Miranova CondominiumsColumbus, Ohio

Structural Option Spring ‘04Chris Crilly

Presentation Outline

Goals

Floor System

Lateral System

Acoustics

Construction Management

Acknowledgments

Questions

Existing Conditions

Project Background

Proposed Solution

Other Considerations

Summary/Conclusions

Problem Statement

Project Background

Columbus, Ohio

Adjacent to I-70

Along Scioto River

Faces North into the city

Location

N

I-70

Project Background

Size

Gross Building AreaGarage - 123,254 SF 5 Stories Tower - 332,862 SF 22 StoriesTotal - 456,116 SF 27 Stories

Cost $52 Million Total Cost

Groundbreaking was in July of 1998 Substantial Completion was in October of 2000 Tenant fit out continued into 2002

Construction Dates

Project Background

Basement Visitor Parking

Ground Floor Reception/Lobby Storage Social Spaces Offices Fitness Areas

Levels 2-4 Resident Parking Small Storage Spaces

Levels 5-28 Condominiums

Building Occupancy

Approximately 146 High-end Luxury Condominiums

Approximately 226 Total parking Spaces

Project Background

Design Architect – Arquitectonica

Architect of Record – HKS Inc.

Structural Engineer – The Thornton–Tomasetti Group

MEP Engineer – Flack & Kurtz Consulting Engineers

Lighting Designer – Lighting Design Alliance

Civil Engineer – E M H & T, Inc.

Construction Manager – Turner Construction Company

Wind Tunnel Consultant – Cermak Peterka Peterson, Inc.

Project Team

Existing Conditions

North Façade – Blue Tinted Glass Curtain Wall

Other Façades – 6” Precast Conc. Panels

Level 1 – 5

120’ x 250’

Tower

60’ x 280’

655’ Radius

Architecture

Existing Conditions

Concrete Mat Foundation

f’c = 4000 psi – Normal Weight Concrete

Placed on a 2” Mud Slab

5’-3” to 5’-9” thick under the tower

2’-9” to 3’-3” thick under 5 story portion

Structure – Foundation

Existing Conditions

8” Post-Tensioned Flat Plate f’c = 5000 psi – Normal Weight Conc. Post Tensioning

½” , 270 ksi Low-Relaxation Strands Banded in 6’ Width over Col. Lines in E/W Direction Uniformly Spaced in N/S Direction

Structure – Floor System

Existing Conditions

Concrete Shear Walls

f’c = 5000 psi – Normal Weight Conc.

Thickness Decreases up the Building

22” to 12” Thick

Structure – Lateral System

Goals/Criteria

Possibility exists for owner to purchase to adjacent units and connect the two to make a larger living space

Problem Statement

Vertically – due to post-tensioned slabs

Very difficult and expensive to execute future expansions:

Horizontally – due to R/C shear walls

Goals/Criteria

Allow greater and cheaper flexibility for possible future renovations

Goals

Vertically

Horizontally

Minimize impact on architecture

Minimize impact on overall cost

Proposed Solution

Steel Systems

More flexible to future changes than concrete

Easier to add openings for stairways and ducts

Lighter

Floor System

Steel floor systems are typically deeper

I will concentrate on Low Floor-to-Floor systems to minimize impact on architecture and cost

Proposed Solution

Steel Braced Frames

More flexible to future changes than concrete shear walls

Easier to add openings for doorways

Lighter

Lateral System

Braced frames allow for only discrete door locations

I will concentrate on maximizing the area for door openings for greater future flexibility

Floor System

Composite Slab and Beam System

Slight modification to Beam-Girder connections over typical connections

Reduces floor depth Reduces fabrication time and costs

Connection

L4x4x12x3” Erection Angle

3 – 1/2” Erection Bolts

Floor System

Infill Beams (N-S Span Direction) W10 x 22 – Center Bay W10 x 17 or W10 x 19 – Outer Bays

Girders (E-W Span Direction) W12 x 26 to W12 x 40

ΔEL b/w TopBeam and TopGirder

1.625” – 1.875” Allows for 1/8” Mill Tolerance 2” Max Required - 2” – 18 gage VLI Deck

Floor System

Connection Check

Yield Line Analysis Initially Studied by W. S. Easterling of Va. Tech. Followed up with Master’s Thesis by Wey-Jen Lee

at Va. Tech

g

g

b

fy

bd

bb

tFR

21

42

2

2

R = Nominal Strength of Girder FlangeFy = Yield Strength of Girdertf = Thickness of Girder Flangebb = Width of Beam Flangebg = Length of Girder Flange (bf/2 – k1)D = Length of Beam Bearingφ = 0.9 - Assumed

Floor System

These Capacities are CONSERVATIVE. Why?

Connection Check

Beam Web Limit states were also checked and found to be OK

Proven by experimental tests Bearing point is assumed to be at Center of Bearing Area

Connection similar to un-stiffened seated connection Bearing point determined by beam web limits states

simultaneously with bending limit state

Floor System

Sound & Impact Transmission through floor system

Investigated under Acoustic Breadth

Other Design Considerations

Floor Vibrations

Typical beams checked

Interior Bays

Fell in upper half of barely perceptible range of the modified

R-M scale

Max. acceleration – 0.339% < 0.5% OK

Exterior Bays

Fell in lower half of slightly perceptible range of the modified

R-M scale

Max acceleration – 0.495% < 0.5% OK

Floor System

A typical composite floor system was also designed Typical connections No depth restrictions Partially composite beams Same beam and girder layout was used

Typical Composite System

Infill Beams – W12x19

Girders – W16x26 to W16x30

Beam to Girder Connections – Shear Tab (3) – ¾” A325 Bolts PL – 3/8” x 4 ½” x 9” A36 5/16” fillet weld φRn = 27.8 k

Floor System

Cost & Time Advantages

Shallow System Heavier Members Slightly more shear studs Less Connection Material Less Beam Fabrication (Copes)

This was done to compare: Material costs Fabrication costs

& Fabrication time

Lateral System

Combination of R/C shear walls and steel braced frames

Steel Braced Frames Replace large shear walls in N-S Direction 3 options studied to:

• Determine most efficient system• Determine most economical system• Maximize available space for future doors

Shear Walls Keep existing walls around 2 building cores Walls added around building core

• Better protection in emergencies• Stiffens building

Lateral System

Option #1: All Braces Option #2: Outer Braces Center Brace – Same as

option #1

Lateral System

Option #3: Eccentrically Braced Frames

Pros 4X area for doors in center frame 2X area for doors in outer frames Smaller Columns Acceptable building and story drifts

Design Summary 4 ft link in larger bay Ext. Columns – W14x426 to W14x48 Int. Columns – 2 to 3 sizes smaller Beams – W16x45 to W18x60 Braces – W12x40 to W12x45

Cons Slightly larger beams Approx. 2X # bracing connections Approx. 2X # braces

Lateral System

Final Design

Outer Braces Center Brace

Lateral System

Comparison b/w Existing and Proposed System

Lateral System

Level 5 Diaphragm

Existing Building used Wind Loads from wind tunnel test

I used Code stipulated loads which were larger

Change in lateral system at level 5 caused large shears in diaphragm

Check proved existing diaphragm to be adequate

Impacts on Arch.

15 ft Building height increase over 20 stories

Locations of existing doors in shear walls had to be slightly moved to accommodate the braces, did not greatly impact space layouts

3 additional columns – easily hidden

8” increase in party wall thickness – 4” loss of living space on each side

Acoustics

Building Code Design Criteria: STC 50 IIC 50 Fire Rating – 2 HR

Floor System

Recommended Design Criteria for Luxury Residences: STC 60 IIC 60

Acoustics

Properties STC 62 IIC 74 – with carpet IIC 60 – with hard flooring on foam rubber underlay Fire Rating – UL No. D916 – 2 HR rating with 3 ½” slab

• Actual slab is 4 ¼”

Acoustics

Building Code Design Criteria: STC 50 Fire Rating – 1 HR

Brace Infill Wall

Properties: STC 60 Fire Rating – UL No. U411

• 2 HR

Recommended Design Criteria for Luxury Residences:

STC 60

Constr. Management

Cost Estimate

Material Labor Equipment TotalFloor Slab 1406825 1195081 194338 2796244Columns 164808 147230 8420 320458

Shear Walls 209181 290109 10497 509787Totals $1,780,814 $1,632,420 $213,255 $3,626,489

Existing Structure CostMaterial Labor Equipment Total

Floor Slab 1406825 1195081 194338 2796244Columns 164808 147230 8420 320458

Shear Walls 209181 290109 10497 509787Totals $1,780,814 $1,632,420 $213,255 $3,626,489

Existing Structure Cost

Material Fabricaction Erection/Labor TotalBeams

Gravity 328309 131203 114878 574390Lateral 19723 1291 5253 26267

Braces 23495 2336 6458 32288Columns

Gravity 122870 1538 31102 155510Lateral 62540 985 15881 79406

Connections 33276 108003 35320 176599Shear Walls 201814 0 459507 661321Floor Slab 926751 0 252953 1179703Fire Protection 42251 0 28743 70994Totals $1,761,028 $245,357 $950,095 $2,956,480

Square Ft. Cost = 8.88 $/SF

Steel Structure CostMaterial Fabricaction Erection/Labor Total

BeamsGravity 328309 131203 114878 574390Lateral 19723 1291 5253 26267

Braces 23495 2336 6458 32288Columns

Gravity 122870 1538 31102 155510Lateral 62540 985 15881 79406

Connections 33276 108003 35320 176599Shear Walls 201814 0 459507 661321Floor Slab 926751 0 252953 1179703Fire Protection 42251 0 28743 70994Totals $1,761,028 $245,357 $950,095 $2,956,480

Square Ft. Cost = 8.88 $/SF

Steel Structure Cost

Constr. Management

Cost Estimate

Item Unit Quantity Material Cost Labor CostGypsum Board (Cols.) SF 1815 0.42 762 0.34 617Gypsum Board (Wall) SF 2480 0.42 1042 0.34 843

Glass Fiber Insulation (Ceiling)

SF 14661 0.14 2053 0.37 5425

Glass Fiber Insulation (Wall)

SF 2480 0.14 347 0.37 918

Precast Curtain Wall SF 348 25.50 8874 5.25 1827Glass Curtain Wall SF 344 20.00 6880 6.00 2064

Totals/Story $19,958 $11,693Totals/Building $399,153 $233,869

Additional CostsItem Unit Quantity Material Cost Labor Cost

Gypsum Board (Cols.) SF 1815 0.42 762 0.34 617Gypsum Board (Wall) SF 2480 0.42 1042 0.34 843

Glass Fiber Insulation (Ceiling)

SF 14661 0.14 2053 0.37 5425

Glass Fiber Insulation (Wall)

SF 2480 0.14 347 0.37 918

Precast Curtain Wall SF 348 25.50 8874 5.25 1827Glass Curtain Wall SF 344 20.00 6880 6.00 2064

Totals/Story $19,958 $11,693Totals/Building $399,153 $233,869

Additional Costs

Constr. Management

Cost Estimate

Totals Structure Savings Total Savings

Existing Structure $3,626,489

Steel Redesign $2,956,480

Additional Costs $633,022

$36,988$670,010

Cost SavingsTotals Structure Savings Total Savings

Existing Structure $3,626,489

Steel Redesign $2,956,480

Additional Costs $633,022

$36,988$670,010

Cost Savings

Constr. Management

Site Logistics

Building

Offices/Trailers

Site Traffic

Cranes

Steel Shakeout

Site Boundary

Summary/Conclusion

Steel System Concrete System Better Option

Total Weight20% Lighter, Smaller Mat

Foundation Possible--- Steel

Ability to Accomadate Renovations

Relatively Easy & Inexpensive

Difficult & Expensive Steel

Cost $37,000 Cheaper --- Steel

Architectural Impacts15 ft Height Increase, Larger Cladding Cost

--- Concrete

AcousticsBetter Properties, but

More ExpensiveMeets Criteria Steel

Floor Vibrations Meets CriteriaNot Typically a Problem in

Concrete Concrete

ConstructionCommon System w/ Minor

ModificationPost-Tensioning Requires

Skilled LaborSteel

ScheduleRequires Spray on Fire

ProofingRequires Post-Tensioning Equal

Steel System Concrete System Better Option

Total Weight20% Lighter, Smaller Mat

Foundation Possible--- Steel

Ability to Accomadate Renovations

Relatively Easy & Inexpensive

Difficult & Expensive Steel

Cost $37,000 Cheaper --- Steel

Architectural Impacts15 ft Height Increase, Larger Cladding Cost

--- Concrete

AcousticsBetter Properties, but

More ExpensiveMeets Criteria Steel

Floor Vibrations Meets CriteriaNot Typically a Problem in

Concrete Concrete

ConstructionCommon System w/ Minor

ModificationPost-Tensioning Requires

Skilled LaborSteel

ScheduleRequires Spray on Fire

ProofingRequires Post-Tensioning Equal

System Comparison

Summary/Conclusion

Conclusion

Bottom Flange Bearing Beam-to-Girder System With Eccentric Chevron Bracing in larger Bays

Acknowledgments

AE Faculty

Dr. Geschwindner – for all of the help and guidance throughout the year Dr. Hanagan – for guidance in understanding new connections Courtney Burroughs – for guidance on acoustical design All other AE faculty – for getting me to the point where I could complete this

Project Team – for allowing me to use the building and providing required materials 

- Pizutti Companies         - Robert Sedlak, Flack & Kurtz

- Kirby Chadwell, HKS Inc.         - Leighton Cochran, CPP - Aine Brazil, The Thornton-Tomasetti Group

  Jeremy Smith, Altoona Pipe & Steel Co. – for all the help in estimating steel costs

  Melissa Toth, P.E. – for all the help, guidance and insight into the AE Thesis Experience

  My Parents – for guidance, support, and giving my the opportunity to attend PSU and make

my dreams come true. 

Friends & Family – for all the support over the past five years 

Sarah Steeves – for putting up with me over the past few months while I was constantly busy with thesis

Questions

Miranova CondominiumsColumbus, Ohio

Structural Option Spring ‘04Chris Crilly

Foundation

3 additional columns added

Reduction of 250k to 750k in tower column loads

Average of 250k net uplift in braced frame cols.

Smaller loads would allow for significantly reduced thickness in mat at most locations

Existing mat would require extra tension reinforcement to distribute uplift forces over area in which mat can resist them

Wide flange or channel shapes

Constr. Management

Other Issues

Steel Lead Time Excavation and construction of foundation & first five stories will

provide sufficient time for steel to be on sight Required lead time will not delay schedule

Schedule Impact Only rough calculations performed Steel structure can be erected faster than existing concrete

structure Additional gypsum board, glass fiber insulation, and curtain

wall will add time to schedule Overall schedule construction duration not effected