Quiz 1 study material/definitions

Question 1

Classification of structures - Beams

Answer 1

Usually straight horizontal members used primarily to carry vertical/transverse loads

Question 2

Classification of structures - columns

Answer 2

Resist axial compressive loads, occasionally columns are subjected to both an axial load and bending moment, these are referred to as beam columns

Question 3

Classification of structures - frame

Answer 3

Composed of beams and columns that are either pin or fixed connected

Question 4

Classification of structures - truss

Answer 4

resist axial compressive and tensile loads. Trusses consist of slender elements, usually arranged in a triangular fashion

Question 5

Types of structures - cables

Answer 5

cables are usually flexible and carry their loads in tension

Question 6

Types of structures - arches

Answer 6

achieves its strength in compression

Question 7

Pin support (definition)

Answer 7

provide reacting forces while allowing the structure to rotate freely

Question 8

Roller (definition)

Answer 8

Transfer forces in one direction, it allows a free movement in the other two directions as well as free rotation around the three direction axes

Question 9

Fixed (definition)

Answer 9

the fixed support provides force and moment reactions in all three directions

Question 10

Determinacy (definition)

Answer 10

a statically determinate structure is one that is stable and all unknown forces can be determined from the equations of equilibrium

Question 11

Internal stability (definition)

Answer 11

a structure is considered to be internally stable if it maintains its shape when detached from the supports (think hammer)

Question 12

static determinacy equation for internally stable structures

Answer 12

r = 3

Question 13

Geometrically unstable structures (definition)

Answer 13

All reactions parallel in the same direction, all lines of reaction are concurrent at the same point

Question 14

Static determinacy equation of internally unstable structures (method 1)

Answer 14

r = 3 + ec
(ec = 1 for each internal hinge and 2 for each internal roller)
r = number of reactions

Question 15

Static determinacy equation of internally unstable structures (method 2)

Answer 15

r + fi = 3nr
(fi = 1 for each internal roller and 2 for each internal hinge)
Nr = number of rigid members
fi = number of internal forces
r = number of reactions

Question 16

Truss determinacy equation

Answer 16

m + r = 2j
m = number of members
r = number of reactions
j = number of joints

Question 17

Frame determinacy equation

Answer 17

3m + r = 3j + ec
m = number of members
r = number of reactions
j = number of joints
ec = equations of condition

Question 18

Moment area method (definition)

Answer 18

graphical interpretations of integrals of the deflection differential equation (changes integration to a calculation of area)
More convenient for beans with loading discontinuities and different EI

Question 19

First moment area theorem (definition)

Answer 19

the change in slope between the tangents to the elastic curves at two points is equal to the area under the M/EI diagram between the two points, provided that the elastic curve is continuous between the two points.
If the area of the M/EI diagram is positive, then the angle at the point to the left to the tangent at the point to the right will be counterclockwise and positive

Question 20

Conjugate beam method (definition)

Answer 20

If the M/EI diagram for a beam is applied as the load on a fictitious (conjugate) beam, then the shear and bending moment at any point on the fictitious beam will be the slope and deflection on the real beam.
The shear and moment on the conjugate beam must be consistent with the slope and deflection on the real beam (criteria for selection the “best friend”)