capstone design presentation

Structural Design of Office Building with Design

Variations for Natural Hazardous Environments

Nkonyeasua G. Adaikpoh

Tennessee State University,Tennessee State University,

Department of Architectural Engineering

April 15, 2009

Introduction

Mr. Moneybags International

has decided to expand his

company’s offices to 3 new

markets. In a bid to move markets. In a bid to move

quickly he hires a Structural

Engineer to perform a feasibility

design per his requirements and

thereafter report the results

and cost.Structural Analysis and Design - Nkonyeasua G. Adaikpoh

Design Evolution

Architectural Components

Governing Texts: Governing Texts:

1. International Building Code (IBC 2006)

2. Architectural Graphics Standards

3. The Architect’s Studio Companion

Structural Analysis and Design - Nkonyeasua G. Adaikpoh

Locations Characteristics

San Francisco Oklahoma CityNew Orleans

� All in the downtown areas of the cities.

� Stiff soils – well compacted

� Disaster prone – added lateral forces

Caused damage

of $1 Billion+ in

2005

Hurricanes

In San Andreas

fault zone.

Pleasant

weather

Earthquakes

Structural Analysis and Design - Nkonyeasua G. Adaikpoh

Gently rolling

hills & shrubs

Temperate, sub-

humid climate

Tornadoes

Severe cyclones

originating over

equatorial

regions,

accompanied by

torrential rain,

Ground shaking

caused by

tectonic

processes.

Measured on the

Richter

Disaster Definitions

Earthquakes TornadoesHurricanes

Violent storms

characterized by

whirling funnels

of wind moving

at great speeds.

Measured on an torrential rain,

lightning, &

winds with

speeds >74mph

Measured on a

Saffir-Simpson

scale, in

categories.

Richter

magnitude scale,

in magnitudes.

Measured on an

enhanced Fujita

scale, in

categories.

USGS NOAA NOAA

Effects on Buildings

Earthquakes TornadoesHurricanes

Photo courtesy USGS and NGDC Stan Honda/AFP/Getty Images © How Stuff Works

Requirements Translation

Preliminary Design

� Occupancy classification – B - Business

� 3-Hour Noncombustible construction

� Type I-A

� Sprinklered building

� Unlimited height and area

� Site cast concrete system

� Two-way post-tensioned flat plate � Two-way post-tensioned flat plate slab with 30’ x 30’ bays

� 300’ maximum travel distance

� Open plan

Planning

Maximum travel

distance – 300ft

Tower Shape

b

(in)

h

(in)

Area, Ai

(in2)

xi

(in) Aixi (in3) yi (in) Aiyi (in3)

dx (xi-

xbar)

dy (yi-

ybar)

Ix =bh3/12 +

Adx2 (in4) Ix TOWER

Iy =bh3/12 +

Ady2(in4) Iy TOWER

%

stiffness x

%

stiffness y

To

we

r 1

-

To

p le

ft

sta

ir 252130 32760 480 15724800 1381 45241560 -421.05 360.40 5854056115

1592015420

4301279897

1184767152 42.22% 22.82%228106 -24168 480-11600640 1381

-

33376008 -421.05 360.40-4262040695 -3116512746

To

we

r 2

-

To

p r

igh

t

sta

ir 252130 32760

132

0 43243200 1381 45241560 418.94 360.40 5796018744

1576793897

4301279897

1184767152 41.82% 22.82%228106 -24168

132

0-31901760 1381

-

33376008 418.94 360.40-4219224847 -3116512746

To

we

r 3

-B

ott

om

left

ele

vato

r

110232 25520 805 20543600 640 16332800 -96.054 -380.59349925238.7

249374333.6

3811194440

1284499982 6.61% 24.74%86208 -17888 805-14399840 640

-

11448320 -96.054 -380.59

-

100550905.1 -2526694458

Bo

tto

m

Shear Wall Stiffness Distribution – Code compliantT

ow

er

4 -

Bo

tto

m

rig

ht

sta

ir

128256 32768 988 32374784 640 20971520 86.945 -380.59426667210.7

352493316.8

4925603018

1538736157 9.35% 29.63%104232 -24128 988-23838464 640

-

15441920 86.945 -380.59

-

74173893.91 -3386866861

SUM = 33456 30145680 34145184 3770676967 5192770442 100.00% 100.00%

Center of stiffness for the building

xbar = 901.1in = 75.1ft

ybar = 1020.6in = 85.0ft

Ix = 3770676967in4

Iy = 5192770442in4

Shear Wall Stiffness Distribution – Code compliant

Column stiffness check

Largest column size = 36 x 36 in

Shape b (in) h (in)

Area, Ai

(in2) xi (in) Aixi (in3) yi (in)

Aiyi

(in3)

Ix =bh3/12

(in4) 6IX (in4) Iy =bh3/12 (in4) 6Iy (in

4)

Co

lum

n

36 36 1296 18 23328 18 23328 139968 839808 139968 839808

Check: I ≥ 6ICheck: IWALL ≥ 6ICOLUMNS

Smallest IX WALL = 249374333.6 > 839808in4

Smallest IY WALL = 1184767152 > 839808in4

ACI 318 Code discussion on slenderness

and stiffness

Architectural Programming

� Shape from McCormac & Nelson

� Open plan - 30ft x 30ft grid

� Dimensions - 150ft x 120ft� Dimensions - 150ft x 120ft

� Floor Area - 17,100sf

� Building Area - 17,100sf x 20 floors

� Occupant load- 100sf/occupant

� Egress requirement- 0.2”/occupant

� Min. egress width/floor = 0.2” x 171 occupants

= 34.2”

� Exit stairway - 30” clear

Architectural Plans

South elevation

Typical Floor Plan

Architectural Plans

Section and partial 3-D

view

Design Evolution Summary

Mixed use structure with parking for all occupants in same building.

Single use structure, 20 Mid-rise building

in 3 locations

Single use structure, 20

floors, regular floor plan

in 3 locations.

Design Evolution

Structural Components

Governing Texts:

1. International Building Code (IBC 2006)

2. ASCE/SEI 7-05 Minimum Design Loads for 2. ASCE/SEI 7-05 Minimum Design Loads for Buildings and Other Structures

3. ACI 318-05 Building Code Requirements for Structural Concrete

4. Building Codes Illustrated

5. Building Structures Illustrated

Structural Analysis and Design - Nkonyeasua G. Adaikpoh, EIT

Structural Effects/Requirements

Produce lateral forces

which the building

must resist via a LFRS

– Lateral Force

Resisting system.

Aims:

� Durability

� Ductility

� Reliability

Structural Requirements

LFRS – Shear Walls

Diaphragm – 2-way flat slabs

Aims:

� Durability

� Ductility

� Reliability

Loading

Dead Load:Dead Load:

8” slab - 100psf

Partition - 10psf

MEP - 8psf

Ceiling - 2psf

Misc. - 5psf

Total - 125psf

Loading

Live Load:

80 psf – considering

light storage, and

partition locations

Loading: Wind Loads

� MWFRS is

designed to resist

high hurricane and

tornado force

winds.

V = 150mph, New Orleans

ex = 2.75 In

ey = 300.625 In

Case 1

Heights (ft) PWx PLx

PE-W

(psf) ForceE-W (kips) PWy PLy

PN-S

(psf)

ForceN-S (kips)

15 7.0 -37.3 44.4 39.9 7.0 -37.3 44.4 49.9

30 11.4 -37.3 48.7 43.8 11.4 -37.3 48.7 54.8

45 14.2 -37.3 51.5 46.4 14.2 -37.3 51.5 58.0

60 16.3 -37.3 53.7 48.3 16.3 -37.3 53.7 60.460 16.3 -37.3 53.7 48.3 16.3 -37.3 53.7 60.4

75 19.0 -37.3 56.4 50.7 19.0 -37.3 56.4 63.4

90 20.0 -37.3 57.4 51.6 20.0 -37.3 57.4 64.5

105 21.0 -37.3 58.4 52.5 21.0 -37.3 58.4 65.6

120 21.0 -37.3 58.4 52.5 21.0 -37.3 58.4 65.6

135 23.5 -37.3 60.9 54.8 23.5 -37.3 60.9 68.5

150 25.0 -37.3 62.3 56.1 25.0 -37.3 62.3 70.1

165 26.0 -37.3 63.3 57.0 26.0 -37.3 63.3 71.3

180 27.0 -37.3 64.3 57.9 27.0 -37.3 64.3 72.4

195 27.8 -37.3 65.1 58.6 27.8 -37.3 65.1 73.2

210 28.5 -37.3 65.9 59.3 28.5 -37.3 65.9 74.1

225 29.3 -37.3 66.7 60.0 29.3 -37.3 66.7 75.0

240 30.1 -37.3 67.5 60.7 30.1 -37.3 67.5 75.9

255 30.9 -37.3 68.2 61.4 30.9 -37.3 68.2 76.8

270 31.6 -37.3 68.9 62.0 31.6 -37.3 68.9 77.6

285 32.3 -37.3 69.6 62.7 32.3 -37.3 69.6 78.3

300 33.0 -37.3 70.3 63.3 33.0 -37.3 70.3 79.1

305 33.2 -37.3 70.5 63.5 33.2 -37.3 70.5 79.4

Loading: Wind Loads

� Designed to withstand

Code-required wind loads

� Includes torsional moments

due to eccentricity of the

shear walls and quartering

winds.winds.

Loading: Wind Loads

� Wind loading

animation – 100%

amplification

� Chapter 11, 12, and 14 in

ASCE/SEI 7-05 code

Loading: Seismic Loads

Seismic Loads Development

Loading: Seismic Load Development

1. Determine the mapped

maximum considered

earthquake (MCE) spectral

response SS and S1.

2. Determine if the structure is

exempt from seismic

requirements

6. Determine Seismic Importance Factor, I

7. Determine seismic base shear, V

8. Distribute V over the height of the

building

9. Determine redundancy coefficient, ρ

10. Determine seismic load effects, E and EM

Steps to Seismic Design

requirements

3. Determine seismic design

requirements (SDC)

4. Determine Analysis

procedures

5. Determine R, Response

Modification Coefficient

10. Determine seismic load effects, E and EM

11. Check drift control requirements

Base shear distribution over the height of the building - San Francisco

Level

Story

Height

(ft)

Height

(ft)

Weight

(kips) WiHik Cvx

Force F

(kips)

MTx

(kip-

ft)

MTy

(kip-

ft)

1 15 15 3240 571320 0.003 8 48 60

2 15 30 3240 2147072 0.012 30 180 225

3 15 45 3240 4657801 0.025 65 391 489

4 15 60 3240 8068892 0.044 113 678 847

5 15 75 3240 12356971 0.067 173 1038 1298

6 15 90 3240 17504439 0.095 245 1471 1838

7 15 105 3240 23497225 0.128 329 1974 2468

8 15 120 3240 30323630 0.165 425 2548 3185

9 15 135 3240 37973664 0.207 532 3190 3988

10 15 150 3240 46438621 0.253 650 3902 4877

Total 150 32400 183539635 1.000 2570


� Designed to withstand

Code required seismic loads

� OTM shown


� Seismic loading

animation – 100%

amplification


�Seismic loading

animation – 50%

amplification

Design: pca Column – Shear Wall Design

Design: pca Column – Column Design

� Same building as

for New Orleans

� Wind speed is

less in Oklahoma

than for New

Orleans, but the

New Orleans

� More building –

20 floors

� Ordinary R.C.

Shear Walls

� Column

dimensions– 30”

� Less building –

10 floors

� Special R.C.

Shear Walls

� Column

dimensions – 28”

Construction Comparison

San Francisco Oklahoma City

Orleans, but the

disasters exact

similar forces

� Rough concrete -

11000 yd3

� Reinforcing -

700 tons

dimensions– 30”

x 30”

� Rough concrete -

11000 yd3

� Reinforcing -

700 tons

dimensions – 28”

x 28”

� Rough concrete

– 6730yd3

� Reinforcing –

375 tons


New Orleans

Concluding summary


� More building – 20

floors

� 54% more rebar

� More than twice

the amount of SF’s

concrete.

� Cost - $ 139.90/sf,

$45,328,000 total

� More building – 20 floors

� About twice as much rebar

� 61% more concrete than SF

� Cost - $139.90/sf, $45, 328,000 total

� Less building – 10

floors

� 46% less

reinforcing bars

� 39% less concrete

� Cost - $161.85/sf,

$27,677,000 total


F.A.Q.• Isn’t the building a tall building? The Council of tall buildings states

that “A tall building is not defined by its height or number of stories. The important criterion is whether or not the design is influenced by some aspect of “tallness.” It is a building in which “tallness” strongly influences planning, design and use. It is a building whose height creates different conditions in the design, construction and operation from those that exist in “common” buildings of a certain region and period.

• Did you consider the soils in designing? Yes, e.g. the seismic design category is based on a mixture of the location on the earth, the soil category is based on a mixture of the location on the earth, the soil type, and the surrounding environment.

• Why didn’t you consider flood loads in your design since the areas you mentioned frequently have flooding? Flood loads are inconsequential to commercial construction once the building is above a certain height, and the wave crest won’t have a significant effect on the building.

• How about the cost of land and building in these places? Well the client would have already sourced the amounts for land in the 3 locations and the building costs differ but I used a national average.


F.A.Q. Contd.

• What are rigid diaphragms? Rigid diaphragms according to the ASCE 7-05 code are diaphragms of concrete slabs or concrete filled metal deck with span-to-depth ratios of 3 or less in structures that have no horizontal irregularities.

• Did you consider P-delta effects in your design considering the height of the building? Yes, in the analysis and design software, RISA-3D and pca-Column I specified the program to calculate P-Δeffects.


Acknowledgements

• Russell Skrabut, PE, LEED AP

• C.W. Yong, PE, LEED AP

• Professor Michael Samuchin, PE, LEED AP


New Orleans

THE END


QUESTIONS?

� More building – 20

floors

� 54% more rebar

� More than twice

the amount of SF’s

concrete.

� Cost - $ 139.90/sf,

$45,328,000 total

� More building – 20 floors

� About twice as much rebar

� 61% more concrete than SF

� Cost - $139.90/sf, $45, 328,000 total

� Less building – 10

floors

� 46% less

reinforcing bars

� 39% less concrete

� Cost - $161.85/sf,

$27,677,000 total


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