PCI Big Beam Contest
Team 1 (XDF)
Junfeng Qian
Shiyu Wang
Qi Wang
Outline
• Introduction
• Analysis & Prediction
• Background
• Beam Test
• Problem Statement
• Design Goals
• Job Description
• Field Trip
• Test Results
• Timeline
• Conclusion
• Concrete Mix
• Lessons Learned
• Beam Design
• Recommendations for PCI Big Beam Contest
• Design Matrix
• Acknowledge
• Final Design
• Reference
• Fabrication
Introduction
• PCI Big Beam Contest for 2012-2013 academic year
• Sponsored by Tpac Company
• A challenge project
Background
• “Pre-stressed concrete is a form of reinforced concrete that
builds in compressive stresses during construction to
oppose those found when in use.”
Problem Statement
• Prestressed Concrete Beam—20 ft. long and tested as a
18 ft. span
• Beam shall carry a total live load between 32 kips39kips
• Beam shall not crack under a total applied load of 20
kips
Design Goals
– Design accuracy
– Low cost
– Low weight
– Largest measured deflection at maximum total applied load
– Meet the requirement of ACI-318-08 and PCI Design Handbook,
7th Edition
Job Description
• Qi Wang– Project Manager
• Shiyu Wang– Coordinator
• Junfeng Qian– Project Engineer
Field Trip
Concrete Mix
Self-Consolidating Concrete
1.
2.
Pros
3.
Lightweight Concrete
Easy to achieve high strength
1.
Low unit weight
transfer and ultimate.
2.
Good to above average 28 day
Low Water Cement ratio assists
compression strength for
with permeability.
lightweight.
Easy to place concrete with
3.
with permeability.
maximum consolidation.
4.
Proven Performance.
5.
High shear values at transfer and
28 days.
Cons
1.
High unit weight.
2.
No air entrainment for severe
4.
Low fire rating.
Easy to place concrete with
maximum consolidation.
5.
High fire rating.
1.
Low shear values at transfer and
28 days.
2.
weather conditions.
3.
Low Water Cement ratio assists
Specific gravity of lightweight
material is unstable.
3.
Low transfer strengths if proper
curing procedures are not used.
Beam Design
• Cross-Section—”I” beam, “T” beam, “Box” beam
• Microsoft Excel software
• 8 design options
• Adjustments for qualified design options based on
weight and cost
Beam Design Cont.
Release Stress
Cross Section
Requirement
f'c
(ksi)
f'ci
(ksi)
Live Load
∆ Equiv
# of
strands
σtop (ksi)
σ bot (ksi)
P crack
(kip)
PU (kip)
EI (kip-in2)
8.5 4.5
3
0.365
-2.198
23.8
33.6
61766449
8.5 4.5
4
0.517
-3.037
34.4
36.8
65442229
8.5 4.5
4
0.356
-2.157
29.8
40.78
68335328
P>20
kips
32 <P<39
(kips)
σtop<7.5 f′c σ bot<0.7 f'ci
Design Matrix
• Cost (35%), Max Deflection (30%), Weight (35%)
Beam 1
Type
Percentile
Cost ($)
35
125
EI (kip-in2)
30
Weight (lb.)
35
Total (10)
100
Beam 2
Beam 3
Measured
Value
Grade
Measured
Value
Grade
10
131
9
143
7
61766449
9
65442229
8
68335328
7
1909.59
10
1900.06
10
1990.31
6
Measured Grade
Value
9.4
9.35
6.65
Final Design
• Cross-Section Details
• Material cost
Materials
Normal Weight Concrete
Prestressing Strand
A615 #5 Rebar
Welded Mesh
A615 #4 Rebar
Total Cost
Amount
0.47 cu yd.
3*20 ft.
5*20 ft.
25.8 lb.
4*0.7 ft.
$ 126.5
Unit Cost
$ 100/cu yd.
$ 0.30/ft.
$ 0.45/lb.
$ 0.50/lb.
$ 0.45/lb.
Cost
$ 47
$ 18
$ 47
$ 13
$1.5
Fabrication
Analysis & Prediction
• Prediction: Cracking load, Maximum Deflection, Ultimate
Load
• Cracking Load & Ultimate Load: Excel Spreadsheet
• Deflection: Response 2000 Computer Software & Excel
Deflection Prediction
• Virtual work Method
∆=
𝑙 𝑚𝑝 𝑚𝑄
𝑑𝑥
0 𝐸𝐼
+
𝑙 𝑉𝑝 𝑉𝑄
𝑘
𝑑𝑥.
0
𝐺𝐴
• mQ = virtual moment produced by virtual moment
• mp = real moment
• E = the modulus of elasticity.
• I = the moment of inertia.
• Vp = real shear force.
• VQ = shear force produced by virtual load.
Beam Test
• Visual Indication of
Deflection
• String Potentiometer
• Video
Test Results
• The point of load cracking is close to the
prediction
• The maximum point load and deflection
at ultimate capacity have a difference to
the prediction
Data Description
Point Load Cracking
(kips)
Ultimate capacity(kips)
Deflection at Midspan (in)
Predicted
23.8
Actual
23.2
Percent Error
2.52%
36.35
1.703
41.54
7.42
14.3%
335.7%
1 Research
1.1 Read Contest Poster
1.2 Gather design criteria
1.3 Prepare a checklist of tasks
2 Literature Search
2.1 Read ACI code and PCI handbook manual
3 Engineering Study
3.3 Material selection
3.4 Cross section selection
4 Preliminary Design and Analysis
4.1 Design spreadsheet
4.2 Design matrix
5 Final Design and Analysis
5.1 Design Verification
5.2 Auto CAD
6 Service during Fabrication
7 Install test instrumentation
8 Beam Test
8.1 Record video and results
9 Submit the design report
9-May
30-Apr
9-Apr
8-Apr
5-Apr
1-Apr
29-Mar
28-Mar
27-Mar
25-Mar
22-Mar
11-Mar
8-Mar
4-Mar
1-Mar
25-Feb
22-Feb
18-Feb
15-Feb
12-Feb
11-Feb
8-Feb
4-Feb
1-Feb
28-Jan
25-Jan
14-Jan
30-Dec
25-Dec
20-Dec
15-Dec
10-Dec
5-Dec
1-Dec
30-Nov
25-Nov
20-Nov
15-Nov
10-Nov
5-Nov
1-Nov
30-Oct
25-Oct
20-Oct
15-Oct
10-Oct
5-Oct
1-Oct
28-Sep
23-Sep
18-Sep
15-Sep
12-Sep
Schedule
10-Sep
Timeline
Conclusion
• Pros:
• Cons:
– Successful Design
– Inaccurate Prediction
– Good Cooperation
– Exceed allowable ultimate
load
– Gain Knowledge
– Familiar with Research
Process
Lessons Learned
• Enrich the knowledge about concrete design and improve
abilities
• Gets the experience on how to work in a group to study the
knowledge of prestressed concrete, computer design, and
conduct the beam test
• Learn how to operate a concrete beam test from this project
• If the team has another opportunity to participate the team
will be carefully notice the operation of Response 2000
program and ultimate load prediction.
Recommendations for PCI Big Beam
Contest
• A discussion of future use of the beam should be required in
the contest rules
• People who have different academic background could
participate in this contest
• The contest committee should assign a technical faculty to
each team
Acknowledge
• Technical Advisor: Dr. Tuchscherer
• Project Manager: David L. Chapin
• Sponsor: Tpac Company
Reference
• ACI Code 318-08
• The 7th Edition of the PCI Design Handbook
Questions
Thank you!