1. Engineering Concepts Chapter 4 Terms

2. ABUTMENT The part of a structure that directly receives thrust or pressure.

3. ARCH BRIDGE  A bridge that uses long span arches for support.

4. BEAM BRIDGE  A bridge whose main structural element consists of a beam set across two or more vertical supporting members.

5. BUCKLE  Failure caused by bending, giving way, or crumpling due to excessive force.

6. BRITTLE  The description for a material which is neither ductile nor malleable and will fail suddenly without warning.

7. 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.

8. DEAD LOAD  A permanent part of a structure. A dead load does not change over time.

9. DENSITY  Mass per unit volume.

10. DYNAMIC LOAD  A quick exertion of force such as an explosion, collision, etc.

11. ELASTIC DEFORMATION RANGE  A range during material testing where if the load is released the material will return to its initial size and shape.

12. FIXTURE  Apparatus used in manufacturing processes to assemble large pieces of material in a consistent fashion.

13. 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. T AE T AC T AB T AD

14. 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.

15. LIVE LOAD  A load moving across or within a structure.

16. MOMENT OF INERTIA  An indication of the stiffness of a particular shape. The higher the moment of inertia, the less the deflection. MOI.

17. 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.

18. 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.

19. 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.

20. PLASTIC DEFORMATION RANGE  A range during material testing where the material will not return to its initial size and shape.

21. REACTIONS  Reactions are passive forces that are induced at the supports of a structure. 70 o 40 o 8N R a = 4N R b = 4N a b c x y 12 cm

22. STATICS  The study of objects in a state of equilibrium.

23. STATIC LOAD  A load that accumulates over time.

24. 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.

25. 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.

26. TENSION  A situation in which force is applied to an object that stretches, expands or lengthens the object.

27. TENSILE  Of or relating to tension; a “tensile” force is a force that serves to stretch, expand, or lengthen an object.

28. TRUSS  A large structural member that consists of many smaller parts, typically in a repeating pattern of geometric shapes.

29. YIELD