AE Senior Thesis 2009
U.S. Pharmacopeia Headquarters
Consolidation
Rockville, MD
Analysis and Design of a Mild Reinforced
One way slab with Post Tensioned Beams
Jeffrey L. Rothermel Jr.
The Pennsylvania State University
Department of Architectural Engineering
Structural Option
Discussion Topics
•Background Information
•Existing Structure
•Design Goals
•Project Stages and Process
•Structural Design
•Mechanical Ductwork Redesign
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
U.S. Pharmacopeia Headquarters
•Owner: U.S. Pharmacopeia
•Architect: Hellmuth, Obata + Kassabaum (HOK)
•Structural: Cagley & Associates Inc.
•MEP: R.G. Vanderweil Engineers
•Construction: DPR Construction Inc.
•6 stories - 91’
•191,000 ft2 of new office and lab space
•New 19,000 ft2 conference center
•Houses chemical and biological labs
•$69 million
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
U.S. Pharmacopeia Headquarters
•Showcase laboratory spaces
•Large open office plans
•Kitchenettes for employees at every floor
•Curtain wall, metal paneling, and beige split face CMU
•Conical auditorium with curtain wall skin
•Enclosed outdoor plaza space
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Existing Conditions
•Two way mild reinforced concrete
flat slab with drop panels
•22’x22’ column grid
Photo courtesy of HOK Inc.
•14’ floor-to-floor heights (Typ.)
•Reinforced concrete moment frames
•Steel framed conference center
•Truncated, conical concrete auditorium
Photo courtesy of HOK Inc.
Photo courtesy of HOK Inc.
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Design Goals
•Lower floor-to-floor heights from 14’ to 13’
•Increase column grid from 22’ to 44’
•Eliminate moment frames
•Reduce ductwork sizes
•Maintain existing ceiling height
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Design Stages
•Investigate 3 alternatives
•Choose optimum system
•Design chosen floor system
•Design matching lateral system
•Resize ductwork mains
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Possible Solutions
Taken From AISC Design Guide 14: Staggered Steel Truss Framing
Staggered Steel Truss system
Two way post tensioned slab
One way slab with post tensioned beams
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Structural Depth Design
Design Process
1. Lay out beams
2. Design slab system
3. Design post tensioned beams
1. Size
2. Tendon quantity
3. Drape
4. Column check
5. Design shear walls
1. Shear reinforcement
2. Flexural reinforcement
3. Coupling beams
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
One way slab with PT beam design
New Beam Layout
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
One way slab with PT beam design
Slab Design
•One way reinforcing
•7” slab typ.
•7-1/2” slab at 250 psf loading
•#5 bars T&B
•#5@ 24” for shrinkage and temperature parallel to beams
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
One way slab with PT beam design
Designed with RAM Concept
per ACI 318-02
•Spans extended to 44’
•Shallow wide beams
•Existing column size kept (24”x24”)
•F’c = 6000 psi
•Class T Transitional
•T-Beam properties
•#6 Bottom at ρmin= 0.004
•#5 Top with no minimum reinforcement
•0.6f’ci compression limit (18.4.1(a))
•7.5√f’c ≤ft ≤ 12√f’c tensile stress limit (18.3.3)
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
One way slab with PT beam design
Design Process
1. Size the beams
2. Add tendons
3. Check stresses
4. Adjust profile
5. Schedule
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
One way slab with PT beam design
•Interior beams typically 48”x14”
•Edge beams typically 30”,32”x14”
•40-60 tendons interior typically
•30-40 tendons in edge typically
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
One way slab with PT beam design
Transfer Girders
•16-30” deep at transfers
•48-56” wide at transfers
•Same depth as existing transfers
•20-50% more post tensioning
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
One way slab with PT beam design
Load Balancing
•Balance % of dead load
•Target balance 60-90%
•Target met in most beams
•A few beams overbalanced
•Some underbalanced
Load Balancing (% DL)
Span
Floor
Col Line
First
A
B
C
D
E
F
G
Second
A
B
C
D
E
F
G
Third
A
B
C
D
E
F
G
Fourth
B
C
D
E
F
G
Penthouse
B
C
D
E
F
G
1
2
3
4
5
6
73
78
80
75
72
78
91
76
91
86
67
69
97
76
71
73
77
50
68
93
99
-2
38
16
16
40
67
-57
19
34
27
62
58
87
97
95
81
92
94
77
75
90
88
83
99
94
88
85
98
95
83
77
82
72
70
74
78
88
91
73
71
74
67
64
72
86
75
76
72
69
64
79
93
76
70
75
70
65
66
82
85
90
65
64
74
86
93
100
95
93
92
93
69
76
80
100
97
76
69
70
69
66
89
92
73
60
71
64
70
110
110
64
39
76
85
64
60
70
100
78
90
61
59
89
84
72
91
67
83
85
93
72
74
69
65
95
99
74
77
78
76
81
81
80
74
69
73
85
100
100
64
88
110
89
100
100
96
100
94
87
90
110
110
88
95
87
72
95
87
100
90
110
78
75
64
87
65
82
86
95
89
90
86
95
82
98
96
100
7
77
83
93
75
32
69
75
75
81
80
88
45
42
100
78
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
One way slab with PT beam design
Existing Column Properties
•Checked using PCA Column
•Moments from RAM Concept at column
•Interior columns sufficient
•Exterior columns require increased rebar
•Required for increased moment
•8#9
12#9
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Shear Wall Design
Existing reinforced concrete moment frames
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Shear Wall Design
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Shear Wall Design
Load Determination
•Method 2 per ASCE 7-05
•4 wind cases investigated
•Seismic loads using Equivalent Lateral
Force Method
•18” trial thickness
•1.6W vs. 1.0E
Taken From ASCE 7-05
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Shear Wall Design
Shear reinforcement as required per
Sec. 11.9
•Each wall/segment designed for shear and
flexure separately
•Minimum shear reinforcing used
•None needed for shear strength
•#4s H,V @18” Typ.
•Moment controlled reinforcing designs
•#8s Vert. for flexure
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Shear Wall Design
Deflections in SAP
•8” Membrane
•Self mass included
•24” mesh
•Full I values for all members
•F’c = 3000 psi
•Wind limitation H/400
•Seismic limitation 0.02hxn
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Shear Wall Design
Coupled shear wall design
SAP
•Member self weight included
•8” Membrane
•Coupling beams extend into wall face
•2’ Rigid end offset
•48” deep beams
•Coupling beams as deep beams
per Sec. 21.9.7
•Designed per Sec. 10.7
•Shear reinforcement per Sec. 11.7
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Mechanical Ductwork design
Design Goals
•Keep loss under .25” WC/100’
•Keep fpm flow under 2500 in
mains over occupied spaces
•Reduce height and increase width
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Mechanical Ductwork Redesign
First Floor
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Mechanical Ductwork Redesign
•Vertical mains shrunk 8-20”
per side
•Maximum horizontal run that
travels under beams is 20”
•Minimum ceiling height is
8’10”
•Average ceiling height can
be +10’6”
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Some Quick Costs
•Savings on façade and ductwork
•More expense on structure
Cost of New Ductwork
Total Weight x 1.15* x Cost (installed) ($/lb) = Total Cost
42,263.2 x 1.15 x
6.79
= $330,012
Cost of Existing Ductwork
Total Weight x 1.15* x Cost (installed) ($/lb) = Total Cost
53,749.2 x 1.15 x
6.79
= $419,700
Savings From Changes $89,688
*15% added for brackets and supports
Façade Savings
Floor
sf curtain wall sf split face CMU sf metal panel
4th
758
-
-
3rd
758
-
56
2nd
204
604
56
1st
204
604
56
Total
1924
1208
168
$/sf
65.65
62.72
34.04
Savings
$4,309.92
$3,933.80
$1,158.72
Total Savings
$9,402.44
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Project Summary
•Post tensioned beam system provides optimal performance
•Wide shallow beams incorporate desired attributes into floors
•48”x14” for most interior beams and 30”x14” for most exterior
•8” shear walls designed for moment
•Mechanical ductwork redesigned to obtain project goals
•Savings on façade and mechanical ducts, more cost in structure
•All goals reasonably attained
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option
Questions/Comments
AE Senior Thesis 2009|U.S. Pharmacopeia Headquarters|Jeffrey L. Rothermel Jr.|Structural Option