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Structural AnalysisStructural AnalysisyyForest Flager, MEng, MDesSForest Flager, MEng, MDesS
Forest Flager, MEng, MDesS
CEE 214
Reid Senescu and John Haymaker
CEE 214October 26, 2009
A dA dAgendaAgenda- Analysis Process- Strengths + Limitations- Future Challenges
Reid Senescu and John Haymaker
CASE STUDY:Washington Monument Analysis Process
Steps for structural analysis:
1) Structural Idealization1) Structural Idealization
2) Applying Loads
3) Calculating Reactions
4) Calculating Internal Forces
5) Calculating Internal Stresses
6) Evaluating Safety and Efficiency6) Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
CASE STUDY:Washington Monument Analysis Process
Steps for structural analysis:
1) Structural Idealization1) Structural Idealization
2) Applying Loads
3) Calculating Reactions
4) Calculating Internal Forces
5) Calculating Internal Stresses
6) Evaluating Safety and Efficiency6) Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
1. Structural Idealization =Structural Modeling Analysis Process
• How can I simplify geometry?
Assume an average cross-section
• How is it supported?
Assume an average cross section
“Fixed” base
Reid Senescu and John Haymaker
1. Structural Idealization =Structural Modeling Analysis Process
Determing an average cross section:
Reid Senescu and John Haymaker
1. Structural Idealization =Structural Modeling Analysis Process
Structural supports (and their idealizations):
Reid Senescu and John Haymaker
1. Structural Idealization =Structural Modeling Analysis Process
Four different types of end conditions:
Reid Senescu and John Haymaker
What do these supports do?
CASE STUDY:Washington Monument Analysis Process
Steps for structural analysis:
1) Structural Idealization1) Structural Idealization
2) Applying Loads
3) Calculating Reactions
4) Calculating Internal Forces
5) Calculating Internal Stresses
6) Evaluating Safety and Efficiency6) Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
2. Applying Loads Analysis Process
What loads act on this structure?
Reid Senescu and John Haymaker
2. Applying Loads Analysis Process
DEAD LOADS:
Reid Senescu and John Haymaker
2. Applying Loads Analysis Process
WIND LOAD:
Reid Senescu and John Haymaker
2. Applying Loads Analysis Process
WIND LOAD:
Reid Senescu and John Haymaker
CASE STUDY:Washington Monument Analysis Process
Steps for structural analysis:
1) Structural Idealization1) Structural Idealization
2) Applying Loads
3) Calculating Reactions
4) Calculating Internal Forces
5) Calculating Internal Stresses
6) Evaluating Safety and Efficiency6) Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
3. Calculating Reactions Analysis Process
Reid Senescu and John Haymaker
3. Calculating Reactions Analysis Process
Reid Senescu and John Haymaker
3. Calculating Reactions Analysis Process
Reactions in the Washington Monument (Dead)
Reid Senescu and John Haymaker
3. Calculating Reactions Analysis Process
Reactions in the Washington Monument (Wind)
Reid Senescu and John Haymaker
CASE STUDY:Washington Monument Analysis Process
Steps for structural analysis:
1) Structural Idealization1) Structural Idealization
2) Applying Loads
3) Calculating Reactions
4) Calculating Internal Forces
5) Calculating Internal Stresses
6) Evaluating Safety and Efficiency6) Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
4. Calculating Internal Forces Analysis Process
Reid Senescu and John Haymaker
4. Calculating Internal Forces Analysis Process
Reid Senescu and John Haymaker
4. Calculating Internal Forces Analysis Process
Reid Senescu and John Haymaker
4. Calculating Internal Forces Analysis Process
Reid Senescu and John Haymaker
4. Calculating Internal Forces Analysis Process
Reid Senescu and John Haymaker
CASE STUDY:Washington Monument Analysis Process
Steps for structural analysis:
1) Structural Idealization1) Structural Idealization
2) Applying Loads
3) Calculating Reactions
4) Calculating Internal Forces
5) Calculating Internal Stresses
6) Evaluating Safety and Efficiency6) Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
5. Calculating Internal Stresses Analysis Process
Reid Senescu and John Haymaker
5. Calculating Internal Stresses Analysis Process
Reid Senescu and John Haymaker
5. Calculating Internal Stresses Analysis Process
Reid Senescu and John Haymaker
5. Calculating Internal Stresses Analysis Process
Reid Senescu and John Haymaker
5. Calculating Internal Stresses Analysis Process
Reid Senescu and John Haymaker
5. Calculating Internal Stresses Analysis Process
Reid Senescu and John Haymaker
5. Calculating Internal Stresses Analysis Process
Reid Senescu and John Haymaker
CASE STUDY:Washington Monument Analysis Process
Steps for structural analysis:
1) Structural Idealization1) Structural Idealization
2) Applying Loads
3) Calculating Reactions
4) Calculating Internal Forces
5) Calculating Internal Stresses
6) Evaluating Safety and Efficiency6) Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
6. Evaluating Safety and Efficiency Analysis Process
Reid Senescu and John Haymaker
6. Evaluating Safety and Efficiency Analysis Process
Reid Senescu and John Haymaker
A l i St th d Li it tiA l i St th d Li it tiAnalysis Strengths and LimitationsAnalysis Strengths and Limitations- Doha Tower Case Study
Reid Senescu and John Haymaker© Forest Flager (Stanford)
Grant Soremekun (Phoenix Int)
CASE STUDY:Doha Tower Strengths and Limitations
PROJECT OVERVIEW:
• Gross Area approx. 115,000m^2
• Chiefly cylindrical tower about 45m in diameter and 182m high at base ofdiameter and 182m high at base of dome
• 3 basement levels, ground floor and 44 upper levels44 upper levels
Reid Senescu and John Haymaker
CASE STUDY:Doha Tower Strengths and Limitations
TYPICAL FLOOR PLATE:
Reid Senescu and John Haymaker
CASE STUDY:Doha Tower Strengths and Limitations
MODELLING VERTICAL STRUCTURAL SYSTEM:
Perimeter Diagrid• Circular RC columns• Diameters ranging from 800mm to 1700mm
Internal Core • RC core continuous from foundation to level 44
W ll thi k i
Reid Senescu and John Haymaker
• Wall thicknesses ranging from 250-600mm
CASE STUDY:Doha Tower Strengths and Limitations
TYPICAL FLOOR:
Core: 2 linked 1D elements with equivalent sections
In-situ slab: 1D perimeter elements and bracing
Diagrid + Ring: equivalent Nodes: fixed (moment)
Reid Senescu and John Haymaker
g g qsections connections typical
CASE STUDY:Doha Tower Strengths and Limitations
VALIDATION OF CORE MODEL:
Tip Defl.= 1.06m Defl.= 0.98m
‘Stick’ Core
Full Core ‘Stick’ Core
Reid Senescu and John Haymaker
Full Core Stick Core
Full Core
CASE STUDY:Doha Tower Strengths and Limitations
VALIDATION OF WIND LOADING ASSUMPTIONS:
Wind DirectionComparison of results:
PartyBase Shear -
Vb (MN)OT Moment - Mo
(MN*m)CSCEC 11 5 1514CSCEC 11.5 1514
Arup (smooth) 8.6 1101Arup
( h bi h) 12 9 1651
Mo
Reid Senescu and John Haymaker
* Coefficients Assessed from Table 7, BS 6399-2
(moucharabieh) 12.9 1651Vb
CASE STUDY:Doha Tower Strengths and Limitations
ISSUE: Differential Movement between Core and Diagrid
South diagrid columns take approx. 2x the loading of North columns
GL
Reid Senescu and John Haymaker
Deflected Tower Axial Loads
GL
CASE STUDY:Doha Tower Strengths and Limitations
ISSUE: Diagrid Detailing
Reid Senescu and John Haymaker
F t Ch llF t Ch llFuture ChallengesFuture Challenges- Process IntegrationDesign Optimizaton (PIDO)
Reid Senescu and John Haymaker© Forest Flager (Stanford)
Grant Soremekun (Phoenix Int)
Structural Design ProcessStructural Design Process Future Challenges
Reid Senescu and John Haymaker
Current Practice:Current Practice:How are we doing?How are we doing?
Future Challenges
Survey of practitioners at Arup: (Flager, Haymaker 2007)
Few design options considered due to significant time spent
Reid Senescu and John Haymaker
managing information
Future ChallengesStructural Shape andStructural Shape andMember SizingMember SizingMember SizingMember Sizing
Reid Senescu and John Haymaker© Forest Flager (Stanford)
Grant Soremekun (Phoenix Int)
Future ChallengesProblem Description:Problem Description:Main Roof Truss Design Main Roof Truss Design
Main Truss191 members68 load combinations
Optimization GoalsShape Member Sizing
ANALYSIS LAYERElement list: not "Cores"
Scale: 1:782.8
g
x
y
z
Reid Senescu and John Haymaker
PLAN SECTIONTRUSS
LOCATION
Results: RationalizedResults: RationalizedMember SizingMember Sizing Future Challenges
Baseline Design
Steel Weight: 1234 t
Max Disp: 416 mm
Optimized Design
Steel Weight: 808 t(-34%)
M Di 309
Reid Senescu and John Haymaker
Max Disp: 309 mm(-27%)
SECTION AREASECTION SIZE BY GROUP
Results: Shape StudiesResults: Shape Studies Future Challenges
Reid Senescu and John Haymaker
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