civil & environmental engineering design
DESCRIPTION
Civil & Environmental Engineering Design. Prof. Michael Chajes, Chair Depart. of Civil & Env. Engineering. Photo by Doug Baker. Webster’s Definition of Design. “to create, fashion, execute, or construct according to plan,” and “to devise for a specific function or end.”. - PowerPoint PPT PresentationTRANSCRIPT
Civil & Environmental Civil & Environmental Engineering DesignEngineering Design
Prof. Michael Chajes, ChairProf. Michael Chajes, ChairDepart. of Civil & Env. EngineeringDepart. of Civil & Env. Engineering
Photo by Doug Baker
Webster’s Definition of DesignWebster’s Definition of Design
“to create, fashion, execute, or construct according to plan,” and “to devise for a specific function or end.”
Webster’s Definition of DesignWebster’s Definition of Design
“to create, fashion, execute, or construct according to plan,” and “to devise for a specific function or end.”
Design ConstraintsDesign Constraints
SafePE code of ethics states: “Engineers, in the fulfillment of their professional duties, shall hold paramount the safety, health, and welfare of the public.”
FunctionalEconomicAesthetically pleasing
No one solution!
Design ExampleDesign Example
Design a shelf for you dorm room
Wood 1” x 8” x 6’
Wall
Design ExampleDesign Example
Design a shelf for you dorm room
Tension Strut
Design ExampleDesign Example
Design a shelf for you dorm room
Compression Strut
Design Tension StrutDesign Tension StrutMode of Failure: FractureMode of Failure: Fracture
8”
6”
10”
LOADSW books = 50 lbs/ftW total = 6 x 50 = 300 lbsEach strut (2 total) = 150 lbsFactor of safety = 2W books/strut = 300 lbs
F=ma, a=0, F=0Vertical direction0 = - 300 lbs + (3/5) F strutF strut = (300) x (5/3)
F strut = 500 lbs
F strut
W books/strut
F shelfFree BodyDiagram
8”
6”
10” STRUT SIZEStress = Force/AreaUse steel rodsStress Ultimate = 36,000 lb/inArea = Force/Stress = 300/36,000
Area required = 0.008 in
2
2
1/8” diameter rod
A = r = d / 40.008 = d / 4d = 0.10 in.1/8 = 0.125 in.
2 2
2
Design Tension StrutDesign Tension StrutMode of Failure: FractureMode of Failure: Fracture
8”
6”
10”
LOADSW books = 50 lbs/ftW total = 6 x 50 = 300 lbsEach strut (2 total) = 150 lbsFactor of safety = 2W books/strut = 300 lbs
F=ma, a=0, F=0Vertical direction0 = - 300 lbs + (3/5) F strutF strut = (300) x (5/3)
F strut = 500 lbs
F strut
W books/strut
F shelfFree BodyDiagram
Design Compression StrutDesign Compression StrutMode of Failure: FractureMode of Failure: Fracture
8”
6”
10”
1/8” diameter rod
STRUT SIZEStress = Force/AreaUse metal rodsStress Ultimate = 36,000 lb/inArea = Force/Stress = 300/36,000
Area required = 0.008 in
2
2
Design Compression StrutDesign Compression StrutMode of Failure: FractureMode of Failure: Fracture
A = r = d / 40.008 = d / 4d = 0.10 in.1/8 = 0.125 in.
2 2
2
8”
6”
10”
steel rod
Design Compression StrutDesign Compression StrutAnother Mode of Failure: ?Another Mode of Failure: ?
P
P
8”
6”
10”
Design Compression StrutDesign Compression StrutMode of Failure: Mode of Failure: BucklingBuckling
Euler Buckling Formula
Pcr = EI / L
Pcr = Buckling loadE = Material stiffnessI = Moment of inertiaL = Length
Pcr = 500 lbsE = 29,000,000 lb/inI rod = r / 4L = 10 in.
22
Pcr
Pcr
4
2
8”
6”
10”
Design Compression StrutDesign Compression StrutMode of Failure: BucklingMode of Failure: Buckling
Strut Size
Pcr = EI / L
500=()(29,000,000)(r / 4)/(10 )
r = 0.12, d = 0.24, 1/4 = 0.25 in.
22
Pcr
Pcr
4
1/4” diameter rod
2 2
8”
6”
10”
Strut Design SummaryStrut Design Summary
1/4” diameter rod Stability *
6”
10”
1/8” diameter rod Strength
1/8” diameter rod Strength *
What did we not consider (failure modes, design criteria)?
Bridge DesignBridge Design
Case Study:Case Study:The New Indian River Inlet BridgeThe New Indian River Inlet Bridge
http://travel.yahoo.com/p-travelguide-577578-map_of_delaware-i
Bridge Location
ExistingIndian River Inlet Bridge
Reason for Replacement: Scour
Scour holes greater than 30 m deep
Specificationsfor the New Bridge
Because the piers of the Because the piers of the existing Indian River existing Indian River Inlet bridge are in the Inlet bridge are in the tidal inlet, scour has tidal inlet, scour has become a serious become a serious problem problem
A new bridge will be A new bridge will be built by 2010 to replace built by 2010 to replace the existing bridgethe existing bridge
The bridge span will be The bridge span will be over 900 ft. in order to over 900 ft. in order to span the inletspan the inlet
http://www.deldot.gov/static/projects/indian_river_bridge/replacement.shtml
Preliminary DesignPreliminary Design
Courtesy of FIGG Engineering GroupCourtesy of FIGG Engineering Group
Preliminary DesignPreliminary Design
Courtesy of FIGG Engineering GroupCourtesy of FIGG Engineering Group
Preliminary DesignPreliminary Design
Courtesy of FIGG Engineering GroupCourtesy of FIGG Engineering Group
Design Constraints/DecisionsDesign Constraints/Decisions
How many can you list?How many can you list?
Design Constraints/DecisionsDesign Constraints/Decisions
Location of bridgeLocation of bridgeSpan of bridgeSpan of bridgeNumber of lanesNumber of lanesAlignment of roadwayAlignment of roadwayType of bridgeType of bridgeBridge aestheticsBridge aestheticsType of foundationType of foundationScour protectionScour protectionEnvironmental impactEnvironmental impactMaterials to be usedMaterials to be usedLoadings to considerLoadings to considerSize of membersSize of members
How will it be constructedHow will it be constructedHow will it be inspectedHow will it be inspectedHow will it be maintainedHow will it be maintainedHow will it be financedHow will it be financed
West Point Bridge Design West Point Bridge Design ProgramProgram
http://bridgecontest.usma.edu
Designing a BreakwaterDesigning a Breakwater
Protecting a Bridge with a Breakwater
Sandbar
Waves
Bridge Roadway
Elevation View
1
30
Bridge Roadway
Pier
3.5 in.
2.25 in. 8 in.
4.5 in.
Plan View
Sandbar
Brick
Water Surface
12 in.
Breakwater
26 in.
QuestionsQuestions