Engineering Concepts Chapter 4 Terms

ABUTMENTThe part of a structure

that directly receives thrust

or pressure.

ARCH BRIDGE A bridge that uses long

span arches for support.

BEAM BRIDGE A bridge whose main

structural element consists of a beam set across two or more vertical supporting members.

BUCKLE Failure caused by

bending, giving way, or crumpling due to excessive force.

BRITTLE The description for a

material which is neither ductile nor malleable and will fail suddenly without warning.

COMPRESSION The effect of a force

which tends to shorten an object in the direction of the force. For example, the towers of a suspension bridge are in compression.

DEAD LOAD A permanent part of a

structure. A dead load does not change over time.

DENSITY Mass per unit volume.

DYNAMIC LOAD A quick exertion of

force such as an explosion, collision, etc.

ELASTIC DEFORMATION RANGE A range during

material testing where if the load is released the material will return to its initial size and shape.

FIXTURE Apparatus used in

manufacturing processes to assemble large pieces of material in a consistent fashion.

FREE-BODY DIAGRAM A sketch of an object

(body) of interest with all the surrounding objects stripped away and all of the forces acting on the object (body) shown.

TAETAC

TAB

TAD

JIG Apparatus used in

manufacturing processes to assemble or measure pieces of material in a consistent fashion, smaller than a fixture and can be moved.

LIVE LOAD A load moving across

or within a structure.

MOMENT OF INERTIA An indication of the

stiffness of a particular shape.  The higher the moment of inertia, the less the deflection.

MOI .

NEWTON’S FIRST LAW (The Law of Inertia) –

Objects at rest tend to stay at rest, and objects in motion tend to stay in motion at a constant speed in a straight line unless acted upon by an unbalanced force.

NEWTON’S SECOND LAW The net force acting on

an object in a given direction is equal to the mass of the object multiplied by the acceleration of the object in the same direction as the net force.

NEWTON’S THIRD LAW The force of one object

(object 1) acting on another object (object 2) is equal in magnitude and opposite in direction to the force of the second object acting upon the first.

PLASTIC DEFORMATION RANGE A range during

material testing where the material will not return to its initial size and shape.

REACTIONS Reactions are passive

forces that are induced at the supports of a structure.

70o 70o

40o

8N

Ra = 4N Rb = 4N

a b

cx

y

12 cm

STATICS The study of objects in

a state of equilibrium. 

STATIC LOAD A load that

accumulates over time.

STRESS-STRAIN CURVE A graph of stress (on

the y-axis) versus strain (on the x-axis) for materials under stress; enables engineers to learn about the strength of material as it deforms elastically and plastically.

SUSPENSION BRIDGE A bridge having a road

or deck hung from a pair of steel cables, each carried by two towers, one at each bank; e.g., the Golden Gate Bridge over San Francisco Bay.

TENSION A situation in which

force is applied to an object that stretches, expands or lengthens the object.

TENSILE Of or relating to

tension; a “tensile” force is a force that serves to stretch, expand, or lengthen an object.

TRUSS A large structural

member that consists of many smaller parts, typically in a repeating pattern of geometric shapes.

YIELD