Compliance Certification .We certify that the entire construction of Sooner or Later was performed in complete compliance with the rules andregulations set by the Regional and National Competitions. The ten participants to be registered at the Regional andNational Competitions are qualified student members and National Student Members of ASCE as specified in therules and regulations of the National Competition. Furthermore, Sooner or Later has been completely built withinthe current academic year of the competition, 2002-2003.

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AnalysisThe primary concern of the structural design of Sooner or Later was to ensure that the hull had adequate

strength and stiffness. The plate elements that form the hull are highly sensitive to weak axis bending and buckling.One way to address this difficulty is through the use ofribs, which shorten the effective length of the elements.However, ribs have the disadvantage of creating abrupt changes in stiffness, which can lead to stress concentrationsand cracking. Instead of using ribs, we chose to use a tumblehome profile to stiffen the hull. This profile increasesthe stability of the elements and increases the gross section modulus of the canoe. This stabilizes the hull andreduces the stresses applied to any given element. The hull thickness was increased from previous years to 5/8" tofurther control out ofplane deflections and buckling.

The team used finite element analysis to determine the stresses on the hull under two-person and four-personloadings. This analysis was done using Ansys. Modern shell elements were used to include the effects ofboth axialand bending forces in the elements. The most severe loading occurs during the coed race when four paddlers are inthe canoe. In the model, each paddler weighed 190 Ibs. This weight was divided into four point loads; 80% wasplaced at the paddlers' knees, and the remaining 20% was placed at their toes. A uniformly distributed pressure overthe wetted surface of the canoe was used to approximate the buoyant force acting on the bottom of the canoe. Thedepth of the wetted surface was determined using statics and the hull geometry ..for mathematical stability of themodel, a single point on the canoe was fixed against translation or rotation in any direction. The exact paddlerlocations were adjusted slightly so that the canoe was in static equilibrium and zero force and moment acted on thefixed point.

Figure I. Finite element model boundary conditions.

One significant difference between a concrete canoe and a typical reinforced concrete structure is that the criticalparameter of the concrete is its tensile strength, instead of its compressive strength. Cracks may be acceptable in atraditional structure, but they are objectionable in a canoe because of the need for the hull to remain water tight.Reinforcement is effective only after cracking initiates. Therefore, the reinforcement in the canoe should not beutilized under service conditions. It is included only as insurance to keep any cracks that do occur from propagatingthrough the entire hull and causing immediate catastrophic failure. The analysis assumed that the concrete andreinforcement would act together as a composite with a single set of material properties. Because concrete is aquasi-brittle material, the material was assumed to remain elastic until failure. The elastic modulus was defined as380 psi, which was estimated using the equation in section 8.5 of ACI 318-02.

The finite element analysis showed a maximum principle stress of203 psi. The principle stress distribution overthe bottom of the hull is shown in Figure 2. The maximum stress occurs on the bottom of the hull under thepaddlers' knees. Using the design philosophy for tension controlled sections in Chapter 22 of ACI 318-02(Structural Plain Concrete), we selected a factor of safety of 1.5. This leads to a required minimum concrete tensilestrength of307 psi.

Figure 2. Finite element analysis results -Principle stress distribution

Cement Mfg. H

p AS

98 156

85 110~ 131 201

172

184 260 2

170 212 3

CementMfJ!;. AG

A x pIb/yd3

binder~

600

700

800

900

1000

1100

1200

IX~

19~ ~I- 90 I 72 I

1167 11671 1481234

,-~Lm

A X

131

135

167

183

576

287 219 261

271

512

1-357 j 272 i1300 1 3581 2611400 14341 240---

Development and TestingAn extensive testing program was undertaken to develop the concrete for Sooner or Later. A new test matrix

was created to systematically study the effects of several variables. A literature review was combined with previousexperience in order to meet the competing demands of finding a suitable mix while controlling the size of the testmatrix. The goal of the mix design was to create an inherently buoyant mix with adequate flexural strength, asdetermined from our finite element analysis. These target values, along with the values achieved with the final mixdesign, are shown in Table 1.

Time allowed only two iterations to find an acceptable mixture.Consequently, the initial matrix had to be very broad to maximize theprobability of bracketing a suitable mix design. The matrix systematicallystudied four variables: cement content, cement manufacturer, latex brand, Table 1. Mix design criteria & resultsand lightweight aggregate type. All batches included the same binder proportioning (70% cement, 20% fly ash, &10% latex solids, by weight) and the same dose of superplasticizer. Water was added to the mixes to achieve aconstant workability. The aggregate in all mixes was 85% light aggregate and 15% graded Ottawa sand, by volume.During batching, quality control was maintained by measuring the unit weight of each mix and comparing it to thetheoretical value. ASTM C138 was adapted for this purpose. We used a smallervolume than specified because thetest batches were very small. Specimens were aircured according to ASTM C192 for 56 days. TheModulus of Rupture (MOR) test, ASTM C78, wasadapted to measure the tensile strength of the trialmixes. Specimen sizes were adjusted to more closelymatch the aspect ratio of the canoe hull elements. Thetest matrix and quantitative results are shown in Table2, and qualitative results of each investigation areshown in Table 3.

The 1 st flight of 50 test mixes located a range with

the required tensile strength and an acceptable unitweight. The ~d flight focused on this area of thematrix to optimize the mix design and to ensureduplicability. After two sets ofbatching, the mix A X & p are different latex admixture brandsproportions for the core of the canoe were selected. S '. d. t ty c I .

ht t..10 Ica es s roloam . ggrega e The outsIde color coats were made by remov1Og the.St cfr th .. d dd.. 1 . t red 1OdIcates final mIx 1OdIcates second flIght area

yroloam om IS mIx an a 1Og m1Oera pIgmen ...A challenge remained to address to relatively slow Table 2. Testing Results -MOR (pSI)

reactivity of the fly ash. Two hypotheses were considered: the fly ash particles do not have enough reaction sitesbecause they are too large or too smooth, or the particles have some sort of a dissolution barrier over their surface.An extensive literature review was uninformative, and consultation with industry mentors provided only anecdotalinformation. One way to address either of the proposed causes is by grinding the fly ash. A study was done toinvestigate this treatment. This work is detailed in a paper written by members of our team, "Mechanical Activationof Fly Ash," which has been accepted for peer review and possible publication in the ASCE Journal of Materials inCivil Engineering. The study found that grinding the fly ash significantly accelerates the strength gain of theconcrete and increases the ultimate strength of the mix. Fineness measurement and scanning electron microscopyindicate that there is a dissolution barrier on the surface of the particles.

Because of the strength of the mix used in Sooner or Later, only minimal reinforcement is used. A single layerof fiberglass mesh centered in the hull section is used to reinforce the entire canoe and prevent crack propagation.The mesh is supplemented by a 5/32"Kevlar cord around the gunwales.l'he Kevlar has a high modulus ofelasticity (26,500 ksi), which helps tohold any gunwale cracks closed.Composite action testing was doneusing flexural testing of plates. Allof the specimens failed by crushingof the concrete and no delaminationwas observed.

Table 3. Qualitative test results

Tan!et Date I Actual DateI Critical Path Event

I Manallement Cherette Aug.27

Aug.30

Sept.29

Ckt. 31

~.15

Jan.20

March 1

Auril15

~Aug. 30

~Nov.4

Ih:.26

Feb. 10

March 5

AI::Ii1 20

Il'reshman Recruitinl!

Begin Mold Construction

I Finish Male Plllir

Cast Canoe

Finish Canoe

I Man:h 10 I March 10 ~

ADril20 Arril 21Prepare Presentation I

Regional Competition

Revise Design Paper

Revise Presentation

i National Competition

ArxiI24-26May 13 Mav 13

J\n1e 15

Jtme 2(}.22

Project Management and ConstructionThe University of Oklahoma School of Civil Engineering and Environmental Science is a relatively small

department. For our student body to create a top-caliber canoe, people must be involved in multiple areas of thedesign and construction process. A single-tier group was created from individuals who had experience in thedifferent aspects of the canoe effort and who were willing to take on the responsibility of coordinating the design,construction, and paddling efforts. A strong focus was placed on building continuity between competition years andincreasing the size of O\lf labor force. Two groups were pursued in this effort: freshmen and sophomores, who arenot yet in Civil Engineering courses and tend to be "invisible" to upperclassmen; and canoe alumni, who can serveas an extensive knowledge base. In the first week of class, a brief presentation was m~de in all freshmen andsophomore engineering classes. The same week, all canoe alumni were invited to a management cherette. Thiswas the first time the OU Concrete Canoe Team made this kind of outreach effort. Another first is the use of aweekly newsletter to keep these links alive throughout the year. Every Monday morning, the newsletter is emailedto anyone who has expressed an interest in the canoe. The distribution list includes students, alumni, facultymembers, administrators, and practitioners. The newsletter informs everyone of the work that was done the weekbefore, work planned for the immediate future, and long term goals and deadlines. It is created by the leadershipgroup and expresses a coherent management philosophy. The organizational scheme incom~g all of theinvolved groups is depicted on page 5.

The projected and actual dates of events on the critical path areshown in Table 4. Target dates for each step were set as early asthought feasible in anticipation of events beyond our control. The Ioriginal critical path target dates were selected based on experienceand engineering judgment. From our understanding of fly ash in I

concrete, we knew that 56 days of curing for the canoe would bedesirable. This established the day of casting the canoe. In turn,this dictated the deadlines for completing the mold and mix design.This type of logic was used to determine all of the target dates.

Variances from our planned dates did occur. For example, IFinish Design Paverwe had CNC plasma cut steel templates of the canoe cross sectionmade. Unfortunately, the steel fabricator had fired the only personwho knew how to run the interface between AutoCad and the CNCmachine. They did not inform us of their problems until after thescheduled delivery date. A student went to their shop and figuredout how to make the interface work in a few hours. Mold makingcommenced within hours of receiving the finished plates. Table4. Critical Path Events

Injection molding was considered in order to get a perfect finish on both surfaces of the canoe without sanding.The plan was to create a mockup of the canoe and have male and female fiberglass molds created around it. Amockup consisting of mortar saturated foam enclosed in plaster and mortar was made, but this procedure did notwork as well as hoped. After two weeks of work, the construction team and an alumni mentor made the qualitycontrol decision that it was best to start over instead of trying to salvage the mockup. The entire output of Christmasbreak was thrown in the dumpster. A forensic investigation determined that some elements of the new system wereimprovements over previous methods and should be retained. The injection molding idea was abandoned because ofa lack of time to develop the system.

A unique shotcrete method of applying concrete inside a female mold was pursued. This method has many ofthe advantages of injection molding, such as a finished outside surface that does not require sanding and better depthcontrol than applying fresh concrete by hand. A male plug was created over the steel plates, and a fiberglasscompany made a four-piece female mold around this plug. While the mold was being created, the details of theshotcrete system were worked out. These included making test pieces to ensure that the concrete could be applied-evenly and that the material would not slump down a vertical surface and to ensure that a paste wax release agentwould work. Unlike injection molding, shotcrete does not require significant equipment: a borrowed drywalltexture gun was used to spray the mix into the mold in thin, uniform lifts. Several layers of gray concrete withstyrofoam beads were sandwiched between very thin layers of colored concrete without styrofoam beads. Theconcrete was patted to consolidate it and ensure that it bonded through the mesh reinforcement. A large caliper wasmade to measure the hull thickness during construction. After the canoe cured for a week, the inside surface wassanded to remove roughness, and the inside layer was applied using a paint roller. Despite several delays, Sooner orLater was cast only 4 days after the target casting day. In summary , our project management and uniqueconstruction methods.proved to be very successful.

Schedule #

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""Latex dosage Design Hull

testing using drag

.Ispreadsheet-Discrete Error found in

Fib~r-mix / spreadSheettesting

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('new" best

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/ investigated.

3-D CAD drawings/ of hull made

CNC Plasma cut

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~Old construction

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/ Control -IlJjectionmold abandoned

~ale Mold

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TABLE 11.C.1-5uMMARY OF MIXTURE PROPORTIONSMIXTURE DESIGNATION: Sooner or Later -Crimson Slip Coat

Component Quantity (whether base or batch) Units

%

~kg/m

""kgij;i'J

""kgij;i'J

""kgij;i'J

~

air content by volume of concrete AIR

c:cement (plain), ASTM Type 788.3225.3112.6

other cementitious material 1 *Description: Class C FlvAsh mi:

m2:

m3:

m4:

other cementitious material 2 *~iption: Xvcrvlic (solids)

other cementitious material 3 *

other cementitious material 4 *Description:

Description:

cm:

c/cm:

mass of all cementitious materials 1126.2 (1)cement to cementitious materials ratio

Base Quantity(SSD aggregates)

(kg/m3)

Aggregates Agg.Volume

{m3)

Batch Quantity(At stock

moisture content)kg/m3

~

~

~

4.

G raded Ottawa Sand

ASTM

C127

BSG (SSD)

(unitless)

2.65

2.7

0.2920.016

773.943.4

I r;rT .

~

W stk,2:

Wstk,3:

W stk,4:

Mica FlakesI ~SSD.l~ 7739

I WSSD.2: -

WSSD,3:

WSSD,4:

43.4

CombinedWSSD,agg:817.3 2.65 0.308 Wstk,agg: 317.3

(2)

water t I w:

~

207.2

3770

IX2: 265~OOO

kg/mi

ml/m.:

m1/m.:

m1/m:.

ml/m.:

kg/m

kg/m

kg/m

kg/m

kg/m

kg/m

I Wbatch:

Advaflowvol. of admixture # 1vol. of admixture #2 Xvcrvlicvol. of admixture #3 Red Piament ix-;:

vol. of admixture #4

Advaflowwater from admixture # 1

water from admixture #2: 0.0

: 168.9

: 0.0water from admixture #3 Red Piqmentwater from admixture #4

total of free (surplus) water from all0.0

207.2--total water

./

~

w:~w:

207.2(3)

concr~~ensity § 21 50.7 kg/mwater to cement ratio 0.26

0.18w/c:

w/cm:water to cementitious material

* If the binder comes from the manufacturer mixed with water, include only the weight of the binder here.t 1 si column is used for the desired total water, the 2nd column is for water added directly to batch

~ w in this column = wbatch + w c.Jmx,1 + w <ximx.2 + Wadmx,3 + w <ximx,4. This value should match the value for w in the previous column.

§ The sum of items in rows (I), (2), and (3)

8

TABLE 11.C.1-SUMMARY OF MIXTURE PROPORTIONS

MIXTURE DESIGNATION: Sooner or Later -Core

ComDonent Quantity (whether base or batch) ~ Units

air contentkvolume of concreteAIR ~ %

cement (plain), ASTM Type: 291.1 c:

other cementitious materiall* Description: Class C FI Ash mi: ki

k,Description: Class C Flv Ash ml: !/m'ml:

other cementitious material 2 *Description: X C

other cementitious material 3 * Description:

other cementitious material 4 * Description:

mass of all cementitious materials

rim'm2:qj.o &

-I: I k~ Im3 11

,

!1

m"-

m4:I I Kf, m:

415.9 I k:cm: (Icement to cementitious materials ratio c/cm:

Base Quantity

(SSD aggregates)(kg/m3)

Agg.Volume

{m3)

Batch Quantity(At stock

moisture content)

kg/m3-

(2)

(3)

842.5 ke/~water to cement ratio 0.26w/c

w/cm: QI water to cementitious material

* If the binder comes from the manufacturer mixed with water, include only the weight of the binder here.t 1 sI column is used for the desired total water, the 2nd column is for water added directly to batch

~ w in this column = wbatch + WOOmx,l + WOOmx.2 + WOOmx,3 + WOOmx,4. This value should match the value for w in the previous column.

§ The sum of items in rows (I), (2), and (3)

9

18

TABLE 11.C.1-SUMMARY OF MIXTURE PROPORTIONSMIXTURE DESIGNATION: Sooner or Later -Cream Slip Coat

Component -Quantity (whether base or batch) Units

%air conte~-volume of concrete AIR

c:

5.0ASTM Type: I (White) 799.6cement (plain),

other cementitious material 1 *Description: Class C FlyAsh 228.5

114.2

~

kg/m~

~

~

~

kg/m~

mi:

m2:

m3:

m4:

other cementitious material 2 *D~tion: Xvcrvlic (solids)

other cementitious material 3 *

other cementitious material 4 *Description:

Description:

cm:

c/cm:

mass of all cementitious materials 1142.30.70

(Icement to cementitious materials ratiol

Base Quantity(SSD aggregates)

(kg/m3)

Aggregates Agg.Volume

{m3)

Batch Quantity(At stock

moisture content)kg/m3

Graded Ottawa Sand WSSD,l: 787.1

ASTM

C127

BSG (SSD)

(unitless)

2.65 0.297 ~ Stk; 1 :

Wstk;2:

Wstk.3:

Wstk.4:

787.1E SSD.2: WSSD,3:

~:

I.

2.

3.

4.

Combined 0.2972.65(2)

water t I Wbatch

Advaflowvol. of admixture # 1I vol. of admixture #2 Xvcrvlicvol. of admixture #3 X3:

X4:vol. of admixture #4

Advaflowwater from admixture # 1 0.0

171.3water from admixture #2 XycrylicI water from admixture #3

water from admixture #4

total of free (surplus) water from all0.0

210.2

~

w:ttotal water

-"

kg/m.:ml/m'

ml/m'ml/m.:ml/m'

kg/mkg/mkg/mkg/mkg/m

kg/m-w:210.2

(3)concrete density § 2139.6 kg/m.1water to cement ratio w/c:

w/cm:

0.260.18water to cementitious material

* If the binder comes from the manufacturer mixed with water, include only the weight of the binder here.

t Ist column is used for the desired total water, the 2nd column is for water added directly to batch~ w in this column = wbatch + w £Olmx,l + w 00mx,2 + Wadmx,3 + Wadmx,4. This value should match the value for w in the previous column.

§ The sum of items in rows (I), (2), and (3)

10