earthquake safe structures
New construction can be made safer in many ways: Skyscrapers and other large structures built on soft ground must be anchored to bedrock, even if it lies hundreds of meters below the ground surface. The correct building materials must be used. Houses should bend and sway. Wood and steel are better than brick, stone, and adobe, which are brittle and will break. Larger buildings must sway, but not so much that they touch nearby buildings. Counterweights and diagonal steel beams are used to hold down sway. Large buildings can be placed on rollers so that they move with the ground. Buildings may be placed on layers of steel and rubber to absorb the shock of the waves. Connections, such as where the walls meet the foundation, must be made strong. In a multi-story building, the first story must be well supported (Figure 1.1). The first floor of this San Francisco build- ing is collapsing after the 1989 Loma Pri- eta earthquake.
To make older buildings more earthquake safe, retrofitting with steel or wood can reinforce a buildings structure and its connections. Elevated freeways and bridges can also be retrofitted so that they do not collapse. Steel trusses were built diagonally and horizontally across windows to retrofit a building at Stanford University in Palo Alto, California. The San Andreas Fault passes just west of the university.
preventing fire damage
Fires often cause more damage than the earthquake. Fires start because seismic waves rupture gas and electrical lines, and breaks in water mains make it difficult to fight the fires (Figure 1.3). Builders zigzag pipes so that they bend and flex when the ground shakes. In San Francisco, water and gas pipelines are separated by valves so that areas can be isolated if one segment breaks.
Why arent all structures in earthquakes zones constructed for maximum safety? Cost, of course. More sturdy structures are much more expensive to build. So communities must weigh how great the hazard is, what different In the 1906 San Francisco earthquake, fire was much more destructive than the ground shaking. building strategies cost, and make an informed decision. In 1868 marked the Hayward Fault erupted in what would be a disastrous earthquake today. Since the fault erupts every 140 years on average, East Bay residents and geologists are working to prepare for the inevitable event. Click image to the left or use the URL below. URL:
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the california memorial stadium has put in $321 million to make sure its stadium is safe during an earthquake. what are some of its safety measures?
a) concrete piers b) silicone fluid-filled shock absorbers c) stone columns --> d) all of the above
what type of ground is best for the large structures to be on?
a) mud b) sand --> c) bedrock d) loose gravel
large buildings need to sway during an earthquake to avoid a lot of damage.
--> a) true b) false
older buildings need to do this in order to withstand an earthquake.
a) grow taller b) pour concrete at the base --> c) retrofitting d) make the building smaller
all buildings could be built to withstand almost any earthquake, but doing this is much too expensive.
--> a) true b) false
which of these helps to make buildings safer during an earthquake?
a) building with brick and stone instead of wood and steel. --> b) placing large buildings on rollers so that they move with the ground. c) buildings that do not sway during an earthquake. d) building on soft ground rather than on bedrock.
what can be done to retrofit a university dorm for safety?
--> a) steel trusses can be built across windows to make a more solid frame. b) the building can be dug up and put on rollers. c) students can be given earthquake hazard kits. d) nothing.
a large quake on the hayward fault in the next 100 years is all but inevitable.
--> a) true b) false
why do fires start during an earthquake?
--> a) gas pipes and electrical lines rupture. b) there is the normal amount of fire, but since the water mains break the fires cant be fought. c) earthquakes have a lot of electrical activity that causes fires. d) all of these.
what can be done to prevent fire damage in a quake?
a) have water mains break so that they release water into potential fire zones. --> b) build gas and water pipes that bend and flex when the ground shakes. c) keep the fire department on high alert at all times so they can mobilize immediately. d) nothing.
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