The Civ il Eng in eer Scho ol at AFIT The AFIT of Today is t he Air Force of Tomor row.
PE EXAM REVIEW: STRUCTURAL MORNING TOPICS
Thomas M. Synovec Capt, USAF AFIT/ENV/GEM 9 September 2013
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Overview The AFIT of Today is t he Air Force of Tomor row.
• Introduction • Topics • Loadings • Determinate Analysis • Mechanics of Materials • Materials • Member Design
• Takeaways • Str uc tu ral PM Exam Vital - Relevant - Connected
Introduction The AFIT of Today is t he Air Force of Tomor row.
• Stru ctu ral Accou nts for 20% of t he Morn ing Exa m • Approximately 8 Questions
• 5 Sub-Topic s • Loadings • Analysis • Mechanics of Materials • Structural Materials • Member Design
• Format • Fundamentals Driven Lecture • Discussion of Individual Sub-Topics Followed by Representative Exam-Style Questions
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The AFIT of Today is t he Air Force of Tomor row.
Loadings
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Loadings The AFIT of Today is t he Air Force of Tomor row.
Loads : Forces or other actions that result from the weight of all building materials, occupants and their possessions, environmental effects, differential movement, and restrained dimensional changes •
Type s o f L oads •
Dead (D)
•
Liv e (L)
•
Construction (Lc)
•
Wind (W)
•
Seismic (E)
•
Rain (R)
•
Snow (S)
•
Fluids (F)
•
Lateral Earth Pressure (H)
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Dead L oads The AFIT of Today is t he Air Force of Tomor row.
•
Dead Lo ads : Consists of the weight of all materials of construction incorporated into the building including, but not limited to, walls, floors, roofs, ceilings, stairways, built-in partitions, finishes, cladding, and other similarly incorporated architectural and structural items and fixed service equipment including the weight of cranes (ASCE 07-05)
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Liv e Lo ads The AFIT of Today is t he Air Force of Tomor row.
•
Live Loads : A load produced by the use and occupancy of the building or other structure that does not include construction or environmental loads, such as wind, snow, rain, earthquake, flood, or dead loads (ASCE 07-05)
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Cons tru cti on (Liv e) Loads The AFIT of Today is t he Air Force of Tomor row.
•
Construction Loads : Typically live loads that occur as a direct result of construction activities
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Transl atin g Loads The AFIT of Today is t he Air Force of Tomor row.
PD = 5 kips
wL = 3 kips/ft wD = 2 kips/ft
5 ft 25 ft Vital - Relevant - Connected
Load Com bin atio ns The AFIT of Today is t he Air Force of Tomor row.
• Two Design Methods with Different Load Combinations • Load and Resistance Factored Design (LRFD) • aka: Strength Design
• Allowable Stress Design (ASD) • aka: Working Stress Design
• For Either Design Method, use the Controlling Load Combination for Analysis/Design • Service Loads or Serviceability Limit States use Unfactored Loads
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LRFD Lo ad Com bi nation s The AFIT of Today is t he Air Force of Tomor row.
1. 1.4(D + F) 2. 1.2(D + F + T) + 1.6(L + H) + 0.5(L r or S or R) 3. 1.2D + 1.6(L r or S or R) + ((0.5 or 1.0)*L or 0.8W) 4. 1.2D + 1.6W + (0.5 or 1.0) *L + 0.5(Lr or S or R) 5. 1.2D + 1.0E + (0.5 or 1.0) *L + 0.2S 6. 0.9D + 1.6W + 1.6H 7. 0.9D + 1.0E + 1.6H Largest Load Controls Design/Analysis
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ASD Load Combinations The AFIT of Today is t he Air Force of Tomor row.
1. D + F 2. D + H + F + L + T 3. D + H + F + (L r or S or R) 4. D + H + F + 0.75(L + T) + 0.75(L r or S or R) 5. D + H + F + (W or 0.7E) 6. D + H + F + 0.75(W or 0.7E) + 0.75L + 0.75(L r or S or R) 7. 0.6D + W + H 8. 0.6D + 0.7E + H Largest Load Controls Design/Analysis Vital - Relevant - Connected
The AFIT of Today is t he Air Force of Tomor row.
Analysis
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Analysis The AFIT of Today is t he Air Force of Tomor row.
• Determ in ate Analysi s i n th e AM • Indeterminate Analysis on Civil-Structural (PM)
• Statics Requir es Equi lib riu m Conditi ons are Met • ∑Fx = 0 • ∑Fy = 0 • ∑M = 0 (About an axis of interest)
• Topic s Cove red in t his Secti on • Connections • Determinacy • Determinate Analysis (Summing Forces) • Superposition using Beam Formulas • Frames • Trusses
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Connections The AFIT of Today is t he Air Force of Tomor row.
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Connections The AFIT of Today is t he Air Force of Tomor row.
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Connections The AFIT of Today is t he Air Force of Tomor row.
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Determinacy The AFIT of Today is t he Air Force of Tomor row.
Xa
Ra
r > 3n (Indeterminate) r = 3n (Determinate) r < 3n (Unstable)
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Rb
Determinacy The AFIT of Today is t he Air Force of Tomor row.
3 = 3(1) Stable
4 = 3(1) Indeterminate
2 = 3(1) Unstable
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Determinacy The AFIT of Today is t he Air Force of Tomor row.
3 = 3(1) Unstable
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Determ in ate An aly si s The AFIT of Today is t he Air Force of Tomor row.
PD = 5 kips
wL = 3 kips/ft wD = 2 kips/ft
5 ft 25 ft Vital - Relevant - Connected
Determ in ate An aly si s The AFIT of Today is t he Air Force of Tomor row.
PD = (1.2)(5 kips) = 6 kips
w = (1.2)(2 kips/ft) + (1.6)(3 kips/ft) = 7.2 kips/ft
5 ft 25 ft Vital - Relevant - Connected
Determ in ate An aly si s The AFIT of Today is t he Air Force of Tomor row.
P = 6 kips w = 7.2 kips/ft
Xa
5 ft 25 ft Ra
Rb
∑Fx = Xa = 0 ∑Ma = (Rb)(25’) – (6k)(5’) – (7.2k/ft)(25’)(12.5’) = 0 Rb = 2280k / 25’ = 91.2 k ∑Fy = Ra + 91.2k – 6k – (7.2k/ft)(25’) = 0 Ra = 94.8 k Vital - Relevant - Connected
Determ in ate An aly si s The AFIT of Today is t he Air Force of Tomor row.
P = 6 kips
w = 7.2 kips/ft
5 ft 10 ft
10 ft P = 6 kips
Ma
w = 7.2 kips/ft
Xa 5 ft 10 ft Ra Vital - Relevant - Connected
10 ft
Determ in ate An aly si s The AFIT of Today is t he Air Force of Tomor row.
P = 6 kips
Ma
w = 7.2 kips/ft
Xa 5 ft 10 ft
10 ft
Ra ∑Fx = Xa = 0 ∑Fy = Ra - 6k – (7.2k/ft)(10’) = 0 Ra = 78.0 k ∑Ma = Ma – (6k)(5’) – (7.2k/ft)(10’) (15’) = 0 Ma = 1110.0 ft-k Vital - Relevant - Connected
Superposition The AFIT of Today is t he Air Force of Tomor row.
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Superposition The AFIT of Today is t he Air Force of Tomor row.
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Superposition The AFIT of Today is t he Air Force of Tomor row.
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Superposition The AFIT of Today is t he Air Force of Tomor row.
Relooking at the Previous Simply Support Example P = 6 kips w = 7.2 kips/ft
Xa
5 ft 25 ft Ra
Rb
Ra = (.5) (7.2k/ft)(25’) + (6 k)(25’ – 5’)/(25’) = 94.8 k Rb = (.5) (7.2k/ft)(25’) + (6 k)(5’)/(25’) = 91.2 k Vital - Relevant - Connected
Frames The AFIT of Today is t he Air Force of Tomor row.
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Frames The AFIT of Today is t he Air Force of Tomor row.
Internal Hinge
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Fixed Connection
Frames The AFIT of Today is t he Air Force of Tomor row.
w = 5 kips/ft
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w = 5 kips/ft
Frames The AFIT of Today is t he Air Force of Tomor row.
w = 5 kips/ft
w = 5 kips/ft Xa
Xa 20 ft
Ra
20 ft
Ra
Rb
Rb 15 ft
15 ft
5 ft
5 ft
∑Fx = Xa = 0
∑Fx = Xa = 0
∑Ma = (Rb)(15’) – (5k/ft)(20’) (10’) = 0 Rb = 66.7 k
∑Ma = (Rb)(15’) – (5k/ft)(5’) (17.5’) = 0 Rb = 29.2 k
∑Fy = Ra + Rb – (5k/ft)(20’) = 0 Ra = -(66.7 k) + (100 k) Ra = 33.3 k
∑Fy = Ra + Rb – (5k/ft)(5’) = 0 Ra = -(29.2 k) + (25 k) Ra = -4.2 k
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Trusses The AFIT of Today is t he Air Force of Tomor row.
• Truss Assumptions • Members are pin connected • Loads placed at nodes only • Axial loading
• Two Me thod s fo r Analyzing Trusses • Method of Joints • Method of Sections
•
Ident if y Zero Force Me mbers
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Trusses The AFIT of Today is t he Air Force of Tomor row.
10 kip H
10 kip I
J
10 kip K
L
8 ft A
G B
C
D
6 @ 6 ft = 36 ft
• Find: Forc e in CJ • Prob lem S olv ing Steps • Solve External Reactions • Use Method of Joints/Sections
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E
F
Trusses The AFIT of Today is t he Air Force of Tomor row.
10 kip H
10 kip I
J
10 kip K
L
8 ft XA
A
G B
C
D
E
F
6 @ 6 ft = 36 ft RA
RG
∑Fx = Xa = 0 ∑MA = (RG)(36’) – (10 k)(6’) – (10 k)(18’) – (10 k)(30’) = 0 RG = 15 k
10 ft 8 ft
∑Fy = RA + RG – (three)(10 k) = 0 RA = (30k) – (15 k) RA = 15 k
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6 ft
Method of J oint s The AFIT of Today is t he Air Force of Tomor row.
Node A
AH
A
AB
RA = 15 k
∑Fy = RA + AH(8’/10’) = 0 (0.8)AH = -15 k AH = -18.75 k = 18.75 k (C) ∑Fx = AB – AH(6’/10’) = 0 AB = (0.6)(18.75k) AB = 11.25 k (T)
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Method of J oint s The AFIT of Today is t he Air Force of Tomor row.
Node H 10 k
HI
H HA HB
∑Fy = -10k – HB + AH(8’/10’) = 0 HB = 15k – 10k HB = 5 k (T) ∑Fx = HI + AH(6’/10’) = 0 HI = (0.6)(18.75k) HI = 11.25 k (C)
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Method of J oint s The AFIT of Today is t he Air Force of Tomor row.
Node B
BH BI B BA
BC
∑Fy = BH + BI(8’/10’) = 0 (0.8)BI = -5k BI = 6.25 k (C) ∑Fx = BC - BI(6’/10’) – BA = 0 BC = 11.25k + (0.6)(6.25k) BC = 15 k (T)
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Method of J oint s The AFIT of Today is t he Air Force of Tomor row.
Node I
IH
IJ
I
IB IC
∑Fy = IB(8’/10’) – IC = 0 IC = (6.25k)(0.8) IC = 5 k (T) ∑Fx = IH + IB(6’/10’) + IJ = 0 IJ = -11.25k - (0.6)(5k) IJ = 15k (C)
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Method of J oint s The AFIT of Today is t he Air Force of Tomor row.
Node C
CI CJ C CB
CD
∑Fy = CJ(8’/10’) + CI = 0 (0.8)CJ = -5k CJ = 6.25 k (C) ∑Fx = -CB – CJ(6’/10’) + CD = 0 CD = -15k – (0.6)(6.25k) CD = 18.75 k (T)
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CJ = 6.25 k (C)
Meth od o f Sect io ns The AFIT of Today is t he Air Force of Tomor row.
10 kip H
10 kip I
J
10 kip K
L
8 ft XA
A
G B
C
D
E
F
6 @ 6 ft = 36 ft RA
RG
Rule s for Making Cuts usin g Method of Se ctio ns 1.
Cut must separate structure into only two parts
2.
Cut cannot pass through more than three members
3.
Cut cannot result in members with concurrent forces
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Meth od o f Sect io ns The AFIT of Today is t he Air Force of Tomor row.
10 kip H
I
J
8 ft XA
A B
C
D
2 @ 6 ft = 12 ft
RA
∑Fy = RA – 10k + (CJ)(8’/10’) = 0 (0.8)CJ = 10k – 15k CJ = 6.25 k (C)
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Zero-Force Memb ers The AFIT of Today is t he Air Force of Tomor row.
• When all t he forc es at a no de are transf or med to t he glo bal x-y coord inate syst em: • If one axis consists of only one force, that force must be zero • If one axis consists of only two forces, those forces must be equal and opposite 10 kip H
10 kip I
J
10 kip K
L
8 ft XA
A
G B
C
D
E
F
6 @ 6 ft = 36 ft RA
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RG
Zero-Force Memb ers The AFIT of Today is t he Air Force of Tomor row.
Where are the zero-force members in the structure below?
10 kip
10 kip 10 kip
G
F
I
H
J
8 ft E
A B
C
D
4 @ 6 ft = 24 ft
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Zero-Force Memb ers The AFIT of Today is t he Air Force of Tomor row.
10 kip
10 kip 10 kip
G
F
I
H
10 kip J
10 kip 10 kip
G
I
H
8 ft E
A B
C
D
4 @ 6 ft = 24 ft
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8 ft E
A B
C
D
4 @ 6 ft = 24 ft
The AFIT of Today is t he Air Force of Tomor row.
Mechani cs o f Materials
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Mech ani cs of Materi als The AFIT of Today is t he Air Force of Tomor row.
Topi cs Covere d in thi s Secti on • Sectio nal Properties • Stress and S tr ain • Stresses • Shear • Flexural (Bending) • Axial (Tension or Compression) • Torsional (Not specified on AM Test) • Combined Stresses
• Cut Dia grams • Shear Diagrams • Moment Dia gr ams • Deflection • Miscellaneous Vital - Relevant - Connected
Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
Secti onal Properties Discu ssed •
Area (A)
•
Location of Centroid (Elastic Neutral Axis)
• •
Moment of Inertia (I) Elastic Section Modulus (S)
•
Radius of Gyration (r)
•
First Moment of the Area (Q)
•
Polar Moment of Inertia (J)
•
Shear Center
•
Kern
h
b
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Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
3”
1
15”
2
2” 25” Vital - Relevant - Connected
Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
1
3”
NA 15”
2
13.93”
2” 25” Vital - Relevant - Connected
Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
1
3”
NA 15”
2
13.93”
2” 25” Vital - Relevant - Connected
Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
1
3”
NA 15”
2
13.93”
2” 25” Vital - Relevant - Connected
Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
1
3”
NA 15”
2
13.93”
2” 25” Vital - Relevant - Connected
Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
Shear Cent er: an imaginary point on a cross-section through which a shear force can be applied without inducing torsion; the shear center is not always located through the centroid P
No Tors ion Vital - Relevant - Connected
P
Torsion
Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
P
P NA
No Tors ion Vital - Relevant - Connected
NA
Torsion
Sect io nal Pro perti es The AFIT of Today is t he Air Force of Tomor row.
Kern: an imaginary zone on a cross-section through which an axial force can be applied and the cross-section can be assumed to be entirely in compression or tension
1.61” 5.51”
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Sect io n Pro perti es The AFIT of Today is t he Air Force of Tomor row.
h
Important t o Remembe r f or Slab Design/Analysis
b Vital - Relevant - Connected
Str ess and Str ain The AFIT of Today is t he Air Force of Tomor row.
•
Materials Te stin g used t o Determi ne Stress and Strain Values fo r Materials at Yield, Ultim ate, and Rupt ur e Strengths
•
Stress and Strain are Propo rtio nal and are relate d by Young’s Modulus (N ormal Stress)
•
Thermal De fo rmati on and Creep Impact Stress and Strain Values Vital - Relevant - Connected
Str ess and Str ain The AFIT of Today is t he Air Force of Tomor row.
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Str ess and Str ain The AFIT of Today is t he Air Force of Tomor row.
Same Slope
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Str ess and Str ain The AFIT of Today is t he Air Force of Tomor row.
Materials Term Strong Weak
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Defini tio n High Ultimate Strength Low Ultimate Strength
Tough
Yields well before Rupture
Brittle
Catastrophic Failure
Hard
High Modulus of Elasticity
Soft
Low Modulus of Elasticity
Stresses The AFIT of Today is t he Air Force of Tomor row.
Stresses Discu ssed • Shear • Flexural (Bending) • Axial (Tension and Compression) • Torsion • Combined Stresses Vital - Relevant - Connected
Shear Stress es The AFIT of Today is t he Air Force of Tomor row.
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Shear Stress es The AFIT of Today is t he Air Force of Tomor row.
V = 2 kips
3”
y1
7”
NA
10”
10”
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Flexu ral ( Bend in g) Str ess es The AFIT of Today is t he Air Force of Tomor row.
+ = Above NA - = Below NA Vital - Relevant - Connected
Flexu ral Stress es The AFIT of Today is t he Air Force of Tomor row.
3”
y1
7”
NA
10”
M = 4 ft-k σ
1
10”
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Axial Stresses The AFIT of Today is t he Air Force of Tomor row.
Compression
Tension
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Axial Stresses The AFIT of Today is t he Air Force of Tomor row.
6.67” NA
3.33” 10”
P = 2 kips 10”
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Axial Stresses The AFIT of Today is t he Air Force of Tomor row.
6.67” NA
3.33” 10”
P = 2 kips
10”
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Tor si on al Stre ss es The AFIT of Today is t he Air Force of Tomor row.
•
Occu rs w hen a S hear Forc e is Lo aded Eccentric ally Ca usin g a Torsi on al Force P arallel to the C ro ss -Sectio n • Visualized as a Moment about the X-Axis (Parallel to Cross-Section)
•
Eccentri c Loading = Loading a Dist ance “ e” fro m the S hear Center
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Com bi ned S tr ess es The AFIT of Today is t he Air Force of Tomor row.
Positive Sign Convention
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Com bi ned S tr ess es The AFIT of Today is t he Air Force of Tomor row.
Positive Sign Convention
Mohr’s Circl e
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Com bi ned S tr ess es The AFIT of Today is t he Air Force of Tomor row.
5 ksi 7 ksi
1. Determine Maximum Normal and Shear Stresses 2. Determine Angle of the Plane of Princ iple Normal S tr esses
25 ksi
3. Draw Moh r’s C ircle
7 ksi
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Com bi ned S tr ess es The AFIT of Today is t he Air Force of Tomor row.
5 ksi 7 ksi
25 ksi
7 ksi
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Com bi ned S tr ess es The AFIT of Today is t he Air Force of Tomor row.
5 ksi 7 ksi
25 ksi
7 ksi
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Com bi ned S tr ess es The AFIT of Today is t he Air Force of Tomor row.
5 ksi 7 ksi
25 ksi
7 ksi
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Combined Stresses The AFI T of Today is
the Air Force of
Tom orrow.
3. Draw Mohr’s Circle
τ
= =
1 25 5 2
(10, 16.55)
=
(-5, 7) (-6.55, 0)
+
16.55 = 6.55 ksi =
.+ −.
= 10.00
2 = 2 12.51 = 25.02 (10, 0)
(26.55, 0) σ
5 ksi
25⁰
7 ksi (25, -7) 25 ksi (10, -16.55) 7 ksi
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Cut Diagrams The AFI T of Today is
the Air Force of
M
M P
P
V
Vital - Relevant - Connected
Tom orrow.
V
Cut Diagr ams The AFIT of Today is t he Air Force of Tomor row.
w = 2 klf M P
V X 20 kips
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Shear Diagr ams The AFIT of Today is t he Air Force of Tomor row.
w = 2 klf
20’
20 kips
20 kips
20 kips
V(x)
10’
Vital - Relevant - Connected
-20 kips
Mom ent Diagr ams The AFIT of Today is t he Air Force of Tomor row.
w = 2 klf
20 kips
10’
10’
20 kips
20 kips V(x) Mmax = 100 ‘k
M(x)
Vital - Relevant - Connected
-20 kips
Deflection The AFIT of Today is t he Air Force of Tomor row.
• Several D if ferent M eth ods f or Determi ni ng Defl ectio ns • Table Lookup and Superposition (Easiest) • Double Integration Method • Conjugate Beam Method • Strain-Energy Method (Internal/External Work) • Virtual Work Method
• Not Coverin g Str ain -Energy and Virt ual Wor k Meth od s • Complicated Given Short Class Duration • Detailed in CERM
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Dou bl e Int egr ati on The AFIT of Today is t he Air Force of Tomor row.
Beam Boundary Conditions End Condition
y
Simple Support
0
Fixed
0
Free Hinge
Vital - Relevant - Connected
y’
y’’
V
M
0 0 0
0
0 0
Dou bl e Int egr ati on The AFIT of Today is t he Air Force of Tomor row.
y’ (L/2 = 10’) = 0
y (0) = 0
Vital - Relevant - Connected
Con ju gate Be am The AFIT of Today is t he Air Force of Tomor row.
Fixed Connection
20 kips 400 ft-k
20 kips
20’
20 kips V(x)
M(x)
Mmax = -400 ft-k
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Con ju gate Be am The AFIT of Today is t he Air Force of Tomor row.
Reversed Support Conditions
Δmax
θmax 20’
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Tabl e Lo ok up The AFIT of Today is t he Air Force of Tomor row.
3EI
3EI
Load Tables Assumes you Know Which Direction the Deflection Acts Vital - Relevant - Connected
Miscellaneous The AFIT of Today is t he Air Force of Tomor row.
w = 2 klf
M = 75 k-ft
7’
5’
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4’
4’
Miscellaneous The AFIT of Today is t he Air Force of Tomor row.
w = 2 klf 99 ft-k
M = 75 ft-k
2 kips 5’
7’
4’
4’
6 kips
2 kips V(x)
-6 kips 9 ft-k M(x)
85 ft-k 99 ft-k
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The AFIT of Today is t he Air Force of Tomor row.
Materials
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Materials The AFIT of Today is t he Air Force of Tomor row.
•
PE Exam Inclu des Several C onc eptual Que st ion s that do n ot Require any Calculations
•
Materials on the AM S ectio n • Steel • Concrete
Material
Tensile Strength
Compressive Strength
Density
Wood (Avg)
1.2 ksi
1.55 ksi
21.7 pcf
1,300 ksi
Masonry
0.4 ksi
2.0 ksi
130 pcf
1,500 ksi
A36 Steel
36 ksi (58 ksi)
36 ksi (58 ksi)
490 pcf
29,000 ksi
Concrete
0.4 ksi
4 ksi
150 pcf
3,600 ksi
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Modulus of Elasticity
Concrete The AFIT of Today is t he Air Force of Tomor row.
•
Good in Compressio n, Ba d in Tensio n • Needs Rebar to Support Tensile Forces
•
Low Stre ngth -to- Weight Ratio Compara tively • Normal Weight Concrete Weighs 150 pcf (Unless Otherwise Stated)
•
Suscept ibl e to Shri nkage a nd Cree p
•
Brit tle Material
•
Widespr ead Usage and Availabil it y • Relatively Cheap
•
Uses ACI Desig n Standards • ACI 318 is Most Widely Used; LRFD Design Methodology Vital - Relevant - Connected
Concrete The AFIT of Today is t he Air Force of Tomor row.
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Concrete The AFIT of Today is t he Air Force of Tomor row.
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Concrete The AFIT of Today is t he Air Force of Tomor row.
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Steel The AFIT of Today is t he Air Force of Tomor row.
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Commo n Types of Stee l • Cast Iron • Carbon (Typical for Construction) • Alloy
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Ductile Ma terial wi th Good Strength -to-W eight Ratio
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Highly Susceptib le to Therma l Deform ation
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AISC Steel Manual is the Design Gu ide • ASD and LRFD are used • Not Uncommon to Have Built-up Sections
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The AFIT of Today is t he Air Force of Tomor row.
Design
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Memb er Desi gn The AFIT of Today is t he Air Force of Tomor row.
• Requir ements f or t he AM Sectio n • Steel Design • Beam Design
• Concrete Design • Beam Design • Slab Design • Footing Design
• Answers on PE Exam are Typically Given for both ASD and LRFD • This Section will Focus on LRFD as it is applicable to both Materials
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Steel Beam Desig n The AFIT of Today is t he Air Force of Tomor row.
Steps For Flexu ral Stee l Desi gn (Beams ) 1. Determine Fy, L, Lb 2. Estimate Beam Weight 3. Calculate Load Combinations 4. Calculate V u and Mu 5. Determine Cb as Applicable 6. Use Tables to Identify Trial Section; Determine ΦMn 7. Check ΦMn ≥ Mu 8. Check ΦVn ≥ Vu 9. Check Deflection using Service Loads
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Con cr ete Bea m Desi gn The AFIT of Today is t he Air Force of Tomor row.
Steps For Flexu ral Conc rete D esi gn (Beams) 1. Estimate Beam Weight 2. Calculate Load Combinations 3. Calculate V u and Mu; Draw Shear and Moment Diagrams 4. Determine Tensile Zones 5. Determine A s 6. Create Trial Section with Steel Reinforcement •
Check Development Length of Bars
7. Check ΦMn ≥ Mu 8. Check ΦVn ≥ Vu; Add Stirrups as Necessary 9. Check Deflection using Service Loads •
Typically Thickness Controlled
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Con cr ete Desi gn The AFIT of Today is t he Air Force of Tomor row.
>.005 (Tension Controlled)
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Beam Desi gn The AFIT of Today is t he Air Force of Tomor row.
PD = (1.2)(5 kips) = 6 kips
PD = (1.2)(5 kips) = 6 kips
w = (1.2)(2 kips/ft) + (1.6)(3 kips/ft) = 7.2 kips/ft
5 ft
5 ft 25 ft Vital - Relevant - Connected
Ins ert Wor ko ut Pro bl em #1
Ins ert Wor ko ut Pro bl em #2
Slabs The AFIT of Today is t he Air Force of Tomor row.
One-Way Slab
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Two-Way Sl ab
Slabs The AFIT of Today is t he Air Force of Tomor row.
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Ins ert Wor ko ut Pro bl em #3
Footings The AFIT of Today is t he Air Force of Tomor row.
Column Footing Vital - Relevant - Connected
Ins ert Wor ko ut Pro bl em #4
The AFIT of Today is t he Air Force of Tomor row.
Takeaways
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Takeaways The AFIT of Today is t he Air Force of Tomor row.
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Pay Attenti on to Units! • English and Metric Units on the PE
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Look f or Shortcu ts w here Available • “Rules of Thumb” • Work Backwards
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Test Designers Create Wrong A nsw er Choic es Based U pon Common Ca lcu lation E rro rs
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You do not Los e Point s for Gue ssi ng • Do not Leave Questions Unanswered
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The AFIT of Today is t he Air Force of Tomor row.
Structural PM Exam
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Str uc tu ral P M For mat The AFIT of Today is t he Air Force of Tomor row.
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7 Topic s • Loadings (12.5%) • Analysis (12.5%) • Mechanics of Materials (12.5%) • Materials (12.5%) • Member Design (25%) • Design Criteria (12.5%) • Other Topics (12.5%)
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LRFD and ASD Design Meth ods Utili zed
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Get Famil iar wi th you r Refere nc es
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Focus on the F undamentals F irst , the n th e Exot ic • Don’t Spend all your Time Studying Prestressed Concrete and Forget to Brush up on Analysis Vital - Relevant - Connected
Struc tura l Bo oks The AFIT of Today is t he Air Force of Tomor row.
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AASHTO LRFD Bridge Design Specifications, 5th edition, 2010,American Association of State Highway & Transportation Officials, Washington, DC.
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International Building Code, 2009 edition (without supplements), International Code Council, Falls Church, VA. (IBC 2009)
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Minimum Design Loads for Buildings and Other Structures, 2005, American Society of Civil Engineers, Reston, VA. (ASCE 07-05)
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Building Code Requirements for Structural Concrete, 2008, American Concrete
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Institute, Farmington Hills, MI. (ACI 318-08) Steel Construction Manual, 13th edition, American Institute of Steel Construction, Inc., Chicago, IL. (AISC 13th Ed.)
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National Design Specification for Wood Construction ASD/LRFD, 2005 edition & National Design Specification Supplement, Design Values for Wood Construction, 2005 edition, American Forest & Paper Association, Washington, DC.
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PCI Design Handbook: Precast and Prestressed Concrete, 6th edition, 2004, Precast/Prestressed Concrete Institute, Chicago, IL.
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Building Code Requirements and Specifications for Masonry Structures (and related commentaries), 2008; The Masonry Society, Boulder, CO; American Concrete Institute, Detroit, MI; and Structural Engineering Institute of the American Society of Civil Engineers, Reston, VA.
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Struc tura l Bo oks The AFIT of Today is t he Air Force of Tomor row.
• Helpful Books • CERM (Lindberg) • Practice Problems for the Civil Engineering PE Exam (Lindberg) • SERM (Williams) • Structural Engineering Solved Problems (Buckner) • All-in-One Civil Engineering PE: Breadth and Depth (Goswami) • Steel Structures: Design and Behavior (Salmon, Johnson, & Malhas) • Reinforced Concrete: A Fundamental Approach (Nawy) • Prestressed Concrete: A Fundamental Approach (Nawy) • Masonry Structures: Behavior and Design (Drysdale & Hamid) • Advanced Mechanics of Materials (Boresi & Schmidt) • Structural Analysis (Hibbler)
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Summary The AFIT of Today is t he Air Force of Tomor row.
• Introduction • Topics • Loadings • Determinate Analysis • Mechanics of Materials • Materials • Member Design
• Takeaways • Str uc tu ral PM Exam Vital - Relevant - Connected
Questions The AFIT of Today is t he Air Force of Tomor row.
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