ES1_Supports and Reactions, Trusses, Method of Joints & Sections

Question 1

It deals primarily with the calculation of external forces which act on rigid bodies in equilibrium.

Answer 1

Statics

Question 2

It is a combination of a large number of particles occupying fixed positions with respect to each other.

Answer 2

Rigid Body

Question 3

Rotation is not a concern, so equilibrium could be satisfied by: Summation of F = 0 (no translation)

Answer 3

Concurrent Forces

Question 4

For a rigid body to be in equilibrium, the net force, as well as the net moment about any arbitrary point O, must be equal to zero.

Summation F = 0
Summation M = 0

Answer 4

Non-concurrent Forces

Question 5

If a support prevents the translation of a body in a given direction, then a ______ is developed on the body in that direction.

Answer 5

Force

Question 6

If rotation is prevented, a _______ is exerted on the body.

Answer 6

Couple moment

Question 7

Number of unknown/s in cables

Answer 7

1

Question 8

Number of unknown/s in contacting surface

Answer 8

1

Question 9

Number of unknown/s in roller support

Answer 9

1

Question 10

Number of unknown/s in pin support

Answer 10

2

Question 11

Pin connections allow rotation. Reactions at pins are _________and NOT _________.

Answer 11

forces, moments

Question 12

Number of unknown/s in constrained pin

Answer 12

1

Question 13

Number of unknown/s in fixed support

Answer 13

3

Question 14

Equations of Equilibrium

Answer 14

Fx=0; Fy=0; M=0

Question 15

A structure composed of slender members joined together at their end points.

Answer 15

Truss

Question 16

It is commonly used in construction consist of wooden struts or metal bars.

Answer 16

Members

Question 17

They lie in a single plane and are often used to support roofs and bridges.

Answer 17

Planar trusses

Question 18

Truss members are connected at their ________ only; thus NO member is continuous through a joint.

Answer 18

extremities

Question 19

A structure made up of a number of straight, slender bars that are joined together at the joints only to form a pattern of triangles (e.g. bridge and roof truss)

Answer 19

Plane Truss

Question 20

When forces tend to pull the member
apart, it is in _______.

Answer 20

tension

Question 21

When the forces tend to compress the member, it is in __________.

Answer 21

compression

Question 22

Members of a truss are slender and not capable of supporting large lateral loads. Loads must be applied at the _______.

Answer 22

Joints

Question 23

A method of solving wherein to calculate the forces in the members of a truss, the equilibrium equations are applied to individual joints (or pins) of the truss.

Answer 23

Method of Joints

Question 24

Consist of cutting a truss into two sections at a point where the bar force is required.

Answer 24

Method of Sections

Question 25

The resulting force system after cutting will generally be ____________ and _________

Answer 25

non-concurrent; coplanar

Question 26

Determinacy of statically determinate trusses

Answer 26

m = 2n - 3

Question 27

Determinacy of truss with a redundant member which makes it statically in determinate

Answer 27

m > 2n - 3

Question 28

in determinacy of trusses, m is the total number of __________

Answer 28

members

Question 29

in determinacy of trusses, n is the total number of __________

Answer 29

joints

Question 30

If a joint has only two noncollinear members and there is no external load or support reaction at that joint, then those two members are

Answer 30

zero force members

Question 31

If three members form a truss joint for which two of the members are collinear and there is no external load or reaction at that joint, then the third non-collinear member is a ____________.

Answer 31

zero force member

Question 32

The region from O to Elastic Limit

Answer 32

Elastic range

Question 33

The region from Elastic Limit to Rupture Strength

Answer 33

Plastic range