplin Hospital The roof will be an all-concrete structure. A

concrete slab with be glued down in which the roof system will be built on. This way if the roof blows away, the concrete slab will still protect the building.

The siding of the hospital will be made out of pre-cast concrete. Pre-cast concrete is made in a controlled facility rather than poured at site. Due to minimum environmental impacts, pre-cast concrete is stronger.

The windows are designed to withstand 250 mph winds.

Anyone Can Plan for Disasters When severe weather strikes, stay

informed by listening to the radio.

Make a disaster survival kit including: water, a tool kit, extra clothing, blankets, a first-aid kit and nonperishable food.

Make sure your family knows where to meet.