Chp. 3 Structural Design Features of Buildings Flashcards
The direction of forces from loads acting on the interior of structural members is expressed as ____________.
Stress
The forces within a structural support system that resist applied loads are referred to as _____________.
reactions R
When a structural support system can support a load equal to or greater than the applied loads, ________ exists. The loss of this can lead to partial or total collapse.
equilibrium
The force of __________ is the most common load imposed on a structure via the weight of the structures components, contents, and any occupancy activity.
gravity
What are additional forces added to a structure that will increase the load that must be supported by a buildings supports and in turn the soil beneath the structure?
- Vibration
- Temperature
- Shrinkage
Stresses in a material are classified according to the direction of the force.
- Tension : pulls material apart; tensile stress
- Compression : Squeezes material; compressive stress
- Shear : slides one plane of a material past an adjacent
plane.
Unique stresses are caused by external load alignments including :
- Axial load
- Eccentric load
- Torsional load
The total stresses within structural members must be lower than the ___________ of the material for the structure to remain intact.
failure point
Fixed in location and quantifiable. Can increase or decrease overtime, generally static.
a dead load
Not fixed or permanent, vary by occupancy, and can be considered static.
a live load
Steady, motionless, constant or applied gradually.
static load
Dynamic loads involve motion and are capable of delivering energy greatly in excess of the weight of the object involved, including impact from :
- wind
- moving vehicles
- earthquakes
- vibration
- falling objects
- emergency or maintenance work
Water at a depth of _______ adds a static load of _____ pounds per square foot.
- 3 inches
- 21 pounds
The effects of wind can be simple or complex, and can occur simultaneously with each other. Factors such as wind speed and direction may influence the overall effect of wind. Other effects of wind include:
- direct pressure
- drag
- negative pressure
- rocking
- vibration
- clean off
Winds are particularly dangerous against walls with insufficient supports. Common locations where walls may be insufficiently braced include :
- construction sites
- demolition sites
- fire damaged buildings
The typical expected life span of a building
50 year period
Failure due to stress may include visible indicators such as:
- cracking
- crumbling
- bending
- breaking
What type of load is mechanical equipment that produces vibrations considered?
a dead static load
Water from fire fighting operations can add an additional ____________ to a building. This load may be dynamic as fire flow or static as accumulated water.
live load
Apply the most complicated load that must be accommodated by structural design.
seismic forces
Seismic loads may be far more complex than wind loads because the movement of the ground beneath a building can be three dimensional. Directional movements include:
- Lateral
- Torsional
- Resonant
Three types of accommodations for seismic forces are:
- expansion joints
- damping mechanisms
- base isolation