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Final Exam Study Guide Flashcards

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1
Q

What is a force that tends to cause a rotation or twist about a point?

A

Moment

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2
Q

What is a moment?

A

a force that tends to cause a rotation or twist about a point

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3
Q

Moment Equation is M= ? * ?

A

M=F*(perp dist to origin)

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4
Q

What are the units of a moment?

A

Force times distance

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5
Q

Name 2 examples of a moment unit

A

kip-ft, kip-in, lb-ft, lb-in

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6
Q

What is the difference between a dead and a superimposed dead load?

A

dead– only the structural weight
superimposed– all permanent loads (flooring, roofing, permanent equipment, MEP)

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7
Q

Name some types of superimposed dead loads

A

flooring, roofing, permanent equipment, MEP

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8
Q

Name some types of dead loads

A

this is me being silly & tricky,,, it’s just the self-weight

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9
Q

What is the load on a structure that is temporary or transient?

A

Live load

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10
Q

What is a live load?

A

A load on a structure that is transient or temporart

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11
Q

What are some examples of live loads?

A

People, vehicles, partitions, furniture, moveable equipment, snow

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12
Q

What are the units of inertia?

A

(unit of length)^4

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13
Q

What is a mathematical expression that describes the relative location of material in a cross section?

A

Moment of Inertia

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14
Q

What is a moment of inertia?

A

Relative location of material in a cross-section. It resists bending stress and deflection

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15
Q

What is another name for moment of inertia?

A

Second moment

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16
Q

What is moment of inertia a measure of?

A

Cross-sectional stiffness

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17
Q

How would one find the Moment of Inertia of Hollow Shapes?

A

If the centroids of two shapes coincide, you may subtract the moment of inertia of the void from the moment of inertia of the overall body. THIS IS CALLED THE NEGATIVE AREA METHOD

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18
Q

What is the manner in which loads travel throughout the structure?

A

Load Path

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19
Q

What is a Load Path

A

the manner in which loads travel throughout the structure

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20
Q

What concept considers the area that a member must support as being halfway between the adjacent similar members?

A

Tributary area

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21
Q

What is tributary area?

A

concept that the area that a member must support as being halfway between the adjacent similar members

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22
Q

Beams are classified based on ____

A

support conditions

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23
Q

What is a simply supported beam?

A

2 supports, 1 on each end

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24
Q

What is a continuous supported beam?

A

3 or more supports

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25
What is a cantilever beam
1 end supported rigidly
26
What is an overhang beam?
2 supports but 1 or both are not located at the end
27
What is a propped beam??
2 supports, 1 end is fixed
28
What is a restrained or fixed beam
both supports are fixed, allowing no rotation
29
What is the mathematical relationship between nominal and actual dimensioning?
1 nominal inch=3/4 actual inch 2-6 n"= -.5" actual 8+" n= -3/4" actual
30
What concept is represented by the equation I/C, where I is the moment of inertia and c is the distance from the centroidal axis to the extreme fiber
section modulus S
31
What is the variable S?
Section modulus, a ratio that can be standardized for materials of given size/makeup & found in tables
32
What is the equation for section modulus S?
I/C Where C is the distance from the centroidal axis to the extreme fiber and I is the moment of inertia This equation is not usually used for standard shapes bc S is in tables
33
What is the variable fb?
fb is the bending stress at the extreme fiber, top or bottom
34
What is the formula for bending stress or flexure?
fb= Mc/I or M/S since S=I/C M is the bending moment in the beam, usually Mmax and found through the shear & moment diagrams S is the section modulus, found in a table
35
What equation could be used to determine the required section modulus when designing a wood beam?
Sreq=M/Fb where Fb is the allowable bending stress M is the maximum bending moment in the beam (shear&stressgraphs)
36
What is a load in which the resultant concentrat4ed load passes through the centroids of all resisting sections
Axial load
37
What is a load in which the loads are applied transversely to the longitudinal axis of the member.
Flexural or bending load
38
What is an axial load?
a load in which the resultant concentrated load passes through the centroids of all resisting sections
39
What is a flexural load?
load in which the loads are applied transversely to the longitudinal axis of the member. also known as bending load
40
Stress flexural
41
What is the quantity of force that acts on a unit of area
stress
42
What is normal or axial stress
force per unit area. Stress acts perp. to the cross-section
43
What is the average value of the axial stress?
f = σ = P / A where P is axial force and A is perp. resisting area
44
What is shear stress?
quantity of tangential force acting over an area parallel to the direction of the applied load. Acts parallel or tangential to the cross-section
45
What is the formula for shear stress?f
fv = τ = V / A Where V is shearing force A is cross-sectional area parallel to load direction
46
What type of stress is the primary concern when designing beams?
flexural or bending stress
47
What is the formula for bending stress
σb = M * c / I where σb is bending stress M is bending moment c is distance from centroid to extreme top & bottom fibers I is moment of inertia
48
Is bending stress for unsymmetrical cross-sections determined by the the smaller or larger of the distances from the centroid line to the extreme top/bottom?
larger of the 2. distance c.
49
What is the sign convention for compression & tension?
compression is (-) tension is (+)
50
What is strain?
deformation per unit length. results from stress or temperature change.
51
What is the symbol δ
deformation
52
What is the symbol ε
normal STRAIN
53
symbol γ?
shear strain
54
What is normal/axial strain?
deformation per unit length resultant from a normal load.
55
What is the formula for normal strain?
ε =δ/L Where ε is strain δ is the change in length L is the original length
56
What is the modulus of elasticity
Also called young's modulus Measure of the material stiffness or how much stress it will take to cause a unit strain (contraction or elongaiton)
57
What is the equation for modulus of elasticity?
Hookes Law: E =σ/ε modulus = stress / strain
58
What is shear strain?
deformation due to shear stress, which is stress acting parallel to the cross section, results in changes to shape but not volume. represented by γ
59
What is the formula for shear strain?
γ = δs/L = tanφ where γ is shear strain δ is shear deformation (distance one point of original side moves) L is original length φ is angle that the original side moves
60
What is bending strain?
deformation per unit length due to bending stress
61
What is the difference between ductile and brittle materials?
Ductile materials have molecular bonds that reform after exceeding the elastic limit that will result in permanent deformaiton while still remaining in one piece without a significant loss in strength. Brittle materials when the elastic loimit is exceeded are unable to reform , causing cracks or seperation of material
62
Give examples of ductile materials
low-carbon steel, aluminum, copper, gold
63
give examples of brittle materials
cast iron, high-carbon steel, ceramics
64
What is lumber grading?
Lumber is graded according to its quality, strength, and appearance, with trained inspectors using standardized criteria such as knots, grain patterns, and defects to assign a grade. This classification ensures that lumber meets industry standards and facilitates its appropriate use in construction and manufacturing.
65
Do grades of lumber go up or down from 1 to 3?
1 is best quality, 3 is cheapest. select structural is highest. below 3 is stud, then construction.
66
What is allowable stress?
Stress that a member can hold. Allowable stress divided by failujre stress provides the factor of safety.
67
Section modulus rectangle?
S = bh^2/6
68
How is stiffness of material evaluated?
Young's modulus or the modulus of elasticity, which is the slope of the straight-line portion of a stress-strain daigram. E = f/ε where f is stress and ε is strain
69
What is ultimate strength?
absolute highest stress magnitude on a stress-strain graph
70
A structural system that distributes loads to supports through a alinear arrangement of various-sized members in patterns of planar triangles
truss
71
What is a truss?
a structure that consists of members assembled such that they resist loads axially only
72
Truss members are connected by ____
smooth pins @ their joints
73
all loading is applied ____ of a truss
at the joints
74
since members are ____, their weight is ____ compared to joint loads.
slender, negligioble
75
What are the only forces oln truss members?
compression & tension
76
What is a zero force member?
An unloaded joint where 3 members frame together. if 2 members are in a straight line, then the 3rd is zero force.
77
What is deflection?
A stiffness requirement representing a change in vertical position of a beam due to the applied loads.
78
What is the equation to find actual deflection on a simple span with a uniform load?
deltamax=5wL^4/384EI where delta is deflection w is the applied loads E is the elastic modulus I is the moment of inertia
79
What is the shortcut formula form Maximum moment of a simply supported beam?
`wL^2/8 where w is the total load (dead+live) L is the length of the beam
80
What is the shortcut for Vmax of a simply supported beam?
wL/2 where w is the total load on the beam L is the length of the beam
81
What is the shortcut for cross-sectional area required of a simpy supported beam?
Areq=1.5Vmax/Fv Where Vmax is the maximum shear on the loaded beam (found by wL/2) Fv is the maximum shearing stress, may be given in the problem.
82
What is the formula for allowable deflection of a simply supported beam?
deltaallowable(DL+LL) = L/240 where L is the length of the beam deltaallowable (LL) = L/360 ***dont forget to multiply L by 12 if it is in feet and not inches

Structures (4 decks)

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