facts

Question 1

reactions for pin

Answer 1

2

Question 2

reactions for roller

Answer 2

1

Question 3

reactions for fixed end

Answer 3

3

Question 4

Point moments will show up in ________ but not in _______ diagrams.

Answer 4

bending moment, shear force

Question 5

What is the sign convention of sagging?

Answer 5

positive

Question 6

What is the sign convention of hogging?

Answer 6

Negative

Question 7

A beam is subjected to sagging. Where is the compression and tension?

Answer 7

tension on bottom of curve, compression on top of curve

Question 8

What is the bending moment at an internal pin?

Answer 8

0

Question 9

Where will the point of zero shear be?

Answer 9

at the maximum bending moment

Question 10

How do point loads and moments represent themselves in shear force and bending diagrams?

Answer 10

PL: vertical shift in SF, cause change in BM
PM: vertical shift in BM, not present in SF

Question 11

What 3 things should be checked for after completing a SF and BM diagram?

Answer 11

reference co-ordinate system, value labels, dimensions

Question 12

What should always be the first step in approaching a problem?

Answer 12

Verifying determinancy

Question 13

Describe the changes in fibre length to the sections below when a beam is subjected to a bending moment
a. neutral axis
b. tension fibres
c. compressive fibres

Answer 13

a. no change
b. elongate
c. shorten

Question 14

What are 4 major assumptions of truss analysis?

Answer 14

The members only connect at the nodes
Members have negligible weight
The pins (at the nodes) are frictionless
The loads are only present at the nodes

Question 15

What is the sign convention for tensile stress/ strains vs compressive stresses/ strains?

Answer 15

tensile = +ve, compressive = -ve

Question 16

What two methods would be used to locate POCs?

Answer 16

similar triangles or polynomials/ simultaneous equations

Question 17

The area under the SF diagram is equal to ______. Hence it can also be said that the BM is the result of __________ the SF diagram.

Answer 17

the change in bending moment, integrating

Question 18

If the SF diagram is first order, what order will the BM be?

Answer 18

second

Question 19

The SF diagram is linear, what will the BM diagram look like?

Answer 19

quadratic curve

Question 20

How should internal support calculations be approached?

Answer 20

deduce as much information as possible about reactions and then split the element into two parts along the pin

Question 21

List the 3 most common types of external supports

Answer 21

roller, pin, fixed end

Question 22

list the 2 most common types of internal support

Answer 22

roller, pin

Question 23

what order line does a UDL produce?

Answer 23

2nd order (linear)

Question 24

what order line does a point load produce?

Answer 24

1st order, parallel lines with vertical shifts

Question 25

How do you locate a POC?

Answer 25

Take moments about the point using an unknown variable x fro the distance and let this moment = 0

Question 26

How do you calculate the maximum bending moment at a located point of zero shear?

Answer 26

equate forces either side of point to zero and solve for the unknown distance (usually occurs in UDLs)
Use this distance to create another point for BM analysis

Question 27

What units are moment of inertia in?

Answer 27

mm^4 or m^4

Question 28

If in doubt about units for length, force or large prefixes: _____________________.

Answer 28

Revert to SI units e.g. metres, newtons and other non-prefixed terms
BE CAREFUL with squared units (e.g. square the power of 10 you are changing by too)