Structural Analysis
y
Forest Flager, MEng, MDesS
Forest Flager, MEng, MDesS
CEE 214
October 26, 2009
Reid Senescu and John Haymaker
A
Agenda
d
- Analysis Process
- Strengths + Limitations
- Future Challenges
Reid Senescu and John Haymaker
CASE STUDY:
Washington Monument
Steps for structural analysis:
1)
Structural Idealization
2)
Applying Loads
3)
Calculating Reactions
4)
Calculating Internal Forces
5)
Calculating Internal Stresses
6)
Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
Analysis Process
CASE STUDY:
Washington Monument
Steps for structural analysis:
1)
Structural Idealization
2)
Applying Loads
3)
Calculating Reactions
4)
Calculating Internal Forces
5)
Calculating Internal Stresses
6)
Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
Analysis Process
1. Structural Idealization =
Structural Modeling
Analysis Process
•
How can I simplify geometry?
Assume an average cross-section
cross section
•
How is it supported?
“Fixed” base
Reid Senescu and John Haymaker
1. Structural Idealization =
Structural Modeling
Determing an average cross section:
Reid Senescu and John Haymaker
Analysis Process
1. Structural Idealization =
Structural Modeling
Structural supports (and their idealizations):
Reid Senescu and John Haymaker
Analysis Process
1. Structural Idealization =
Structural Modeling
Four different types of end conditions:
What do these supports do?
Reid Senescu and John Haymaker
Analysis Process
CASE STUDY:
Washington Monument
Steps for structural analysis:
1)
Structural Idealization
2)
Applying Loads
3)
Calculating Reactions
4)
Calculating Internal Forces
5)
Calculating Internal Stresses
6)
Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
Analysis Process
2. Applying Loads
What loads act on this structure?
Reid Senescu and John Haymaker
Analysis Process
2. Applying Loads
DEAD LOADS:
Reid Senescu and John Haymaker
Analysis Process
2. Applying Loads
WIND LOAD:
Reid Senescu and John Haymaker
Analysis Process
2. Applying Loads
WIND LOAD:
Reid Senescu and John Haymaker
Analysis Process
CASE STUDY:
Washington Monument
Steps for structural analysis:
1)
Structural Idealization
2)
Applying Loads
3)
Calculating Reactions
4)
Calculating Internal Forces
5)
Calculating Internal Stresses
6)
Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
Analysis Process
3. Calculating Reactions
Reid Senescu and John Haymaker
Analysis Process
3. Calculating Reactions
Reid Senescu and John Haymaker
Analysis Process
3. Calculating Reactions
Reactions in the Washington Monument (Dead)
Reid Senescu and John Haymaker
Analysis Process
3. Calculating Reactions
Reactions in the Washington Monument (Wind)
Reid Senescu and John Haymaker
Analysis Process
CASE STUDY:
Washington Monument
Steps for structural analysis:
1)
Structural Idealization
2)
Applying Loads
3)
Calculating Reactions
4)
Calculating Internal Forces
5)
Calculating Internal Stresses
6)
Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
Analysis Process
4. Calculating Internal Forces
Reid Senescu and John Haymaker
Analysis Process
4. Calculating Internal Forces
Reid Senescu and John Haymaker
Analysis Process
4. Calculating Internal Forces
Reid Senescu and John Haymaker
Analysis Process
4. Calculating Internal Forces
Reid Senescu and John Haymaker
Analysis Process
4. Calculating Internal Forces
Reid Senescu and John Haymaker
Analysis Process
CASE STUDY:
Washington Monument
Steps for structural analysis:
1)
Structural Idealization
2)
Applying Loads
3)
Calculating Reactions
4)
Calculating Internal Forces
5)
Calculating Internal Stresses
6)
Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
Analysis Process
5. Calculating Internal Stresses
Reid Senescu and John Haymaker
Analysis Process
5. Calculating Internal Stresses
Reid Senescu and John Haymaker
Analysis Process
5. Calculating Internal Stresses
Reid Senescu and John Haymaker
Analysis Process
5. Calculating Internal Stresses
Reid Senescu and John Haymaker
Analysis Process
5. Calculating Internal Stresses
Reid Senescu and John Haymaker
Analysis Process
5. Calculating Internal Stresses
Reid Senescu and John Haymaker
Analysis Process
5. Calculating Internal Stresses
Reid Senescu and John Haymaker
Analysis Process
CASE STUDY:
Washington Monument
Steps for structural analysis:
1)
Structural Idealization
2)
Applying Loads
3)
Calculating Reactions
4)
Calculating Internal Forces
5)
Calculating Internal Stresses
6)
Evaluating Safety and Efficiency
Reid Senescu and John Haymaker
Analysis Process
6. Evaluating Safety and
Efficiency
Reid Senescu and John Haymaker
Analysis Process
6. Evaluating Safety and
Efficiency
Reid Senescu and John Haymaker
Analysis Process
A l i Strengths
Analysis
St
th and
d Limitations
Li it ti
- Doha Tower Case Study
© Forest Flager (Stanford)
Grant
Soremekun
(Phoenix
Int)
Reid
Senescu
and John
Haymaker
CASE STUDY:
Doha Tower
PROJECT OVERVIEW:
• Gross Area approx. 115,000m^2
• Chiefly cylindrical tower about 45m in
diameter and 182m high at base of
dome
• 3 basement levels, ground floor and
44 upper levels
Reid Senescu and John Haymaker
Strengths and Limitations
CASE STUDY:
Doha Tower
TYPICAL FLOOR PLATE:
Reid Senescu and John Haymaker
Strengths and Limitations
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
• Wall
W ll thi
thicknesses
k
ranging
i
from 250-600mm
Reid Senescu and John Haymaker
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
g + Ring:
g equivalent
q
sections
Reid Senescu and John Haymaker
Nodes: fixed (moment)
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’
Stick Core
Full Core
Reid Senescu and John Haymaker
CASE STUDY:
Doha Tower
Strengths and Limitations
VALIDATION OF WIND LOADING
ASSUMPTIONS:
Wind Direction
Comparison of results:
Mo
Vb
Party
Base Shear Vb (MN)
OT Moment - Mo
(MN*m)
CSCEC
11 5
11.5
1514
Arup (smooth)
8.6
1101
Arup
(
(moucharabieh)
h bi h)
12 9
12.9
1651
* Coefficients Assessed from Table 7, BS 6399-2
Reid Senescu and John Haymaker
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
Deflected Tower Axial Loads
Reid Senescu and John Haymaker
CASE STUDY:
Doha Tower
ISSUE: Diagrid Detailing
Reid Senescu and John Haymaker
Strengths and Limitations
F t
Future
Challenges
Ch ll
- Process Integration
Design Optimizaton (PIDO)
© Forest Flager (Stanford)
Grant
Soremekun
(Phoenix
Int)
Reid
Senescu
and John
Haymaker
Structural Design Process
Reid Senescu and John Haymaker
Future Challenges
Current Practice:
How are we doing?
Future Challenges
Survey of practitioners at Arup: (Flager, Haymaker 2007)
Few design options considered due to significant time spent
managing information
Reid Senescu and John Haymaker
Structural Shape and
Member Sizing
© Forest Flager (Stanford)
Grant
Soremekun
(Phoenix
Int)
Reid
Senescu
and John
Haymaker
Future Challenges
Problem Description:
Main Roof Truss Design
Future Challenges
Main Truss
¾
191 members
¾ 68 load combinations
Optimization Goals
ANALYSIS LAYER
Element list: not "Cores"
Scale: 1:782.8
¾
Shape
¾ Member Sizing
g
z
y
x
TRUSS
LOCATION
PLAN
Reid Senescu and John Haymaker
SECTION
Results: Rationalized
Member Sizing
Future Challenges
Baseline Design
Steel Weight: 1234 t
Max Disp: 416 mm
Optimized Design
Steel Weight: 808 t
(-34%)
M Disp:
Max
Di
309 mm
(-27%)
Reid Senescu and John Haymaker
SECTION SIZE
AREABY GROUP
Results: Shape Studies
Reid Senescu and John Haymaker
Future Challenges