Chapter 3 Flashcards
The direction of forces from Loads acting on the interior of structural members is expressed as?
Stress
The force is with any structural support system that resists applied loads are referred to as?
Reactions
When a structural support system can support a load equal to or greater than the applied loads?
Equilibrium
Any effect that a structure must be designed to resist, including the forces of gravity, wind, earthquakes or soil pressure
Load
Factors that work against the strength of any piece of apparatus, equipment, or structural support.
Stress
Measurement of force intensity is calculated as force divided by area
Stress
Any interaction that may change the motion of an object. Simple measure of weight, usually expressed in pounds
Force
A reaction with any structural component that opposes a vertical load.
Bending moment
Force acting to draw an object toward the earths center, force is equal to the objects wait
Gravity
The most common load impose on a structure via the weight of the structures components, content, and any occupancy activity
Gravity
Stress is within the material are classified according to?
The direction of the force
Pulls the material apart; referred to as?
Tension. Referred to as tensile stress
Squeezes the material: referred to as?
Compression. Referred to as compressive stress
Slides on the plane of the material passed an adjacent plane
Shear
Vertical or horizontal force that pulls material apart for example the force exerted on the bottom cord of a truss
Tension
Stress in a structural member that tends to stretch the member or pull it apart; often used to know the greatest amount of force a component Can withstand without failure
Tensile stress
Vertical And/or horizontal forces that push the mass of a material together for example the force exerted on the top chord of a truss
Compression
Stress resulting went to forces act on a body in opposite directions in parallel adjacent planes
Shear stress
Theoretical slice of a three dimensional structural component to enable area and stress calculations
Cross section
Unique stresses are caused by external load alignments including:
Ask your load. Eccentric load. Torsional load.
Application of forces caused by earth quakes
Seismic load
Most significant force generated by earthquakes
Lateral loads that create horizontal motion
Forces produced by earthquakes travel in waves. These are the most complex forces that can be exerted on a building.
Seismic forces
Area of discontinue it he in the earths crust associated with movement by tectonic plates
Fault
Movement of a shockwave through the ground or structure after a large detonation: may cause additional damage to surrounding structures
Seismic effect
Absorb resonant energy as the structure begins to move
Damping mechanisms
Isolates the building from the horizontal movement of the earths surface
Base isolation
Two common methods of base isolation
Shear systems. Sliding systems
Load that exerts a horizontal force against a structure. Calculated as a live load.
Lateral load
Includes seismic activity and soil pressure against vertical restraints such as retaining walls and foundations
Lateral load
Movements of relatively large amplitude resulting from a small force applied at the natural frequency of a structure
Resonance
Structural accommodation that allows building sections to move independently of each other
Expansion joint
Structural element designed to control vibration from resonance
Damping mechanism
Some types of structural stiffness are particularly effective against seismic loads, two types are:
Sheer walls and cross bracing. Structural support redundancy.
Typical truss Shapes span distances of?
22 to 70 feet, but trust spans in modern construction may exceed 100 feet
Lightweight steel trusses known as:
Bar joist
Light weight wood or metal trusses known as?
Truss joist
Have become common in the floor construction taking the place of solid joist
These are a critical factor in the strength of the truss
Connectors in truss assemblies
Three dimensional trust structures
Space frame
Steel stud walls:
Studs are placed
12 to 16” apart
Membrane structures-
Fabrics weigh less than other roof systems:
About 2 pounds per square foot
The dynamic load of a stream discharging 250 gallons per minute may impact it’s target with___pounds of water per minute
2,080
In some cases, dewatering operations will be necessary because water at a depth of 3 inches adds a static load of___pounds per square foot
21
