Chapter 3 Flashcards
Force
In physics: Any interaction that may change the motion of an object. Simple measure of weight, usually expressed in pounds (kilograms).
Load
Any effect that a structure must be designed to resist, including the forces of gravity, wind, earthquakes, or soil pressure.
Stress
Factors that work against the strength of any piece of apparatus, equipment, or structural support. Measurement of force intensity is calculated as a force divided by area.
Equilibrium
Condition of balance that exists when a structural system is capable of supporting the applied load.
Bending Moment
A reaction within a structural component that opposes a vertical load. When the bending moment is exceeded, the component will fail. Bending stress can be calculated from the bending moment.
Gravity (G)
Force acting to draw an object toward the earth’s center; force is equal to the object’s weight.
Wind
Horizontal movement of air relative to the surface of earth.
Tension
Vertical or horizontal force that pulls material apart; for example, the force exerted on the bottom chord of a truss.
Tensile Stress
Stress in a structural member that tends to stretch the member or pull it apart; often used to denote the greatest amount of force a component can withstand without failure.
Compression
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.
Shear Stress
Stress resulting when two forces act on a body in opposite directions in parallel adjacent planes.
Cross-Section
Theoretical slice of a 3-dimensional structural component to enable area and stress calculations.
Axial Load
Load applied to the center of the cross-section of a member and perpendicular to that cross-section. It can be either tensile or compressive, and creates uniform stresses across the cross-section of the material.
Eccentric Load
Load perpendicular to the cross-section of the structural member, but which does not pass through the center of the cross-section. An eccentric load creates stresses that vary across the cross-section and may be both tensile and compressive.
Torsional Load
Load applied off-center from the cross-section of the structural component and at an angle to or in the same plane as the cross-section; produces a twisting effect that creates shear stresses in a material.
Failure Point
Point at which material ceases to perform satisfactorily; depending on the application, this can involve breaking, permanent deformation, excessive deflection, or vibration.
Factor of Safety
Ratio of the failure point of a material to the maximum design stress; indicates the strength of a structure beyond the expected or actual loads.
Dead Load
Weight of the structure, structural members, building components, and any other features permanently attached to the building that are constant and immobile.
Live Load
(1) Items within a building that are movable but are not included as a permanent part of the structure. (2) Force placed upon a structure by the addition of people, objects, or weather.
Static Load
Load that is steady, motionless, constant, or applied gradually.
Dynamic Load
Loads that involve motion, including impact from wind, falling objects, and vibration. Also known as Shock Landing.
Wind Moving vehicles Earthquakes Vibration Falling objects Emergency or maintenance work
Concentrated Load
Load that is applied at one point over a small area.
Dewatering
Process of removing water from a building.
Kinetic Energy
Energy processed by a moving object because of its motion.
Negative Pressure
Air pressure less than that of the surrounding atmosphere; a partial vacuum.
Seismic Forces
Forces produced by earthquakes travel in waves. These are the most complex forces that can be exerted on a building.
Fault
Area of discontinuity in the earth’s crust associated with movement by tectonic plates.
Seismic Effect
Movement of a shock wave through the ground or structure after a large detonation; may cause additional damage surrounding structures.
Seismic Load
Application of forces caused by earthquakes.
Lateral Load
Load that exerts a horizontal force against a structure. Calculated as a live load; includes seismic activity and soil pressure against vertical restraints such as retaining walls and foundations.
Horizontal Motion
Side-to-side, swaying motion.