Forest

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


Analysis Process



2)

Applying Loads

3)


4)


5)


6)



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


1. Structural Idealization = Structural Modeling Determing an average cross section:


Analysis Process

1. Structural Idealization = Structural Modeling Structural supports (and their idealizations):


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



2)

Applying Loads

3)


4)


5)


6)



Analysis Process

2. Applying Loads What loads act on this structure?


Analysis Process

2. Applying Loads DEAD LOADS:


Analysis Process

2. Applying Loads WIND LOAD:


Analysis Process

2. Applying Loads WIND LOAD:


Analysis Process



2)

Applying Loads

3)


4)


5)


6)



Analysis Process

3. Calculating Reactions


Analysis Process

3. Calculating Reactions


Analysis Process

3. Calculating Reactions Reactions in the Washington Monument (Dead)


Analysis Process

3. Calculating Reactions Reactions in the Washington Monument (Wind)


Analysis Process



2)

Applying Loads

3)


4)


5)


6)



Analysis Process

4. Calculating Internal Forces


Analysis Process



Analysis Process



Analysis Process



Analysis Process



Analysis Process



2)

Applying Loads

3)


4)


5)


6)



Analysis Process

5. Calculating Internal Stresses


Analysis Process



Analysis Process



Analysis Process



Analysis Process



Analysis Process



Analysis Process



Analysis Process



2)

Applying Loads

3)


4)


5)


6)



Analysis Process

6. Evaluating Safety and Efficiency


Analysis Process

6. Evaluating Safety and Efficiency


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


Strengths and Limitations

CASE STUDY: Doha Tower TYPICAL FLOOR PLATE:



CASE STUDY: Doha Tower


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



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



VALIDATION OF CORE MODEL:

Tip Defl.= 1.06m

Defl.= 0.98m

‘Stick’ Core

Full Core

‘Stick’ Stick Core Full Core




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



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



F t Future Challenges Ch ll - Process Integration Design Optimizaton (PIDO)


Structural Design Process


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


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


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


Future Challenges