allison lamb structural emphasis april 16, 2003 new science center lateral system redesign

Allison LambStructural Emphasis April 16, 2003

New Science CenterLateral System Redesign

Allison LambKutztown University

New Science Center April 16, 2003

Presentation Outline

Background Existing Structural Proposal Redesign Other Considerations Fire Protection Acoustical Recommendations

Background

Project Team Owner

Pennsylvania System of Higher Education Architect

Stv Architects Engineer

Stv Incorporated

Background

Delivery Method Design – Bid – Build

Dates of Construction 3/18/02 – 10/3/04

Several Phase Project Addition

3/18/02 – Present Overall Cost

$16 million Addition Cost

$11.4 million

Background

Location Kutztown University

campus Berks County,

Pennsylvania Building Function

Academic Building Science Departments Classrooms, Labs, Offices

Background

Architecture Brick facade Large glass Atrium Floor Layout

Red – offices Green – Classrooms Blue – Labs Magenta – Vertical circulation Yellow – Storage/building systems Black – atrium space

First Floor

Second Floor

Third Floor

Fourth Floor

Existing Structural

Gravity System Composite Framing

5 in. Concrete 1 ½ in. composite metal deck 50 ksi Steel beams and girders 50 ksi Steel columns

Roof Framing Roof joists 50 ksi beams and girders

Existing Structural

Lateral System Steel moment frames

2 in E-W Direction 2 In N-S direction Typical Connection

Existing Structural

Foundations 4000 psi concrete rock bearing drilled

piers with grade beams in the unexcavated portion of the building

spread footings in the basement portion

Proposal

Replace current lateral system Redesign Criteria

lateral force resisting system must: be designed to resist the lateral loads perform to the required serviceability criteria

under the design loads lateral force resisting system must not:

compromise the architectural aesthetics and functionality of the building’s spaces

disrupt the other building systems be prohibitively expensive

Proposal

Alternative #1 incorporate braced frames into the

structure Alternative #2

create several frames with partially restrained connections

Alternative #3 some combination of braced frames

and partially restrained frames

Redesign

Gravity System Realign columns into grid system for

more options Resize members using RAM

Check flexure, shear, deflection, composite action

Smaller member sizes Second Floor Vibration Issue

Leave second floor member sizes unchanged

Original Layout New Layout

Redesign

Lateral System Alternative #1 –

Braced Frames typical placement Architectural

repercussions Add a column

Redesign

Alternative #2 – PR Frames Use several frames and take advantage of

the stiffness in the PR connections

Redesign

Alternative #3 Use braced frames in East – West

direction and PR Frames in North – South Direction

Redesign

Braced Frames Initial member

sizes determined by gravity requirements

Checked with Ram using ASCE 7-95 lateral loads

Members increased to meet strength requirements

Redesign

Frames modeled in STAAD to determine stiffness

ASCE 7-98 Lateral Loads distributed by rigidity

Member sizes increased to meet strength and stiffness requirements under lateral loads including torsion

Redesign

Drift due to wind limited to H/400 Allowable 1.875” Actual 1.406”

Drift due to seismic limited to 2% of the story height below

LevelActual Drift

(inches)Story Drift

(inches)

Allowable Story Drift

(inches)

5(Roof) 1.113 0.306 5.08

4 0.807 0.349 3.52

3 0.458 0.307 3.52

2 0.151 0.151 2.88

LevelActual Drift

(inches)

Allowable Drift (inches)

Story Drift (inches)

(inches)

5(Roof) 1.406 1.875 0.409 0.635

4 0.997 1.240 0.439 0.440

3 0.558 0.800 0.353 0.440

2 0.205 0.360 0.205 0.360

Redesign

Final member sizes Columns - W14x109 Beams - W30x90 Braces - 2L5x5x7/8

Redesign

PR Frames Method of Flexible wind connections or

type 2 with wind (ASD) Beams designed as simple beams Columns designed to provide frame stability connections designed to resist the factored

lateral loads and have sufficient ductility to accommodate the rotations

Redesign

Initial member sizes determined by flexible moment connection method

frames modeled in STAAD as FR and stiffness determined

Lateral Loads redistributed by rigidity

Member sizes increased to provide adequate strength and stiffness requirements

Redesign

Drift determined as per conservative British Wind-Moment Approach

Drift determined using FR connections, then multiplied by 1.5 to account for actual PR connections

Wind drift limited to H/400 Allowable total drift = 1.875” Actual total drift = 1.220”

Seismic Drift limited to 2 inchesLevelActual Drift

(inches)Allowable Drift

(inches)Story Drift

(inches)Allowable Story

Drift (inches)

5(Roof) 1.220 1.875 0.080 0.635

4 1.140 1.240 0.202 0.440

3 0.938 0.800 0.336 0.440

2 0.602 0.360 0.602 0.360

LevelActual Drift

(inches)Story Drift

(inches)

5(Roof) 1.938 0.162 5.08

4 1.776 0.355 3.52

3 1.421 0.536 3.52

2 0.885 0.885 2.88

Redesign

Final Member sizes Beams W30x99 Columns W14x145

Connection Double Web Angle Top and Bottom Seat Designed to resist shear Moment-Rotation Characteristics determined Typical connection

Other Considerations

Foundations Changing layout of frames, adding

additional columns and relocating columns

Redesign for bearing, shear, and overturning

Architectural New column layout changes room sizes

slightly

Mechanical System Changing some room sizes will affect

the mechanical load for those spaces Lighting System

Room size changes will affect the lighting layout

Cost Comparison Gravity System

Redesign = total savings of $72,596.67 Lateral System

PR Frames = increase of $23,696.66 Braced Frames = Savings of $54,633.43

Fire Protection

Automatic wet sprinkler protection to provide 100% protection coverage

IBC 2000 Code Requirements Business Group B occupancy type Type IB construction

Building Element Fire Rating (hours)

Structural FrameIncluding columns, girders

Floor ConstructionIncluding supporting beams

Roof ConstructionIncluding Supporting beams, joists

Fire Protection

Floor Construction UL Design No. D902

4.5” concrete min. Spray applied fire

resistive materials None required for floor 1-1/16” inch to the

beams and girders

Fire Protection

Columns UL Design No. X501

Spray Applied Fire resistive materials

1 3/8” coating Glass Fiber Gauze 2 1/16” coats

Acoustical

300 seat auditorium/lecture hall Room Size

109 ft3 per person Preferred range 80–150 ft3 per person

Room Shape Sloped 5˚ Best sloped 7˚ or more

Acoustical

Room Materials Red - Gypsum Board Blue - Fabric-Wrapped

acoustical panels Magenta - Acoustical

ceiling tile Yellow - Wooden chair

rail Green - Pinch-pleated

drapery

Acoustical

Reverberation Times Calculation using sound absorption

properties of materials Optimal - less than 0.8s from 250 to 4000

Reverberation Times (s)

Conditions 125 Hz 500 Hz 4000 Hz

Fully Occupied 0.49 0.33 0.26

One-half Occupied

0.52 0.35 0.27

Recommendations

Gravity System Consider redesigned member sizes but verify

vibration requirements Lateral System

Use braced frames in the east-West direction Use original moment frames in North-South

Direction Fire Protection

Choose system to meet minimum code requirements

Acoustical Consider increasing the slope of the room

acknowledgements

Thank you

Stu Rothenberger of STV Architects for all of the information that made thesis possible

All of my Friends and Family especially Mike, I couldn’t have done this without you

The AE Faculty for their expertise and help

Happy Birthday to me

Questions

Any Questions?

Background

Mechanical System Variable Volume System 8 AHUs handling 146,275 CFM Lab Spaces

Once Through Air Humidified

Other Spaces – 50% Outside Air, 50% Recirculated

650 Ton Chiller 650 Ton Cooling Tower Natural gas fired 143 HP Boiler

Background

Lighting System Interior lighting provided by fluorescent

lighting fixtures auditorium/lecture hall has fluorescent fixtures

for normal lighting and 75 watt incandescent fixtures for dimming

controlled by local switches throughout the building

Exit and emergency lighting connected to the emergency distribution system

exterior building lighting consists of metal halide fixtures

Background

Electrical System Splice into existing13.2kV campus distribution

feeder Interior unit substation transforms voltage to

208/120 volt service main power distribution is a 208/120 volt, 3

phase, 4 wire system emergency and standby power provided by a

natural-gas-fired engine generator

allison lamb structural emphasis april 16, 2003 new science center lateral system redesign

floor slide

expensive slide

stv incorporated slide

basement portion slide

structural foundations

lateral loads

ksi steel beams

ksi beams

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