Chapter 3 - The Way Buildings are Built: Structural Design Features O Flashcards
What are some of the sources loads arise from?
gravity, wind, earthquakes, and soil pressure
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_______ creates a force on a building through the weight of the building components and all its contents.
Gravity
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Force acting to draw an object toward the earth’s center; force is equal to the objects weight.
Gravity
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When air is in motion, it possesses _______ _______ according to the following fundamental relationship.
kinetic energy
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Forces of wind on a building:
- ________ ________ - the impact effect the wind has on a surface. This force may be reduced by streamlining the surface encountered
Direct pressure
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Forces of wind on a building:
- __________ ______ - when wind encounters an object its fluid nature causes it to flow around the object. This exerts a drag effect on the object.
Aerodynamic drag
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Forces of wind on a building:
- ________ ________- a suction effect produced on the downwind side of the building resulting in an outward pressure.
Negative pressure
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The energy possessed by a moving object is ?
Kinetic Energy
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Secondary effects produced by the wind:
- _______ _______ - a back and forth effect due to variations in the velocity of the wind
Rocking effects
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Secondary effects of the wind:
- ________ - wind passing over a surface such as a roof may cause _______ of the surface depending on the velocity of the wind and the harmonic characteristics of the surface.
Vibration / vibration
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Secondary effects of the wind:
- _____-____ _____ - the tendency of wind to dislodge objects from a building
Clean-off effect
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Earthquakes can cause vibrational motion of the surface that subjects buildings to forces known as ______ ______ that can be very destructive, as history has shown.
seismic forces
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________ forces are produced in a structural member when it is twisted
Torsional
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________ forces are movements of relatively large amplitude resulting from a small force applied at the natural frequency of a structure
Resonant
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Soil _________ occurs where the soil is of a loose, sandy nature and is saturated with water.
liquefaction
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The tendency of a body to remain in motion or at rest until it is acted upon by force is called ?
Inertia
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Buildings with geometric ___________ are inherently more susceptible to damage from earthquakes than buildings having a __________ design.
irregularities / symmetrical
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To overcome the difference and possible damage due to height differences in sections of a building a ______ ______ can be designed into the structure between the two sections
seismic joint
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One method to protect a building against earthquake forces is to increase a buildings stiffness through the use of _____ _____ and ______ ______.
shear walls and cross bracing
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Earthquakes
Another method for increasing a buildings stability is to use continuous structures with a high degree of ___________ in their ____________ _________.
redundancy / structural frames
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__________ ________ are typically installed at the connections between columns and beams, and they absorb energy as the structure begins to move.
Damping mechanisms
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A structural element designed to control vibration is called ?
Damping Mechanism
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The basic concept of _____ ________ is to isolate the building from horizontal movement of the earths surface.
base isolation
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- _________ ________ - Create a layer between the building and the foundation, which has a low horizontal stiffness
Elastomeric bearings
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