PCI Big Beam Contest

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29 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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PCI Big Beam Contest

Team 1 (XDF)


Junfeng Qian

Shiyu

Wang

Qi Wang

Outline


Introduction






Background


Problem
Statement


Design Goals



Job
Description


Field
Trip


Concrete
Mix


Beam Design


Design Matrix


Final Design


Fabrication



Analysis & Prediction


Beam Test


Test Results


Timeline


Conclusion


Lessons Learned


Recommendations for PCI Big Beam Contest


Acknowledge


Reference



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 kips
-
39kips


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



M
eet 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

Lightweight Concrete

Pros

1.
Easy to achieve high strength
transfer and ultimate.

2.
Low Water Cement ratio assists
with permeability.

3.
Easy to place concrete with
maximum consolidation.

4.
Proven Performance.

5.
High shear values at transfer and
28 days.

1.
Low unit weight

2.
Good to above average 28 day
compression strength for
lightweight.

3.
Low Water Cement ratio assists
with permeability.

4.
Easy to place concrete with
maximum consolidation.

5.
High fire rating.

Cons

1.
High unit weight.

2.
No air entrainment for severe
weather conditions.

3.
Low fire rating.

1.
Low shear values at transfer and
28 days.

2.
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

Live Load



Equiv

Cross Section

f'
c

(ksi)

f'
ci

(ksi)

# of
strands

σ
top

(ksi)

σ
bot

(ksi)

P crack
(kip)

PU (kip)

EI (kip
-
in
2
)



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

Requirement




σ
top
<
7
.
5

f′
c


σ
bot
<0.7 f'
ci

P>20
kips

32 <P<39
(kips)



Design Matrix


Cost (35%), Max Deflection (30%), Weight (35%)



Beam 1

Beam 2

Beam 3

Type

Percentile

Measured
Value

Grade

Measured
Value

Grade

Measured
Value

Grade

Cost ($)

35

125

10

131

9

143

7

EI (kip
-
in2)

30

61766449

9

65442229

8

68335328

7

Weight (lb.)

35

1909.59

10

1900.06

10

1990.31

6

Total (10)

100

9.4

9.35

6.65

Final Design


Cross
-
Section Details


Material cost


Materials

Amount

Unit Cost

Cost

Normal Weight Concrete

0.47 cu yd.

$ 100/cu yd.

$ 47

Prestressing Strand

3*20 ft.

$ 0.30/ft.

$ 18

A615 #5 Rebar

5*20 ft.

$ 0.45/lb.

$ 47

Welded Mesh

25.8 lb.

$ 0.50/lb.

$ 13

A615 #4 Rebar

4*0.7 ft.

$ 0.45/lb.

$1.5

Total Cost

$ 126.5



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


=


𝑝

𝑄
𝐸𝐼

0
𝑑𝑥
+

𝑘
𝑉
𝑝
𝑉
𝑄
𝐺𝐴
𝑑𝑥

0
.


m
Q

=
virtual moment produced by virtual
moment


m
p

=

real
moment


E
=

the modulus of elasticity.


I
=

the moment of inertia.


V
p

=

real shear
force.


V
Q

= 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

Predicted

Actual

Percent Error

Point Load Cracking
(kips)

23.8

23.2

2.52%

Ultimate

capacity
(kips
)

36.35

41.54

14.3%

Deflection at
Midspan

(
in)

1.703

7.42

335.7%

Timeline

10-Sep
12-Sep
15-Sep
18-Sep
23-Sep
28-Sep
1-Oct
5-Oct
10-Oct
15-Oct
20-Oct
25-Oct
30-Oct
1-Nov
5-Nov
10-Nov
15-Nov
20-Nov
25-Nov
30-Nov
1-Dec
5-Dec
10-Dec
15-Dec
20-Dec
25-Dec
30-Dec
14-Jan
25-Jan
28-Jan
1-Feb
4-Feb
8-Feb
11-Feb
12-Feb
15-Feb
18-Feb
22-Feb
25-Feb
1-Mar
4-Mar
8-Mar
11-Mar
22-Mar
25-Mar
27-Mar
28-Mar
29-Mar
1-Apr
5-Apr
8-Apr
9-Apr
30-Apr
9-May
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
Schedule
Conclusion


Pros:


Successful Design


Good Cooperation


Gain Knowledge


Familiar with Research
Process


Cons:


Inaccurate Prediction


Exceed allowable ultimate
load

Lessons Learned


E
nrich
the knowledge
about concrete design and
improve
abilities


G
ets
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.



R
ecommendations 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


Reference


Technical Advisor: Dr.
Tuchscherer


Project Manager:
David
L.
Chapin


Sponsor:
Tpac

Company

Acknowledge


ACI Code 318
-
08


T
he
7th Edition of the PCI Design Handbook

Questions


Thank you!