2009-0306 lhs intro to eng
TRANSCRIPT
Introduction to Engineering
Tzuyang Yu Assistant Professor, Ph.D.
Department of Civil and Environmental Engineering University of Massachusetts Lowell (UML)
March 6, 2009 Lowell High School
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Outline
n What is Engineering?
n Scope and Process of Engineering
n Great Engineering Achievements in the 20th Century
n Example of Engineering Design
n Engineering Research Approach
n Summary
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What is Engineering?
n If it is green, it is biology.
n If it stinks, it is chemistry.
n If it doesn’t work, it is physics.
n If it works but no one knows why, it is engineering. – Anonymous
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What is Engineering? n “The scientist explains that which exists; the
engineer creates that which never was.” –– Theodore von Karman (1881~1963), a Hungarian-German-American engineer and physicist who was active primarily in the fields of aeronautics and astronautics
von Karman at the California Institute of Technology Vortex 4
What is Engineering?
Engineers
Engineering science Engineering problem
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What is Engineering? n Engineering involves:
n Science n Math n Writing n Problem solving n Speaking n Teamwork n etc…
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What is Engineering? n Engineer, as a noun, is from French “to contrive”. n Engineers: “One who contrives, designs, or
invents; an author, designer (const. of); also absol. an inventor, a plotter, a layer of snares.” –– Oxford English Dictionary
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Scope of Engineering
n If Engineering = Problem Solving,
– Does this mean any problem? – or only problems dealing with a technology
component?
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Process of Engineering n Invention n Research n Design n Development n Production/Realization
Cost Cycle
Risk Mitigation
I-35 Minneapolis Bridge Collapse, MN (2007) 9
Great Engineering Achievements in the 20th Century
n Electrification n Automobile n Airplane n Safe and abundant water n Electronics n Radio and TV n Agricultural
Mechanization n Computers n Telephone n Air Conditioning and
Refrigeration
n Interstate Highways n Space Exploration n Internet n Imaging Technologies n Household Appliance n Health Technologies n Petroleum and Gas
Technologies n Laser and Fiber Optics n Nuclear Technologies n High Performance
Materials 10
n A clear classification of high-rise buildings with respect to their structural system is difficult.
n A rough classification can be made with respect to effectiveness in resisting lateral loads.
Example of Engineering Design – Design of High-rise Buildings
Structural Systems: n Moment resisting frame systems n Braced frame, shear wall systems n Core and outrigger systems n Tubular systems
¨ Framed tubes ¨ Trussed tubes ¨ Bundled tubes
n Hybrid systems 11
10
20 30
40
50 60
70
80
90
100
110
Type I Shear Frames Type II Interacting Systems Type III Partial Tubular Systems Type IV Tubular Systems
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Type II Type III
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Type IV
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Sem
i-Rig
id
Fram
e
Rig
id F
ram
e
Fram
e w
ith S
hear
Tru
ss
Fram
e w
ith S
hear
ban
d an
d
Out
rigge
r Tru
sses
End
Cha
nnel
Fra
med
Tub
e w
ith
Inte
rior S
hear
Tru
sses
End
Cha
nnel
and
Mid
dle
I Fr
amed
Tub
es
Exte
rior F
ram
ed T
ube
Bun
dled
Fra
med
Tub
e
Exte
rior D
iago
naliz
ed T
ube
# of Floors
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Development of Structural Systems
50 100 150 200 250 300 350 400 450 500 550
m
Frame Systems Tube in Tube
Bundled Tube
Tubular Systems Hybrid Systems
World’s Tallest Buildings by Year
(Figure source: www.skyscrapers.com) 13
Structural Loads n Gravity loads
¨ Dead loads ¨ Live loads ¨ Snow loads
n Lateral loads ¨ Wind loads ¨ Seismic loads
n Special load cases ¨ Impact loads ¨ Blast loads
Earthquake Load
Snow Load
Wind Load
Dead Loads
Live Loads
Blast Load
Impact Load
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Gravity Loads n Floor systems account for a major portion of the gravity loads n Selection of the floor system may influence structural behavior
and resistance n Structural use plays a major role in selection of the floor system
¨ Office buildings n large simply supported spans
¨ Residential and hotel buildings n short continuous spans
Types of floor systems • Concrete • Steel • Composite • Prestressed concrete
Composite floor systems
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Wind Loads
Plan view
Wind
zQ
hQzQ
hQ
hQ hQ
2zQ KV I=
z
h z z HQ Q
==
H
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Seismic Loads
Spe
ctra
l res
pons
e
acce
lera
tion
(g)
Period (sec)
0 2 4 6 8
Response with increasing damping
Decreasing V/W
sV C W= ¥
V
W
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Final Design – Design of Member Dimensions
s max."6
Bottom of bend
Max. slope1:6
sSpecial tiesto resistoutward thrust
max. to bottomof beam bars
"3
12s
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Construction – Before
Royal Albert Bridge, UK (1859)
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Construction – Now
Lavant viaduct (Talubergang P19 Lavant), Austria (1985) 20
Steps in Engineering Research
n Observe n Simplify n Analyze n Model n Experiment
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Engineering Research Approaches
n Theoretical investigation (e.g., formulation, derivation, proof)
( ) [ ], 2,
1, expc
c
B
s js j B
S r t d i tR
ω π
ω π
ω ω+
−
= ⋅∫
( ) ( )2
,0 0
, , ,sR
sj i j i s j
RD t dr d G r S r tt
π
ξ φ φ⎛ ⎞− = ⋅⎜ ⎟
⎝ ⎠ ∫ ∫
, ,s sbp
R RF t C D tt t t
ξ ξ∂⎛ ⎞ ⎛ ⎞− = ⋅ −⎜ ⎟ ⎜ ⎟∂⎝ ⎠ ⎝ ⎠
( )
( )
0
0
, ,
,
s
s
Rtt
s s
Rtt
s
R RD t dt D t M t tt t t t
Rdt D t M t tt t
ξ ξ
ξ
−
−
∂ ∂⎛ ⎞ ⎛ ⎞ʹ′ ʹ′− = ⋅ − ⋅ −⎜ ⎟ ⎜ ⎟∂ ∂⎝ ⎠ ⎝ ⎠
∂⎛ ⎞ʹ′ ʹ′= ⋅ − ⋅ −⎜ ⎟ ∂⎝ ⎠
∫
∫ ( )int
0
, ,sR
sRI r d F tt
θ
φ ξ ξ⎛ ⎞= ⋅ −⎜ ⎟
⎝ ⎠∫22
Engineering Research Approaches
n Numerical Simulation
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Y (m
)
Hx at time = 17 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)Hx at time = 20 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 23 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 26 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 29 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)Hx at time = 32 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 35 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 38 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 41 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
X (m)
Y (m
)
Hx at time = 44 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
X (m)
Y (m
)
Hx at time = 47 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
X (m)
Y (m
)
Hx at time = 50 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 17 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 20 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 23 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)Hx at time = 26 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 29 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 32 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 35 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)Hx at time = 38 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Y (m
)
Hx at time = 41 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
X (m)
Y (m
)
Hx at time = 44 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
X (m)
Y (m
)
Hx at time = 47 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
X (m)
Y (m
)Hx at time = 50 ns
1 1.2 1.4
0.6
0.7
0.8
0.9
1
Engineering Research Approaches
n Experimentation
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15.7 cm 15.2 cm
(Concrete core)
3.8 cm 3.8cm
2.5 cm 30.4 cm
Summary
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n Engineering is the backbone of every civilization. n Engineering is an applied science. n Engineering includes a number of very diverse disciplines. Each
discipline usually includes several specialized areas. à Engineers are differentiated by the material or the structure or the property they study.
n Engineering is about how to make things or how to make things work, which is very practical.
n For whichever research topic engineers investigate, there must be a practical problem behind it.
n Good engineers must have learned from their practical experience.