The Pennsylvania State University
Spring Semester 2007
Michael Szott
Structural Option
Senior Thesis Presentation
Duquesne University Forbes Expansion
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Presentation Outline
Introduction
Proposed Analysis
Structural Depth Study
o
o
Lateral system redesign
Gravity system redesign
Breadth Studies
o
o
Acoustics
Construction cost comparison
Conclusions and Recommendations
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Location
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Location
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Project Overview
Project Team
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o
o
o
o
o
Duquesne University
DRS Architects
Jendoco Construction
Atlantic Engineering Services
Dodson Engineering
Hornfeck Electrical
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Project Overview
Building Statistics
o
Construction dates
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o
Building occupancy
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Mixed Use – retail, student fitness, office, entertainment
Building size
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March 2006 – December 2007/January2008
7 stories – 125,000 sq. ft.
Project cost
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$24 million
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Project Overview
Existing Structural System
o
Gravity system
o
o
Lateral system
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o
Composite steel construction
Concentrically braced frames
Foundations
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o
Auger cast piles
Grade Beams
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Project Overview
Typical – Floors 1-3
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Project Overview
Long Span Framing, Floors 4-5
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Proposed Analysis
Lateral Resisting System
o
More efficient bracing scheme?
Gravity System – Vibration Analysis
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o
Intermixed activity spaces
Long span conditions
Interior Acoustical Performance
Impact on Construction Cost
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Lateral Redesign
Lateral Bracing Locations
Typical Frame
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Lateral Redesign
Three Alternate Bracing Schemes
o
Modified concentric bracing
o
Chevron bracing
o
Alternating diagonals (K-bracing)
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Lateral Redesign
Design Criteria
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o
IBC 2003
ASCE 7-02
Applied Loads
o
o
o
IBC2003 section 1616.6 :
“analysis must be performed
except when structures are
assigned to Seismic Design
Category A”
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
o
o
Dead
Live
Snow
Wind
Seismic
Structural Depth: Lateral Redesign
Individual Frames: RAM Advanse
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Optimization
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o
Minimal Weight
Member check
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Local Buckling
Overall System: RAM Frame
o
Drift check
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Lateral Redesign
Existing - Tension Only
Modified –
Tension/Compression
Chevron Bracing
LC: DL+0.75LL+0.75W
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
“K” Bracing
Structural Depth: Lateral Redesign
Existing Frame Design
o
o
o
HSS 6x4x1/4 – 8x4x5/8
Columns: W14x53 – 132
Beams:
W33x118
Modified Ten. – Comp.
o
o
o
HSS 4x3x1/4 – 9x7x1/4
Columns: W14x53 – 211
Beams:
W33x118
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Chevron Bracing
o
o
o
HSS 4x3x1/4 – 10x8x3/8
Columns: W14x53 – 211
Beams:
W24x76
“K” Bracing
o
o
o
HSS 4x3x1/4 – 12x10x1/2
Columns: W10x45 – W24x131
Beams:
W33x118
Structural Depth: Lateral Redesign
Lateral System Weight Comparison
Bracing Layout
X-Bracing (T only)
X-Bracing (T-C)
Chevron Bracing
K-Bracing
Component weights
HSS Braces
Beams/Columns
46.5
198.7
38.4
202.5
37.9
178.2
37.4
192.4
Chevron Bracing
o
Least weight of all systems
o
Smallest frame beams
o
Controlling deflection limits – L/600 or 0.3”
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Totals
245.2
240.9
216.1
229.8
Structural Depth: Lateral Redesign
Overall Building Drift (in.)
Bracing Layout Drift @ HR Drift @ IR Drift @ 5th
Existing
5.6
3.3
2.1
X-Bracing (T/C)
4.6
2.6
1.5
Chevron Bracing
4.8
2.7
1.5
K-Bracing
5
2.9
1.6
Drift at High Roof Level
Drift at Intermediate Roof Level
Drift at 5th Floor Level
o
Pedestrian bridge
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
H/400
3.96
3.96
3.96
3.96
Structural Depth: Gravity Redesign
Vibration Design: AISC Design Guide 11
o
o
Floor vibrations due to human activity
Criteria based on rhythmic activity
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o
o
Aerobics
Dining and Dancing
Serviceability issue – not strength
o
Design to avoid personal discomfort
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Gravity Redesign
Four Critical Spaces Analyzed
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o
o
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2nd floor Aerobic/Fitness areas
3rd floor gymnasium (typical bays)
4th floor gymnasium (long spans)
5th floor ballroom (long spans)
o
o
Designed for partially loaded bays
Modified constant “k” used
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Gravity Redesign
Acceleration Limits

Dancing/Dining
0.02g

Aerobics only
0.06g

Gymnasium
0.10g-0.15g
(i.e. basketball, etc…)
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Gravity Redesign
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Gravity Redesign
Existing Fitness Framing
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20’8” span
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o
o
Beams: W12x16 @ 7’ o.c.
Girders: W16x31 (21’0”)
31’4” span
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o
Beams: W18x40 @ 7’ o.c.
Girders: W18x35 (21’0”)
fn(reqd) (Hz)
Span
20' 8"
31' 4"
fn(act)
8.48
5.18
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
1st Harmonic 2nd Harmonic ap/g (%g) ao/g (%g)
5.38
8.03
0.051
0.06
5.38
8.03
0.45
0.06
Structural Depth: Gravity Redesign
New Fitness Framing
o
31’4” span
o
o
Beams: W21x83 @ 7’ o.c.
Girders: W21x83 (21’0”)
fn(reqd) (Hz)
Span
20' 8"
fn(act)
8.48
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
1st Harmonic 2nd Harmonic ap/g (%g) ao/g (%g)
5.38
8.03
0.051
0.06
Structural Depth: Gravity Redesign
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Gravity Redesign
Existing Ballroom Framing
o
79’6” span
o
o
o
Beams: W36x210 @ 7’ o.c.
Girders: W27x84 (21’0”)
Criteria not met
fn(act)
fn(reqd)
3.89
5.4
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
ap/g (%g) ao/g (%g)
0.105
0.02
Structural Depth: Gravity Redesign
Ballroom Redesign
o
Departure from Design Guide 11
o
Partial loading vs. Fully loaded bays
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Gravity Redesign
New Ballroom Framing
o
Conventional
o
o
o
Beams: W40x372 @ 7’ o.c.
Girders: W30x90 (21’0”)
Castellated Beams
o
o
o
Modified wide flange sections
Lighter and more stiff
Economical
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Structural Depth: Gravity Redesign
Castellated Ballroom Framing
o
79’6” span
o
o
Beams: CB50x221 @ 7’ o.c.
Girders: W27x84 (21’0”)
fn(act)
fn(reqd)
5.4
5.4
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
ap/g (%g) ao/g (%g)
0.019
0.02
Structural Depth: Gravity Redesign
Floor Use (Floor #)
Ballroom (5th)
Gym
(4th)
Gym
(3rd)
Aerobic (2nd)
Totals
Framing Weight (kips)
Existing
Alternate
428.9
406.2
377.5
321.9
127.4
162.8
132.2
153.8
1066
1044.7
Overall Effects of New Framing
o
o
o
o
Lighter gravity system
Reduced clear height in both gym spaces
Improved vibrational performance
Cost?
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Breadth Study: Construction Cost
Castellated Sections
o
o
Less material, reduced material cost
2 man hours to convert from wide flange to castellated
o
“…in general, spans longer than 40’ can recoup these costs.”
- Billy Milligan, VP of CMC Steel Products
Delivery
o
From Hope, AR
o
o
Distance:
Cost:
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
1015 miles
$65,500
Breadth Study: Construction Cost
Existing G ravity Fram ing per Floor (not including O+P)
Floor No. Material/Fabrication Labor/Delivery
Totals
2
$148,817.05
$10,943.67
$159,760.72
3
$143,289.60
$11,070.40
$154,360.00
4
$453,475.10
$10,612.77
$464,087.87
5
$452,528.50
$9,665.95
$462,194.45
$1,240,403.04
Alternate G ravity Fram ing per Floor (not including O+P)
Floor No. Material/Fabrication Labor/Delivery
Totals
2
$173,202.95
$11,216.79
$184,419.74
3
$183,722.60
$11,112.59
$194,835.19
4
$357,415.10
$28,596.20
$386,011.30
5
$458,540.10
$36,454.99
$494,995.09
$1,260,261.32
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Material savings, greater than
fabrication costs
Delivery costs drive more
expensive system
Breadth Study: Construction Cost
Lateral Frames
o
Structural tubing more expensive than wide flange sections
o
o
Fabrication and connection costs
Chevrons bracing: least material = least cost
o
Frame beams considerably smaller
Lateral System Cost Comparison (not including O+P)
Lateral System
Material/Fabrication
Labor
Totals
Existing Fram es
$313,054.75 $13,660.18 $326,714.93
Alt.#1: Concentric
$324,612.25 $13,710.44 $338,322.69
Alt #2: Chevron
$282,774.40 $12,160.28 $294,934.68
Alt #3: "K" Bracing
$347,034.25 $10,364.08 $357,398.33
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Conclusions and Recommendations
A chevron bracing scheme offers a reduction in
weight and material
Redesigning the lateral system will save on material
costs
Castellated beams improve floor vibrations and
decrease floor weight over long spans
Gravity system costs increase slightly
Suggested improvements are cost feasible
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
??
Michael J. Szott
Structural Option
Duquesne University Multipurpose Facility
Questions??